The present invention relates to novel biocompatible Ta-Nb-Ti alloys, methods for preparing the same, and uses thereof.

BACKGROUND

Titanium (Ti) or titanium alloys (z.B. Ti-6A1-4V), are the material most frequently used in dental implants, orthopedic implants, prostheses, and vascular stents because of their outstanding physical and biological properties, such as low density, excellent mechanical strength, corrosion resistance (prevention of corrosive damage to the implant), and biocompatibility (no tissue damage by the implant material or by corrosive/abrasive particles).

The surface chemistry and structure of titanium or titanium alloys are prime factors governing bone integration. The mechanisms of the superior biocompatibility of titanium and titanium alloys are presently unknown and implants composed thereof or coated therewith still provoke a significant inflammatory response.

Besides titanium, also tantalum (Ta) and niobium (Nb) are established in medical technology and are used in various applications: Ta is used for suture wires, wire meshes, and nets, as well as skull implants. It is particularly corrosion-resistant and supports the in-growth of bone structures into the implant structures. Nb is used as OXINIUM® alloy in knee implants, and there are studies showing that Nb as a component has better bio-compatibility than cobalt, nickel, or vanadium, for example.

During the last years, the modem material class multi-component high-entropy alloys (HEAs), has gained tremendous attention in the field, which can be attributed to two main reasons.

Firstly, the new concept of combining several elements (at least 5 principal elements with concentrations between 5 and 35 at. %) in contrast to conventional alloys, mostly containing only two or three elements in addition to the main alloy constituent, results in a broad variety of possible combinations, thus leading to completely novel alloys with exceptional properties.

Secondly, recently developed refractory metal-based high-entropy alloys (RHEAs) have shown properties that are superior to those of current state-of-the-art alloys, which are attributed to several unique thermodynamic effects. However, besides the outstanding mechanical properties, abrasion resistance, and thermal resistance, a vast variety of chemical elements used in RHEAs also belong to the category of biocompatible elements, hence promising to lead to the development of potentially superior biomedical materials.

The present invention is based on the surprising finding that novel Ta-Nb-Ti alloys show superior biocompatibility such as a markedly reduced inflammatory capacity, and, in addition, have an anti-bacterial and anti-fibrosis effect, which makes them particularly suitable for use as a biomedical material, e.g. for medical devices such as implants or prostheses.

SUMMARY OF THE INVENTION

In a first aspect, the invention relates to a biocompatible alloy comprising, consisting essentially of or consisting of a metal composition selected from the group consisting of Ta- Nb-Ti, Ta-Nb-nTi, Ta-Nb-Ti+X+Y, and Ta-Nb-nTi+mX+kY, wherein n, m, or k = 1-70 atomic % and X, Y = Pt, Zr, Co, Cr, V, Ag, Au, Ni, Hf, Mo, W, Al, Mn, Cu, Li, rare earths, Fe, or Ir.

In a second aspect, the invention relates to a material composed of or coated with the inventive biocompatible alloy.

In a third aspect, the invention relates to a material composed of or coated with the inventive biocompatible alloy for use as a material with anti-bacterial and/or anti-inflammatory effects.

In a fourth aspect, the invention relates to a material composed of or coated with the inventive biocompatible alloy for use as a material with an anti-fibrotic effect.

In a fifth aspect, the invention relates to a material composed of or coated with the inventive biocompatible alloy for use as a material for prostheses with reduced or no septic prosthesis loosening.

In a sixth aspect, the present invention relates to a coating comprising the inventive biocompatible alloy.

In a seventh aspect, the invention relates to the use of the inventive biocompatible alloy as a coating.

In an eighth aspect, the invention relates to the inventive biocompatible alloy for use as coating or substrate/bulk material with anti-bacterial and/or anti-inflammatory effects.

In a ninth aspect, the present invention relates to the inventive biocompatible alloy for use as coating or substrate/bulk material with an anti-fibrotic effect. In a tenth aspect, the present invention relates to the inventive biocompatible alloy for use as coating or substrate/bulk material for prostheses with reduced or no septic prosthesis loosening.

In an eleventh aspect, the present invention relates to the use of the inventive biocompatible alloy as coating or substrate/bulk material with anti-bacterial and/or anti-inflammatory effects.

In a twelfth aspect, the present invention relates to the use of the inventive biocompatible alloy as coating or substrate/bulk material with an anti-fibrotic effect.

In a thirteenth aspect, the present invention relates to the use of the inventive biocompatible alloy as coating or substrate/bulk material for prostheses with reduced or no septic prosthesis loosening.

In a fourteenth aspect, the present invention relates to the use of a material composed of or coated with the inventive biocompatible alloy as a material with anti-bacterial and/or antiinflammatory effects.

In a fifteenth aspect, the present invention relates to the use of a material composed of or coated with the inventive biocompatible alloy as a material with an anti-fibrotic effect.

In a sixteenth aspect, the present invention relates to the use of a material composed of or coated with the inventive biocompatible alloy as a material for prostheses with reduced or no septic prosthesis loosening.

