HYDROGELS FOR DRUG DELIVERY

[0001] The domain of the invention is therapy, in particular drug delivery. More particularly the invention is about an implant comprising a hydrogel which may incorporate active principles, such as peptides, hormones, proteins or small molecules. [0002] The aim is to prevent, treat or cure disease by administration of a suitable dose of an active pharmaceutical ingredient (API). The invention is also about a crosslinked polymer, its precursors, a process for obtaining the crosslinked polymer and a process for obtaining a hydrogel, in particular a hydrogel containing API.

[0003] By "API" is meant Active Pharmaceutical Ingredient. This is the main ingredient of the medicine that causes the desired effect of the medicine.

[0004] Hydrogels can be used as controlled drug or active pharmaceutical ingredient release systems.

[0005] Hydrogels comprise or consist of polymers that are crosslinked in a 3D network. They can either be natural or synthetic, homopolymers or copolymers. They have the ability to absorb and retain large amounts of water. This is known as the swelling of hydrogels.

[0006] In order to have a system which may be an implant able to deliver active principle, many features have to be obtained.

[0007] Among these features may be cited:

Either a low degradability, in particular a low biodegradability, or no biodegradability, or a good in vivo stability, in order for the implant API to be retrievable, or, on the contrary a biodegradability allowing the disappearance of the system, in particular once active principle(s) is(are) completely or almost completely delivered, in order to disappear from the body,

- a good mitigation of the foreign body response, or a good biocompatibility, in particular a low cytotoxicity and a good local tolerance.

[0008] In order to be used as controlled release systems for API, hydrogels must have particular characteristics so as to exhibit all or part of the desired properties such as disclosed above as well as good mechanical and rheological properties.

[0009] Among the rheological and mechanical properties that are of high interest for the hydrogel may be cited:

- a good homogeneity, which can be linked to a good transparency or translucency,

- appropriate resistance and flexibility toward stress and strain mechanics, in particular when being handled and implanted, - a defined mesh size to control the release rate of the API,

- according to the aimed controlled release, the stability in-vivo may be tuned differently, in some cases, a good stability in vivo, i.e., resistance to hydrolytic, enzymatic, or oxidative degradation, is sought, and in other cases a good biodegradability is sought.

[00010] Another very important problem to be solved for delayed release of APIs systems is the burst effect. The burst effect is characterized by a significant amount of dose being observed just after injection.

[00011] Among parameters which can give indications on the rheological and mechanical desired properties may be cited: tan 6 (called loss tangent) which gives indication on mechanical properties,

G', which gives indication on the elastic modulus (stiffness), and on the mesh size, compression and/or traction deformation at break, which gives indication on the elasticity and resistance of the hydrogel, swellability, which gives indications on the water content, dimensions and mechanical properties.

[00012] Among the problems to be solved is obtaining a hydrogel with properties allowing: a manipulation for implanting the hydrogel without breaking it, and/or the gel to remain in place after implantation, for example allowing the hydrogel not to get folded after implantation and/or to be immobilized relative to the tissue on which it is implanted, or

- An implantation of the gel via a minimally invasive procedure, in particular a subcutaneous injection.

[00013] Another problem to be dealt with relates to the sedimentation of API during the crosslinking leading to gelation, in particular in the case of particulate API.

[00014] The applicant surprisingly found that the presence of hyaluronic acid or sodium or potassium hyaluronate salts in the crosslinking mixture helps improving a homogeneous repartition of API, in particular in the case of particulate API, in the hydrogel. In other words this decreases the effect of sedimentation of API or paticulate API.

[00015] In an embodiment the of hyaluronic acid or sodium or potassium hyaluronate salts has a weight average molecular (Mw) ranging from 100 to 5 000 kg/mol. [00016] In an embodiment the of hyaluronic acid or sodium or potassium hyaluronate salts has Mw ranging from 250 to 4 000 kg/mol.

[00017] In an embodiment the of hyaluronic acid or sodium or potassium hyaluronate salts has Mw ranging from 500 to 3 750 kg/mol.

[00018] In an embodiment the of hyaluronic acid or sodium or potassium hyaluronate salts has a Mw ranging from 750 to 3 500 kg/mol.

[00019] In an embodiment the of hyaluronic acid or sodium or potassium hyaluronate salts has a Mw ranging from 1 000 to 3 250 kg/mol.

[00020] In an embodiment the concentration of hyaluronic acid or sodium or potassium hyaluronate salts in the hydrogel ranges from 0.5 to 30 mg/ml.

[00021] In an embodiment the concentration of hyaluronic acid or sodium or potassium hyaluronate salts in the hydrogel ranges from 0.5 to 20 mg/ml.

[00022] In an embodiment the concentration of hyaluronic acid or sodium or potassium hyaluronate salts in the hydrogel ranges from 0.5 to 10 mg/ml.

[00023] In an embodiment the concentration of hyaluronic acid or sodium or potassium hyaluronate salts in the hydrogel ranges from 0.5 to 5 mg/ml.

[00024] In an embodiment the concentration of hyaluronic acid or sodium or potassium hyaluronate salts in the hydrogel ranges from 0.75 to 2.5 mg/ml.

[00025] In an embodiment the concentration of hyaluronic acid or sodium or potassium hyaluronate salts in the hydrogel ranges from 1.0 to 1.5 mg/ml.

[00026] In an embodiment with a hyaluronic acid or sodium or potassium hyaluronate salts of Mw ranging from 1 000 to 2000 kg/mol, in particular of around 1 500 kg/mol, its concentration is ranging from 0.5 to 2 mg/ml.

[00027] In an embodiment with a hyaluronic acid or sodium or potassium hyaluronate salts of 1 000 to 2 000 kg/mol, in particular around 1 500 kg/mol, its concentration is ranging from 1.0 to 1.5 mg/ml.

[00028] In an embodiment with a hyaluronic acid or sodium or potassium hyaluronate salts of Mw ranging from 2 000 to 4 000 kg/mol, in particular of around 3 000 kg/mol, its concentration is ranging from 0.5 to 1.5 mg/ml.

[00029] In an embodiment with a hyaluronic or sodium or potassium hyaluronate salts acid of Mw ranging from 2 000 to 4000 kg/mol, in particular of around 3 000 kg/mol, its concentration is ranging from 0.7 to 1.2 mg/ml.

[00030] The suitability of the hydrogel depends on its bulk structure, thus important parameters used to characterize the network structure of the hydrogel according to the invention are the polymer volume fraction in the swollen state, the molecular weight of the polymer chain between two neighboring cross-linking points, and the corresponding mesh size. [00031] The problem is solved by the provision of a new cross-linked dextran polymer, bearing anionic groups, wherein at least two saccharidic units of dextran belonging to two different polymer chains are covalently crosslinked by at least one central linker radical L(-)i, this at least radical being a at least divalent linear, branched or cyclic alkyl radical comprising at least a polyethylene glycol chain.

[00032] The problem is solved by the provision of a new cross-linked dextran polymer, bearing anionic groups, wherein at least two saccharidic units of dextran belonging to two different polymer chains are covalently crosslinked by at least one central linker radical L(-)i, this at least radical being a at least divalent linear, branched or cyclic alkyl radical comprising at least a poly(oxazoline) (POx)chain.

[00033] The problem is solved by the provision of a new cross-linked dextran polymer, bearing anionic groups, wherein at least two saccharidic units of dextran belonging to two different polymer chains are covalently crosslinked by at least one central linker radical L(-)i, this at least radical being a at least divalent linear, branched or cyclic alkyl radical comprising at least a polyethylene glycol chain, or this at least radical being a at least divalent linear, branched or cyclic alkyl radical comprising at least a poly(oxazoline) (POx)chain.

[00034] The properties of this family of hydrogels are tunable and tailorable to the applications by choosing and adapting the cross-linking reaction conditions, the substitution degree and molecular weight of the dextrans and cross-linkers.

[00035] The cross-linked dextran polymer according to the invention is a dextran polymer Dx bearing anionic groups wherein the at least divalent radical L(-)i is covalently bound to the dextran polymer backbone with i -W- radicals, wherein, a) L(-)i is a linear or branched polyether, or L(-)i is a linear or branched poly(oxazoline), b) i is the valence of L and the number of -W- radicals bound to the dextran polymer and is an integer comprised from 2 to 8 (2 < i < 8), c) -W- is a radical comprising at least a radical alkyl linear or branched and optionally comprising heteroatoms such as oxygen, nitrogen or sulfur, aromatic cycles, polyether or poly(oxazoline) derivatives and that does not comprise two or more alpha aminoacid residues in particular linked by peptidic bond(s). [00036] The cross-linked dextran polymer according to the invention is a dextran polymer Dx bearing anionic groups wherein the at least divalent radical L(-)i is covalently bound to the dextran polymer backbone with i-W-radicals, wherein, a) L(-)i is a linear or branched polyether, b) i is the valence of L and the number of-W-radicals bound to the dextran polymer and is an integer comprised from 2 to 8 (2 < i < 8), c) -W- is a radical comprising at least a radical alkyl linear or branched and optionally comprising heteroatoms such as oxygen, nitrogen or sulfur, aromatic cycles, polyether derivatives and that does not comprise two or more alpha aminoacid residues in particular linked by peptidic bond(s).

[00037] The cross-linked dextran polymer according to the invention is a dextran polymer Dx- bearing anionic groups wherein the at least divalent radical L is covalently bound to the dextran polymer backbone with i W radicals, wherein, a) L is a linear or branched poly(oxazoline), b) i is the valence of L and the number of -W- radicals bound to the dextran polymer and is an integer comprised from 2 to 8 (2 < i < 8), c) -W- is a radical comprising at least a radical alkyl linear or branched and optionally comprising heteroatoms such as oxygen, nitrogen or sulfur, aromatic cycles, polyether derivatives and that does not comprise two or more alpha aminoacid residues in particular linked by peptidic bond(s).

[00038] In an embodiment the implant is obtained via molding.

[00039] In an embodiment, the implant obtained by molding exhibits a low degradability, in particular a low biodegradability, or no biodegradability, or a good in- vivo stability. This may allow to obtain an implant which is retrievable, and thus which may be easily extracted.

[00040] In another embodiment the implant is obtained by injection of precursors of the hydrogel with an API.

[00041] In an embodiment, the implant obtained by injection of precursors of the hydrogel with an API exhibits a biodegradability allowing the disappearance of the system, in particular once active principle(s) is(are) completely or almost completely delivered, in order to disappear from the body.

[00042] In an embodiment, the invention concerns an injection device comprising the precursors of the hydrogel and at least an API.

[00043] In an embodiment, the precursors are in the same compartment. [00044] In an embodiment, the precursors are in different compartments and are mixed just before injection. By "just before injection" is meant at most 5 minutes before the end of injection, in particular at most 3 minutes before the end of injection, more particularly at most 1 minutes before the end of injection, even more particularly at most 30 seconds before the end of injection.

[00045] When referring to an API, whether specified as a particular compound or a compound class the term used is intended to encompass not only the specified molecular entity or entities but also pharmaceutically acceptable, pharmacologically active analogs and derivatives thereof, including, but not limited to, salts, esters, prodrugs, conjugates, active metabolites, crystalline forms, enantiomers, stereoisomers, and other such derivatives, analogs, and related compounds.

[00046] In an embodiment the API is chosen among the progestogens. Non limiting examples of progestogens include desogestrel, dienogest, drospirenone, ethisterone, etonogestrel, gestodene, levonorgestrel, medroxyprogesterone, megestrol, norethindrone, norgestimate, and esters of any of the foregoing, when the compound allows for esterification (e.g., medroxyprogesterone acetate, megestrol acetate, norethindrone acetate, etc.).

[00047] In an embodiment the API is chosen among the cancer drugs. Non-limiting examples of cancer drugs include coxorubicin, paclitaxel, camptothecin, docetaxel, pemetrexed, curcumin, gemcitabine, dabrafenib, dexamethasone, gefitinib, lenvatinib, methotrexate, thalidomide, vinblastine, vincristine, cyclophosphamide, ifosfamide, glyciphosphoramide, nimustine, carmustine, comustine, 5-fluorouracil, doxifluridine, mercaptopurine, cisplatin, and combinations thereof.

[00048] In an embodiment the API is chosen among corticosteroids. Non-limiting examples of the corticosteroids include cortisone, prednisone, prednisolone, methylprednisolone, dexamethasone, betamethasone, hydrocortisone, and combinations thereof.

[00049] In an embodiment the API is chosen among hormones. Non- limiting examples hormones include alclometasone, prednisone, dexamethasone, triamcinolone, cortisone, fludrocortisone, dihydrotachysterol, oxandrolone, oxabolone, testosterone, nandrolone, diethylstilbestrol, ethinyl estradiol, norethisterone, medroxyprogesterone acetate, hydro xyprogesterone caproate, estrogen, estradiol, estriol, estrone, cortisol, 11 -deoxy cortisol, aldosterone, corticosterone, 11-deoxycorti-costerone, aldosterone, progestin, pregnenolone, progesterone, 17a-hydroxy progesterone, 17a-hydroxy pregnenolone, dehydroepiandrosterone, androstenedoil, androstenedione, dihydrotestosterone, melatonin, thyroxine, and combinations thereof.

[00050] In an embodiment the API is chosen among drugs for pain relief. Nonlimiting examples of drugs for pain relief include NSAIDS, opioids or local anesthetics.

[00051] Non-limiting examples of NSAIDS include Indomethacin, Sulindac,

Etodolac, Tolmetin, Ketorolac, Oxaprozin, Fenoprofen, Flurbiprofen, Ibuprofen, Ketoprofen, Naproxen, Nambumetone, Meclofenamate, Diclofenac, Piroxicam, Meloxicam, Celecoxib, Rofecoxib, Valdecoxib, Aspirin, and combinations thereof.

[00052] Non-limiting examples of opioids include Fentanyl, Alfentanil, Sufentanil, Remifentanil, Methadone, and combinations thereof.

[00053] Non-limiting examples of local anesthetics include Dibucaine, Bupivacaine, Lidocaine, Procaine, Mepivacaine, Rapivacaine, and combinations thereof.

[00054] In an embodiment the API is chosen among anti-VIH drugs. Non-limiting examples of anti-VIH drugs include islatravir, cabotegravir, rilpivirine, dapivirine, tenofovir alafenamide, lenacapavir, elsulfavirine and combinations thereof.

[00055] In an embodiment the API is chosen among anti-malaria drugs. Nonlimiting examples of anti-malaria drugs are Atovaquone, proguanil, ivermectin and combinations thereof.

In an embodiment the API is chosen among anti-tuberculosis drugs and anti HPV (Human Papillomavirus).

[00056] In an embodiment, the API is chosen from proteins, in particular among monoclonal antibodies, also called mAb.

[00057] In particular the protein has a molecular weight of more than or equal to 50 000 g/mol.

[00058] In particular the protein has a molecular weight of more than or equal to 60 000 g/mol.

[00059] In particular the protein has a molecular weight of more than or equal to 70 000 g/mol.

[00060] In particular the protein has a molecular weight of more than or equal to

80 000 g/mol.

[00061] In an embodiment the API is an antibody fragment.

[00062] In an embodiment, the API is chosen from peptides.

[00063] In an embodiment the peptide is a GLP-1 receptor agonist. [00064] In an embodiment the GLP-1 receptor agonist is Semaglutide.

[00065] In an embodiment the peptide is a growth factor, also called GF.

[00066] In an embodiment the mixture of hydrogel precursors and API is administered by injection in a tumor or close to the tumor, or by intramuscular, subcutaneous, intraarticular, intraocular, or intraperitoneal way.

[00067] In an embodiment the implant is placed close to the target of the API. By "close to the target of the API" is meant the distance between the closest part of the implant to the target is less than 5 cm, in particular less than 2.5 cm, more particularly less than 1cm, even more particularly less than 5mm. In an embodiment the implant is in part or totally in the target of the API.

[00068] In an embodiment the implant allows a long-acting release, in particular more than a week, more particularly more than a month, still more particularly more than 6 months, or even more than a year.

[00069] In an embodiment the implant allows a controlled release, for example a release close to the target of the API and/or a controlled rate of release of the API.

[00070] In an embodiment, the API is incorporated in particulate form.

[00071] In an embodiment, the particles have a diameter D50 ranging from 0.5 to

20 pm, in particular from 1 to 15 pm and more particularly from 1.5 to 10 pm, and even more particularly from 1.5 to 5 pm.

[00072] In an embodiment, the particles have a Ferret Diameter ranging from 0.5 to 20 pm, in particular from 1 to 15 pm and more particularly from 1.5 to 10 pm, and even more particularly from 1.5 to 5 pm.

[00073] In an embodiment the API particles are larger than the mesh size of the hydrogel.

[00074] In an embodiment, the API is hydrophobic or hydrophobized in order to be in a particulate form in suspension into the hydrogel of the invention.

[00075] The hydrophobization of hydrophilic API could be done by encapsulation methods, controlled precipitation with a hydrophobic excipient, emulsification and other classical methods used in galenic.

[00076] In an embodiment the API is incorporated in a system or forms a complex resulting in a decrease of diffusion of the API in the gel. [00077] In an embodiment, the API is incorporated in a system or forms a complex having a water solubility lower than the water solubility of the API alone.

[00078] In an embodiment, the API is incorporated in a system or forms a complex allowing a controlled release, in particular a delayed release of the API compared to the one of the API alone.

[00079] In an embodiment-W-comprises at most 60 carbon atoms.

[00080] In an embodiment-W-comprises at most 60 carbon atoms without counting any -CH2-CH2O- radicals.

[00081] In an embodiment-W-comprises at most 50 carbon atoms.

[00082] In an embodiment-W-comprises at most 50 carbon atoms without counting any -CH2-CH2O- radicals.

[00083] In an embodiment-W-comprises at most 40 carbon atoms.

[00084] In an embodiment-W-comprises at most 40 carbon atoms without counting any -CH2-CH2O- radicals.

[00085] In an embodiment-W-comprises at most 30 carbon atoms.

[00086] In an embodiment-W-comprises at most 30 carbon atoms without counting any -CH2-CH2O- radicals.

[00087] In an embodiment-W-comprises at most 20 carbon atoms.

[00088] In an embodiment-W-comprises at most 20 carbon atoms without counting any -CH2-CH2O- radicals.

[00089] In an embodiment-W-comprises at most 10 carbon atoms.

[00090] In an embodiment-W-comprises at most 10 carbon atoms without counting any -CH2-CH2O- radicals.

[00091] In an embodiment-W-comprises at most 10 oxygen atoms.

[00092] In an embodiment-W-comprises at most 10 oxygen atoms without counting any -CH2-CH2O- radicals.

[00093] In an embodiment-W-comprises at most 5 oxygen atoms.

[00094] In an embodiment-W-comprises at most 5 oxygen atoms without counting any -CH2-CH2O- radicals.

[00095] The crosslinked dextran hydrogel according to the invention is a dextran polymer wherein the central-linker L(-)i is a linear, or a branched polyethylene glycol (PEG) radical.

[00096] By branched PEG is meant various PEG arms connected by a linear, branched, or cyclic alkyl, or by an aromatic, comprising between 2 to 20 carbon atoms and may comprise heteroatoms such as nitrogen, oxygen, or sulphur. [00097] In one embodiment, the crosslinked dextran hydrogel according to the invention is a dextran polymer wherein the central-linker L(-)i is a branched PEG radical which possesses at most 8 arms.

[00098] In an embodiment, the central-linker L(-)i is a PEG chosen among the PEG of formula I : Formula I

Wherein:

• i is an integer comprised from 2 to 8 (2 < i < 8)

• p is an integer equal to 0 or 1, and if i=2 then p=0

• q is an integer comprised from 8 to 1000 (8 < q < 1000)

• r is an integer equal to 0 or 1

• Q is either a carbon atom, or a linear, branched, or cyclic alkyl chain, or an aromatic, comprising 2 to 10 carbon atoms and may comprise heteroatoms such as nitrogen, oxygen, or sulphur

• the * represents the sites of f4, which is an amine function, or an ether, or a thioether function, or an amide function, or a carbamate function or a carbonnitrogen covalent bond, or a carbon-aromatic carbon covalent bond, or a carboncarbon covalent bond if the crosslinking process is made by a Native Chemical Ligation (NCL).

