OMNIPHOBIC ANTIMICROBIAL MICROPARTICLES AND COMPOSITIONS THEREOF

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present disclosure claims the benefit of priority from U.S. patent application no. 63/415,078, filed October 11 , 2022, the contents of which are incorporated herein by reference in their entirety.

FIELD

[0002] The present application relates to an omniphobic and antimicrobial wrinkled microparticle comprising a polymeric core that comprises a wrinkled shell covering at least a portion of the core, and one or more hydrophobic molecular layers and one or more nanoparticle layers attached to the shell. The present application also relates to an optionally sprayable composition comprising the microparticles of the present application, and methods and uses thereof. The present application further relates to methods of preparing the microparticles of the present application. INTRODUCTION

[0003] Transmission of infectious diseases caused by bacteria and viruses continues to be a major societal concern, accounting for substantial morbidity with massive economic implications. ^11-31 According to the Centers for Disease Control and Prevention (CDC), more than 2.8 million bacterial infections occur in the U.S. annually, resulting in more than 35,000 deaths. The estimated national cost for associated treatments is reported to be more than $4.6 billion annually. ¹⁴¹ Among the various pathways via which infectious agents move from a natural reservoir to a susceptible host, contaminated surfaces in high touch environmental areas play a key role in the chain of transmission. ¹¹ ’ ⁴⁵¹ Such surfaces are responsible for 20% to 40% of nosocomial infections, ¹⁶¹ and are often the source of outbreaks - specifically in healthcare settings. ¹⁷¹

Health care providers that come in contact with contaminated surfaces have a 42% to 52% risk of contaminating their hand or glove - a level of risk similar to what is seen following direct contact with infected patients. ¹⁸¹ Surface transmission is further highlighted within closed environments, such as aircraft cabins. In fact, studies have found that in less than 2 to 3 hours, most high touch surfaces within an aircraft cabin are contaminated. The rapid transmission of pathogenic agents within such an environment is further highlighted by the fact that virtually all touchable surfaces are contaminated within 5 to 6 hours. ¹⁶¹ Ultimately, there is a need for methods that prevent the transmission of pathogens via high touch surfaces, in order to reduce the prevalence of resultant infections.

[0004] In an effort to overcome the surface-based transmission of infectious diseases, passive (/.e., repellent antifouling surfaces) and active (/.e., antimicrobial agents) approaches have been extensively explored. Active prevention through the use of biocides such as antibiotics, disinfectants, antiseptics, inorganic metal ions, or preservatives has shown great promise in reducing contamination by instantaneously killing bacteria. ¹³ ’ ^9-121 However, such biocides can pose harmful health effects, such as eye irritation (hydrogen peroxide), long term damage to DNA and fertility (quaternary ammonium compounds), and the in vivo enrichment of metal ions, paired with respiratory complications (bleach). ^113-151 In addition, they aggravate biofilm formation and increase microbial resistance. ¹¹ ’ ¹³ ’ ¹⁷ Contrarily, engineered repellent surfaces - such as omniphobic surfaces, resist both initial bacterial adhesion upon contact and prevent colonization through steric repulsion. ¹¹⁸ ’ ¹⁹¹ Hierarchal-structured surfaces represent a class of omniphobic surfaces that show bacterial repellency through a reduction in the contact area available for bacterial attachment. ¹²⁰ ’ ²¹¹ Although promising, the fabrication of such hierarchically-structured surfaces involves methods such as electrospinning, ¹²²¹ photolithography, ¹²³²⁴¹ laser ablation, ¹²⁵¹ or photoablation, ¹²⁶¹ which are limited to specific materials and form factors and are too difficult to scale up for large volume manufacturing. Methods to fabricate hierarchically-structured surfaces through the self-assembly of hydrophobic nanomaterials on plastic films followed by substrate shrinking ¹²⁷¹ have been developed to overcome the scale up issues encountered in the abovementioned processes. However, these methods can only be applied to specific heat-shrinkable substrates, limiting their widespread implementation. ¹²¹ ’ ²⁸¹