In a seventeenth aspect, the present invention relates to a method for the manufacture of an inventive biocompatible alloy, wherein the process comprises melting/remelting or mechanical milling/alloying elemental Ti, Nb, Ta, and/or hydrides of the respective elements as well as partially or entirely pre-alloyed starting materials in the respective relative amounts in an arc-melting device under an Ar atmosphere, in a powder mill/attrition device under inert gas atmosphere and/or subsequent sintering processes and/or fabricated by additive or generative manufacturing methods.

In an eighteenth aspect, the present invention relates to a method for treating bone damages comprising implanting a material composed of or coated with the inventive biocompatible alloy.

In a nineteenth aspect, the present invention relates to a method for treating septic prosthesis loosening comprising implanting a prosthesis composed of or coated with the inventive biocompatible alloy. This summary of the invention does not necessarily describe all features and/or all aspects of the present invention. Other embodiments will become apparent from a review of the ensuing detailed description.

DETAILED DESCRIPTION

Definitions

In the following the invention is described in more detail with reference to the Figures. The described specific embodiments of the invention, examples, or results are, however, intended for illustration only and should not be construed to limit the scope of the invention as indicated by the appended claims in any way.

It is to be understood that this invention is not limited to the particular methodology, protocols, and reagents described herein as these may vary It is also to be understood that the terminology used herein is to describe particular embodiments only, and is not intended to limit the scope of the present invention which will be limited only by the appended claims. Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art.

Each of the documents cited in this specification (including all patents, patent applications, scientific publications, manufacturer's specifications, instructions, etc ), whether supra or infra, is hereby incorporated by reference in its entirety. In the event of a conflict between the definitions or teachings of such incorporated references and definitions or teachings recited in the present specification, the text of the present specification takes precedence.

The term “comprising” or variations thereof such as “comprise(s)” according to the present invention (especially in the context of the claims) is to be construed as an open-ended term or non-exclusive inclusion, respectively (i.e., meaning "including, but not limited to,") unless otherwise noted.

The term "comprising" shall encompass and include the more restrictive terms "consisting essentially of' or "comprising substantially", and "consisting of'.

In the case of chemical compounds or compositions, the terms "consisting essentially of' or "comprising substantially" mean that specific further components can be present, namely those not materially affecting the essential characteristics of the compound or composition, e.g., unavoidable impurities.

The terms “a”, “an”, and “the” as used herein in the context of describing the invention (especially in the context of the claims) should be read and understood to include at least one element or component, respectively, and are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context.

In addition, unless expressly stated to the contrary, the term “or” refers to an inclusive “or” and not to an exclusive “or” (i.e., meaning “and/or”).

All numeric values are herein assumed to be modified by the term “about”, whether or not explicitly indicated. Recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein.

The use of terms “for example”, “e g ”, “such as”, or variations thereof is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. These terms should be interpreted to mean “but not limited to” or “without limitation”.

The term “biocompatible”, as used herein, refers to the ability of a biomaterial to perform its desired function for medical therapy, without eliciting any undesirable local or systemic effects in the recipient or beneficiary of that therapy, but generating the most appropriate beneficial cellular or tissue response in that specific situation, and optimizing the clinically relevant performance of that therapy.

The term “alloy”, as used herein, refers to a mixture of chemical elements of which at least one is a metal. Unlike chemical compounds with metallic bases, an alloy will retain all the properties of a metal in the resulting material, such as electrical conductivity, ductility, opacity, and luster, but may have properties that differ from those of the pure metals, such as increased strength or hardness. In some cases, an alloy may reduce the overall cost of the material while preserving important properties. In other cases, the mixture imparts synergistic properties to the constituent metal elements such as corrosion resistance or mechanical strength. The present inventors found that the alloy as described herein has outstanding anti-bacterial and/or antiinflammatory effects, such as growth-limiting/inhibiting effects on bacteria. They also found that the alloy as described herein has anti-fibrotic effects. When coated on prothesis, the present inventors further found reduced or no septic prothesis loosening over time.

The term “rare earths”, as used herein, refers to the elements Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.

The term “atomic percent” (at. %), as used herein, refers to the number of atoms of an element in 100 atoms representative of a substance. The term “interstitially solvable elements” as used herein, refers to elements that are completely or partially soluble in the metal lattice of an alloy.

The term “equiatomic alloy”, as used herein, refers to an alloy where the metallic elements are present in equal atomic percentages.