[00099] In an embodiment q is an integer comprised from 80 to 500

(80 < q < 500).

[000100] In an embodiment q is an integer comprised from 100 to 300

(100 < q < 300).

[000101] In an embodiment, the cross-linked dextran polymer according to the invention is a dextran polymer wherein L(-)i is a radical issued from a linear or branched mercaptopolyethyleneglycol comprising at least 2 sulfur atoms and comprising at most 8 arms, which: a) number-average molecular weight (Mn) is comprised from 500 to 40 000 g/mol (500 < Mn < 40 000 g/mol) or b) polymerisation degree (DP) is comprised from 8 to 1000 (8 < DP < 1000).

[000102] In an embodiment, the cross-linked dextran polymer according to the invention is a dextran polymer wherein L(-)i is a radical issued from a linear or branched mercaptopolyethyleneglycol comprising at least 2 sulfur atoms and comprising at most 8 arms, which: a) Mn is comprised from 1000 to 25 000 g/mol (1000 < Mn < 25 000 g/mol) or b) polymerisation degree (DP) is comprised from 15 to 600 (15 < DP < 600).

[000103] In an embodiment, the cross-linked dextran polymer according to the invention is a dextran polymer wherein L(-)i is a radical according to formula I, issued from the thiol polyethylene glycols or mercaptopoly(oxyethylenes) cited in the following table:

[000104] In an embodiment, the cross-linked dextran polymer according to the invention is a dextran polymer wherein L(-)i is a radical according to formula I issued from a pentaerythritol tetra(mercaptoethyl) polyoxyethylene, CAS# 188492-68-4. [000105] In an embodiment, the cross-linked dextran polymer according to the invention is a dextran polymer wherein L(-)i is a radical according to formula I issued from a linear (mercaptoethyl)polyoxyethylene, CAS# 68865-60-1. [000106] In an embodiment, the cross-linked dextran polymer according to the invention is a dextran polymer wherein L(-)i is a radical according to formula I, issued from a pentaerythritol poly(oxyethylene) azide cited in the following table:

[000107] In an embodiment, the cross-linked dextran polymer according to the invention is a dextran polymer wherein L(-)i is a radical according to formula I, issued from a pentaerythritol poly(dibenzocyclooctyne) polyoxyethylene cited in the following table:

[000108] In one embodiment, the crosslinked dextran hydrogel according to the invention is a dextran polymer wherein the central-linker L is a linear, or a branched POx radical. [000109] In an embodiment, the cross-linked dextran polymer according to the invention is a dextran polymer wherein L is a linear or branched POx radical comprising at most 8 arms, which number-average molecular weight (Mn) is comprised from 500 to 40 000 g/mol (500 < Mn < 40 000 g/mol).

[000110] In an embodiment, the cross-linked dextran polymer according to the invention is a dextran polymer wherein L is a linear or branched POx radical comprising at most 8 arms, which number-average molecular weight (Mn) is comprised from 1000 to 25 000 g/mol (1 000 < Mn < 25 000 g/mol).

[000111] In one embodiment, the POx central linker is a 2-arm POx, chosen among the linkers of formula XII. Formula XII

Wherein:

• The radical -R is a linear, -(CHz)™— CH3 with m an integer comprised from 0 to 4 (0 < ni < 4), branched, or cyclic alkyl derivative.

• The * represents the sites of s, which is an amine function, or an ether function, or a thioether function, or an amide function, or a carbamate function, or a carbonnitrogen covalent bond, or a carbon-aromatic carbon covalent bond.

[000112] In one embodiment, the POx central linker is a 2-arm POx, chosen among the linkers of formula XII bis.

Formula Xllbis

Wherein:

• The radical -R is a linear, -(CHz)™— CH3 with m an integer comprised from 0 to 4 (0 < ni < 4), branched, or cyclic alkyl derivative.

• The * represents the sites of fs, which is an amine function, or an ether function, or a thioether function, or an amide function, or a carbamate function, or a carbonnitrogen covalent bond, or a carbon-aromatic carbon covalent bond. [000113] In one embodiment, the POx central linker is a 4-arm POx, chosen among the linkers of formula XIII. Formula XIII

Wherein:

• The radical -R is a linear, -(CH2)m— CH3 with m an integer comprised from 0 to 4 (0 < ni < 4), branched, or cyclic alkyl derivative.

• The * represents the sites of fs, which is an amine function, or an ether function, or a thioether function, or an amide function, or a carbamate function, or a carbon-nitrogen covalent bond, or a carbon-aromatic carbon covalent bond.

[000114] In another embodiment, the POx central linker is a 4-arm POx, chosen among the linkers of formula XIV:

Wherein:

• The radical -Ri is a linear, -(CH2)m— CH3 with m an integer comprised from 0 to 4 (0 < ni < 4), branched, or cyclic alkyl derivative.

• The divalent radical -R2- is a linear, -(CH2)n2- with n2 an integer comprised from 2 to 6 (2 < n2 < 6).

• The * represents the sites of s, which is an amine function, or an ether function, or a thioether function, or an amide function, or a carbamate function, or a carbon-nitrogen covalent bond, or a carbon-aromatic carbon covalent bond. [000115] In another embodiment, the POx central linker is a 4-arm POx, chosen

The radical -R is a linear, -(CH2)m— CH3 with ni an integer comprised from 0 to 4 (0 < ni < 4), branched, or cyclic alkyl derivative.

In one embodiment, Ri = -CH2— CH2- and 2 is a linear, -(CH2)n2- with n2 an integer comprised from 2 to 6 (2 < n2 < 6)

In another embodiment, 2 = -CH2— CH2- and Ri is a linear, *-(CH2)n2-* with n2 an integer comprised from 2 to 6 (2 < n2 < 6)

The * represents the sites of s, which is an amine function, or an ether function, or a thioether function, or an amide function, or a carbamate function, or a carbon-nitrogen covalent bond, or a carbon-aromatic carbon covalent bond.

[000116] The hydroxyl functions of the dextran polymer Dx- can be functionalised by at least one specific anionic group such as: alkyl carboxylate, sulphate anions, or sulfonate anions, or phosphate anions, or phosphonate anions.

[000117] In one embodiment, the hydroxyl functions of the dextran polymer Dx can be functionalised by sulphate anions in salified form, and optionally by alkyl carboxylate derivatives in salified form.

[000118] In another embodiment, the hydroxyl functions of the dextran polymer Dx can be functionalised by sulfonate anions in salified form, and optionally by alkyl carboxylate derivatives in salified form. [000119] In another embodiment, the hydroxyl functions of the dextran polymer backbone Dx-, can be functionalized by phosphate anions in salified form, and optionally by alkyl carboxylate derivatives in salified form.

[000120] In another embodiment, the hydroxyl functions of the dextran polymer Dx can be functionalised by phosphonate anions in salified form, and optionally by alkyl carboxylate derivatives in salified form.

[000121] In another embodiment, the hydroxyl functions of the dextran polymer Dx can be functionalised by alkyl carboxylate derivatives in salified form.

[000122] The specific anionic groups defined previously are chosen among the groups of formula II: Formula II

Wherein:

• * represents the link to the O atoms of the dextran to form an ether function.

• y=2 or 3.

• When y=2, alkyl carboxylate derivatives, then: o Y=C and a=l. o k=l, 1=0 and m=0. o R2=Alkyl.

• When y=3, anionic group, then: o Y=S and a=l, or Y=P and a=2. o k=0 or 1. o 1=0 or 1. o m=0 or 1. o n = l or 2, in particular n = 1, o o=0 or 1. o if 1=1 then m=l. o Rs=linear, branched, or cyclic alkyl which may contain one heteroatom such as nitrogen, or aromatic, or PEG.

• And, Z is a counter ion, which can be an alkali metal and z=l, or which can be an alkaline earth metal and z=2. [000123] In a preferred embodiment, the dextran backbone, Dx-, can be functionalised by sulphate anions in salified form, and optionally by alkyl carboxylate derivatives in salified form.

[000124] In another preferred embodiment, the dextran backbone, Dx-, can be functionalised by alkyl sulfonate anions in salified form, and optionally by alkyl carboxylate derivatives in salified form.

[000125] In another preferred embodiment, the dextran backbone, Dx-, can be functionalised by sulfonate anions in salified form, supported by an alkyl chain comprising a dimethyl-ammonium cation, and optionally by alkyl carboxylate derivatives in salified form.

[000126] In another preferred embodiment, the dextran backbone, Dx-, can be functionalised by alkyl carboxylate derivatives in salified form.

[000127] In an embodiment, the cross-linked dextran polymer bearing anionic groups according to the invention is a dextran polymer wherein the dextran polymer backbone is according to formula III, Formula III wherein R is chosen among c) -H, a anionic group of formula II, or a -W- radical bearing a L(-)i crosslinker, d) i is comprised from 20 to 5000 (20 < i < 5000), e) -W- and L(-)i radicals having the previously defined meanings.

[000128] In an embodiment, the cross-linked dextran polymer according to the invention is a dextran polymer wherein the dextran polymer backbone is a dextran having a weight average molecular weight (Mw) comprised from 5 to 1000 kDa before cross-linking and substitution.

[000129] In other words, the cross-linked dextran polymer according to the invention is obtained after substitution and crosslinking of a native dextran polymer having a weight average molecular weight (Mw) comprised from 5 to 1000 kDa.

[000130] In an embodiment, the cross-linked dextran polymer according to the invention is a dextran polymer wherein the dextran polymer backbone is a dextran having a weight average molecular weight (Mw) comprised from 5 to 250 kDa before cross-linking and substitution.

[000131] In an embodiment, the cross-linked dextran polymer according to the invention is a dextran polymer wherein the dextran polymer backbone is a dextran having a weight average molecular weight (Mw) comprised from 5 to 100 kDa before cross-linking and substitution.

[000132] In an embodiment, the cross-linked dextran polymer according to the invention is a dextran polymer wherein the dextran polymer backbone is a dextran having a weight average molecular weight (Mw) comprised from 5 to 50 kDa before cross-linking and substitution.

[000133] In an embodiment, the cross-linked dextran polymer according to the invention is a dextran polymer wherein the dextran polymer backbone is a dextran having a weight average molecular weight (Mw) comprised from 5 to 25 kDa before cross-linking and substitution.

[000134] In an embodiment, the cross-linked dextran polymer according to the invention is a dextran polymer wherein the dextran polymer backbone is a dextran having a weight average molecular weight (Mw) comprised from 250 to 1000 kDa before cross-linking and substitution.

[000135] In an embodiment, the cross-linked dextran polymer according to the invention is a dextran polymer wherein the dextran polymer backbone is a dextran having a weight average molecular weight (Mw) comprised from 10 to 500 kDa before cross-linking and substitution.

[000136] In an embodiment, the cross-linked dextran polymer according to the invention is a dextran polymer wherein the dextran polymer backbone is a dextran having a weight average molecular weight (Mw) comprised from 20 to 500 kDa before cross-linking and substitution.

[000137] In an embodiment, the cross-linked dextran polymer according to the invention is a dextran polymer wherein the dextran polymer backbone is a dextran having a weight average molecular weight (Mw) comprised from 20 to 100 kDa before cross-linking and substitution.

[000138] In an embodiment, the cross-linked dextran polymer according to the invention is a dextran polymer wherein the dextran polymer backbone is a dextran having a weight average molecular weight (Mw) comprised from 20 to 50 kDa before cross-linking and substitution.

[000139] In an embodiment, the cross-linked dextran polymer according to the invention is a dextran polymer wherein the dextran polymer backbone is a dextran having a weight average molecular weight (Mw) comprised from 40 to 250 kDa before cross-linking and substitution. [000140] In an embodiment, the cross-linked dextran polymer according to the invention is a dextran polymer wherein the dextran polymer backbone is a dextran having a weight average molecular weight (Mw) comprised from 40 to 100 kDa before cross-linking and substitution.

[000141] In an embodiment, the cross-linked dextran polymer according to the invention is a cross-linked dextran polymer wherein the degree of substitution (DSi) of the dextran backbone with the a -W- radical bearing a L(-)i crosslinker is comprised in the range from 0.001 to 0.4 (0.001 < DSi < 0.4).

[000142] In an embodiment, the cross-linked dextran polymer according to the invention is a cross-linked dextran polymer wherein the degree of substitution (DSi) of the dextran backbone with the -W- radical bearing a L(-)i crosslinker is comprised in the range from 0.01 to 0.4 (0.01 < DSi < 0.4).

[000143] In an embodiment, the cross-linked dextran polymer according to the invention is a cross-linked dextran polymer wherein the degree of substitution (DSi) of the dextran backbone with the -W- radical bearing a L(-)i crosslinker is comprised in the range from 0.05 to 0.4 (0.05 < DSi < 0.4).

[000144] In an embodiment, the cross-linked dextran polymer according to the invention is a cross-linked dextran polymer wherein the degree of substitution (DSi) of the dextran backbone with the -W- radical bearing a L(-)i crosslinker is comprised in the range from 0.1 to 0.4 (0.1 < DSi < 0.4).

[000145] In an embodiment, the cross-linked dextran polymer according to the invention is a cross-linked dextran polymer wherein the dextran polymer backbone is a dextran having a weight average molecular weight (Mw) is from 5 to 250 kDa before cross-linking and substitution and the degree of substitution (DSi) of the dextran backbone with the -W- radical bearing a L(-)i crosslinker groups is comprised in the range from 0.1 to 0.4 (0.1 < DSi < 0.4).

[000146] In an embodiment, the cross-linked dextran polymer according to the invention is a cross-linked dextran polymer wherein the dextran polymer backbone is a dextran having a weight average molecular weight (Mw) is from 20 to 100 kDa before cross-linking and substitution and the degree of substitution (DSi) of the dextran backbone with the -W- radical bearing a L(-)i crosslinker groups is comprised in the range from 0.2 to 0.4 (0.2 < DSi < 0.4).

[000147] In an embodiment, the cross-linked dextran polymer according to the invention is a cross-linked dextran polymer wherein the dextran polymer backbone is a dextran having a weight average molecular weight (Mw) from 20 to 100 kDa before cross-linking and substitution and the degree of substitution (DSi) of the dextran backbone with the -W- radical bearing a L(-)i crosslinker is comprised in the range from 0.2 to 0.3 (0.2 < DSi < 0.3).

[000148] In an embodiment, the cross-linked dextran polymer according to the invention is a cross-linked dextran polymer wherein the dextran polymer backbone is a dextran having a weight average molecular weight (Mw) is from 250 to 1000 kDa before cross-linking and substitution and the degree of substitution (DSi) of the dextran backbone with the -W- radical bearing a L(-)i crosslinker is comprised in the range from 0.001 to 0.4 (0.001 < DSi < 0.4).

[000149] In an embodiment, the cross-linked dextran polymer according to the invention is a cross-linked dextran polymer wherein the dextran polymer backbone is a dextran having a weight average molecular weight (Mw) from 250 to 1000 kDa before cross-linking and substitution and the degree of substitution (DSi) of the dextran backbone with the -W- radical bearing a L(-)i crosslinker is comprised in the range from 0.01 to 0.4 (0.01 < DSi < 0.4).

[000150] In an embodiment, the cross-linked dextran polymer according to the invention is a cross-linked dextran polymer wherein the dextran polymer backbone is a dextran having a weight average molecular weight (Mw) from 250 to 1000 kDa before cross-linking and substitution and the degree of substitution (DSi) of the dextran backbone with the -W- radical bearing a L(-)i crosslinker is comprised in the range from 0.05 to 0.4 (0.05 < DSi < 0.4).

[000151] In an embodiment, the cross-linked dextran polymer according to the invention is a cross-linked dextran polymer wherein the dextran polymer backbone is a dextran having a weight average molecular weight (Mw) from 250 to 1000 kDa before cross-linking and substitution and the degree of substitution (DSi) of the dextran backbone with the -W- radical bearing a L(-)i crosslinker groups is comprised in the range from 0.1 to 0.4 (0.1 < DSi < 0.4).

[000152] In an embodiment, the cross-linked dextran polymer according to the invention is a cross-linked dextran polymer wherein the degree of substitution (DS4) of the dextran backbone with a radical of formula I is comprised in the range from 0.5 to 3 (0.5 < DS ₄ < 3).

[000153] In an embodiment, the cross-linked dextran polymer according to the invention is a cross-linked dextran polymer wherein the degree of substitution (DS ₄ ) of the dextran backbone with a radical of formula I is comprised in the range from 1 to 2.75 (1 < DS ₄ < 2.75).

[000154] In an embodiment, the cross-linked dextran polymer according to the invention is a cross-linked dextran polymer wherein the degree of substitution (DS ₄ ) of the dextran backbone with a radical of formula I is comprised in the range from 1.5 to 2.5 (1.5 < DS ₄ < 2.5).

[000155] In an embodiment, the cross-linked dextran polymer according to the invention is a cross-linked dextran polymer wherein the degree of substitution (DS ₄ ) of the dextran backbone with a radical of formula I is comprised in the range from 1.75 to 2.25 (1.75 < DS ₄ < 2.25).

[000156] In an embodiment, the cross-linked dextran polymer according to the invention is a cross-linked dextran polymer wherein the degree of substitution of carboxylate (DSc) of the dextran backbone is comprised in the range from 0.2 to 3 (0.2 < DSc < 3).

[000157] In an embodiment, the cross-linked dextran polymer according to the invention is a cross-linked dextran polymer wherein the degree of substitution of carboxylate (DSc) of the dextran backbone is comprised in the range from 0.3 to 2.5 (0.3 < DSc < 2.5).

[000158] In an embodiment, the cross-linked dextran polymer according to the invention is a cross-linked dextran polymer wherein the degree of substitution of sulfate, sulfonate, phosphate, phosphonate (DS3) of the dextran backbone is comprised in the range from 0.2 to 2.5 (0.2 < DS3 < 2.5).

[000159] In an embodiment, the cross-linked dextran polymer according to the invention is a cross-linked dextran polymer wherein the degree of substitution of sulfate, sulfonate, phosphate, phosphonate (DS3) of the dextran backbone is comprised in the range from 0.3 to 2.0 (0.3 < DS3 < 2.0).

[000160] In an embodiment, the cross-linked dextran polymer according to the invention is a cross-linked dextran polymer having a molar ratio (DC) between the molar concentration of the -W- radical and the molar concentration of the reactive functions of the cross-linker L(-)i comprised in a range from 0.5 to 1.5 (0.5 < DC < 1.5).

[000161] In an embodiment, the cross-linked dextran polymer according to the invention is a cross-linked dextran polymer having a molar ratio between the molar concentration of the -W- radical and the molar concentration of the reactive functions of the cross-linker L(-)i is comprised in a range from 0.8 to 1.2 (0.8 < DC < 1.2).

[000162] In an embodiment, the cross-linked dextran polymer according to the invention is a cross-linked dextran polymer having a molar ratio between the molar concentration of the -W- radical and the molar concentration of the reactive functions of the cross-linker L(-)i is comprised in a range from 0.9 to 1.1 (0.9 < DC < 1.1). [000163] In an embodiment, the cross-linked dextran polymer according to the invention is a cross-linked dextran polymer having a molar ratio between the molar concentration of the -W- radical and the molar concentration of the reactive functions of the cross-linker L(-)i is comprised in a range from 0.95 to 1.05 (0.95 < DC < 1.05). [000164] In an embodiment, the cross-linked dextran polymer according to the invention is a cross-linked dextran polymer having a molar ratio between the molar concentration of the -W- radical and the molar concentration of the reactive functions of the cross-linker L(-)i is 1 (DC = 1).