[0005] A universal and simple surface coating method applicable to a wide range of materials and form factors is highly desirable to combat the adhesion, accumulation, proliferation, and subsequent biofilm formation of bacteria on surfaces. Among different coating methods such as drop casting, ¹²⁹¹ dip coating, ¹³⁰¹ and spin-coating, ¹³¹¹ spray coating demonstrates significant advantages as it can be applied to surfaces during manufacturing via roll-to-roll processing, or introduced post substrate fabrication, regardless of its material properties and shape. ^132-351 Furthermore, spray coating provides a unique flow field that can localize particle deposition, thus facilitating the fabrication of hierarchically textured surfaces. ¹³⁵¹ Recent studies have exploited this property for the facile and scalable spray coating of both omniphobic, multi-leveled micro/nanostructures and a water and oil repellent, hierarchically-structured zinc oxide-polydimethylsiloxane (PDMS) composite. ¹³⁶³⁷¹ While intriguing, these coatings have not revealed any antibacterial effects and are thus limited to their singular function as oil and water repellent materials. Concurrently, the spray-coating of silanizing agents, highly networked silver nanoflakes, and a conformable polytetrafluoroethylene encapsulating solution has all been utilized in the textile industry to produce omniphobic and bacteria-repellent garments. ¹³⁸¹ However, the fabrication of these coatings rely on complex and timeconsuming methods that are limited to specific substrates. Combined with the fact that all aforementioned coatings rely solely on omniphobicity forthe reduction of adhered bacteria - a one-dimensional approach that limits their effectiveness, the need for a more widely applicable omniphobic spray is clear.

[0006] A facile method for preparing a bi-functional sprayable coating that combines antifouling (passive) and antibacterial/anti-viral (active) properties to “repel and kill” pathogens remains elusive in scientific literature. ¹³⁹⁴⁰¹ In a recent effort, Ye et al. developed a spray coating consisting of fluorinated mesoporous silica nanoparticles and quaternary ammonium salt mesoporous silica nanoparticles to induce anti-adhesion and contact-killing antibacterial activity. However, this surface only repelled high surface tension liquids such as distilled water. Its lack of repellency towards low surface tension liquids limits its real-world applicability. ¹⁴⁰¹

[0007] As such, there remains a need to develop an agent suitable for surface treating a variety of substrates to provide omniphobic, repellency properties and antimicrobial properties while being easily applied to the substrates.

SUMMARY

[0008] Shown herein is a bi-functional coating that can be deposited universally onto a variety of surfaces via different coating methods, for example via spray coating. The coating employs hierarchically structured, wrinkled polymeric, for example PDMS or PLA, microparticles decorated with metal-based nanoparticles such as gold nanoparticles (AuNPs). The particle-based coating possesses a three-tiered structural hierarchy including polymeric particles at a microscale, structural wrinkles at a tens of microns scale, and metal-based nanoparticles (e.g. gold nanoparticles) at a nanoscale. These tiers worked synergistically to “repel and kill” bacteria and viruses. This coating was applied to glass, polystyrene, stainless steel, textile, and paper substrates. The repellency and biocidal activity of the coating were shown comprehensively via wettability studies, as well as bacterial and viral adhesion and growth tests. These biological tests demonstrated the efficacy of the coating against societal relevant pathogens including Staphylococcus aureus (MRSA), Pseudomonas aeruginosa, and Phi6 - a bacterial virus often used as a surrogate for SARS-CoV-2. ^[41] Subsequent evaluation of the coating’s ability to prevent biofilm formation has shown that the microparticles of the present application were able to prevent the accumulation and proliferation of pathogenic organisms, once present on a surface. Lastly, the coating was shown to be effective under select real-world and complex environments.

[0009] Accordingly, in one aspect, the present application includes an omniphobic and antimicrobial microparticle comprising a polymeric core comprising a wrinkled shell covering at least a portion of the core; and one or more hydrophobic molecular layers and one or more nanoparticle layers attached to the shell.