The term “medical device”, as used herein, refers to a non-naturally occurring object or artificial object that is used to examine and/or treat a subject, that is inserted or implanted in a subject, or that is applied to a surface of a subject. An implantable device is one intended to be completely imbedded in the body without any structure left outside the body (e.g. an implant or a prothesis). An insertable device is one that is partially imbedded in the body but has a part intended to be external (e g. a catheter or a drain). Medical devices can be intended for shortterm or long-term residence where they are positioned. A hip implant is intended for several years of use, for example. By contrast, a tissue expander may only be needed for a few months, and is removed thereafter. Insertable devices tend to remain in place for shorter times than implantable devices, in part because they come into more contact with microorganisms that can colonize them. The medical devices described herein are composed of or are coated with the biocompatible alloy of the present invention. Said alloy has an anti-bacterial and/or anti-inflammatory effect. Thus, the medical device has a longer life time and can remain longer in the subject’s body. The subject described herein may be a human or an animal. The medical device may be an extracorporeal medical device, an implant, preferably a prothesis, or a catheter.

The term “extracorporeal medical device”, as used herein, refers to device whose function is performed outside the body. Extracorporeal devices are the artificial organs that remain outside the body while treating a patient. Extracorporeal devices are useful, for example, in hemodialysis and cardiac surgery.

The term “implant”, as used herein, refers to an artificial material intended for placement in a human or animal body. In particular, the term “implant”, as used herein, refers to an artificial material implanted in the body to remain there permanently or at least for a longer period of time. The term “implant”, as used herein, can be applied to the entire spectrum of medical devices intended for placement in a human or animal body. The implant is preferably a prosthesis.

The term “prosthesis”, as used herein, refers to a medical device that replaces a missing body part, which may be lost through trauma, disease, or a condition present at birth (congenital disorder). A prosthesis is intended to restore the normal functions of the missing body part. A “prosthesis” can also be designated as prosthetic implant.

Preferably, the prosthesis is an endoprosthesis. The term “endoprosthesis (from the Greek endo “inside”), as used herein, refers to a joint replacement. It remains permanently in the body and replaces a damaged joint in whole or in part. An endoprosthesis which replaces a damaged joint in whole is designated as total endoprosthesis and an endoprosthesis which replaces a damaged joint in part is designated as partial endoprosthesis. Preferably, the endoprosthesis is a hip joint or a knee joint.

The surgical procedure for replacing the joint with a prosthesis is called arthroplasty.

The term “coating”, as used herein, refers to any layer covering a surface, e g. of a material or article such as medical device. In the present invention, the inventive biocompatible alloy is used for coating or as coating. The biocompatible alloy to be coated can be in form of a liquid, a paste, a semi-solid, or a solid. It is preferred that the coating completely and/or uniformly covers the surface of the material to be coated. The coating has preferably a thickness of between 1 nm and 1000 pm, preferably 40 nm and 50 pm, more preferably between 0.1 pm and 10 pm and most preferably between 0.5 pm and 5 pm The coating can be achieved by dip coating and/or spray coating, as well as thin- film technology processes (such as CVD, PVD) and powder pack cementation.

Medical devices, such as implants or prostheses, are widely used to replace damaged tissues or to treat various diseases. However, they may cause microbial infections such as bacterial or fungal infections, when introduced into the body of a subject.

The inventive alloy as described herein has an anti-microbial effect or activity, specifically a growth-limiting/inhibiting effect on microorganisms. The microorganisms are preferably selected from the group consisting of bacteria, viruses, archaea, fungi and protists.

The term “anti-microbial effect or activity” of a material, as used herein, is associated with the property of the material to kill or inhibit microorganisms. Particularly, the inhibition of microorganisms is achieved by slow down the rate of growth of the microorganisms. The term “antimicrobial activity or effect”, as used herein, can also be defined as a collective term for all active principles that inhibit the growth of microorganisms, prevent the formation of colonies of microorganisms, and may destroy microorganisms.

The material may be a material composed of or coated with the inventive alloy as described herein.

The inventive alloy as described herein has an anti-bacterial effect or activity, specifically a growth-limiting/inhibiting effect or activity on bacteria.

The term “anti-bacterial effect or activity” of a material, as used herein, is associated with the property of the material to kill or inhibit bacteria. Particularly, the inhibition of bacteria is achieved by slow down the rate of growth of the bacteria. The term “anti-bacterial activity or effect”, as used herein, can also be defined as a collective term for all active principles that inhibit the growth of bacteria, prevent the formation of colonies of bacteria, and may destroy bacteria.

The material may be a material composed of or coated with the inventive alloy as described herein.

The growth of microorganisms such as bacteria may be inhibited by the material composed of or coated with the inventive alloy by at least 1%, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, 98% or 99%, or by 100% as compared to a material not being composed or coated with the inventive alloy. Preferably, bacteria growth is inhibited by at least 20%. More preferably, bacteria growth is inhibited by at least 40%. Even more preferably, bacteria growth is inhibited by at least 60%. Most preferably, bacteria growth is inhibited by at least 90% or of even 100%.

As mentioned above, medical devices, such as implants or prostheses, are widely used to replace damaged tissues or to treat various diseases. However, besides the risk of microbial infections such as bacterial or fungal infections, an inflammatory response usually occurs. Here, recent progress in the field of anti-inflammatory biomaterials is described. The inventive alloy as disclosed herein prevents or does not cause an inflammatory response in the body of a subject.