[000165] In an embodiment, the cross-linked dextran polymer according to the invention is a cross-linked dextran polymer having a molar ratio (DC) between the molar concentration of the -(A-f2)a-Gi- radical and the molar concentration of the reactive functions of the cross-linker L(-)i comprised in a range from 0.5 to 1.5 (0.5 < DC < 1.5). [000166] In an embodiment, the cross-linked dextran polymer according to the invention is a cross-linked dextran polymer having a molar ratio between the molar concentration of the -(A-f2)a-Gi- radical and the molar concentration of the reactive functions of the cross-linker L(-)i is comprised in a range from 0.8 to 1.2 (0.8 < DC < 1.2).

[000167] In an embodiment, the cross-linked dextran polymer according to the invention is a cross-linked dextran polymer having a molar ratio between the molar concentration of the -(A-f2)a-Gi- radical and the molar concentration of the reactive functions of the cross-linker L(-)i is comprised in a range from 0.9 to 1.1 (0.9 < DC < 1.1).

[000168] In an embodiment, the cross-linked dextran polymer according to the invention is a cross-linked dextran polymer having a molar ratio between the molar concentration of the -(A-f2)a-Gi- radical and the molar concentration of the reactive functions of the cross-linker L(-)i is comprised in a range from 0.95 to 1.05 (0.95 < DC < 1.05).

[000169] In an embodiment, the cross-linked dextran polymer according to the invention is a cross-linked dextran polymer having a molar ratio between the molar concentration of the -(A-f2)a-Gi- radical and the molar concentration of the reactive functions of the cross-linker L(-)i is 1 (DC = 1).

[000170] In an embodiment, the cross-linked dextran polymer according to the invention is a cross-linked dextran polymer obtained from a reaction between the reactive function of the-W-precursor and the reactive function of the (L)i precursor where reactive functions are present in the same concentration (DC = 1) and are comprised in a range going from 5 to 25 mM. [000171] In an embodiment they are comprised in the range of 5 to 10 mM.

[000172] In an embodiment they are comprised in the range of 10 to 15 mM.

[000173] In an embodiment they are comprised in the range of 15 to 20 mM.

[000174] In an embodiment they are comprised in the range of 20 to 25 mM.

[000175] In an embodiment -W- is chosen among the radicals of formula IV. Formula IV

Wherein

• * represents the site of fi and ° represents the site of attachment with L.

• a is an integer equal to 0 or 1.

• b is an integer equal to 0 or 1.

• c is an integer equal to 0 or 1.

• In one embodiment a = 0, fi is an ether function, or a carbamate function.

• In one embodiment a= l, o the divalent radical -A- is a linear, -(CH2)ni- with m an integer comprised from 1 to 7 (1 < ni < 7), branched, or cyclic alkyl derivative. It may also be branched by at least one hydroxyl group, -CH2— CH(OH)— (CH2)n2- with n2 an integer comprised from 1 to 5 (1 < n2 < 5); fi is an ether function, or a carbamate function, and f2 is an amide function.

Or, o the divalent radical -A- is a linear polyether (PEG) derivative; fi is an ether function, or a carbamate function, and f2 is an amide function.

Or, o in another embodiment the divalent radical -A- is a 4-Alkyl-l,4-triazole derivative or a 4-PEG-l,4-triazole derivative; fi is an ether function, or a carbamate function, and f2 is a carbon-nitrogen covalent bond.

Or, o in another embodiment the divalent radical -A- is a l-Alkyl-l,4-triazole derivative or a l-PEG-l,4-triazole derivative; fi is an ether function, or a carbamate function, and f2 is a carbon-aromatic carbon covalent bond.

• The divalent radical -Ri- is a linear, branched, or cyclic alkyl derivative, and/or an aromatic derivative, and/or a polyether (PEG) derivative, which can contain heteroatoms such as nitrogen, oxygen, or sulphur. o If b=0, then fi is an ether function, or a carbamate function. o If b=l, then fi is an ether function, or a carbamate function, and fs is an amide function, or an amine function, or an ether function, or a thioether function, or a carbamate function, or a carbon-nitrogen covalent bond, or a carbon-aromatic carbon covalent bond or a carbon-carbon covalent bond if the crosslinking process is made by a Native Chemical Ligation (NCL).

• The divalent radical -Gi- is a linear, branched, or cyclic alkyl derivative, or an aromatic derivative, which can contain heteroatoms such as: at most 5 nitrogen atoms, at most 10 oxygen atoms, at most 5 sulphur atoms, or at most one phosphorus atom. In a preferred embodiment, -Gi- is a succinimide derivative, or an alkyl sulfone derivative which can contain one heteroatom such as oxygen or sulphur, or an ethyl amide derivative, or a 1,4-triazole derivative, or a multicycle derivative from a Diels-Alder reaction, or an aromatic phosphine derivative created by a Staudinger ligation, or a cysteine derivative coming from a Native Chemical Ligation. o If c=0, then fi, is an ether function, or a carbamate function. o If c=l, then fi, is an ether function, or a carbamate function, and f4 is an amine function, or an amide function, or a carbamate function, or a thioether function, or an ether function, or a carbon-nitrogen covalent bond, or carbon-aromatic carbon covalent bond, or a carbon-carbon covalent bond if the crosslinking process is made by a Native Chemical Ligation (NCL)

[000176] In this embodiment, the cross-linked dextran polymer according to the invention is chosen among the dextran polymers of formula V.

Wherein

• fi, f2, fs, f4, -A-, -Ri-, -Gi- are defined as above in Formula IV, and

• Dx- is a dextran moiety, which can be substituted by specific anionic groups in salified form, and optionally by alkyl carboxylate derivatives in salified form as previously defined.

• The integer i is the valence of the central-linker L, and the number of, identical or different, [Dx— fi— (A— f ₂ ) _a — (Ri— fs)b— (Gi— f4)c] radicals connected to L.

• The central-linker L is a polyether (PEG) derivative, which can be linear or branched.

[000177] In one embodiment L is linked to the same [Dx— fi— (A— f ₂ )a— (Ri— fs)t>— (Gi— f4)c] radicals. [000178] In one embodiment L is linked to different [Dx— fi— (A— f2)a— (Ri— fs)t>— (Gi— f4)c] radicals.

[000179] If a=O, then:

• In one embodiment, fi is an ether function.

• In another embodiment, fi is a carbamate function.

[000180] If a = l, then:

• In one embodiment, fi is an ether function.

• In another embodiment, fi is a carbamate function.

[000181] If a=0 and b=0, then:

• In one embodiment, fi is an ether function.

• In another embodiment, fi is a carbamate function.

[000182] If a=0 and b=l, then:

• In one embodiment, fi is an ether function.

• In another embodiment, fi is a carbamate function.

[000183] If a = b=c=0, then:

• In one embodiment, fi is an ether function.

• In another embodiment, fi is a carbamate function.

[000184] The cross-linked dextran polymer according to the invention is a dextran polymer Dx- bearing anionic groups wherein an at least divalent radical L(-)i is covalently bound to the dextran polymer backbone with i radicals, chosen among the dextrans of formula X, Formula X

Wherein :

• a is an integer equal to 0 or 1.

• i is an integer comprised from 2 to 8, (2 < i < 8).

• L can be linked to the same [Dx— fi— (A— f2)a— Gi— fs] radicals, or to different ones.

• Dx- is a dextran moiety, which can be substituted by specific anionic groups in salified form, and optionally by alkyl carboxylate derivatives in salified form.

• fi is an ether function.

• The divalent radical -A- is a linear, -(CH2)m- with m an integer comprised from 1 to 7 (1 < ni < 7), branched, or cyclic alkyl derivative. It may also be branched by at least one hydroxyl group, -CH2— CH(OH)— (CH2)n ₂ - with n2 an integer comprised from 1 to 5 (1 < n2 < 5) • f2 is an amide function.

• The divalent radical -Gi- is a linear, branched, or cyclic alkyl derivative, or an aromatic derivative, which can contain heteroatoms such as: at most 5 nitrogen atoms, at most 10 oxygen atoms, at most 5 sulphur atoms. In a preferred embodiment, -Gi- is a succinimide derivative, or an alkyl sulfone derivative which can contain one heteroatom such as oxygen or sulphur, or a 1,4-triazole derivative.

• The integer i is the valence of the central-linker L, and the number of, identical or different, [Dx— fi— (A— fz)a— Gi— fs] radicals connected to L.

• fa is an amine function, or a thioether function, or an ether function, or an amide function, or a carbamate function, or a carbon-nitrogen covalent bond, or carbon-aromatic carbon covalent bond.

• The central-linker L is a poly(oxazoline) (POx) derivative, which can be linear or branched.

[000185] In one embodiment, respective to formula V, the divalent radical -A- is a linear polyether (PEG) derivative chosen among the PEG of following formula:

Wherein:

• m is an integer equal to 0 or 1.

• n2 is an integer comprised from 1 to 7 (1 < ni < 7).

• The * represent the sites of fi and f2.

• In a preferred embodiment, the * represent the sites of fi and f2, which are respectively ether and amide functions.

[000186] In another embodiment, respective to formula V, the divalent radical -A- is a l-Alkyl-l,4-triazole derivative, or a l-PEG-l,4-triazole derivative, chosen among the triazole derivative of following formula:

Wherein: • X is either a linear *-(CH2)m-* with ni an integer comprised from 1 to 7 (1 < m < 7), branched, or cyclic alkyl derivative, or X is a PEG derivative.

• The * represents the site of fi and the dotted bond represents f2.

[000187] In another embodiment, respective to formula V, the divalent radical -A- is a 4-Alkyl-l,4-triazole derivative, or a 4-PEG-l,4-triazole derivative, chosen among the triazole derivative of following formula:

Wherein:

• X is either a linear *-(CH2)m-* with ni an integer comprised from 1 to 7 (1 < ni < 7), branched, or cyclic alkyl derivative, or X is a PEG derivative.

• The * represents the site of fi and the dotted bond represents f2.

[000188] If a = l, then:

• In one embodiment, f2 is an amide function.

• In another embodiment, f2 is a carbon-nitrogen covalent bond.

• In another embodiment, f2 is a carbon-aromatic carbon covalent bond.

[000189] In one embodiment -A-, respective to formula X, is a linear, -(CH2)ni- with ni an integer comprised from 1 to 7 (1 < ni < 7), branched, or cyclic alkyl derivative. It may also be branched by at least one hydroxyl group, -CH2— CH(OH)— (CH2)n2- with n2 an integer comprised from 1 to 5 (1 < n2 < 5).

[000190] In one embodiment, respective to formula V, the divalent radical -Ri- is a linear alkyl derivative, according to the following formula:

Wherein:

• ni is an integer comprised from 1 to 7 (1 < ni < 7).

• In one embodiment, if a = l, then the * represent the sites of f2 and fs.

• In another embodiment, if a=0, the * represent the sites of fi and fs.

[000191] In another embodiment, respective to formula V, the divalent radical -Riis a polyether (PEG) derivative, according to the following formula:

Wherein:

• m is an integer equal to 0 or 1.

• n2 is an integer comprised from 1 to 7 (1 < n2 < 7).

• In one embodiment, if a = l, then the * represent the sites of f2 and fs.

• In another embodiment, if a=0, the * represent the sites of fi and fs.

[000192] In another embodiment, respective to formula V, if a=0, then the divalent radical -Ri- may be a branched alkyl, wherein at least one hydroxyl group is attached to the alkyl chain in p position from fi, which is an ether function.

Wherein:

• ri2 is an integer comprised from 1 to 5 (1 < n2 < 5).

• In another embodiment if a=0, the * represent the sites of fi and fs.

[000193] In a preferred embodiment, respective to formula V, the divalent radical - Ri- is a linear alkyl derivative, according to the following formula:

Wherein: the * represent the sites of f2, which is an amide function, and fs, which is an amide function.

[000194] In a preferred embodiment, respective to formula V, the divalent radical - Ri- is a PEG derivative, according to the following formula:

Wherein:

• ni is an integer comprised from 1 to 7 (1 < m < 7).

• The * represent the sites of f2 and fs, which are two amide functions.

[000195] If b=l, then:

• In one embodiment, fs is an amine function. • In another embodiment, fs is an ether function.

• In another embodiment, fs is a thioether function.

• In another embodiment, fs is an amide function.

• In another embodiment, fs is a carbamate function.

• In another embodiment, fs is a carbon-nitrogen covalent bond.

• In another embodiment, fs is a carbon-aromatic carbon covalent bond.

• In another embodiment, if the crosslinking process is made by a Native Chemical Ligation (NCL), then fs is a carbon-carbon covalent bond.

[000196] The nature of radical -Gi- depends on the crosslinking process, below are described the different crosslinking process together with the -Gi- radicals.

[000197] In one embodiment, the crosslinking process is realized with a Michael addition with maleimide derivatives, or vinyl sulfone derivatives, or acrylamide derivatives.

[000198] In one embodiment, respective to formula V, the divalent radical -Gi- is a succinimide derivative according to the following formula:

Wherein:

• X is either a linear *-(CH2)m-* with m an integer comprised from 1 to 7 (1 < m < 7), branched, or cyclic alkyl derivative, or X is an aromatic, or X is a PEG derivative.

• In one embodiment if b= 1, then the * represent the sites of fs and f4.

• In another embodiment if a = b=0, then the * represent the sites of fi and f4.

• In another embodiment if a = l and b=0, then the * represent the sites of f2 and f ₄ .

• In a preferred embodiment, X is an ethyl group and the * represent the sites of f2, which is an amide function, and f4, which is a thioether function.

[000199] In one embodiment, respective to formula X, the divalent radical -Gi- is a succinimide derivative according to the following formula:

Wherein:

• R is a linear, branched, or cyclic alkyl derivative, or R is an aromatic, or R is a PEG derivative.

• The * represent the sites of f2, which is an amide function, and fs, which is an amine function, or an ether function, or a thioether function.

[000200] In one embodiment, respective to formula V, if b=0, c=l and L is a POx derivative, the divalent radical -Gi- is a succinimide derivative according to the following formula:

Wherein:

• R is a linear, branched, or cyclic alkyl derivative, or R is an aromatic, or R is a PEG derivative.

• The * represent the sites of f2, which is an amide function, and fs, which is an amine function, or an ether function, or a thioether function.

[000201] In another embodiment, respective to formula X, the divalent radical -Gi- is a succinimide derivative according to the following formula:

Wherein:

• X is an oxygen atom, or a sulphur atom, or a nitrogen atom.

• R is a linear, branched, or cyclic alkyl derivative, or R is a PEG derivative. • The * represents the site of f2, which is an amide function, and the dotted bond represents fs, which is a carbon-nitrogen covalent bond.

[000202] In another embodiment, respective to formula V, if b=0, c=l and L is a POx derivative, the divalent radical -Gi- is a succinimide derivative according to the following formula:

Wherein:

• X is an oxygen atom, or a sulphur atom, or a nitrogen atom.

• R is a linear, branched, or cyclic alkyl derivative, or R is a PEG derivative.

• The * represents the site of f2, which is an amide function, and the dotted bond represents fs, which is a carbon-nitrogen covalent bond.

[000203] In another embodiment, respective to formula V, the divalent radical -Gi- is a diethyl sulfone derivative according to the following formula:

Wherein:

• In one embodiment if b= 1, the * represent the sites of fs and f4.

• In another embodiment if a = b=0, the * represent the sites of fi and f4.

• In another embodiment if b=0, the * represent the sites of f2 and f4.

• In a preferred embodiment, the * represent the sites of fs and f4, which are thioether functions.

[000204] In another embodiment, respective to formula V, the divalent radical -Gi- is a sulfone derivative according to the following formula:

Wherein:

• ni is an integer comprised from 0 to 7 (0 < ni < 7).

• X is either an oxygen atom, or a sulphur atom, or a CH2 group. • In one embodiment if b= 1, the * represent the sites of fs and f4.

• In another embodiment if a = b=0, the * represent the sites of fi and f4.

• In another embodiment if a = l and b=0, the * represent the sites of f2 and f4.

• In preferred embodiment a=l, b=0, X is a sulphur atom, ni=2, f2 is an amide function, and f4 is a thioether function.

[000205] In another embodiment, respective to formula X, the divalent radical -Gi- is a sulfone derivative according to the following formula:

Wherein:

• ni is an integer comprised from 0 to 7 (0 < ni < 7).

• X is an oxygen atom, or a sulphur atom, or a CH2 group.

• The * represent the sites of f2, which is an amide function, and fs, which is an amine function, or an ether function or a thioether function.

[000206] In another embodiment, respective to formula V, if b=0, c=l and L is a POx derivative, the divalent radical -Gi- is a sulfone derivative according to the following formula:

Wherein:

• ni is an integer comprised from 0 to 7 (0 < ni < 7).

• X is an oxygen atom, or a sulphur atom, or a CH2 group.

• The * represent the sites of f2, which is an amide function, and fs, which is an amine function, or an ether function or a thioether function.

[000207] In another embodiment, respective to formula V, the divalent radical -Gi- is an acrylamide derivative according to the following formula:

Wherein: • In one embodiment, the * represents the site of fs, which is an amine function, or an ether function, or a thioether function, and the dotted bond represents f4, which is a carbon-nitrogen covalent bond.

• In another embodiment, the dotted bond represents fs, which is a carbonnitrogen covalent bond, and the * represents the site of f4, which is an amine function, or an ether function, or a thioether function.

[000208] In one embodiment, the crosslinking process is realised with a 1,3- cycloaddition between alkyne and azide derivatives, known as 1,3-dipolar cycloaddition or Huisgen reaction.

[000209] In one embodiment, respective to formula V, the divalent radical -Gi- is a 1,4-triazole derivative according to the following formula:

Wherein the two dotted bonds represent fs and f4 which are covalent bonds or chemical functions defined previously and after.

[000210] In one embodiment, respective to formula X, the integer a = l , the divalent radical -Gi- is a 1,4-triazole derivative according to the following formula:

Wherein:

• Ri is a linear, branched, or cyclic alkyl derivative, which can contain heteroatom such as oxygen, or Ri is an aromatic derivative, or Ri is a PEG derivative.

• The * represents the site of f2, which is an amide function, and the dotted bond represents fs, which is either a carbon-nitrogen covalent bond or a carbonaromatic carbon covalent bond.

[000211] In one embodiment, respective to formula V, the integer a=c=l, and L is a Pox derivative, the divalent radical -Gi- is a 1,4-triazole derivative according to the following formula:

Wherein:

• Xi is a linear, branched, or cyclic alkyl derivative, which can contain heteroatom such as oxygen, or Xi is an aromatic derivative, or Xi is a PEG derivative.

• The * represents the site of f2, which is an amide function, and the dotted bond represents f4, which is either a carbon-nitrogen covalent bond or a carbon- aromatic carbon covalent bond.

[000212] In another embodiment, respective to formula X, the integer a=0, the divalent radical -Gi- is a 1,4-triazole derivative according to the following formula:

Wherein:

• The * represents the site of fi, which is an ether function, and the dotted bond represents fs, which is a carbon-nitrogen covalent bond.

[000213] In another embodiment, respective to formula V, the integer a=0, b=0, c=l and L is a Pox derivative, the divalent radical -Gi- is a 1,4-triazole derivative according to the following formula:

Wherein:

• The * represents the site of fi, which is an ether function, and the dotted bond represents f4, which is a carbon-nitrogen covalent bond.

[000214] In one embodiment, the crosslinking process is realised with a 1,3- cycloaddition between strain alkyne and azide derivatives, known as Strain-promoted azide-alkyne cycloaddition, or SPAAC.

[000215] In one embodiment, respective to formula X, the integer a=l, the crosslinking process is realised with a 1,3-cycloaddition between strain alkyne and azide derivatives, known as Strain-promoted azide-alkyne cycloaddition or SPAAC.