[0010] In another aspect, the present application includes a method of preparing an omniphobic and antimicrobial microparticle comprising combining a polymer and a surfactant to obtain a polymer microparticle comprising a polymeric core and a shell covering at least a portion of the core, the shell comprising the surfactant; treating the polymer microparticle under conditions to wrinkle at least a portion of the shell; and coating the polymer microparticle with one or more hydrophobic molecular layers and one or more nanoparticle layers through attachment to the shell to obtain the omniphobic and antimicrobial microparticle.

[0011] In another aspect, the present application includes an omniphobic and antimicrobial surface treatment composition comprising the omniphobic and antimicrobial microparticle of the present application or an omniphobic and antimicrobial microparticle prepared by a method of the present application; and a solvent.

[0012] In another aspect, the present application includes a method of surface treatment of a substrate to provide omniphobic and/or antimicrobial properties comprising applying a binder on a surface of the substrate; applying a layer of an omniphobic and antimicrobial surface treatment composition of the present application on the surface of the substrate; and drying the surface of the substrate applied with the binder and the surface treatment composition.

[0013] In another aspect, the present application includes a substrate surface treated by a surface treatment method of the present application.

[0014] In another aspect, the present application includes a material comprising a substrate and the omniphobic and antimicrobial microparticle of the present application or an omniphobic and antimicrobial microparticle prepared by a method of the present application, wherein the microparticle is present on a surface of the substrate.

[0015] In another aspect, the present application includes a device or an article comprising a material of the present application.

[0016] In another aspect, the present application includes a device or article comprising a surface, wherein at least a portion of the surface comprises a material of the present application.

[0017] In another aspect, the present application includes a device or article comprising a surface, wherein at least a portion of the surface has been treated by a surface treatment method of the present application.

[0018] In another aspect, the present application includes a method of preventing, reducing, or delaying adhesion, or adsorption of a biological material onto a device in contact therewith, comprising: treating at least one surface of the device with an omniphobic and antimicrobial surface treatment composition of the present application, optionally by a surface treatment method of the present application.

[0019] In another aspect, the present application includes a use of an omniphobic and antimicrobial microparticle of the present application or a surface treatment composition of the present application in preventing, reducing, or delaying adhesion, or adsorption of a biological material onto a device in contact therewith.

DRAWINGS

[0020] The embodiments of the disclosure will now be described in greater detail with reference to the attached drawings in which:

[0021] Figure 1 shows the development of wrinkled omniphobic microparticles and their subsequent characterizations, (a) Exemplary schematic illustration of the sequential steps used for the exemplary fabrication of hMPs. (a2) Alternative Exemplary schematic illustration of the method of preparing hMPs and application on a glass surface, (b-f) Scanning electron microscopy images of (b) uniform PDMS microparticles (scale bar is 100 pm), (c) wrinkled microparticles (scale bar is 10 pm), (d) wrinkled surface revealing bucky-ball and dimple like textures formed on the surface post wrinkling (scale bar is 10 pm), (e) magnified image of the surface of wrinkled microparticles (scale bar is 1 pm), and (f) AuNPs deposition within surface wrinkles (scale bar is 500 nm).

[0022] Figure 2 shows SEM images of exemplary microparticles. Scanning electron microscopy (SEM) images of (a) polydimethylsiloxane (PDMS) microparticles deposited on glass surface (scale bar is 200 pm), (b) a magnified image of the wrinkled and textured PDMS surface (scale bar is 5 pm), (c) a magnified image of the wrinkles on the surface of the particles (scale bar is 1 pm), and (d) deposition of gold nanoparticles (scale bar is 100 nm). Images (a-c) were captured using a Magellan 40, while image (d) was captured with a JEOL JSM-7000F.

[0023] Figure 3 shows energy-dispersive X-ray spectroscopy (EDS) analysis of an exemplary coated glass side. The analysis was conducted on top left SEM image at 5 different spectra confirming presence of gold nanoparticles within the wrinkles.