The term “anti-inflammatory effect or activity” of a material, as used herein, is associated with the property of the material to reduce inflammation (such as redness, swelling, and/or pain) in the body. An anti-inflammatory material is able to block certain substances in the body that cause inflammation or that does not cause inflammation due to its own composition/structure. The material may be a material composed of or coated with the inventive alloy as described herein.

As mentioned above, medical devices, such as implants or prostheses, are widely used to replace damaged tissues or to treat various diseases. However, they may lead to an increased fibrosis when introduced into the body of a subject. The increased fibrosis is associated with a subsequent restriction of the range of motion of the affected medical devices, e g. joints.

In addition to the anti-microbial such as anti-bacterial effect and the anti-inflammatory effect, the inventive alloy as described herein has an anti-fibrotic effect. In this way, movement restrictions after implantation of a medical device can be prevented.

Fibrotic and scarring processes are mainly derived by the proliferation of fibroblasts and exuberant extracellular matrix (ECM) expression. The term “anti-fibrotic effect or activity” of a material, as used herein, is associated with the property to prevent such fibrotic and scarring processes in the body.

The material may be a material composed of or coated with the inventive alloy as described herein.

Due to the use of the inventive alloy as described herein, as prosthesis coating, for example, a prothesis loosening can be reduced or inhibited.

The prosthesis loosening can be reduced or inhibited with the inventive alloy as a coating by at least 1%, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, 98% or 99%, or by 100% as compared to a prosthesis not coated with the inventive alloy. Preferably, prosthesis loosening is inhibited by at least 20%. More preferably, prosthesis loosening is inhibited by at least 40%. Even more preferably, prosthesis loosening is inhibited by at least 60%. Most preferably, prosthesis loosening is inhibited by at least 90% or of even 100%.

The term “substrate/bulk material”, as used herein, refers to the alloy and or the coating in a compact state after processing.

No language in this specification should be construed as indicating any non claimed element as essential to the practice of the invention.

Embodiments

The present invention is based on the surprising finding that novel Ta-Nb-Ti alloys show superior biocompatibility such as a markedly reduced inflammatory capacity, and, in addition, have an anti-bacterial and anti-fibrosis effect, which makes them particularly suitable for use as a biomedical material, e.g. for implants or prostheses.

Thus, in a first aspect, the present invention relates to a biocompatible alloy compris- ing/consisting essentially of/consisting of a metal composition selected from the group consisting of Ta-Nb-Ti, Ta-Nb-nTi, Ta-Nb-Ti+X+Y, and Ta-Nb-nTi+mX+kY, wherein n, m, or k = 1-70 atomic % and X, Y = Pt, Zr, Co, Cr, V, Ag, Au, Ni, Hf, Mo, W, Al, Mn, Cu, Li, rare earths, Fe, or Ir. It is preferred that n, m, or k = 1-50 atomic %. It is more preferred that n, m, or k = 1- 40 atomic %. It is even more preferred that n, m, or k = 1-30 atomic %. It is still even more preferred that n, m, or k = 1-20 atomic %.

In one embodiment of the present invention, the biocompatible alloy may be selected from the group consisting of Ta-Nb-Ti, Ta-Nb-lOTi, Ta-Nb-50Ti, Ta-Nb-70Ti, Ta-Nb-Ti- 6.2Co, Ta-Nb-Ti-6.2Cr, Ta-Nb-Ti-2.2Co-2.2Cr, Ta-Nb-Ti-Hf, Hf-Nb-Ti, Ta-Nb-Ti-Zr, Hf-Nb- Ti-Zr, and Ta-Nb-Ti-Hf-Zr, wherein the relative amounts of each element preferably vary by no more than ± 15 atomic %, e.g. ± 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 atomic %. In another embodiment of the present invention, the biocompatible alloy additionally comprises one or more compounds or combinations selected from the group consisting of oxides, nitrides, borides, silicides, hydrides, and carbides, in particular AI2O3, ZrCh, TiCh, Y2O3, HfCh, TiN, Cas[OH |(PO4)3], TiC, TilU and OXINIUM®(a Zr-Nb alloy commercially available from Smith & Nephew pic, London, UK).

In yet another embodiment of the present invention, the biocompatible alloy additionally comprises one or more interstitially solvable elements selected from the group consisting of C, O, N, H, and B; wherein the relative amounts of each element in each particular phase are maximum 2 atomic %, e.g. 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, or 2 atomic %.

The biocompatible alloys of the present invention have anti-bacterial and/or anti-inflammatory and/or anti-fibrotic effects and/or reduce or prevent septic prosthesis loosening.

The anti-bacterial effects preferably comprise a growth-limiting/inhibiting effect on bacteria.

The anti-inflammatory effects comprise reducing or preventing inflammation in the body or body parts, resulting, e.g., in redness, swelling, and pain.