[000216] In one embodiment, respective to formula V, the integer a=c=l, b=0 and L is a Pox derivative, the crosslinking process is realised with a 1,3-cycloaddition between strain alkyne and azide derivatives, known as Strain-promoted azide-alkyne cycloaddition or SPAAC.

[000217] In one embodiment, respective to formula V, the divalent radical -Gi- is a triazole derivative according to the following formula:

Wherein:

• The dotted circle represents a cyclooctene derivative, coming from strained cyclooctyne, which can contain one heteroatom such as nitrogen, oxygen, or sulphur, and is optionally functionalised by linear, branched, or cyclic alkyl derivatives comprising between 2 to 20 carbon atoms, or by aromatics derivatives, or by heteroatoms such as nitrogen, oxygen, or sulphur, or halogens, especially fluorine.

• The two dotted bonds represent fs and f4, which are covalent bonds or chemical functions defined previously and after.

• In another embodiment if a = b=0, the two dotted bonds represent fi and f4.

• In another embodiment if a = l and b=0, the two dotted bonds represent f2 and f ₄ .

• In a preferred embodiment, the dotted bonds represent f2, which is an amide function, and f4, which is a carbon-nitrogen covalent bond.

[000218] In another embodiment, respective to formula V, the divalent radical -Gi- is a triazole derivative according to the following formula:

Wherein:

• The dotted circle represents a cyclooctene derivative, coming from strained cyclooctyne, which can contain one heteroatom such as nitrogen, oxygen, or sulphur, and is optionally functionalised by linear, branched, or cyclic alkyl derivatives comprising between 2 to 20 carbon atoms, or by aromatics derivatives, or by heteroatoms such as nitrogen, oxygen, or sulphur, or halogens, especially fluorine.

• X is either a linear *-(CH2)m-* with ni an integer comprised from 1 to 7 (1 < ni < 7), branched, or cyclic alkyl derivative, or X is a PEG derivative.

• The two dotted bonds represent fs and f4, which are covalent bonds or chemical functions defined previously and after.

• In another embodiment if a = b=0, the * represent the sites of fi, and the dotted bond represents f4.

• In another embodiment if a = l and b=0, the * represent the sites of fi, and the dotted bond represents f4.

• In a preferred embodiment, X is a PEG derivative, the dotted bonds represent f2 and f4, which are amide functions.

[000219] In another embodiment, respective to formula X, the divalent radical -Gi- is a triazole derivative according to the following formula:

Wherein:

• The dotted circle represents a cyclooctene derivative, coming from strained cyclooctyne, which can contain one heteroatom such as nitrogen, oxygen, or sulphur, and is optionally functionalised by linear, branched, or cyclic alkyl derivatives comprising between 2 to 20 carbon atoms, or by aromatics derivatives, or by heteroatoms such as nitrogen, oxygen, or sulphur, or halogens, especially fluorine.

• Ri is a linear, branched, or cyclic alkyl derivative, which can contain heteroatom such as oxygen, or Ri is an aromatic derivative, or Ri is a PEG derivative.

• R2 is a linear, branched, or cyclic alkyl derivative, which can contain heteroatom such as oxygen, or R2 is an aromatic derivative, or R2 is a PEG derivative.

• The * represents the site of f2, which is an amide function, and the dotted bond represents fs, which is a carbon-nitrogen covalent bond, or an amide function, or a carbamate function.

[000220] In another embodiment, respective to formula V, b=0 and c= 1, the divalent radical -Gi- is a triazole derivative according to the following formula:

Wherein:

• The dotted circle represents a cyclooctene derivative, coming from strained cyclooctyne, which can contain one heteroatom such as nitrogen, oxygen, or sulphur, and is optionally functionalised by linear, branched, or cyclic alkyl derivatives comprising between 2 to 20 carbon atoms, or by aromatics derivatives, or by heteroatoms such as nitrogen, oxygen, or sulphur, or halogens, especially fluorine.

• Xi is a linear, branched, or cyclic alkyl derivative, which can contain heteroatom such as oxygen, or Xiis an aromatic derivative, or Xiis a PEG derivative.

• Xzis a linear, branched, or cyclic alkyl derivative, which can contain heteroatom such as oxygen, or Xzis an aromatic derivative, or Xzis a PEG derivative.

• The * represents the site of fz, which is an amide function, and the dotted bond represents f4, which is a carbon-nitrogen covalent bond, or an amide function, or a carbamate function.

[000221] In a preferred embodiment, respective to formula V, the divalent radical -

Gi- is a triazole derivative according to the following formula:

Wherein: the * represents the site of fz, which is an amide function, and the dotted bond represents f4, which is a carbon-nitrogen bond.

[000222] In a preferred embodiment, respective to formula X, the divalent radical - Gi- is a triazole derivative according to the following formula:

Wherein: The * represents the site of f2, which is an amide function, and the dotted bond represents fs, which is a carbon-nitrogen covalent bond.

[000223] In another preferred embodiment, respective to formula V, the divalent radical -Gi- is a triazole derivative according to the following formula:

Wherein:

X is a PEG derivative.

The * represent the sites of f2 and f4, which are amide functions.

[000224] In another preferred embodiment, respective to formula X, the divalent radical -Gi- is a triazole derivative according to the following formula: Wherein:

• Ri is a linear, branched, or cyclic alkyl derivative, which can contain heteroatom such as oxygen, or Ri is an aromatic derivative, or Ri is a PEG derivative.

• The * represent the sites of f2 and fs, which are amide functions.

[000225] In another preferred embodiment, respective to formula V, the divalent radical -Gi- is a triazole derivative according to the following formula:

Wherein:

• Xi is a linear, branched, or cyclic alkyl derivative, which can contain heteroatom such as oxygen, or Xi is an aromatic derivative, or Xi is a PEG derivative.

• The * represent the sites of f2 and f4, which are amide functions.

[000226] In another embodiment, respective to formula V, the divalent radical -Gi- is a triazole derivative according to the following formula:

Wherein: the * represents the site of fs, and the dotted bond represents f4.

[000227] In another embodiment, respective to formula V, the divalent radical -Gi- is a triazole derivative according to the following formula:

Wherein, the dotted bond represents fs, and the * represents the site of f4. [000228] In one embodiment, respective to formula V, the crosslinking process is realized with a Diels-Alder cycloaddition between maleimide and furane derivatives.

[000229] In one embodiment, the divalent radical -Gi- is a multiple cycle derivative, composed of one succinimide moiety, according to the following formula:

Wherein:

• X is either a linear *-(CH2)m-* with m an integer comprised from 1 to 7 (1 < ni < 7), branched, or cyclic alkyl derivative, or X is a PEG derivative.

• Xi is either a linear *-(CH2)m-* with m an integer comprised from 0 to 7 (0 < ni < 7), branched, or cyclic alkyl derivative.

• X2 is either -H or -Me.

• In one embodiment if a = b=l, the * represent the sites of fs and f4.

• In another embodiment if a = b=0, the * represent the sites of fi and f4.

• In another embodiment if a = l and b=0, the * represent the sites of f2 and f4.

[000230] In one embodiment, the crosslinking process is realised with an inverse electron-demand Diels-Alder reaction or IEDDA, between tetrazine and norbornene derivatives.

[000231] In one embodiment, respective to formula V, the divalent radical -Gi- is a multiple cycle derivative, composed of one pyridazine moiety, according to the following formula:

Wherein: • X is either a linear *-(CH2)m-* with m an integer comprised from 1 to 7 (1 < ni < 7), branched, or cyclic alkyl derivative, or X is an aromatic derivative, or X is a PEG derivative.

• In one embodiment if a = b=l, the * represent the sites of fs and f4.

• In another embodiment if a = b=0, the * represent the sites of fi and f4.

• In another embodiment if a = l and b=0, the * represent the sites of f2 and f4.

[000232] In another embodiment, respective to formula V, the divalent radical -Gi- is a multiple cycle derivative, composed of one pyridazine moiety, according to the following formula:

Wherein:

• X is either a linear *-(CH2)m-* with m an integer comprised from 1 to 7 (1 < ni < 7), branched, or cyclic alkyl derivative, or X is an aromatic derivative, or X is a PEG derivative.

• In one embodiment if a = b=l, the * represent the sites of fs and f4.

• In another embodiment if a = b=0, the * represent the sites of fi and f4.

• In another embodiment if a = l and b=0, the * represent the sites of fz and f4.

[000233] In one embodiment, the crosslinking process is realised with a Staudinger ligation, between an aromatic phosphine and an azide derivative.

[000234] In one embodiment, respective to formula V, the divalent radical -Gi- is an aromatic derivative, according to the following formula:

Wherein:

• In one embodiment if a = b=l, the * represent the sites of fs and f4.

• In another embodiment if a = b=0, the * represent the sites of fi and f4.

• In another embodiment if a= 1 and b=0, the * represent the sites of f2 and f4.

[000235] In one embodiment, the crosslinking process is realised with a Native Chemical Ligation (NCL), between thioester and N-terminal cysteine derivatives.

[000236] In one embodiment, respective to formula V, the divalent radical -Gi- can be formalised according to the following formula:

Wherein:

• The dotted line represents a carbon-nitrogen covalent bond.

• In one embodiment if a = b=l, the * and the dotted line represent the sites of fs and f4.

• In another embodiment if a = b=0, the * and the dotted line represent the sites of fi and f4.

• In another embodiment if a = l and b=0, the * and the dotted line represent the sites of f2 and f4.

If c=l, then:

• In one embodiment, f4 is an amine function.

• In another embodiment, f4 is an ether function.

• In another embodiment, f4 is a thioether function. • In another embodiment, f4 is an amide function.

• In another embodiment, f4 is a carbamate function.

• In another embodiment, f4 is a carbon-nitrogen covalent bond.

• In another embodiment, f4 is a carbon-aromatic carbon covalent bond.

• In another embodiment, if the crosslinking process is made by a Native Chemical Ligation (NCL), then f4 is a carbon-carbon covalent bond.

[000237] In one embodiment, f3 is an amine function.

[000238] In another embodiment, f3 is an ether function.

[000239] In another embodiment, f3 is a thioether function.

[000240] In another embodiment, f3 is an amide function.

[000241] In another embodiment, f3 is a carbamate function.

[000242] In another embodiment, f3 is a carbon-nitrogen covalent bond.

[000243] In another embodiment, f3 is a carbon-aromatic carbon covalent bond.

[000244] The invention also concerns the dextran polymers of formula VIII before the crosslinking reaction.

Formula VIII

Wherein

• fi, f2, fa, Dx are defined as above if none of a, a', b and b' are equal to 0,

• and

• x equal 0 or 1.

• if a, a', b and b' are equal to 0, x is equal to 0 and Dx is a dextran polymer backbone according to formula III, wherein R is chosen among -H or a anionic group of formula II,

• if one of b' and c is not equal to 0 -A'- is -A- as defined above,

• if b', b and c are equal to 0, a is equal to 0 and A' is the precursor of A before the crosslinking reaction.

• if c is not equal to 0, R'i is Ri as defined above and G'i is the precursor of Gi.

• if c is equal to 0, b is equal to 0 and R'i is the precursor of Ri before the crosslinking , reaction.

[000245] In an embodiment, respective to formula VIII, A' is an alkyl carboxylate derivative or a poly(oxyethylene)carboxylate derivative, or an alkyl azide derivative, or a poly(oxyethylene)azide derivative, or a propargyl derivative, or a poly(oxyethylene)propargyl derivative, or a 2-hydroxyalkyl carboxylate, or a 2- hydroxyalkylamine.

[000246] The invention also concerns the dextran polymers of formula XVIII before the crosslinking reaction.

Wherein

• fi, f2, Dx are as defined above if a is not equal to 0,

• and

• if a is equal to 0, fi is an ether function and G'i is a propargylic derivative,

• if a is not equal to 0 -A' is A as defined above.

[000247] In an embodiment, respective to formula XVIII, if a=l, A' is an alkyl carboxylate derivative, or a 2- hydroxyalkyl carboxylate, or a 2-hydroxyalkylamine.

[000248] In an embodiment, respective to formula VIII, if a=l, b=0 and L is a POx derivative, A' is an alkyl carboxylate derivative, or a 2-hydroxyalkyl carboxylate, or a 2- hydroxyalkylamine.

[000249] A' as carboxylate derivatives can be formalized with the following formulas:

[000250] A' as azide derivatives, respective to formula VIII, can be formalized with the following formulas:

[000251] A' as propargyl derivatives, respective to formula VIII, can be formalized with the following formulas: [000252] A' as a 2-hydroxyalkyl carboxylate derivative can be formalized with the following formula:

[000253] A' as a 2-hydroxyalkylamine derivatives can be formalized with the following formula:

Wherein: n is an integer comprised from 1 to 7 (1 < n < 7) m is an integer comprised from 1 to 5 (1 < m < 5)

- fi is defined as previously.

[000254] In an embodiment, respective to formula VIII, if a=l, R'I is an alkyl radical or a poly(oxyethylene) radical bearing a terminal amine, or a terminal hydroxyl, or a terminal thiol, or a terminal carboxylate, or a terminal azide, or a terminal alkyne.

[000255] R'I can be formalized as follows:

[000256] R'i ascarboxylate derivatives can be formalized with the following formulas:

[000257] R'i as azide derivatives can be formalized with the following formulas:

Wherein: n is an integer comprised from 1 to 7 (1 < n < 7)

- X= -NH ₂ , or -OH, or -SH

- f ₂ is defined as previously.

[000258] Or, in another embodiment, respective to formula VIII, if a=0, then R'I is a branched alkyl, wherein at least one hydroxyl group is attached to the alkyl chain in P position from fi, and having a terminal hydroxyl, or a terminal thiol, or a terminal azide, or a terminal alkyne.

R'i can be formalized as follows:

Wherein: n is an integer comprised from 1 to 5 (1 < n < 5)

- X= -NHz, or -OH, or -SH, or -N ₃ , or -C=CH

- fi is defined as previously.

[000259] Or, in another R'I is a propargyl derivatives, and can be formalized with the following formulas:

Wherein: n is an integer comprised from 1 to 7 (1 < n < 7)

- fi is defined as previously.

[000260] In an embodiment G'l, respective to formula VIII, is a maleimide derivative, or a vinylsulfone derivative, or a strained cyclooctyne derivative, or an azide derivative, or propargyl derivative, or a furane derivative, or an acrylamide derivative, or a norbornene derivative, or a trans-cyclooctene derivative, or a tetrazine derivative, or an aromatic phosphine, or a cysteine, or a thioester, or a thiol derivative, or an amine derivative, or a hydroxyl derivative.

[000261] In an embodiment, respective to formula XVIII, if a=l, G'l is a maleimide derivative, or a vinylsulfone derivative, or a strained cyclooctyne derivative, or an azide derivative, or propargyl derivative, or a thiol derivative, or an amine derivative, or a hydroxyl derivative.

[000262] In an embodiment, respective to formula VIII, if a=l, b=0 and L is a POx derivative, G'l is a maleimide derivative, or a vinylsulfone derivative, or a strained cyclooctyne derivative, or an azide derivative, or propargyl derivative, or a thiol derivative, or an amine derivative, or a hydroxyl derivative. [000263] G'I as a thiol, an amine or a hydroxyl derivative, respective to formula VIII, can be formalized as follow:

[000264] G'I as a thiol, an amine or a hydroxyl derivative, respective to formula

XVIII, can be formalized as follow:

[000265] G'i as a maleimide, respective to formula VIII, can be formalized as follows:

[000266] G'i as maleimide, respective to formula XVIII, can be formalized as follows:

[000267] G'i as a vinylsulfone, respective to formula VIII, can be formalized as follows:

[000268] G'i as vinylsulfone, respective to formula XVIII, can be formalized as follows: [000269] G'i as a strained cyclooctyne, respective to formula VIII, can be formalized [000270] G'i as a strained cyclooctyne, respective to formula XVIII, can be

[000271] G'i as azide derivatives, respective to formula VIII, can be formalized with the following formula:

' N ₃

[000272] G'i as azide derivatives, respective to formula XVIII, can be formalized with the following formula:

[000273] G'i as propargyl derivatives, respective to formula VIII, can be formalized with the following formula: [000274] G'i as propargyl derivatives, respective to formula XVIII, can be formalized with the following formula:

Wherein:

• n is an integer comprised from 0 to 7 (0 < ni < 7)

• R is a linear, branched, or cyclic alkyl derivative, or R is a PEG derivative

• X= -NH ₂ , or -OH, or -SH

• Xi is an oxygen atom, or a sulphur atom, or a CH ₂ group

• f ₂ is defined as previously.

[000275] In an embodiment, if a=0, G'i is a propargyl derivative.

[000276] G'i as a propargyl derivative can be formalized as follow:

Wherein:

• fi is defined as previously.

[000277] G'i asfurane derivatives, respective to formula VIII, can be formalized with the following formula:

[000278] G'i as acrylamide derivatives, respective to formula VIII, can be formalized with the following formula:

[000279] G'I as norbornene derivatives, respective to formula VIII, can be formalized with the following formula: [000280] G'i as trans-cyclooctene derivatives, respective to formula VIII, can be formalized with the following formula:

[000281] G'i as tetrazine derivatives, respective to formula VIII, can be formalized with the following formula:

[000282] G'i as aromatic phosphine derivative, respective to formula VIII, can be formalized with the following formula:

[000283] G'i as cysteine derivatives, respective to formula VIII, can be formalized with the following formula:

[000284] G'i as thioester derivatives, respective to formula VIII, can be formalized with the following formula:

Wherein:

- X= -NH ₂ , or -OH, or -SH - Xi= -O-, or -S- n is an integer equal to 0 or 1

- Ri= Alkyl

- X2= -CH2-, or aromatic

- R ₂ = -H, or -CH3

- fs is defined as previously.

- The dotted bonds represent fs, which is a carbon-nitrogen covalent bond, or a carbon-carbon covalent bond.

[000285] The invention also concerns a hydrogel comprising the cross-linked dextran polymer according to the invention.

[000286] In an embodiment the hydrogel is transparent.

[000287] By "transparent" is meant that in conditions disclosed in Example C21 of application PCT/EP2022/050466 for visual inspection an observer considered the sample transparent compared to the standard 2 (6 NTU) and/or the UV absorbance of the hydrogel as measured in Example C21 of application PCT/EP2022/050466 is lower than 0.06 (Absorbance Units).

[000288] In an embodiment the hydrogel is visually transparent and has a UV absorbance < 0.06 (Abs. Units).

[000289] In an embodiment the hydrogel according to the invention is characterized in that Tan 6 is lower than 1.

[000290] In the present specification, Tan 6 is the ratio of the loss modulus G" to the storage modulus (also called elastic modulus) G' (Tan 6 = G"/G')-

[000291] In an embodiment the hydrogel according to the invention is characterized in that Tan 6 is less than or equal to 0.5.

[000292] In an embodiment the hydrogel according to the invention is characterized in that Tan 6 is less than or equal to 0.1.

[000293] In an embodiment the hydrogel according to the invention is characterized in that Tan 6 is less than or equal to 0.05.

[000294] In an embodiment the hydrogel according to the invention is characterized in that Tan 6 is less than or equal to 0.01.

[000295] In an embodiment the hydrogel according to the invention is characterized in that after swelling in water the cross-linked dextran polymer concentration is comprised from 0.01 to 0.2 g/g. [000296] In an embodiment the hydrogel according to the invention is characterized in that after swelling in water the cross-linked dextran polymer concentration is comprised from 0.03 to 0.1 g/g.

[000297] In an embodiment the hydrogel according to the invention is characterized in that after swelling in water the cross-linked dextran polymer concentration is comprised from 0.05 to 0.1 g/g.

[000298] In an embodiment, the hydrogel is translucid.

[000299] In another embodiment the hydrogel is transparent.

[000300] In an embodiment, the hydrogel has a Young modulus comprised between 1 to 200 kPa.