[0024] Figure 4 shows the characterization results of microparticle coatings, (a) Surface characterizations illustrating the wetting properties of PDMS microparticles (MPs), FOTS-treated microparticles, and exemplary hMPs. (b) Hexadecane CA and water SA of various exemplary hMP spray-coated substrates, (c) Optical images depicting the change in the spherical shape of water (blue-dyed) and hexadecane droplets on exemplary coated (left) and uncoated (right) substrates, (d) Water CA of various substrates before and after exemplary hMP spray coating. All reported values are the mean of at least three measurements and associated error bars represent one standard deviation from the mean.

[0025] Figure 5 shows the results from physical characterizations of the exemplary coating of Example 2. (a) Representative optical profilometry topographical results of (i) uncoated glass and (ii) coated glass surfaces, as well as (iii) average thickness results of a coated glass surface, (b) Average roughness results of a coated and uncoated glass surface, (c, i-ii) SEM images demonstrating the homogeneity of a coated surface (scale bar is 1 mm for (i) and 100 pm for (ii)). (d) Graph representing the different spray coatings and associated water contact angle measurements on a coated glass surface.

[0026] Figure 6 shows investigation of various surface texturing on the omniphobicity of the exemplary coating of Example 2. SEM images of coatings fabricated under the following conditions: (i) 10:1 PDMS: curing agent at 80°C for 6 hours (scale bar is 1 pm), (ii) 10:1 PDMS: curing agent at 80°C for 2 hours (scale bar is 1 pm), (iii) 10:1 PDMS: curing agent at 50°C for 6 hours (scale bar is 1 pm), (iv) 10: 1 PDMS: curing agent at 50°C for 2 hours (scale bar is 1 pm), (v) 10: 1 PDMS: curing agent at 40°C for 2 hours (scale bar is 100 pm), (vi) 5:1 PDMS: curing agent at 80°C for 2 hours (scale bar is 1 pm), (b) Wettability characterizations of the different wrinkling conditions, (c) Plot illustrating the wavelength measurements of the different degrees of wrinkles, (d) Graph displaying the contact angle and contact angle hysteresis of coatings consisting of different sizes of PDMS microparticles with water and hexadecane, (e) Plot illustrating the relationship between the wavelength of the wrinkles and the radius of the PDMS microparticles with sizes A: ~20 pm (scale bar is 1 pm), B: ~60 pm (scale bar is 10 pm), and C: -100 pm (scale bar is 10 pm).

[0027] Figure 7 shows the results from stability, durability, and robustness testing of the coating of Example 3. (a) Contact and SA measurements illustrating the change in water and oil repellency after heat treatment and UV irradiation, (b) Plot illustrating the wettability of a coated glass surface after 30 and 60 days, (c-d) Water contact angle measurements after (c) sonicating a glass-coated surface in ethanol for a maximum of 15 mins (d) and post continuous and repetitive stamping of a glass-coated surface with a polydimethylsiloxane stamp, (e) Plot demonstrating the wear-induced change in contact angle hysteresis with various liquids, (f, i-ii) Optical images of hMP coated glass surfaces after perpendicular scratches (the scale bar is 500 pm), (g) Optical images depicting the flexibility of a coated textile.

[0028] Figure 8 shows results from self-cleaning test of hMP-coated glass surfaces. Colony forming unit assay was conducted at 2 time points using methicillin- resistant Staphylococcus aureus (MRSA). Graphs are depicted on a logarithmic scale representing the mean value of four different surfaces.

[0029] Figure 9 shows the results of pathogen repellency and killing tests, (a) Schematic illustrating the repellency and killing behavior of different exemplary tiered microparticles, (b-d) Colony forming unit assay performed at different time points on glass surfaces using (b) MRSA, (c) P. aeruginosa, and (d) Phi6 depicting the pathogen adherence, (e) SEM images of glass surfaces stamped with (i, ii) P. aeruginosa and (iii, iv) MRSA on uncoated glass surfaces (left) and coated glass surfaces (right). Red arrow points towards the MRSA colonies found on the surface of PDMS microparticles. The scale bars on larger SEM images are 10 pm and 1 pm for the insets, (f) Fluorescence images of live/dead assay at different time points for MRSA and P. aeruginosa. Live cells are represented in green and dead cells in red. (g-h) Quantification and comparison of the normalized area coverage on a coated glass surface by live and dead cells normalized to the uncoated surface using (g) MRSA and (h) P. aeruginosa. Error bars represent standard error from the mean, (i-j) CFU assay performed at different time points on uncoated, FOTS microparticle spray-coated and hMPs spray-coated wells using (i) MRSA and (j) P. aeruginosa. Graphs are depicted on a logarithmic scale and error bars represent one standard deviation from the mean. Each measurement consists of at least four data points. The red dotted line represents the initial inoculum of bacteria. Significance is shown through asterisks corresponding to *P<0.05, **P<0.01 , ***P<0.001 and ****P<0.0001.