The anti-fibrotic effects comprise reducing or preventing fibrosis, also known as fibrotic scarring, i.e., a pathological wound healing in which connective tissue replaces normal parenchymal tissue to the extent that it goes unchecked, leading to considerable tissue remodeling and the formation of permanent scar tissue.

In a second aspect, the present invention relates to a material or an article composed of or coated with the inventive biocompatible alloy.

It is preferred that the coating completely and/or uniformly covers the surface of the material or article to be coated. The coating has preferably a thickness of between 1 nm and 1000 pm, preferably 40 nm and 50 pm, more preferably between 0.1 pm and 10 pm and most preferably between 0.5 pm and 5 pm. The coating can be achieved by dip coating and/or spray coating, as well as thin-film technology processes (such as CVD, PVD) and powder pack cementation.

In a third aspect, the invention relates to a material or an article composed of or coated with the inventive biocompatible alloy for use as a material or an article with anti-bacterial and/or anti-inflammatory effects. Preferably, the anti-bacterial effects comprise a growth-limiting/inhibiting effect on bacteria.

The growth of bacteria may be inhibited by the material or article composed of or coated with the inventive alloy by at least 1%, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, 98% or 99%, or by 100% as compared to a material or an article not being composed or coated with the inventive alloy. Preferably, bacteria growth is inhibited by at least 20%. More preferably, bacteria growth is inhibited by at least 40%. Even more preferably, bacteria growth is inhibited by at least 60%. Most preferably, bacteria growth is inhibited by at least 90% or of even 100%.

In a fourth aspect, the invention relates to a material or article composed of or coated with the inventive biocompatible alloy for use as a material or article with an anti-fibrotic effect.

Thus, the material or article composed of or coated with the inventive biocompatible alloy has anti-bacterial and/or anti-inflammatory and/or anti-fibrotic effects.

In a fifth aspect, the invention relates to a material or article composed of or coated with the inventive biocompatible alloy for use as a material or article for prostheses with reduced or no septic prosthesis loosening.

More preferably, the material or article composed of or coated with the inventive biocompatible alloy as described above is a medical device, e g , an implant (e g., a dental implant), a prosthesis (e.g., a hip or knee prosthesis), a tool, a bone pin, a bone screw, a bone plate, or a container. When the material or article is a prosthesis the anti-bacterial and anti-fibrotic effects of the inventive alloys reduce or prevent septic prosthesis loosening. The medical profession understands prosthesis loosening to mean that an endoprosthesis (also known as an implant), for example, the components of an artificial hip joint or knee joint, are no longer firmly anchored in the bone. Prosthesis loosening is a phenomenon that occurs in approximately 8% of all implanted joint prostheses within 10 years of installation. This affects approximately 10,000 to 12,000 patients per year worldwide.

In a sixth aspect, the present invention relates a coating comprising the inventive biocompatible alloy.

The coating has preferably a thickness of between 1 nm and 1000 pm, preferably 40 nm and 50 pm, more preferably between 0.1 pm and 10 pm and most preferably between 0.5 pm and 5 pm. The coating can be achieved by dip coating and/or spray coating, as well as thin-film technology processes (such as CVD, PVD) and powder pack cementation.

The coating may be applied onto a material (e g. medical device) or article.

In a seventh aspect, the present invention relates to the use of the inventive biocompatible alloy as a coating or substrate/bulk material.

The biocompatible alloy to be coated can be in form of a liquid, a paste, a semi-solid, or a solid. It is preferred that the coating completely and/or uniformly covers the surface of the material to be coated. The coating has preferably a thickness of between 1 nm and 1000 pm, preferably 40 nm and 50 pm, more preferably between 0.1 pm and 10 pm and most preferably between 0.5 pm and 5 m. The coating can be achieved by dip coating and/or spray coating, as well as thin-film technology processes (such as CVD, PVD) and powder pack cementation.

The coating may be applied onto a material (e g. medical device) or article.

In an eighth aspect, the invention relates to the inventive biocompatible alloy for use as coating or substrate/bulk material with anti-bacterial and/or anti-inflammatory effects. Preferably, the anti-bacterial effects comprise a growth-limiting/inhibiting effect on bacteria.

In a ninth aspect, the present invention relates to the inventive biocompatible alloy for use as coating or substrate/bulk material with an anti-fibrotic effect.

In a tenth aspect, the present invention relates to the inventive biocompatible alloy for use as coating or substrate/bulk material for prostheses with reduced or no septic prosthesis loosening.

In an eleventh aspect, the present invention relates to the use of the inventive biocompatible alloy as coating or substrate/bulk material with anti-bacterial and/or anti-inflammatory effects. Preferably, the anti-bacterial effects comprise a growth-limiting/inhibiting effect on bacteria.

In a twelfth aspect, the present invention relates to the use of the inventive biocompatible alloy as coating or substrate/bulk material with an anti-fibrotic effect.

In a thirteenth aspect, the present invention relates to the use of the inventive biocompatible alloy as coating or substrate/bulk material for prostheses with reduced or no septic prosthesis loosening.