[000301] In an embodiment, the hydrogel has a Young modulus comprised between 5 to 200 kPa.

[000302] In an embodiment, the hydrogel has a Young modulus comprised between 20 to 200 kPa.

[000303] In an embodiment, the hydrogel has a Young modulus comprised between 30 to 200 kPa.

[000304] In an embodiment, the hydrogel has a Young modulus comprised between 50 to 200 kPa.

[000305] In an embodiment, the hydrogel has a Young modulus comprised between 30 to 180 kPa.

[000306] In an embodiment, the hydrogel has a Young modulus comprised between 50 to 150 kPa.

[000307] In an embodiment, the hydrogel has a Young modulus comprised between 5 to 100 kPa.

[000308] In an embodiment, the hydrogel has a Young modulus comprised between 10 to 90 kPa.

[000309] In an embodiment, the hydrogel has a Young modulus comprised between 10 to 75 kPa.

[000310] In an embodiment, the hydrogel has a G' comprised from 0.5 to 70 kPa.

[000311] In an embodiment the hydrogel has a compression deformation at break of more than or equal to 10 %.

[000312] In an embodiment the hydrogel has a compression deformation at break of more than or equal to 15 %.

[000313] In an embodiment the hydrogel has a compression deformation at break of more than or equal to 20 %. [000314] In an embodiment the hydrogel has a compression deformation at break of more than or equal to 25 %.

[000315] In an embodiment the hydrogel has a compression deformation at break of more than or equal to 30 %.

[000316] In an embodiment the hydrogel has a compression deformation at break of more than or equal to 35 %.

[000317] In an embodiment the hydrogel has a compression deformation at break of more than or equal to 40 %.

[000318] In an embodiment the hydrogel has a compression deformation at break of more than or equal to 45 %.

[000319] In an embodiment the hydrogel has a compression deformation at break of more than or equal to 50 %.

[000320] In an embodiment the hydrogel has a compression deformation at break of more than or equal to 55 %.

[000321] In an embodiment the hydrogel has a compression deformation at break of more than or equal to 60 %.

[000322] In an embodiment the hydrogel has a traction deformation at break of more than or equal to 10 %.

[000323] In an embodiment the hydrogel has a traction deformation at break of more than or equal to 15 %.

[000324] In an embodiment the hydrogel has a traction deformation at break of more than or equal to 20 %.

[000325] In an embodiment the hydrogel has a traction deformation at break of more than or equal to 25 %.

[000326] In an embodiment the hydrogel has a traction deformation at break of more than or equal to 30 %.

[000327] In an embodiment the hydrogel has a traction deformation at break of more than or equal to 35 %.

[000328] In an embodiment the hydrogel has a traction deformation at break of more than or equal to 40 %.

[000329] In an embodiment the hydrogel has a swelling ratio of more than 0.7.

[000330] In an embodiment the hydrogel has a swelling ratio of more than 0.8.

[000331] In an embodiment the hydrogel has a swelling ratio of more than 0.9.

[000332] In an embodiment the hydrogel has a swelling ratio of more than 1.

[000333] In an embodiment the hydrogel has a swelling ratio of more than 1.1. [000334] In an embodiment the hydrogel has a swelling ratio of more than or equal to 1.2.

[000335] In an embodiment the hydrogel has a swelling ratio of more than or equal to 1.3.

[000336] In an embodiment the hydrogel has a swelling ratio of more than or equal to 1.4.

[000337] In an embodiment the hydrogel has a swelling ratio of more than or equal to 1.5.

[000338] In an embodiment the hydrogel has a swelling ratio of more than or equal to 1.6.

[000339] In an embodiment the hydrogel has a swelling ratio of less than or equal to 5.

[000340] In an embodiment the hydrogel has a swelling ratio of less than or equal to 4.

[000341] In an embodiment the hydrogel has a swelling ratio of less than or equal to 3.

[000342] In an embodiment the hydrogel has a swelling ratio of less than or equal to 2.8.

[000343] In an embodiment the hydrogel has a swelling ratio of less than or equal to 2.5.

[000344] In an embodiment the hydrogel has a swelling ratio of less than or equal to 2.3.

[000345] In an embodiment the hydrogel has a water content of at least 80 wt%.

[000346] In an embodiment the hydrogel has a water content of at least 85 wt%.

[000347] In an embodiment the hydrogel has a water content of at least 90 wt%.

[000348] In an embodiment the hydrogel has a water content of at least 97 wt%.

[000349] In an embodiment the hydrogel has a water content of at least 96 wt%.

[000350] In an embodiment the hydrogel has a water content of at least 95 wt%.

[000351] In an embodiment the hydrogel has a water content of at least 94 wt%.

[000352] In an embodiment the hydrogel has a water content of at least 93 wt%.

[000353] In an embodiment the hydrogel has a water content of at most 99 wt%.

[000354] In an embodiment the hydrogel has a water content of at most 98 wt%.

[000355] an embodiment the hydrogel according to the invention is characterized in that it further comprises an API. [000356] In an embodiment, the cross-linked dextran polymer according to the invention is a dextran polymer bearing anionic groups of formula II wherein the at least divalent radical L(-)i is covalently bound to the dextran polymer backbone with i -W- radicals, wherein i is 2, 4 or 8.

[000357] In an embodiment, the cross-linked dextran polymer according to the invention is a dextran polymer bearing anionic groups of formula X wherein the at least divalent radical L(-)i is covalently bound to the dextran polymer backbone with i radicals, wherein i is 2, 4 or 8.

[000358] In an embodiment, the cross-linked dextran polymer according to the invention is a dextran polymer bearing anionic groups of formula II wherein the at least divalent radical L(-)i is covalently bound to the dextran polymer backbone with i -W-- radicals, wherein, i is 2.

[000359] In an embodiment, the cross-linked dextran polymer according to the invention is a dextran polymer bearing anionic groups of formula X wherein the at least divalent radical L(-)i is covalently bound to the dextran polymer backbone with i radicals, wherein, i is 2.

[000360] In an embodiment, the cross-linked dextran polymer according to the invention is a dextran polymer bearing anionic groups of formula II wherein the at least divalent radical L(-)i is covalently bound to the dextran polymer backbone with i -W- radicals, wherein, i is 4.

[000361] In an embodiment, the cross-linked dextran polymer according to the invention is a dextran polymer bearing anionic groups of formula X wherein the at least divalent radical L(-)i is covalently bound to the dextran polymer backbone with i radicals, wherein, i is 4.

[000362] In an embodiment, the cross-linked dextran polymer according to the invention is a dextran polymer bearing anionic groups of formula II wherein the at least divalent radical L(-)i is covalently bound to the dextran polymer backbone with i -W- - radicals, wherein, i is 8.

[000363] In an embodiment, the cross-linked dextran polymer according to the invention is a dextran polymer bearing anionic groups of formula X wherein the at least divalent radical L(-)i is covalently bound to the dextran polymer backbone with i radicals, wherein, i is 8.

[000364] The cross-linking step is a gelation step that leads to the formation of a hydrogel according to the invention. [000365] The hydrogel formation kinetic is function of the temperature and could be modulated by the reactant's concentrations, pH and temperature.

[000366] In an embodiment the time to obtain a hydrogel according to the invention is comprised from 1 minute to 6 hours.

[000367] In an embodiment the cross-linking step is carried out for 1 hour.

[000368] In an embodiment the temperature of the cross-linking step is comprised from 4°C to room temperature (20-25°C) and could vary between the step of mixing and the step of gelation and moulding.

[000369] In an embodiment the mixing is performed at 4°C and the gelation is carried out at room temperature (20-25°C) for 1 hour.

[000370] In an embodiment the mixing is performed at room temperature (20- 25°C).

[000371] In an embodiment the mixing is performed at 4°C or room temperature (20-25°C) and the gelation is carried out at room temperature (20-25°C) for 1 hour. [000372] In an embodiment, the gelation is carried out at 37 °C.

[000373] In an embodiment, after cross-linking or gelation, the hydrogel is swelled in a buffer solution, the pH of the buffer solution is comprised from 5 to 8, preferably from 6 to 8 and more preferably from 6.8 to 7.5.

[000374] In an embodiment, the buffer solution is a PBS solution at pH 7.4.

[000375] In an embodiment, the buffer solution is a Tris solution at pH 7.4.

[000376] In an embodiment, the buffer solution is a Tris solution at pH 8.

[000377] In an embodiment the swelling allows the hydrogel mass being increased by 1, 2, 3 or 4 compared to its initial mass.

[000378] The invention also concerns a process to synthetize a cross-linked dextran polymer according to the invention, into the form of a hydrogel, comprising the steps of: a) preparation of a sterile solution comprising a dextran bearing anionic groups of formula II and at least two precursors of -W- b) preparation of a sterile solution of a precursor of L(-)i c) addition of the sterile solution obtained from step b) to the solution obtained from step a), d) the addition being directly done in a mould or the solutions are introduced into a mould after being mixed, e) cross-linking and gelation, for example at room temperature (20-25°C) or at 37°C, f) unmoulding and swelling to obtain an hydrogel. [000379] In an embodiment steps c) and d) are done simultaneously.

[000380] In an embodiment, the swelling is done into a PBS solution at pH 7,4.

[000381] The invention also concerns a process to synthetize a cross-linked dextran polymer according to the invention, into the form of a hydrogel, comprising the steps of: a) preparation of a sterile solution comprising a dextran bearing anionic groups of formula X and at least two precursors of -(A-f2)a-Gi-, -(A'-f2)a- G'i-, b) preparation of a sterile solution of a precursor of L(-)i c) addition of the sterile solution obtained from step b) to the solution obtained from step a), d) the addition being directly done in a mould or the solutions are introduced into a mould after being mixed, e) cross-linking and gelation, for example at room temperature (20-25°C) or at 37°C, f) unmoulding and swelling to obtain an hydrogel.

[000382] In an embodiment steps c) and d) are done simultaneously.

[000383] In an embodiment, the swelling is done into a PBS solution at pH 7,4.

[000384] Dextrans bearing anionic groups of formula II are prepared by grafting or substitution on the hydroxyl groups borne by the dextrans. In an embodiment the dextrans bearing anionic groups of formula II are prepared by grafting or substituting the carboxymethyl groups borne by the carboxymethyl dextrans.

[000385] Dextrans bearing anionic groups of formula X are prepared by grafting or substitution on the hydroxyl groups borne by the dextrans. In an embodiment the dextrans bearing anionic groups of formula X are prepared by grafting or substituting the carboxymethyl groups borne by the carboxymethyl dextrans.

[000386] In an embodiment of the process according to the invention an active pharmaceutical ingredient (API) is entrapped into the hydrogel.

[000387] The invention also concerns a therapeutic use of the hydrogel according to the invention as a therapeutic implant to administer the API to a mammal.

[000388] The invention also concerns a process to prepare a hydrogel comprising an API comprising the steps of: a) preparation of a sterile solution comprising a dextran a dextran bearing anionic groups of formula II and at least two precursors of -W-, b) preparation of a sterile solution of a precursor of L(-)i, c) preparation of a suspension of an API, d) mixing the API suspension obtained from step c) and the solution obtained from the step b) or a), e) addition of the sterile solution obtained from step a) or b) which is not used in step d) to the suspension obtained from step d), f) the addition of step e) being either done directly in a mould or the solutions are introduced into a mould after being mixed, g) cross-linking and gelation reaction at room temperature (20-25°C), h) unmoulding and swelling to obtain an hydrogel comprising an API.

[000389] The invention also concerns a process to prepare a hydrogel comprising an API comprising the steps of: a) preparation of a sterile solution comprising a dextran a dextran bearing anionic groups of formula II and at least two precursors of -W-, b) preparation of a sterile solution of a precursor of L(-)i, c) preparation of a suspension of an API, d) mixing the API suspension obtained from step c) and the solution obtained from the step b) or a), e) addition of the sterile solution obtained from step a) or b) which is not used in step d) to the suspension obtained from step d), f) the addition of step e) being either done directly in the barrel of a syringe or the solution I suspension are introduced into the barrel of a syringe after being mixed, g) injection of the mixture from step f). h) cross-linking and gelation reaction at room temperature (20-25°C), i) unmoulding and swelling to obtain an hydrogel comprising an API.

[000390] The invention also concerns a process to prepare a hydrogel comprising biological cells comprising the steps of: a) preparation of a sterile solution comprising a dextran a dextran bearing anionic groups of formula X and at least two precursors of -(A-f2)a-Gi-, - (A'-f ₂ )a-G'i-, b) preparation of a sterile solution of a precursor of L(-)i, c) preparation of a suspension of biological cells, d) mixing the biological cells suspension obtained from step c) and the solution obtained from the step b) or a), e) addition of the sterile solution obtained from step a) or b) which is not used in step d) to the solution obtained from step d), f) the addition of step e) being either done directly in a mould or the solutions are introduced into a mould after being mixed, g) cross-linking and gelation reaction at room temperature (20-25°C), h) unmoulding and swelling to obtain an hydrogel comprising API.

[000391] In an embodiment, the swelling is done into a PBS solution at pH 7.4.

[000392] The invention also concerns an implantable device comprising at least a hydrogel according to the invention and obtained according to the process of the invention.

[000393] The invention also concerns a hydrogel for use as a medicament.

[000394] The invention also concerns a hydrogel for use in the treatment of a disease such as diabetes.

[000395]

[000396] The invention also concerns an implant consisting of the hydrogel according to the invention used for drug delivery.

[000397] The invention also concerns an implant comprising the hydrogel according to the invention used for drug delivery.

[000398] The invention also concerns an implant comprising the hydrogel according to the invention and an API used for drug delivery.

[000399] In an embodiment, at least 50 % of the surface the hydrogel is directly in contact with the medium in which it is implanted.

[000400] In an embodiment, at least 75 % of the surface the hydrogel is directly in contact with the medium in which it is implanted.

[000401] In an embodiment, at least 90 % of the surface the hydrogel is directly in contact with the medium in which it is implanted.

[000402] In an embodiment, at least 95 % of the surface the hydrogel is directly in contact with the medium in which it is implanted.

[000403] In an embodiment, 99 % of the surface the hydrogel is directly in contact with the medium in which it is implanted.

[000404] In an embodiment, at least 50 % of the surface the hydrogel is directly in contact with the exterior of the device or implant. [000405] By « directly in contact with the exterior » means there is no separation between the hydrogel and the exterior, for example no wall made of a non-hydrogel material between the hydrogel and the exterior of the device or implant.

[000406] In an embodiment, at least 75 % of the surface the hydrogel is directly in contact with the exterior of the device or implant.

[000407] In an embodiment, at least 90 % of the surface the hydrogel is directly in contact with the exterior of the device or implant.

[000408] In an embodiment, at least 95 % of the surface the hydrogel is directly in contact with the exterior of the device or implant.

[000409] In an embodiment, at least 99 % of the surface the hydrogel is directly in contact with the exterior of the device or implant.

[000410] In an embodiment, 100 % of the surface the hydrogel is directly in contact with the exterior of the device or implant.

[000411] The API are entrapped into the maze of cross-linked dextran hydrogel.

[000412] In this specification the word "entrapped" is equivalent to "encapsulated" or "encapsulation".

[000413] The hydrogel matrix allows passage of small molecules e.g., API, API being entrapped into the hydrogel.

[000414] Typically, API are hormone and peptide drugs chosen amongst PTH protein, insulin and coagulation factors.

[000415] In an embodiment, this mesh size is less than 1 pm.

[000416] In another embodiment it is less than 100 nanometers, preferably less than

10 nanometers, and more preferably around 5 nanometers.

[000417] In an embodiment the invention concerns an implant comprising a ring, a net, the hydrogel according to the invention and an API.

[000418] The ring and net structure allow the hydrogel to be easily manipulated, a good resistance to manipulation, including for implantation. This is also true even with a hydrogel having a larger mesh size (for example with a lower DS of-W-and lower concentrations of reactive groups during crosslinking).

[000419] The ring and net structure allow the hydrogel to be easily manipulated, a good resistance to manipulation, including for implantation. This is also true even with a hydrogel having a larger mesh size (for example with a lower DS -(A-f2)a-Gi- and lower concentrations of reactive groups during crosslinking). [000420] Figure 1 represents an implant (1) comprising a hydrogel (11) comprising an API (not represented), a ring (12) and a net (13). Upper part of the ring, lower part of the ring and net can be glued together (not represented).

[000421] Figure 2 represents an implant (1) comprising a hydrogel (11) comprising an API (not represented), a ring (12) and a net (13), where the hydrogel is concave.

[000422] Figure 3 is a top view of an implant (1) comprising a hydrogel (11) comprising an API (not represented), a ring (12) and a net (13).

[000423] Figure 4 represents an implant (1) comprising a hydrogel without API(20) sandwiching a hydrogel comprising an API (21). The upper part of 20 being optional.

[000424] Figures 5A shows the pharmacokinetics of LNG from B5-37 and B5-16 (Median LNG concentration in ng/ml over time in days)

[000425] Figures 5B shows the pharmacokinetics of LNG from B5-15 and B5-16 (Median LNG concentration in ng/ml over time in days)

[000426] Figures 6A shows the pharmacokinetics of LNG from B5-19 and B5-20 (Median LNG concentration in ng/ml over time in days)

[000427] Figure 6B shows the Cumulative input of LNG from B5-19 and B5-20 (Cumulative input over time in days)

[000428] In an embodiment the ring has an internal diameter of 10 to 100 mm.

[000429] In an embodiment the ring has an internal diameter of 15 to 50 mm.

[000430] In an embodiment the ring has a diameter of 0.5 to 5 mm

[000431] In an embodiment the ring has a diameter of 0.5 to 10 mm.

[000432] In an embodiment the ring has a diameter of 0.5 to 5 mm.

[000433] In an embodiment the ring has a total (lower plus upper part and glue) thickness of 100 to 3000 pm.

[000434] In an embodiment the ring has a total (lower plus upper part and glue) thickness of 150 to 2000 pm.

[000435] In an embodiment the ring has a total thickness of 200 to 5000 pm.

[000436] In an embodiment the ring has a total thickness of 500 to 3000 pm.

[000437] In an embodiment the ring has a rectangular, square or round section.

[000438] In an embodiment the ring material is a bioinert material.

[000439] In an embodiment, the ring material is a biocompatible elastomer.

[000440] In an embodiment the ring material is chosen from the group consisting of silicone, in particular PDMS, polyurethanes, polyether, polyether polyester copolymers and polypropylene oxide.

[000441] In an embodiment the ring material is silicone.

[000442] In an embodiment the ring material is PDMS. [000443] In an embodiment the net is non-biodegradable.

[000444] In an embodiment the net is biocompatible.

[000445] In an embodiment the net is non absorbable.

[000446] In an embodiment the net is a surgical mesh.

[000447] In an embodiment the filament material of the net material is chosen among the group consisting of Polypropylene, Polyethylene, polyester, in particular PET,

PTFE, PVDF (polyvinylidene fluoride) and ePVDF (extended PVDF).

[000448] In an embodiment the filament material of the net is chosen among the group consisting of Polypropylene, polyester, in particular PET, PTFE and PVDF (polyvinylidene fluoride).

[000449] In an embodiment the filament material of the net is chosen among the group consisting of Polypropylene and polyester, in particular PET.

[000450] In an embodiment the filament material of the net is chosen among the group consisting of Polypropylene.

[000451] In an embodiment the filament material of the net is chosen among the group consisting of is polyester, in particular PET.

[000452] In an embodiment the net has a thickness ranging from 50 to 500 pm.

[000453] In an embodiment the m net has a thickness ranging from 100 to 300 pm.

[000454] In an embodiment, the filament diameter is ranging from 0.08 to 0.2 mm.

[000455] In an embodiment the pore size is ranging from 0.4 to 4 mm.

[000456] In an embodiment the pore size is ranging from 0.6 to 2 mm.