[0030] Figure 10 shows the antimicrobial activity of functionalized gold nanoparticles. Growth assay using MRSA depicts the substantial reduction in bacterial growth for functionalized gold nanoparticles relative to pure gold nanoparticles. Graphs are depicted on a logarithmic scale and error bars represent standard errorfrom the mean. Each measurement consists of at least four data points.

[0031] Figure 11 shows an evaluation of the stability of gold nanoparticles in solution on the omniphobic microparticles (OMPs). Trial 1 depicts the colony forming unit of a spray-coated 96 well plate using MRSA relative to the control (uncoated 96 wellplate). Between the trials, the plate was excessively washed, and the growth assay was performed another time (trial 2), 4 weeks later. Graphs are depicted on a logarithmic scale and error bars represent standard error from the mean. The red dotted line represents the initial inoculum of bacteria.

[0032] Figure 12 shows the effect of AuNP size and density on antimicrobial activity, (a-c) SEM images of the OMPs coating consisting of AuNP concentration of (a) 5 pg/mL, (b) 50 pg/mL, and (c) 100 pg/mL (scale bar is 1 pm), (d-e) Bacterial growth graphs depicting (d) the effect of AuNP concentration and (e) AuNP size on the antimicrobial activity of the coating.

[0033] Figure 13 shows the results from pathogen transfer assays under real-world conditions, (a, i) Schematic illustration of the pathogen transfer test performed to study the pathogenic repellency of a coated versus uncoated latex glove, (a, ii) CFU assays illustrating the bacterial transfer on coated and uncoated gloves using MRSA. (c) PFU assay depicting the transfer of viruses on gloves, (d) CFU assay showing the adherence of pathogens on a pair of tweezers and textile taped on a lab coat. Graphs are depicted on a logarithmic scale and error bars represent one standard deviation from the mean. Significance is shown through asterisks corresponding to *P<0.05, **P<0.01 , ***P<0.001 and ****P<0.0001. (e) Pie chart depicting the different bacteria found on the textiles after PCR sequencing.

[0034] Other features and advantages of the present application will become apparent from the following detailed description. It should be understood, however, that the detailed description and the specific examples, while indicating embodiments of the disclosure, are given by way of illustration only and the scope of the claims should not be limited by these embodiments but should be given the broadest interpretation consistent with the description as a whole.

DESCRIPTION OF VARIOUS EMBODIMENTS

I. Definitions

[0035] Unless otherwise indicated, the definitions and embodiments described in this and other sections are intended to be applicable to all embodiments and aspects of the present disclosure herein described for which they are suitable as would be understood by a person skilled in the art. [0036] The term “microparticle(s) of the application” or “microparticle(s) of the present application” and the like as used herein refers to an omniphobic, antimicrobial wrinkled microparticle comprising PDMS core and metal-based nanoparticles. For example, microparticles of the application include the hierarchal microparticles as described herein.

[0037] The term “composition(s) of the application” or “composition(s) of the present application” and the like as used herein refers to a composition, such a sprayable composition, comprising one or more microparticles of the application.

[0038] The term “and/or” as used herein means that the listed items are present, or used, individually or in combination. In effect, this term means that “at least one of” or “one or more” of the listed items is used or present.

[0039] As used in the present disclosure, the singular forms “a”, “an” and “the” include plural references unless the content clearly dictates otherwise. For example, an embodiment including “a microparticle” should be understood to present certain aspects with one microparticle, or two or more additional microparticle.