In a fourteenth aspect, the present invention relates to the use of a material or an article composed of or coated with the inventive biocompatible alloy as a material or an article with anti-bacterial and/or anti-inflammatory effects. Preferably, the anti-bacterial effects comprise a growth-limiting/inhibiting effect on bacteria.

In a fifteenth aspect, the present invention relates to the use of a material or an article composed of or coated with the inventive biocompatible alloy as a material or an article with an anti-fibrotic effect.

In a sixteenth aspect, the present invention relates to the use of a material or an article composed of or coated with the inventive biocompatible alloy as a material or an article for prostheses with reduced or no septic prosthesis loosening.

More preferably, the material or article composed of or coated with the inventive biocompatible alloy as described above is a medical device, e.g., an implant (e.g., a dental implant), a prosthesis (e.g., a hip or knee prosthesis), a tool, a bone pin, a bone screw, a bone plate, or a container. Thus, the material or article composed of or coated with the inventive biocompatible alloy has anti-bacterial and/or anti-inflammatory and/or anti-fibrotic effects. When the material or article is a prosthesis the anti-bacterial and anti-fibrotic effects of the inventive alloys reduce or prevent septic prosthesis loosening. The medical profession understands prosthesis loosening to mean that an endoprosthesis (also known as an implant), for example, the components of an artificial hip joint or knee joint, are no longer firmly anchored in the bone. Prosthesis loosening is a phenomenon that occurs in approximately 8% of all implanted joint prostheses within 10 years of installation. This affects approximately 10,000 to 12,000 patients per year worldwide.

In a seventeenth aspect, the present invention relates to a method for the manufacture of the inventive biocompatible alloy, wherein the process comprises melting/remelting or mechanical milling/alloying elemental Ti, Nb, Ta, and/or hydrides of the respective elements as well as partially or entirely pre-alloyed starting materials in the respective relative amounts in an arc-melting device under an Ar atmosphere, in a powder mill/attrition device under inert gas atmosphere and/or subsequent sintering processes and/or fabricated by additive or generative manufacturing methods.

As to the preferred embodiments of the inventive biocompatible alloy, it is referred to the first aspect of the present invention.

In one embodiment of the inventive method for manufacturing an inventive biocompatible alloy a subsequent heat treatment is used, e g. to ensure sufficient homogeneity of the alloy.

In an eighteenth aspect, the present invention relates to a method for treating bone damages comprising implanting a material composed of or coated with the inventive biocompatible alloy.

In a nineteenth aspect, the present invention relates to a method for treating septic prosthesis loosening comprising implanting a prosthesis composed of or coated with the inventive biocompatible alloy.

All uses described above may be in vitro or in vivo uses.

BRIEF DESCRIPTION OF THE FIGURES

The following Figures are merely illustrative of the present invention and should not be construed to limit the scope of the invention as indicated by the appended claims in any way.

FIGURE 1 shows the calculation of nucleus to cytoplasm ratio for the tested alloys for validation of the osteoblast attachment to alloy surfaces. FIGURE 2 shows the expression of inflammatory and fibrosis marker genes by monocytes incubated on the novel biocompatible alloy Ta-Nb-Ti, compared to standard implant materials data and elemental Ta and Nb.

FIGURE 3 shows the anti-bacterial effects of the novel biocompatible Ta-Nb-Ti alloy in comparison to the pure components of the alloy and other alloys used as biomaterials.

EXAMPLE

The example given below is for illustrative purposes only and does not limit the invention described above in any way.

Production, preparation, and analysis of substrate materials

For sample production of an equiatomic Ta-Nb-Ti alloy as an example of an inventive alloy, high purity elemental chips or flakes of Ta (99 9%), Nb (99.9%), and Ti (99.6%) were used as starting materials and were carefully weighed. The alloying process was carried out in a conventional arc-melting device under Ar atmosphere. Each sample was as re-melted five times to ensure sufficient homogeneity.

Afterward, the produced oblong-shaped (due to the use of an elongated mold) melted product was cut into 2mm thick slices by means of electric discharge machining (EDM). One slice was used for microstructural analysis and thus metallographically prepared (ground with SiC paper to 1000 grit, polished using 3 pm and 1 pm diamond suspension, and finished using colloidal silica suspension subsequently) afterward. The remaining slices were cleaned from the EDM-burr and ground to a defined grit size of 1200.

To identify the phases present, X-ray diffraction analysis (XRD) was performed on a X’Pert Pro (PANalytical, Almelo, The Netherlands), using Co Ka radiation. Microstructural observations were carried out using scanning electron microscopy (ESEM XL30 FEG, FEI, Hillsboro, OR, USA), using back-scattered electron (BSE) imaging with the following setup: Centaurus BSE detector with an acceleration voltage of 25 kV, magnification of lOOx and a working distance of 11.4 mm.

To determine the elemental distribution and the chemical composition of the alloy, (Si(Li))-detector energy-dispersive X-ray spectroscopy (EDS) analysis equipped with Genesis software (ED AX, Mahwah, NJ, USA) was conducted.