[000457] In an embodiment fabric of the net is chosen from the group consisting of knitted fabric, warp knitted fabric, woven fabric, non-woven fabric.

[000458] In an embodiment fabric of the net is chosen from the group consisting of warp knitted fabric, in particular multi-filament.

[000459] In an embodiment the net is treated in order to increase the hydrophilicity. [000460] In an embodiment the net is treated with a base, in particular on polyester, more particularly on PET.

[000461] In an embodiment this treatment is functionalisation of the surface from reactive function, such as -OH, -COOH, and reactive molecules or polymer.

[000462] The grafted polymer could thus expose reactive functions for a further reaction with the hydrogel or a precursor of hydrogel, such as a thiol function.

[000463] In an embodiment this treatment is done by adsorption of synthetic polymers, such as poloxamers or polyvinyl pyrrolidone (PVP) or of natural polymers, such as collagen, or of surfactants after a chemical or physical treatment. [000464] In an embodiment the net remains below the exterior end of the ring.

[000465] In an embodiment the net is not in contact with the exterior of the implant comprising a ring, a net and the hydrogel.

[000466] In an embodiment the glue is biocompatible.

[000467] In an embodiment the glue is a biocompatible silicone glue, such as Silbione MED ADH 4200 supplied by Elkem.

[000468] In an embodiment the glue remains below the exterior end of the ring.

[000469] For example, a warp knit Polyester surgical net fabric type PETKM3002 (1x0.9mm pore size) supplied by SurgicalNet™ was treated in NaOH IM for 5 hours at 70°C and rinsed with deionized water and ethanol 96%. The treatment led to an increased hydrophilicity of the net fabric leading to an improved wetting with aqueous solutions.

[000470] For example, a ring net construct may be obtained following the process below:

Biocompatible PDMS sheets supplied by Grace Biolabs or Interstate Speciality Product is cut in a form of a square incorporating a circular empty disc using a stainless-steel punch,

- A part of the treated polyester surgical net described is introduced in between two square PDMS pieces: The two PDMS pieces and the surgical net are glued together with biocompatible silicone glue (Silbione MED ADH 4200 supplied by Elkem). The circular empty discs are aligned, and the surgical net is kept tense during gluing,

- then, the square construct is cut with a stainless-steel punch to obtain the final object constituted by two PDMS rings sandwiching a surgical net and glued together, and

- The pieces are washed with a solution of poloxamer F127 at 1% and rinsed with water before steam sterilization.

[000471] In an embodiment, the implant can be obtained by the following process: Hydrogel compositions are incorporated in the Ring Mesh constructs. The concentrated polymer solutions are mixed with a pipette and a controlled volume of the mixture is introduced in a ring net construct adhering to a glass slide, Crosslinking leading to gelation is carried out. Then the Ring Mesh + Hydrogel composition is introduced in a Tris 150 mM /NaCI 30 mM I Cystein 10 mM solution at pH 8 or in PBS at pH 7.4,

The hydrogel was rinsed with PBS solution without cysteine and further immersed in the PBS solution overnight at 37°C. The hydrogel piece was then stored in PBS solution at 4°C until being used.

[000472] Hydrogel/Ring Mesh implants can then be easily manipulated with tweezers and are foldable for the need of surgical implantation. Moreover, it is possible to fix the ring with sutures.

[000473] The hydrogel volume can be adjusted with the internal diameter and the thickness or the ring net construct. For the same ring net construct, the hydrogel volume can be adjusted to control the convexity / concavity of the hydrogel above the ring level. [000474] In an embodiment, the hydrogel comprises a first layer of the hydrogel wich does not comprise API and a second layer of the hydrogel which comprises API.

[000475] Such a structure may be obtained with a process as disclosed in this application, but with two steps of adding hydrogel precursors first step is adding hydrogel precursors without API as a first layer, and the second step is adding the hydrogel precursor with API while the gelation of the first step is not finished, in particular at a time corresponding to 5 to 25 % of the gelation time of the first hydrogel, as a second layer.

EXAMPLES

Part A - CHEMISTRY

Example Al: Synthesis of substituted dextran

Table 1: List of synthesized polysaccharides

Polymer 1 - Dextran Methyl Carboxylate and Vinyl Sulfone Polymer 1.1 - Dextran Methyl Carboxylate

[000476] 65 g (0.4 mol of glucoside units, 1.2 mol of hydroxyl functional groups) of dextran having a weight-average molar mass of 40 kg/mol (Pharmacosmos, degree of polymerization n = 205), are dissolved in water (285 g/L) at 30°C, then NaBI- (74 mg, 1.95 mmol) is added and the mixture is stirred at 30°C for 2 h. To this solution is added sodium chloroacetate (140 g, 1.2 mol) and the mixture is heated at 65°C for 1 h. 10 N NaOH (200 mL, 2 mol) is then slowly added over 1.5 h and the mixture is stirred at 65°C for 1 h. The mixture is diluted with water (120 mL), cooled to room temperature, neutralized with acetic acid and then purified by ultrafiltration on PES membrane (MWCO 5 kDa) against phosphate buffer pH 7, then water. The polymer 1.1 concentration of the final solution is determined by dry extract, and then an acid/base assay is carried out in order to determine the degree of substitution with methyl carboxylate.

[000477] According to the dry extract: [polymer 1.1] = 50.6 mg/g

[000478] According to the acid/base assay, degree of substitution with methylcarboxylate (DS2) = 1.2

Polymer 1.2 - Dextran Methyl Carboxylate

[000479] 90 g (0.35 mol of glucoside units) of freeze-dried polymer 1.1 are dissolved in water (260 g/L) at 65°C, then sodium chloroacetate (204 g, 1.75 mol) is added and the mixture is maintained at 65°C for 1 h. 10 N NaOH (175 mL, 1.75 mol) is then slowly added over 1 h and the mixture is stirred at 65°C for a further 1 h. Another portion of sodium chloroacetate (122 g, 1.05 mol) is then added and the mixture is maintained at 65°C for 0.5 h. 10 N NaOH (105 mL, 1.05 mol) is then slowly added over 1 h and the mixture is stirred at 65°C for a further 1 h. The mixture is diluted with water, cooled to room temperature, neutralized with acetic acid and then purified by ultrafiltration on PES membrane (MWCO 5 kDa) against phosphate buffer pH 7, then water. The polymer 1.2 concentration of the final solution is determined by dry extract, and then an acid/base assay is carried out in order to determine the degree of substitution with methyl carboxylate.

[000480] According to the dry extract: [polymer 1.2] = 48.4 mg/g

[000481] According to the acid/base assay, degree of substitution with methylcarboxylate (DS2) = 2.1

Polymer 1 - Dextran Methyl Carboxylate and Vinyl Sulfone

[000482] To 207 g of the solution of polymer 1.2 (48.4 mg/g, DS2 = 2.1, 10.0 g, 30.28 mmol of glucoside units), 2-hydroxypyridine 1-oxide (HOPO) (1.68 g, 15.14 mmol) is added and the mixture is cooled to 4°C. To this solution are added 2-[[2- (ethenylsulfonyl)ethyl]thio]ethanamine hydrochloride (VS) (2.10 g, 9.08 mmol) (synthesized according: S. A. Stewart et al., Soft Matter, 2018, 14, 8317), EtsN (1.27 mL, 9.08 mmol) and /V-ethyl-/V'-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) (2.90 g, 15.14 mmol) and the reaction mixture is stirred between 4°C and 25°C for 2 h. Two additional additions of EDC (2.90 g, 15.14 mmol) are performed every 2 h. The mixture is diluted with NaCI (9 g/L in water), then purified by ultrafiltration on PES membrane (MWCO 5 kDa) against NaCI (9 g/L in water), carbonate buffer pH 9-10, NaCI (9 g/L in water), phosphate buffer pH 7, NaCI (9 g/L in water), and then water. The polymer 1 concentration of the final solution is determined by dry extract, and the degree of substitution with vinyl sulfone is determined by ^X H NMR in D2O. The final solution is stored at -20°C.

[000483] According to the dry extract: [polymer 1] = 21.3 mg/g

[000484] According to ^X H NMR (D2O), degree of substitution with vinyl sulfone

(DSi) = 0.25

Polymer 2 - Dextran Methyl Carboxylate Sulfate and Maleimide

Polymer 2.1 - Dextran Methyl Carboxylate

[000485] 50 g (0.31 mol of glucoside units, 0.93 mol of hydroxyl functional groups) of dextran having a weight-average molar mass of 40 kg/mol (Pharmacosmos, degree of polymerization n = 205), are dissolved in water (225 g/L) at 30°C, then NaBI- (2 x 58 mg, 2 x 1.54 mmol) is added every 30 minutes and the mixture is stirred at 30°C for 1 h. To this solution is added sodium chloroacetate (72 g, 0.62 mol) and the mixture is heated at 65°C for 1 h. 10 N NaOH (103 mL, 1.03 mol) is then slowly added over 1.5 h and the mixture is stirred at 65°C for 1 h. The mixture is diluted with water (85 mL), cooled to room temperature, neutralized with acetic acid and then purified by ultrafiltration on PES membrane (MWCO 5 kDa) against phosphate buffer pH 7, then water. The polymer 2.1 concentration of the final solution is determined by dry extract, and then an acid/base assay is carried out in order to determine the degree of substitution with methyl carboxylate.

[000486] According to the dry extract: [polymer 2.1] = 46.3 mg/g

[000487] According to the acid/base assay, degree of substitution with methylcarboxylate (DS2) = 0.8

Polymer 2.2 - Dextran Methyl Carboxylic acid

[000488] 550 g of the solution of polymer 2.1 obtained above (46.3 mg/g, DS2 =

0.8, 25.5 g, 112.6 mmol of glucoside units) is protonated with an acidified sulfonic resin (Purolite C100H, 2.0 eq/L, 200 mL, 400 mmol) for 2 h. The resulting solution is filtered, then freeze-dried.

Polymer 2.3 - Dextran Methyl Carboxylate Sulfate

[000489] 10.0 g (48.0 mmol of glucoside units) of freeze-dried polymer 2.2 are dissolved in a mixture of DMF (320 mL) and formamide (80 mL). After complete dissolution, 2-methyl-2-butene (80 mL, 755.2 mmol) is slowly added. A SCh-DMF complex (58.8 g, 383.9 mmol) is rapidly added, and the reaction mixture is stirred at 30°C for 3 h. The mixture is neutralized by slow addition of 5 % aq. NaHCC (800 mL) and purified by ultrafiltration on PES membrane (MWCO 5 kDa) against 30 % v:v EtOH in NaCI (9 g/L in water), NaCI (9 g/L in water), then water. The polymer 2.3 concentration of the final solution is determined by dry extract, and the degree of substitution with sulfate is determined by liquid chromatography after complete sulfate hydrolysis of a representative sample.

[000490] According to the dry extract: [polymer 2.3] = 39.6 mg/g

[000491] According to the LC analysis, degree of substitution with sulfate (DS3) = 1.5

Polymer 2 - Dextran Methyl Carboxylate Sulfate and Maleimide

[000492] To 303 g of the solution of polymer 2.3 obtained above (39.6 mg/g, DS3 = 1.5, DS2 = 0.8, 12.0 g, 31.64 mmol of glucoside units), 2-hydroxypyridine 1-oxide (HOPO) (1.76 g, 15.82 mmol) is added and the mixture is cooled to 4°C. To this solution are added /V-(2-aminoethyl)maleimide hydrochloride (Mai) (1.68 g, 9.49 mmol) and N- ethyl-/V'-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) (3.03 g, 15.82 mmol) and the reaction mixture is stirred at 4°C for 2 h. Two additional additions of EDC (3.03 g, 15.82 mmol) are performed every 2 h. The mixture is diluted with phosphate buffer pH 7, then purified by ultrafiltration on PES membrane (MWCO 5 kDa) against phosphate buffer pH 7, NaCI (9 g/L in water) and then water. The polymer 2 concentration of the final solution is determined by dry extract, and the degree of substitution with maleimide is determined by ^X H NMR in D2O. The final solution is stored at -20°C.

[000493] According to the dry extract: [polymer 2] = 22.2 mg/g

[000494] According to ^X H NMR (D2O), degree of substitution with maleimide (DSi) = 0.25

Polymer 3 - Dextran Methyl Carboxylate Sulfate and Maleimide

Polymer 3.1 - Dextran Methyl Carboxylate

[000495] Using a process similar to the one used for the preparation of polymer 2.1, starting from a dextran having a weight-average molar mass of 40 kg/mol (0.25 mol of glucoside units, 0.75 mol of hydroxyl functional groups, degree of polymerization n = 205), and with sodium chloroacetate (35.9 g, 0.31 mol) and 10 N NaOH (82 mL, 0.82 mol) at 60°C, polymer 3.1 is obtained.

According to the dry extract: [polymer 3.1] = 44.2 mg/g

According to the acid/base assay, degree of substitution with methylcarboxylate (DS2) = 0.5

Polymer 3.2 - Dextran Methyl Carboxylic acid

Using a process similar to the one used for the preparation of polymer 2.2, starting from polymer 3.1 (44.2 mg/g, DS2 = 0.5, 12.0 g, 59.4 mmol of glucoside units), polymer 3.2 is obtained. Polymer 3.3 - Dextran Methyl Carboxylate Sulfate

Using a process similar to the one used for the preparation of polymer 2.3, starting from polymer 3.2 (4.0 g, 20.9 mmol of glucoside units), polymer 3.3 is obtained.

According to the dry extract: [polymer 3.3] = 22.0 mg/g

According to the LC analysis, degree of substitution with sulfate (DS3) = 1.9

Polymer 3 - Dextran Methyl Carboxylate Sulfate and Maleimide

Using a process similar to the one used for the preparation of polymer 2, starting from polymer 3.3 (22.0 mg/g, DS2 = 0.5, DS3 = 1.9, 4.6 g, 11.6 mmol of glucoside units), and with /V-(2-aminoethyl) maleimide hydrochloride (615 mg, 3.48 mmol), polymer 3 is obtained.

According to the dry extract: [polymer 3] = 12.3 mg/g

According to ^X H NMR (D2O), degree of substitution with maleimide (DSi) = 0.23

Polymer 4 - Dextran Methyl Carboxylate Sulfate and Vinyl Sulfone

Using a process similar to the one used for the preparation of polymer 1, starting from polymer 2.3 (35.7 mg/g, DS2 = 0.8, DS3 = 1.5, 10.0 g, 26.37 mmol of glucoside units), and 2-[[2-(ethenylsulfonyl)ethyl]thio]ethanamine hydrochloride (1.83 g, 7.91 mmol), polymer 4 is obtained.

According to the dry extract: [polymer 4] = 21.8 mg/g

According to ^X H NMR (D2O), degree of substitution with vinyl sulfone (DSi) = 0.28

Polymer 5 - Dextran Methyl Carboxylate Sulfonate and Maleimide

Polymer 5.1 - Dextran Methyl Carboxylate Sulfonate

To 400 g of solution of polymer 1.2 (48.4 mg/g, DS2 = 2.1, 19.4 g, 58.63 mmol of glucoside units) are added HOPO (9.77 g, 87.95 mmol), 3-amino-l-propanesulfonic acid (Homotaurine) (9.79 g, 70.36 mmol), EtsN (9.81 mL, 70.36 mmol) and EDC (16.86 g, 87.95 mmol) and the reaction mixture is stirred at 25°C for 2 h. Two additional additions of EDC (16.86 g, 87.95 mmol) are performed every 2 h. The mixture is diluted with phosphate buffer pH 7, then purified by ultrafiltration on PES membrane (MWCO 5 kDa) against phosphate buffer pH 7, NaCI (9 g/L in water) and then water. The polymer 5.1 concentration of the final solution is determined by dry extract, and the degree of substitution with homotaurine is determined by ^X H NMR in D2O. The final solution is stored at 4°C.

According to the dry extract: [polymer 5.1] = 40.9 mg/g

According to ^X H NMR (D2O), degree of substitution with homotaurine (DS3) = 1.15 Polymer 5 - Dextran Methyl Carboxylate Sulfonate and Maleimide

Using a process similar to the one used for the preparation of polymer 2, starting from polymer 5.1 (40.9 mg/g, DS2 = 2.1, DS3 = 1.15, 9.4 g, 20.0 mmol of glucoside units), and with /V-(2-aminoethyl) maleimide hydrochloride (1.06 g, 6.0 mmol), polymer 5 is obtained.

According to the dry extract: [polymer 5] = 19.9 mg/g

According to ^X H NMR (D2O), degree of substitution with maleimide (DSi) = 0.25

Polymer 6 - Dextran Methyl Carboxylate Ammonio-Sulfonate and Maleimide

Polymer 6.1 - Dextran Methyl Carboxylate Ammonio-Sulfonate

Using a process similar to the one used for the preparation of polymer 5.1, starting from polymer 1.2 (48.4 mg/g, DS2 = 2.1, 7.3 g, 22.11 mmol of glucoside units), and with HOPO (2.95 g, 26.53 mmol), 3-((2-aminoethyl)-dimethylammonio)propane-l-sulfonate (SB) (7.51 g, 26.53 mmol) (synthesized according: L. Yang et al., J. Mater. Chem. B, 2013, 1, 1421), EtsN (7.4 mL, 53.06 mmol) and EDC (3 x 5.09 g, 3 x 26.53 mmol), polymer 6.1 is obtained.

According to the dry extract: [polymer 6.1] = 34.6 mg/g

According to ^X H NMR (D2O), degree of substitution with SB (DS3) = 0.7

Polymer 6 - Dextran Methyl Carboxylate Ammonio-Sulfonate and Maleimide

Using a process similar to the one used for the preparation of polymer 2, starting from polymer 6.1 (34.6 mg/g, DS2 = 2.1, DS3 = 0.7, 7.5 g, 16.7 mmol of glucoside units), and with /V-(2-aminoethyl) maleimide hydrochloride (885 mg, 5.01 mmol), polymer 6 is obtained.

According to the dry extract: [polymer 6] = 15.0 mg/g

According to ^X H NMR (D2O), degree of substitution with maleimide (DSi) = 0.22

Polymer 7 - Dextran Methyl Carboxylate and Cyclooctyne (DBCO)

To 30 g of solution of polymer 1.2 (48.4 mg/g, DS2 = 2.1, 1.45 g, 4.39 mmol of glucoside units), HOPO (244 mg, 2.20 mmol) and DMF (25 mL) are added, and the mixture is cooled to 4°C. To this solution are added 3-amino-l-(ll,12-didehydrodibenz[b,f]azocin- 5(6/7)-yl)-l-propanone (DBCO-NH2) (365 mg, 1.32 mmol) in DMF (5 mL) and EDC (422 mg, 2.20 mmol) and the reaction mixture is stirred between 4°C and 25°C for 2 h. Two additional additions of EDC (422 mg, 2.20 mmol) are performed every 2 h. The mixture is diluted with phosphate buffer pH 7, then purified by ultrafiltration on PES membrane (MWCO 5 kDa) against phosphate buffer pH 7, NaCI (9 g/L in water) and then water. The polymer 7 concentration of the final solution is determined by dry extract, and the degree of substitution with DBCO-NH2 is determined by ^X H NMR in D2O. The final solution is stored at -20°C.

According to the dry extract: [polymer 7] = 6.1 mg/g

According to ^X H NMR (D2O), degree of substitution with DBCO-NH2 (DSi) = 0.28

Polymer 8 - Dextran Methyl Carboxylate and Azide

Using a process similar to the last step used for the preparation of polymer 2 (step from polymer 2.3 to polymer 2), starting from polymer 1.2 (48.4 mg/g, DS2 = 2.1, 6.2 g, 18.8 mmol of glucoside units), and with ll-azido-3,6,9-trioxaundecan-l-amine (N3- PEG3-NH2) (1.23 g, 5.64 mmol), polymer 8 is obtained.