[0040] In embodiments comprising an “additional” or “second” component, such as an additional or second microparticle, the second component as used herein is chemically different from the other components or first component. A “third” component is different from the other, first, and second components, and further enumerated or “additional” components are similarly different.

[0041] As used in this disclosure and claim(s), the words "comprising" (and any form of comprising, such as "comprise" and "comprises"), "having" (and any form of having, such as "have" and "has"), "including" (and any form of including, such as "include" and "includes") or "containing" (and any form of containing, such as "contain" and "contains"), are inclusive or open-ended and do not exclude additional, unrecited elements or process steps.

[0042] The term “consisting” and its derivatives as used herein are intended to be closed terms that specify the presence of the stated features, elements, components, groups, integers, and/or steps, and also exclude the presence of other unstated features, elements, components, groups, integers and/or steps. [0043] The term “consisting essentially of”, as used herein, is intended to specify the presence of the stated features, elements, components, groups, integers, and/or steps as well as those that do not materially affect the basic and novel characteristic(s) of these features, elements, components, groups, integers, and/or steps.

[0044] The present description refers to a number of chemical terms and abbreviations used by those skilled in the art. Nevertheless, definitions of selected terms are provided for clarity and consistency.

[0045] The terms "about", “substantially” and “approximately” as used herein mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed. These terms of degree should be construed as including a deviation of at least ±5% of the modified term if this deviation would not negate the meaning of the word it modifies or unless the context suggests otherwise to a person skilled in the art.

[0046] The term "suitable" as used herein means that the selection of the particular compound or conditions would depend on the specific synthetic manipulation to be performed, and the identity of the molecule(s) to be transformed, but the selection would be well within the skill of a person trained in the art. All process/method steps described herein are to be conducted under conditions sufficient to provide the product shown. A person skilled in the art would understand that all reaction conditions, including, for example, reaction solvent, reaction time, reaction temperature, reaction pressure, reactant ratio and whether or not the reaction should be performed under an anhydrous or inert atmosphere, can be varied to optimize the yield of the desired product and it is within their skill to do so.

[0047] The term “alkyl” as used herein, whether it is used alone or as part of another group, means straight or branched chain, saturated alkyl groups. The number of carbon atoms that are possible in the referenced alkyl group are indicated by the prefix “Cni-n2”. For example, the term C1-1 oal ky I means an alkyl group having 1 , 2, 3, 4, 5, 6, 7, 8, 9 or 10 carbon atoms.

[0048] The term “alkylene”, whether it is used alone or as part of another group, means straight or branched chain, saturated alkylene group, that is, a saturated carbon chain that contains substituents on two of its ends. The number of carbon atoms that are possible in the referenced alkylene group are indicated by the prefix “Cni-n2”. For example, the term C2-6alkylene means an alkylene group having 2, 3, 4, 5 or 6 carbon atoms.

[0049] The term “alkane” as used herein means straight or branched chain, saturated alkane, that is a saturated carbon chain.

[0050] The term “hydrolysable group” as used herein means a functional group that can be cleaved or displaced by a nucleophilic group such as water, hydroxyl groups, amine groups, etc.

[0051] The term “halo” as used herein refers to a halogen atom and includes F, Cl, Br and I.

[0052] The term “atm” as used herein refers to atmosphere.

[0053] The term “MS” as used herein refers to mass spectrometry.

[0054] The term “aq.” as used herein refers to aqueous.

[0055] The term “hMPs” as used herein refers to hierarchal microparticles.

[0056] HCI as used herein refers to hydrochloric acid.

[0057] The term “room temperature” as used herein means a temperature in the range of about 20°C and 25°C.

[0058] The term “wrinkling” as used herein refers to any process for forming wrinkles in a material. The term “wrinkled shell” as used herein refers to a surface or a portion of a surface that contains microscale to nanoscale folds.

[0059] The term “hierarchical” as used herein refers to a material having a range of microscale to nanoscale structural features on the surface of the material.