The surface roughness of the samples was analyzed by using a confocal microscope (psurf expert, NanoFocus AG, Oberhausen, Germany) on a surface area of 322 x 321 pm, using a 20x magnification objective with a lateral (x, y) measuring range of 800 pm. In addition, the contact angles of the surfaces were determined using an optical contact angle and drop contour analyzer (OCA 20, DataPhysics Instruments GmbH, Filderstadt, Germany) and the corresponding software (SCA 20, DataPhysics Instruments GmbH, Filderstadt, Germany).

To characterize the hardness of the alloy produced, microhardness analysis was carried out using 20 HVO.1 indents in a square grid across the entire sample surface, using an automatic hardness tester VH3300 (Wilson/Buehler, Esslingen, Germany).

Furthermore, to examine and evaluate the biocompatibility of the alloy Ta-Nb-Ti, cell cultivation experiments were carried out on the surface of the specimens and compared to state- of-the-art biomaterials, such as wrought alloy Co-28Cr-6Mo or alloy Ti-6A1-4V, as well as to samples of pure Ta, Nb, and Ti.

Osteoblast (SaQs Cells) attachment assay

SaOs-2 cells were seeded with a cell number of 0.3 x 10 ⁵ inlOO uL for 2 h on platelets of standard implant alloys (Co-28Cr-6Mo, Ti-6A1-4V, and pure Ti), elemental Ta and Nb, and novel biocompatible alloy Ta-Nb-Ti to let the cells attach to the surface. Afterward, 1 mL DMEM (Dulbecco Modified Eagle Medium) culture medium with the addition of 10% FCS (fetal calf serum) and 1% penicillin/ streptomycin was pipetted into each well to cover the platelets with cells.

On the following day, the cells were fixed with 4% formaldehyde and washed three times with PBS (phosphate-buffered saline).

Subsequently, the samples were incubated with 200 pL of PBS with Phalloidin Alexa Fluor 488 (1 : 100) and DAPI (4 ^F ,6-Diamidino-2-phenylindol) (1:1000) in the dark for 15 min (room temperature, RT). Excess staining solution was removed by washing three times with PBS. The samples were stored at 4 °C in the dark until further use.

Imaging was performed with a Zeiss fluorescence microscope (Axio Observer.Zl, Zeiss, Jena, Germany) at 63 Ox magnification. Fluorescence was detected at the wavelengths 488 nm (Phalloidin green) and 454 nm (DAPI blue). Four images were taken of each sample. For evaluation, the area of one cell (green fluorescence) was divided by the size of the nucleus (blue fluorescence) using ImageJ.

FIGURE 1 shows the calculation of nucleus to cytoplasm ratio for the tested alloys (Mean ± SEM standard error of mean ), N = 3, p = 0.4 using one-way ANOVA (analysis of variance)) fora validation of the cell attachment to alloy surfaces.

Good colonization and no negative effects were observed compared to the reference samples. Monocyte inflammatory reaction test

Mona-mac-6 cells (MM6) are a human acute monocytic leukemia derived cell line. These cells were cultured at a density 0.5 x 10 ⁶ in 100 pL on the different alloy specimens for 24 h. Subsequently, the cells were lysed using TRIZol, and RNA (ribonucleic acid) was isolated for quantitative RT-PCR (reverse transcription polymerase chain reaction).

RNA extraction, cDNA synthesis, real-time RT-PCR

Total RNA was extracted from cells using TRIZol reagent (Invitrogen, Thermo Fisher Scientific). Thus, 1 ng of total RNA from each sample was reverse transcribed using the High- Capacity cDNA (complementary deoxyribonucleic acid) Reverse Transcription Kit (Applied Biosystems) using random primers. Quantitative PCR (polymerase chain reaction) was performed with SYBR green using Applied Biosystems™ and Quantstudio 6 (Thermo Fisher Scientific). At an annealing temperature of 60 °C primers for human interleukin- 1 P (hIL-ip), human tumor necrosis factor-oc (hTNF-a), human interleukin-6 (hIL-6), and human glyceralde- hyde-3 -phosphate dehydrogenase (hGAPDH) were used. Absolute quantification was carried out using standard curves. Target gene expression was normalized to GAPDH.

FiGURE 2 shows the expression of inflammatory marker genes (IL-6, IL-ip, TNF-ot) and fibrosis marker genes (TGF-P, fibronectin) by monocytes incubated on novel biocompatible alloy Ta-Nb-Ti, compared to standard implant materials data and elemental Ta and Nb. Quantitative RT-PCR results (a) IL-6 expression on tested implant materials, (b) IL-ip expression, (c) TNF-oc expression, (d) TGF-P expression and (e) Fibronectin expression (N = 5). GAPDH was used as housekeeping. The values are given as mean with SEM and were analyzed for statistical significance using a one-way ANOVA with Dunn's post-hoc test. * p <0.05; ** p < 0.01. With regard to the fibrosis markers, the novel alloy Ta-Nb-Ti is comparable with the reference samples and thus showed no negative influence of the alloy composition. With regard to the inflammation markers, however, the novel alloy Ta-Nb-Ti showed a significantly lower value than the reference samples, which indicates an anti-inflammatory effect of the alloy.