According to the dry extract: [polymer 8] = 24.6 mg/g

According to ^X H NMR (D2O), degree of substitution with N3-PEG3-NH2 (DSi) = 0.28

Polymer 9 - Dextran Methyl Carboxylate Phosphonate and Maleimide

Using a process similar to the one used for the preparation of polymer 5.1, starting from polymer 1.2 (41.3 mg/g, DS2 = 2.1, 4.13 g, 12.51 mmol of glucoside units), and with HOPO (695 mg, 6.25 mmol), 3-aminopropylphosphonic acid (261 mg, 1.88 mmol), EtsN (262 pL, 1.88 mmol) and EDC (3 x 1.20 g, 3 x 6.25 mmol), polymer 9.1 is obtained. According to the dry extract: [polymer 9.1] = 16.0 mg/g

According to ^X H NMR (D2O), degree of substitution with 3-aminopropylphosphonic acid (DS3) = 0.05

Polymer 9 - Dextran Methyl Carboxylate Phosphonate and Maleimide

Using a process similar to the one used for the preparation of polymer 2, starting from polymer 9.1 (16.0 mg/g, DS2 = 2.1, DS3 = 0.05, 2.64 g, 7.83 mmol of glucoside units), and with /V-(2-aminoethyl) maleimide hydrochloride (415 mg, 2.35 mmol), polymer 9 is obtained.

According to the dry extract: [polymer 9] = 8.0 mg/g

According to ^X H NMR (D2O), degree of substitution with maleimide (DSi) = 0.25

Polymer 10 - Dextran Methyl Carboxylate Phosphonate and Maleimide

Using a process similar to the one used for the preparation of polymer 5.1, starting from polymer 1.2 (41.3 mg/g, DS2 = 2.1, 4.13 g, 12.51 mmol of glucoside units), and with 3-aminopropylphosphonic acid (2.09 g, 15.01 mmol), a solution is obtained. The pH of this solution is adjusted to pH 2 by the addition of 1 M HCI. After 16 h, the solution is neutralized with 1 M NaOH and then purified by ultrafiltration on PES membrane (MWCO 5 kDa) against NaCI (9 g/L in water) and then water.

According to the dry extract: [polymer 10.1] = 13.3 mg/g

According to ^X H NMR (D2O), degree of substitution with 3-aminopropylphosphonic acid (DS3) = 0.75

Polymer 10 - Dextran Methyl Carboxylate Phosphonate and Maleimide

Using a process similar to the one used for the preparation of polymer 2, starting from polymer 10.1 (13.3 mg/g, DS2 = 2.1, DS3 = 0.75, 3.32 g, 7.59 mmol of glucoside units), and with /V-(2-aminoethyl) maleimide hydrochloride (402 mg, 2.28 mmol), polymer 10 is obtained.

According to the dry extract: [polymer 10] = 11.5 mg/g

According to ^X H NMR (D2O), degree of substitution with maleimide (DSi) = 0.21

Polymer 11 - Dextran Methyl Carboxylate Sulfate and Cyclooctyne (DBCO)

Using a process similar to the one used for the preparation of polymer 7, starting from polymer 2.3 (33.3 mg/g, DS2 = 0.8, DS3 = 1.5, 10.0 g, 26.37 mmol of glucoside units), and with DBCO-NH2 (2.19 g, 7.91 mmol), polymer 11 is obtained.

According to the dry extract: [polymer 11] = 23.3 mg/g

According to ^X H NMR (D2O), degree of substitution with DBCO-NH2 (DSi) = 0.23

Polymer 12 - Dextran Methyl Carboxylate and Cyclooctyne (DBCO)

Polymer 12.1 - Dextran Methyl Carboxylate

Using a process similar to the one used for the preparation of polymer 1.2, starting from a dextran having a weight-average molar mass of 250 kg/mol, polymer 12.1 is obtained. According to the dry extract: [polymer 12.1] = 44.6 mg/g

According to the acid/base assay, degree of substitution with methylcarboxylate (DS2) = 2.0

Using a process similar to the one used for the preparation of polymer 7, starting from polymer 12.1 (44.6 mg/g, DS2 = 2.0, 15.6 g, 48.42 mmol of glucoside units), and with DBCO-NH2 (803 mg, 2.91 mmol), polymer 12 is obtained.

According to the dry extract: [polymer 12] = 20.4 mg/g

According to ^X H NMR (D2O), degree of substitution with DBCO-NH2 (DSi) = 0.06

Polymer 13 - Dextran Methyl Carboxylate and Cyclooctyne (DBCO)

13.1 - Dextran Using a process similar to the one used for the preparation of polymer 1.2, starting from a dextran having a weight-average molar mass of 500 kg/mol, polymer 13.1 is obtained. According to the dry extract: [polymer 13.1] = 45.3 mg/g

According to the acid/base assay, degree of substitution with methylcarboxylate (DS2) = 2.0

Polymer 13 - Dextran Methyl Carboxylate and Cvclooctvne (DBCO)

Using a process similar to the one used for the preparation of polymer 7, starting from polymer 13.1 (45.3 mg/g, DS2 = 2.0, 9.06 g, 28.12 mmol of glucoside units), and with DBCO-NH2 (466 mg, 1.69 mmol), polymer 13 is obtained.

According to the dry extract: [polymer 13] = 21.7 mg/g

According to ^X H NMR (D2O), degree of substitution with DBCO-NH2 (DSi) = 0.06

Polymer 14 - Dextran Methyl Carboxylate and Vinyl Sulfone

To a 100 mM NaOH solution of polymer 1.1 (20.0 mg/mL, DS2 = 1.2, 5.0 g, 19.37 mmol of glucoside units) is rapidly added divinylsulfone (38.8 mL, 387.3 mmol). After 4 minutes at room temperature, the reaction is stopped by adjusting the pH to 6 with 1 M HCI. The mixture is diluted with phosphate buffer pH 7, then purified by ultrafiltration on PES membrane (MWCO 5 kDa) against phosphate buffer pH 7, NaCI (9 g/L in water) and then water. The polymer 14 concentration of the final solution is determined by dry extract, and the degree of substitution with vinyl sulfone is determined by ^X H NMR in D2O. The final solution is stored at -20°C.

According to the dry extract: [polymer 14] = 20.7 mg/g

According to ^X H NMR (D2O), degree of substitution with vinyl sulfone (DSi) = 0.17

Polymer 15 - Dextran Methyl Carboxylate and Triazole-PEG-Azide

Polymer 15.1 - Dextran Methyl Carboxylate and Propargyl

20 g (123.4 mmol of glucoside units, 370.1 mmol of hydroxyl functional groups) of dextran having a weight-average molar mass of 40 kg/mol (Pharmacosmos, degree of polymerization n = 205), are dissolved in water (300 g/L) at 30°C, then NaBH4 (2 x 23 mg, 2 x 0.6 mmol) is added every 30 minutes and the mixture is stirred at 30°C for 1 h. The mixture is cooled at 10°C, then KOH (5.54 g, 98.7 mmol) and benzyltriethylammonium chloride (1.69 g, 7.4 mmol) are added in one portion. A solution of propargyl bromide (5.87 g, 49.3 mmol) in toluene (43% w:w) is then slowly added over 30 minutes and the mixture is stirred at 10°C for 20 minutes and at 25°C for 18 h. The mixture is heated at 60°C and sodium chloroacetate (71.8 g, 616.8 mmol) is added in one portion. After 1 h, 10 N NaOH (56.7 mL, 567 mmol) is slowly added over 1.5 h and the mixture is stirred at 60°C for 1 h. Another portion of sodium chloroacetate (43.1 g, 370.1 mmol) is added in one portion. After 1 h, 10 N NaOH (37.0 mL, 370 mmol) is slowly added over 1.5 h and the mixture is stirred at 60°C for 1 h. The mixture is diluted with water (54 mL), cooled to room temperature and neutralized with acetic acid. Phosphate buffer pH 7 (750 mL) and EtOH (575 mL) are added, the mixture is filtered and then purified by ultrafiltration on PES membrane (MWCO 5 kDa) against phosphate buffer pH 7, NaCI (9 g/L in water), then water. The polymer 15.1 concentration of the final solution is determined by dry extract, the degree of substitution with propargyl is determined by ^X H NMR in D2O, then an acid/base assay is carried out in order to determine the degree of substitution with methyl carboxylate. According to the dry extract: [polymer 15.1] = 40.9 mg/g

According to ^X H NMR (D2O), degree of substitution with propargyl = 0.24

According to the acid/base assay, degree of substitution with methylcarboxylate (DS2) = 1.8

Polymer 15 - Dextran Methyl Carboxylate and Triazole-PEG-Azide

To 39 g of solution of polymer 15.1 (40.9 mg/g, DSi = 0.24, DS2 = 1.8, 1.6 g, 5.06 mmol of glucoside units), are successively added sodium ascorbate (48.1 mg, 0.24 mmol), copper sulfate pentahydrate (30.3 mg, 0.12 mmol), tris(3- hydroxypropyltriazolylmethyl)amine (THPTA) (105.5 mg, 0.24 mmol) and 1,17-diazido- 3,6,9, 12, 15-pentaoxaheptadecane (4.03 g, 12.1 mmol). The reaction mixture is stirred at room temperature for 18 h, diluted with phosphate buffer pH 7, then purified by ultrafiltration on PES membrane (MWCO 5 kDa) against phosphate buffer pH 7, NaCI (9 g/L in water) and then water. The polymer 15 concentration of the final solution is determined by dry extract, and the degree of substitution with azide is determined by ^X H NMR in D2O. The final solution is stored at -20°C.

According to the dry extract: [polymer 15] = 7.0 mg/g

According to ^X H NMR (D2O), degree of substitution with azide (DSi) = 0.24

Polymer 16 - Dextran Methyl Carboxylate and Methyl Furan

Using a process similar to the last step used for the preparation of polymer 2 (step from polymer 2.3 to polymer 2), starting from polymer 1.2 (50.8 mg/g, DS2 = 2.1, 17.8 g, 53.9 mmol of glucoside units), and with 5-methylfurfurylamine (1.80 g, 16.17 mmol), polymer 16 is obtained.

According to the dry extract: [polymer 16] = 30.2 mg/g

According to ^X H NMR (D2O), degree of substitution with Furan (DSi) = 0.30 Polymer 17 - Dextran Methyl Carboxylate and Tetrazine

Using a process similar to the one used for the preparation of polymer 7, starting from polymer 1.2 (50.8 mg/g, DS2 = 2.1, 5.08 g, 15.38 mmol of glucoside units), and with (4-(6-methyl-l,2,4,5-tetrazin-3-yl)phenyl)methanamine hydrochloride (1.1 g, 4.62 mmol), polymer 17 is obtained.

According to the dry extract: [polymer 17] = 11.7 mg/g

According to ^X H NMR (D2O), degree of substitution with tetrazine (DSi) = 0.25

Polymer 18 - Dextran Glycine Carbamate and Cyclooctyne (DBCO)

Polymer 18.1 - Dextran Glycine Carbamate

100 g (0.62 mol of glucoside units, 1.85 mol of hydroxyl functional groups) of dextran having a weight-average molar mass of 40 kg/mol (Pharmacosmos, degree of polymerization n = 205), are dissolved in water (300 g/L) at 30°C, then NaBI- (2 x 116 mg, 2 x 3.08 mmol) is added every 30 minutes and the mixture is stirred at 30°C for 1 h. The mixture is diluted with phosphate buffer pH 7, cooled to room temperature and then purified by ultrafiltration on PES membrane (MWCO 5 kDa) against phosphate buffer pH 7, then water. The resulting solution is filtered, then freeze-dried to give intermediate polymer 18.1.1.

25 g (154.2 mmol of glucoside units, 462.6 mmol of hydroxyl functional groups) of polymer 18.1.1 are dissolved in DMF/DMSO 50: 50 (185 g/L) at 80°C, then toluene (25 mL) and l,4-diazabicyclo[2.2.2]octane (6.92 g, 61.7 mmol) are added. 32 g of the reaction mixture is distilled, then ethyl isocyanatoacetate (51.9 mL, 462.6 mmol) is slowly added over 30 minutes. The mixture is diluted with DMF (150 mL), stirred at 80°C for 18 h, then cooled to room temperature. Water is added (900 mL) and the resulting precipitate is filtered. The precipitate is suspended in H2O/EtOH (70:30) (2.5 L) and the pH of the solution is adjusted to pH 13 by the addition of 10 N NaOH. After 2 h, the mixture is neutralized with 6 M HCI, filtered, then purified by ultrafiltration on PES membrane (MWCO 5 kDa) against NaCI (9 g/L in water) and then water. The polymer 18.1 concentration of the final solution is determined by dry extract, and then an acid/base assay is carried out in order to determine the degree of substitution with glycine carbamate.

According to the dry extract: [polymer 18.1] = 47.8 mg/g

According to the acid/base assay, degree of substitution with glycine carbamate (DS2) = 2.4 Polymer 18 - Dextran Glycine Carbamate and Cvclooctvne (DBCO)

Using a process similar to the one used for the preparation of polymer 7, starting from polymer 18.1 (47.8 mg/g, DS2 = 2.4, 5.98 g, 13.07 mmol of glucoside units), and with DBCO-NH2 (1.08 g, 3.92 mmol), polymer 18 is obtained.

According to the dry extract: [polymer 18] = 20.8 mg/g

According to ^X H NMR (D2O), degree of substitution with DBCO-NH2 (DSi) = 0.28

Polymer 19 - Dextran Glycine Carbamate and Maleimide

Using a process similar to the one used for the preparation of polymer 2, starting from polymer 18.1 (47.8 mg/g, DS2 = 2.4, 5.98 g, 13.07 mmol of glucoside units), and with /V-(2-aminoethyl) maleimide hydrochloride (693 mg, 2.92 mmol), polymer 19 is obtained.

According to the dry extract: [polymer 19] = 22.8 mg/g

According to ^X H NMR (D2O), degree of substitution with maleimide (DSi) = 0.26

Example A2 : Polyethylene glycol derivatives comprising at least two reactive functions

[0001] Commercial Polyethylene glycol (PEG) derivatives functionalized with reactive functions were purchased. The reactive functions include thiols ("PEG-SH"). Multi-arms homofunctional having different molecular weights and bearing different functions were used and are shown in the following Table 2.

Table 2: List of commercial PEG derivatives used Part B - PHYSICO-CHEMISTRY

Example Bl: Preparation of suspension of LNG or other API

[000476] Levonorgestrel (LNG) and Triamcinolone acetonide (TCA) powder were purchased from Sigma Aldrich (Saint Quentin Fallavier, France)

[000477] A concentrated solution of NaCI was prepared by weighing the appropriate weight of NaCI and adding the appropriate weight of sterile deionized water before sterile filtration (0.22 pm). A concentrated solution of polysorbate 80 was prepared by weighing the appropriate weight of polysorbate 80 and adding the appropriate weight concentration solution of NaCI and sterile deionized water before sterile filtration (0.22 pm). A concentrated suspension of levonorgestrel or other API was prepared by weighing the appropriate weight of levonorgestrel or other API and adding the appropriate weight of sterile concentrated solution of polysorbate 80. The suspension was mixed using vortex.

[000478] The suspension of LNG or other API was diluted at 0.7 mg/mL. Microscopy evaluation was carried out using microscope equipped with a x40 lens. The Ferret Diameter was reported.

Example B2: Preparation of solutions of concentrated polysaccharide functionalized with vinyl sulfone (VS) groups or other functionalized polysaccharide

[000479] A concentrated polysaccharide solution was prepared by weighing the appropriate weight of a sterile freeze-dried polysaccharide obtained according to part Al and adding the appropriate weight of sterile deionized water. The solution was placed on an orbital shaker overnight at 70 rpm for complete solubilization. The mass concentration of the solution of polysaccharide (mg/g) was determined by dry extract. The volume concentration of the solution of polysaccharide (mg/mL) was determined by density measurements, weighing three times 100 pL of solution. The sterile solution was frozen at -20°C until being used.

Example B3: Preparation of solutions of concentrated PEG derivative [000480] A concentrated solution of PEG derivative (from the list according to table 2) was prepared by weighing the appropriate weight of a PEG derivative powder and adding the appropriate weight of sterile deionized water. The solution was placed on roller shaker at 15 rpm for 2 h for complete solubilization before sterile filtration (0.22 pm). The mass concentration of the PEG solution (mg/g) was determined by dry extract. The volume concentration of the PEG solution (mg/MI) was determined by density measurements, weighing three times 100 pL of solution. The sterile solution was frozen at -20°C until being used.

Example B4: Hydrogels preparation

[000481] The hydrogels were prepared from LNG or other API concentrated suspension, polysaccharide and PEG derivatives concentrated sterile solutions prepared according to example Bl, B2 and B3, respectively, and made an aseptic environment. [000482] A concentrated suspension of LNG or other API in PEG derivatives solution was prepared by weighing the appropriate weight of concentrated suspension of LNG or other API and adding the appropriated weight of concentrated sterile PEG derivatives solution and sterile deionized water.

[000483] Polysaccharide sterile solution and suspension of LNG or other API in PEG derivatives solution were adjusted with a concentrated NaCI solution to obtain isotonic stock solutions (300 mOsm/kg) and equilibrated either at room temperature (20-25°C). [000484] Polysaccharide sterile solution was buffered with lOmM of 2-(N- morpholino)ethanesulfonic acid (MES) for pH 6 or tris(hydroxymethyl)aminomethane (Tris) for pH 8 or pH7.4 and suspension of LNG or other API in PEG derivatives solutions was buffered with lOmM of MES for pH 6, before sterile filtration (0.22 pm).

[000485] A concentrated suspension of LNG or other API in PEG derivative was added to a concentrated solution of polysaccharide in a 2 mL Eppendorf at 4°C or at room temperature (20-25°C). The volume ratio of the suspension of LNG in PEG to the polysaccharide solution was 70:30 (%:%), 60:40 (%:%) or 50:50 (%:%) depending on hydrogel composition.

Example B4A: Hydrogels preparation for preformed implant

[000486] Using a process similar to the one used for the preparation of hydrogel B4, the suspension of LNG in PEG solution and the polysaccharide solution were mixed with a pipette and a controlled volume of this reconstituted solution was introduced in a circular silicone isolator adhering to a glass slide or spherical silicone isolator. The filling of circular silicone isolator with hydrogel is performed in air or immersed in synovial like medium (aqueous hyaluronic acid solution at 5 mg/mL). Crosslinking leading to gelation was carried out for 1 h at 37°C. The hydrogel was unmolded then was immersed in 5 mL of the PBS solution overnight at 37°C. The hydrogel piece was then stored in 5 mL of PBS solution at 4°C until being used.

Example B4B: Hydrogels preparation for injected implant

Example B4B1 : Hydrogels preparation for injected implant via a regular syringe [000487] Using a process similar to the one used for the preparation of hydrogel B4, the suspension of LNG or other API in PEG solution and the polysaccharide solution were mixed with a pipette and a controlled volume of this reconstituted solution was inserted in a syringe with a 21G in order to be immediately injected.

Table 5: Molded hydrogel geometries conditions

Example B4B2: Hydrogels preparation for injected implant via a dual syringe.

[000488] A concentrated suspension of API in PEG derivatives solution was prepared by weighing the appropriate weight of concentrated suspension of API and adding the appropriated weight of concentrated sterile PEG derivatives solution and sterile deionized water.

[000489] Polysaccharide sterile solution and suspension of API in PEG derivatives solution were adjusted with a concentrated NaCI solution to obtain isotonic stock solutions (300 mOsm/kg) and equilibrated either at room temperature (20-25°C).

[000490] Polysaccharide sterile solution was buffered with lOmM of 2-(N- morpholinojethanesulfonic acid (MES) for pH 6 or tris(hydroxymethyl)aminomethane (Tris) for pH 8 or pH7.4 and suspension of LNG in PEG derivatives solutions was buffered with lOmM of MES for pH 6, before sterile filtration (0.22 pm).