Tests for anti-bacterial effect

Staphylococcus capitis adhesion test

S. capitis (DSM 20326 (from Leibniz Institute DSMZ) was cultivated overnight in tryptic Soy Broth (TSB). The following day 1 ml TSB was inoculated with a 1 : 100 dilution of the S. captitis overnight culture with an optical density of 1 at 600 nm (OD600) for 24 hours. The medium was removed and washed twice with PBS and subsequently fixed with 4 % paraformaldehyde for 30 min at room temperature. The samples were incubated with 1 ml PBS and 4', 6- diamidine-2-phenylindole (DAPI 1 : 1000) to visualize the adhering bacteria on the surface. The amount of adhering bacteria was quantified in 630x magnification microscopic pictures (Zeiss fluorescence microscope Axio Observer.Zl, Jena, Germany). The fluorescence of the (DAPI) was excited by a wavelength of 454 nm. Pictures from five different areas from each sample were taken and evaluated by counting the amount of bacteria with ImageJ software.

Antibacterial capacity

The key step in biofilm formation on endoprosthetic implant materials is the adhesion of pathogens to the respective material. To test the bacterial adhesion to the novel alloys the samples were incubated for 24 hours with S. capitis. To quantify the amount of adhering bacteria DAPI was used to visualize the DNA of the bacteria, and then the bacteria were counted using ImageJ (data not shown).

FIGURE 3 shows the anti-bacterial effects of the novel biocompatible Ta-Nb-Ti alloy in comparison to the pure components of the alloy (Ta, Nb, and Ti) and other alloys used as biomaterials (Ti-6A1-4V, CoCrMo). S. capitis = Staphylococcus capitis, E coli = Escherichia coli. It can be seen that the number of bacteria on the novel Ti-Nb-Ti alloy was many times lower than the number on all other reference samples.

Statistical analysis of the biocompatibility experiments

If not stated otherwise, the data are presented as mean ± standard deviation (SM. The Friedman test was applied to test for statistical significance. The level of significance was set at p < 0.05 for all statistical tests. Statistical analysis was performed using GraphPad Prism (Version 7, GraphPad Software, San Diego, CA, USA).

Results and discussion

To test the usability of the novel alloys of the present invention as an endoprosthetic implant material in an intraosseous application, human osteosarcoma cells (SaOs-2) were incubated on the novel sample alloy Ta-Nb-Ti, as well as on reference elements Ta and Nb and samples, which are already used as implant material (Co-28Cr-6Mo, Ti-6A1-4V, and pure Ti). To evaluate the interaction of the osteoblast-like cells with the different materials, the attachment and spreading of these cells on the surfaces were investigated. Phalloidin was used to visualize the cytoskeleton. Phalloidin can penetrate the cells and binds with high selectivity to the F-actin of the cytoskeleton. For imaging, the Phalloidin is fluorescently labeled with Alexa Fluor 488, which stains the cytoskeleton of the cell green. There is no difference in the number of osteoblasts attached to the different surfaces. Furthermore, the ratio between nucleus and cytoplasm was evaluated to compare the attachment behavior of the cells. Again, there was no difference observed between the alloys tested, indicating no negative effect on the osteoblasts (FIGURE 1). A reaction towards a foreign material in the human body is an unavoidable process that takes place whenever any material is implanted. This reaction is mostly inflammatory (e.g., IL- 6 and TNF-a) and can develop into a fibrotic response (TGF-P and fibronectin) over time. Therefore, in a subsequent step, the inflammatory potential of the novel alloys was tested using a monocyclic cell line (MM6). These cells were incubated for 24 h on the different platelets and the reaction of these cells towards either inflammation (FIGURE 2 a-c) or fibrosis marker genes (FIGURE 2 d,e) was investigated using qRT-PCR. No significant differences between Co-28Cr-61Mo, Ti-6A1-4V, pure Ti, Ta, and Nb were observed.

However, a significantly reduced expression of IL-6 (about 20-fold, p = 0.006), IL-1 (about 3-fold, p = 0.007), and TNF alpha (about 2-told, p = 0.04) was observed comparing alloy Ta-Nb-Ti to the other samples examined. Especially, in comparison to pure Ti or Ti-6A1-4V, alloy Ta-Nb-Ti showed a markedly reduced inflammatory capacity The most surprising result is that alloy Ta-Nb-Ti appears to be more resistant to inflammation in comparison with the respective elements Ta, Nb, and Ti. No changes in expression were observed for fibrosis markers demonstrating an anti-fibrotic effect.

While certain representative embodiments and details have been shown to illustrate the present invention, it will be apparent to those skilled in this art that various changes and modifications can be made and that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described and claimed.