[000491] Dual syringe injection with mixing chamber (Twin-Syringe Biomaterial Delivery System (M-Svstem) from MedMix®): Polysaccharide sterile solution and suspension of API in PEG derivatives solution are placed separately in two syringes of ImL. A connector to connect the flux of the two syringes is extended by a mixing chamber with a male lueur lock that is screwed onto the 21G needle. By pushing on both syringes at the same time with a medmix® clamp, the hydrogel is reconstituted and immediately injected.

Example B4C: Hydrogels preparation for reconstitution

[000492] RTU vials are prepared with each 1 ml of Polysaccharide sterile solution at the corresponded final concentration in gel. This solution is freeze-dried. The lyophilisat is then transferred to a 2 ml syringe on which a 21G x 25 mm needle has been adapted (BD Microlance Ref: 301156). Once the lyophilisat is transferred, the level pusher is adjusted by pushing the piston up to 1 ml.

[000493] The volume of the PEG-SH solution is placed in an Eppendorf of 1.5 ml. The volume is sucked into the syringe with needle. Excess air is drawn to empty the needle. The syringe is agitated until the lyophilisat is completely solubilized, if necessary, air is ejected by holding the needle upwards by adjusting the volume to ~1 ml to promote mixing. The bubble is then ejected with the needle upwards, then the gels are poured into their locations.

Example B5: Hydrogel compositions

[000494] Different hydrogel compositions were prepared according to the protocol described in Example B4A and B4B. Concentrations of the two reactive groups (vinylsulfone (VS) on polymers reacting with thiol (SH) and polymers (polysaccharide) and PEG derivatives) correspond to the final concentration after mixing.

Table 6: Compositions of various hydrogels made of polysaccharide and PEG derivatives.

Table 7: Structures of the hydrogels B5-1 to B5-43

Exemple B6 : Viscosity of precursors concentration solution

[000496] Flow curve measurement was carried out with a rotational rheometer (AR2000, TA instrument) equipped with a cone plate geometry. Logarithmic sweep tests were carried out at 25°C, with shear rate ranging from 10 to 1000 s ^-1 . The dynamic viscosity was reported as function of shear rate. The precursor solutions present Newtonian fluid behavior. The dynamic viscosity is represented by the mean viscosity in the range tested.

Table 8: Results of hydrogel viscosity characterization.

[000497] The hydrogels according to the invention exhibit a viscosity suitable for injection thought 20-27G needle and patient compliance.

Example B7: Hydrogel rheological characterization

[000498] Oscillatory shear test was carried out with a rotational rheometer (AR2000, TA instrument) equipped with a cone plate geometry. The cross-linking leading to gelation was done "in situ", meaning that drops of polysaccharide and PEG derivative concentrated solutions (containing or not LNG suspension or other API) were introduced between cone one and plate and mixed by rotation of the geometry before starting oscillations measurements. Oscillation time sweep tests were carried out at 37°C, with a constant strain of 0.1% and constant oscillation frequency of 1 Hz. The storage modulus G' (i.e. elastic modulus) and Tan 6 (ratio G"/G') values were reported at 3600 s in the plateau region of the measure of (G',G") as a function of time.

Table 9: Results of hydrogel rheological characterization.

[000499] Hydrogels present low values of Tan 6, meaning that G' was much higher than G" which is a typical property of chemically cross-linked hydrogels behaving as solid elastic materials (see Polysaccharide Hydrogels: Characterization and Biomedical Applications, 2016 Pan Stanford Publishing Pte. Ltd.; Chapter 3, page 97). [000500] Increasing the pH was a way to accelerate the cross-linking leading to gelation of hydrogels prepared from polysaccharide bearing VS groups and PEG-SH. For example, going from pH 6 to pH 8 leads to a faster gelation.

[000501] This can allow a fine tuning of the gelation speed which could be convenient as fast gelation could be beneficial to avoid gel spreading whereas slow gelation could be beneficial for polymer mix casting or injection before gelation.

Example B8: Hydrogel swelling and water content

[000502] The hydrogel piece was weighed right after unmolding (wo) and after overnight swelling (wovemight) in the PBS solution. The swelling ratio was defined as the mass ratio wovernight/wo. The water content of the hydrogel was deducted from the measurement of hydrogel mass in the swollen state and the control of polymer precursors concentrations implemented to synthetize the hydrogel.

Table 10: Hydrogel swelling and water content.

[000503] Hydrogels contain high water content. Water content varies depending on polymer precursors structures and concentrations.

[000504] The hydrogels according to the invention exhibit very good swelling properties suitable for an implanted gel in subcutaneous site or in synovial medium in case of intra-articular administration.

[000505] The reconstitution of the gel solution from lyophilizate does not modify the swelling properties.

Example B9: Determination of mechanical resistance of the hydrogels.

[000506] For compression, a swollen cylindrical hydrogel piece as described in Example B5 was introduced in a flat glass crystallizer and immersed in PBS. The uniaxial compression was done in PBS at 20-25°C by using a universal mechanical tester apparatus (Zwickroell) equipped with flat compression plates, at a speed of 0.2 mm/min. Initial thickness of the sample was determined from the contact of the plate with the hydrogel, when the force starts to increase. The deformation is defined by the ratio of the compression displacement (mm) and the initial thickness (mm). The deformation at break was determined from the force/displacement curve. The break is defined when a decrease of the force versus displacement was observed.

[000507] The hydrogels according to the invention exhibit very good mechanical resistances features (included in the case of reconstituted formula B9-11, B9-12, B9- 13) combining deformability and stiffness suitable for implantation, conservation of mechanical properties in tissue and removability. [000508] In the case of injection in the synovial medium, the deformation properties of gel are not sensitively modified. Table 11: Mechanical resistance of hydrogels

Example B10A: In vitro release experiment of LNG or other API from suspension and from hydrogel

[000509] Suspension of LNG or other API described in Example Bl was introduced in a glass bottle and immersed with 100 mL of a buffer solution of PBS (lx)/ BSA (20 g/L) at pH 7.4 and supplemented with 1% (v/v) Pen/Strep solution. The experiment was conducted at 37°C under constant orbital shaking (80). The entire media was centrifuged at 10000 g during 15 minutes at 20°C at different timepoint. 80 mL of buffer were sampled and replaced by fresh buffer. The concentration of LNG or other API in sample were determined by HPLC. The cumulative fraction of LNG or other API released at each time point corresponding to the ratio of the cumulative quantity of LNG or other API release to the initial quantity of LNG or other API in the suspension is reported.

[000510] Hydrogels (prior swelling) with encapsulated suspension of LNG or other API as listed in Example B5 were each introduced in a glass bottle and immersed with 100 mLor an appropriate volume of a buffer solution of PBS (lx)/ BSA (20 g/L) at pH 7.4 and supplemented with 1% (v/v) Pen/Strep solution. The experiment was conducted at 37°C under constant orbital shaking (80-200 rpm). 80 % of buffer was sampled at different timepoint and replaced by fresh buffer as often as needed to maintain the sink conditions. The concentration of LNG or other API in sample were determined by HPLC. The cumulative fraction of LNG or other API released at each time point corresponding to the ratio of the cumulative quantity of LNG or other API release to the initial quantity of LNG or other API in the unswollen hydrogel is reported.

Table 12: in vitro release rate of LNG or other API in pg/day

Table 13: in vitro cumulative release of LNG or other API in % [000511] These hydrogels allow a slower and longer release of levonorgestrel compared to suspension Bl-2. Duration of the release can be modulated through the quantity of levonorgestrel loaded in the hydrogels.

Example B10B: In vitro release experiment of LNG from hydrogel [000512] Hydrogel's composition B5-9 (100 pL prior swelling) was introduced in a mold dived in a glass bottle containing 100 mL of a buffer solution of PBS (lx)/ BSA (20 g/L) at pH 7.4 and supplemented with 1% (v/v) Pen/Strep solution. The experiment was conducted at 37°C under constant orbital shaking (80 rpm) for 2 hours. The entire volume of buffer was sampled. The concentration of LNG in sample was determined by HPLC. The cumulative fraction of LNG released at 2 hours in the unswollen hydrogel is reported. Hydrogel B5-9 releases around 1% of total during the 2 hours after introduction of the gel precursor in the buffer, showing the absence of burst effect.

Example Bll: Ex vivo subcutaneous administration of hydrogels

[000513] Hydrogel's composition B5-8, B5-10 and B5-13 (400 pL prior swelling) were injected subcutaneously in pork belly within 7 sec through 1-mL syringe equipped with a 21-G needle at room temperature. The cross-linking leading to gelation occurred at 37°C.

[000514] The hydrogels according to the invention were palpable, homogenous, nondiffused and removable from subcutaneous tissue.

Example B12: In situ gelation of hydrogels in synovial medium

[000515] To evaluate the possibility of local administration of TCA loaded hydrogels into a synovial medium, hydrogel's composition B5-31, B5-38, B5-39, B5-40, B5-41, B5-42 (170 pL prior swelling) were injected into a synovial like medium composed of 5 mg/mL of hyaluronic acid aqueous solution at 37°C through 1-mL syringe equipped with a 21-G needle. The cross-linking leading to gelation occurred at 37°C.

[000516] The hydrogels composition according to the invention were suitable to form a gel inside viscous fluid such as synovial like medium.

[000517] According to the hydrogel composition, the initial viscosity and the gelation onset change influencing the hydrogel spreading in synovial like medium and the TCA depleted zone surrounding the center of the gel richer in TCA particles.

[000518] To conduct to a circumscribed hydrogel with homogeneous dispersion of TCA in gel, short gelation onset is more suitable.

Table 14: Hydrogel surface and depleted zone observed on hydrogel injected in synovial like medium

Example B13: Hydrogel reconstitution from polysaccharide precursors lyophilizate

[000519] To improve the shelf life of the polysaccharide precursor, it can be lyophilized.

To evaluate the reconstitution of the polysaccharide precursors lyophilizate by the PEG precursor solution according to the example B4C and the possibility of injection, the time of complete solubilization, the initial viscosity of solution before gelation and the time to gel viscosity to reach 50 mPa.s were measured.

[000520] The lyophilizates are quickly solubilized leading to low viscosity solution for at least 52s before gelation allowing the injection through until 21G.

Table 15: Viscosity of solution and time of complete solubilization of polysaccharide precursors lyophilizate by PEG precursor solution Example B14: LNG distribution into the implant

[000521] To determine the API dispersion, injected hydrogel in rat from two different study are explanted at D2 and D30 and carefully observed to determine the presence of LNG depleted zone.

Table 16: depleted zone of hydrogels

[000522] According to the gelation time and the viscosity of hydrogel before gelation (depending of the polymer concentration and of the presence of hyaluronic acid) the gel diffuse more or less into the subcutaneous tissue. The gel diffusion lead to more or less circumscription of the implant and conduct to an implant presenting a more or less large initial LNG depleted zone close to the surface of the hydrogel.

[000523] The corresponding plasmatic levels have been measured and it appeared that the more the depleted zone increases the lower is the plasmatic level. Thus, by tuning the depleted zone of the hydrogel, it is possible to adjust the plasmatic level.

Example Cl: In vivo tolerance of B5-16 and B5-20 a. Test item preparation

[000524] According to the gelation time, test item was prepared just before subcutaneous administration. The formulation gels in 30 seconds to 3 minutes into the animal subcutaneous site. To respect the gelation time of the test item, the whole administration procedure, i.e. reconstitution, loading and injection stages, have be completed within approximately 1 minute.

[000525] Injection of hydrogel

[000526] A volume of either 200 pL of B5-16 or 300 pL B5-20 was administered, representing respectively a dose of 8,4 mg or 25,2 mg/animal. Each formulation as administered to a group of 15 female Wistar rats, in the interscapular area. b. Clinical assessment

[000527] The animals were regularly monitored for behavior and survival. Similarly, regular observation of the implantation site was carried out.

[000528] To perform regular macroscopic observations (i.e. tolerance, inflammatory appearance, facility of explantation, adhesion to surrounding tissue), and to achieve matter balance between LNG released from hydrogels during the pharmacokinetic study and the residual LNG in the explants, explantations followed by sacrifice were carried out at different times.

Table 17: Explantation timing for macroscopic analysis of local tolerance and material balance, i.e. polymer and LNG, for B5-16 and B5-20.

[000529] At 6 months post-implantation of B5-20 and B5-16 respectively, no clinical signs were observed during the study. The animals gained body weight regularly. No scraping of the implant site was observed, and the hydrogel was always subcutaneously perceptible and detectable by palpation, with no apparent signs of inflammation or petechiae. c. Evolution of the hydrogel in vivo

[000530] Ultrasound were performed to assess the behavior (geometry, degradation, fragmentation) of the hydrogel over time.

[000531] Prior to image acquisition, the animals were anesthetized with isoflurane.

[000532] Ultrasound monitoring indicated that hydrogels mostly remain unchanged over time.

[000533] Peripheral hypoechoic zone was observed, which seems to become more pronounced over time. This area corresponded to the LNG depletion zone over time and made it possible to monitor the gradual release of API. d. Macroscopic and histological appareance

[000534] The hydrogels were carefully observed at the time of and after surgery using a binocular magnifying glass.

[000535] Explants dedicated to histology were processed into paraffin blocks, cut, and stained with Hematoxylin-Eosin. The local reactions to the B5-20 hydrogel were assessed histologically at Day 38 post-implantation, in accordance with to the published recommendation, ISO 10993-6:2016 Biological evaluation of medical devices — Part 6 - Tests for local effects after implantation.

[000536] Hydrogels were well tolerated, whatever the composition. No signs of inflammation were observed at the implant site or in the surrounding tissue.

[000537] Hydrogels were adherent to tissues but extractable without surgical blade. The explants were always associated with an adherent hybrid tissue, easily removable, well vascularized with no apparent hemorrhage, and non-fibrous appearance. In situ polymerization of the hydrogel led to the integration of cells and surrounding tissue, which had no impact on the good tolerance of the test item.

[000538] LNG distribution was homogeneous within the hydrogel. API was still present within the B5-16 and B5-20 hydrogels, after 6 months of study respectively. A peri-hydrogel zone without API was observed, more pronounced for composition B5-16, indicating a release of LNG from the edge of the hydrogel, as described in ultrasound analysis.

[000539] Slight fibrosis always admixed with macrophages, but never with lymphocytes, and rarely with giant cells (Grade 1) was noted on histological analysis. No inflammation was noted, supporting good tolerance of the hydrogel B5-20.

Example C2: In vivo tolerance of B5-17 and injection feasability with a twin syringe system a. Test item preparation

[000540] According to the gelation time, test item was prepared just before subcutaneous administration. The formulation gels in 6 seconds into the animal subcutaneous site. To respect the gelation time of the test item, the whole administration procedure, i.e. reconstitution, loading and injection stages, should be completed in less than approximately 1 minute.

[000541] Polysaccharide sterile solution and suspension of API in PEG derivatives solution must be homogenized beforehand. A volume of 200 pL of each solution was collected in two separated syringes of 1 mL. The use of the twin syringe MedMix® was detailed in example B4B2.

[000542] A volume of 200 pL of B5-17 was administered, representing a dose of 8.4 mg/animal, in the interscapular area. This dose was tested on an animal. b. Injection of hydrogel

[000543] A volume of 200 pL of B5-17 was administered, representing a dose of 8.4 mg/animal. The design of the study is similar to that presented in Example Cl. Only one animal was included in the study. c. Clinical assessment

[000544] The animal was regularly monitored for behavior and survival. Similarly, regular observation of the implantation site was carried out.

[000545] To perform early macroscopic observations (i.e. tolerance, inflammatory appearance, facility of explantation, adhesion to surrounding tissue) explantation followed by sacrifice was carried 48 hours post-implantation.

[000546] At 48 hours post-implantation of B5-17, no clinical signs were observed during the study. No scraping of the implant site was observed, and the hydrogel was always subcutaneously perceptible and detectable by palpation, without apparent signs of inflammation or petechiae. d. Macroscopic appareance

[000547] The hydrogel was carefully observed at the time of and after surgery using a binocular magnifying glass. [000548] Hydrogel was tolerated. No signs of inflammation were observed at the implant site or in the surrounding tissue.

[000549] Hydrogel was adherent to tissues but extractable without surgical blade. The explant was associated with an adherent tissue, easily removable, and non-fibrous appearance. B5-17, composed by N3-DCBO chemistry, induced rapid gelation of the hydrogel, limiting subcutaneous diffusion of the polymer and favouring dispersion of LNG in the hydrogel with less tissue adhesion.

Example C3: In vivo tolerance of B5-43 in minipigs and release of Levonorgestrel into hydrogel a. Test item preparation

[000550] According to the gelation time, test item was prepared just before subcutaneous administration. The formulation gels in 30 seconds to 3 minutes into the animal subcutaneous site. To respect the gelation time of the test item, the whole administration procedure, i.e. reconstitution, loading and injection stages, should be completed within approximately 1 minute. b. Injection of hydrogel

[000551] A volume of 300 pL of B5-43 as administered, representing a dose of 25,2 mg/animal. The hydrogel was administered to a female Gottingen minipig, in the axillary area. e. Clinical assessment

[000552] The animal was regularly monitored for behavior and survival. Similarly, regular observation of the implantation site was carried out.

[000553] To perform macroscopic observations (i.e. tolerance, inflammatory appearance, facility of explantation, adhesion to surrounding tissue) explantation followed by sacrifice was carried 1 month post-implantation.

[000554] At 1 month, no clinical signs were observed during the study. The animal gained body weight regularly. No scraping of the implant site was observed, no apparent signs of inflammation or petechiae. f. Macroscopic appareance

[000555] The hydrogel was carefully observed at the time of and after surgery using a binocular magnifying glass.

[000556] Hydrogels were well tolerated. No signs of inflammation were observed at the implant site or in the surrounding tissue.

[000557] Hydrogels were adherent to tissues but extractable without surgical blade. The explant was associated with an adherent hybrid tissue, easily removable, well vascularized with no apparent haemorrhage, and non-fibrous appearance. In situ polymerization of the hydrogel led to the integration of cells and surrounding tissue, which had no impact on the good tolerance of the test item.

Example DI in rats - Pharmacokinetics (PK)

[000558] The pharmacokinetics of LNG after subcutaneous injection of hydrogels was assessed in rats. The design of the study was similar to that presented in Example B10A LNG was assayed in rat plasma using qualified LC-MS/MS assay method.

[000559] The hydrogel B5-37, B5-15, and B5-16, were administered in different groups of rats. Pharmacokinetic profile of B5-37 was observed on 66 days, when those of B5-15 and B5-16 were pursued up to 180 days.

Median PK concentrations of B5-37 and B5-16 are presented on fig 5A. Median PK concentration of B5-15 and B5-16 are presented on fig 5B.

Fig 5A showed that the LNG concentration is stable during all the duration of the observation. In particular no initial burst is observed (a burst is characterized by a significant amount of dose being observed just after injection).

Fig 5B showed that a constant concentration between 0.5 and 1 ng/mL was obtained for at least 6 months (180 days) and that at 9 months (270 days) plasmatic concentration of LNG was still measurable.

Example D2 in rat: - Pharmacokinetics (PK)

[000560] The effect of loading of the formulations on the LNG pharmacokinetics was assessed after subcutaneous injection of hydrogels in rat. The design of the study was similar to that presented in Example DI. LNG was assayed in plasma using LC-MS/MS assay method.

[000561] The same volume of 200 pL of hydrogels B5-19 and B5-20 was respectively injected in rat.

Median PK concentrations are presented on fig 6A.

Hydrogels at two different loadings and same volume, i.e. at two different total doses led to similar PK profiles. The loading of LNG into the hydrogel has an impact on the part of the dose which is released in the body.

This can also be observed on the cumulative input which is presented on fig 6B.