[0060] The term “naked nanoparticle” or the like as used herein refers to a nanoparticle that is not attached to a linker such as an organosilane linker.

[0061] The term “omniphobic” as used herein in respect to a material refers to a material that exhibits both hydrophobic (low wettability for water and other polar liquids) and oleophobic (low wettability for low surface tension and nonpolar liquids) properties. Such omniphobic materials with very high contact angles are often regarded as “selfcleaning” materials, as contaminants will typically bead up and roll off the surface. II. Microparticles and Compositions of the Disclosure

[0062] In one aspect, the present application includes an omniphobic and antimicrobial microparticle comprising a polymeric core comprising a wrinkled shell covering at least a portion of the core; and one or more hydrophobic molecular layers and one or more nanoparticle layers attached to the shell.

[0063] In some embodiments, the shell covering at least a portion of the core is a rigid layer covering substantially all of the core. In some embodiments, wrinkles are introduced in the shell by using mechanical tension, mechanical stretching, mechanical compression, heat or swelling induced stress, or a combination thereof. In some embodiments, wrinkles are formed by exerting stress o greater than a critical wrinkled stress Oc of the shell.

[0064] In some embodiments, the polymeric core comprises an elastomeric polymer. In some embodiments, the polymeric core comprises a viscoelastic polymer with low Young’s modulus, low intermolecular forces and/or withstands elastic deformation. In some embodiments, the polymeric core comprises a polymer selected from natural rubber, silicone elastomers, polyurethane, polybutadiene, PDMS, polylactic acid (PLA), and mixtures thereof. In some embodiments, the polymer comprises PDMS, or polylactic acid (PLA). In some embodiments, the polymer is PDMS, polylactic acid (PLA), or a mixture thereof. In some embodiments, the polymer is PDMS.

[0065] Other suitable polymers include polymers that are formed by monomers that are soluble in organic solvents and hydrolysable, but less soluble or insoluble in aqueous medium. In some embodiments, the polymers are biocompatible.

[0066] In some embodiments, the shell comprises a surfactant that comprises a plurality of hydroxyl groups. In some embodiments, the surfactant is partially hydrolyzed to provide the plurality of hydroxyl groups. In some embodiments, the surfactant is a siloxane surfactant.

[0067] In some embodiments, the surfactant is selected from 3-(2- methoxyethoxy)propyl-methyl-bis(trimethylsilyloxy)silane, ethane-1 ,2-diol;propane-1 ,2- diol, polyoxyethylene (20) sorbitan monolaurate, 3-(3-hydroxypropyl)- heptamethyltrisiloxane, ethoxylated, acetate, and combinations thereof.

[0068] In some embodiments, the one or more hydrophobic molecular layers comprise a fluorosilane layer. In some embodiments, the fluorosilane layer comprises fluorosilane moieties, each of the fluorosilane moieties having a structure of Formula I

R ¹

R ² -Si-X-(CF ₂ ) _n CF ₃

R ³

(I) wherein

X is a single bond or is Ci-6alkylene; n is an integer of from 0 to 12; and

R ¹ , R ² and R ³ are each independently a point of attachment to a hydroxyl group of the plurality of hydroxyl groups of the shell, a hydroxyl group, or a hydrolysable group, wherein at least one of R ¹ , R ² and R ³ is the point of attachment to the shell.

[0069] In some embodiments, n is 4 to 9. In some embodiments, n is 5 to 7.

[0070] In some embodiments, X is Ci-3alkylene, In some embodiments X is CH2CH2.

[0071] In some embodiments, the hydrolysable group is an alkoxy such as an C1- ealkoxy, halo such as Cl, or Br, or trihaloalkylsulfonate such as trifluoromethylsulfonate.

[0072] In some embodiments, the fluorosilane layer comprises (1 H,1 H, 2H,2H- perfluorooctyl)silane, (1 H,1 H, 2H,2H-perfluorodecyl)silane, or combinations thereof.

[0073] In some embodiments, the one or more nanoparticle layers comprises nanoparticles selected from polymer nanoparticles, insulator nanoparticles, metal-based nanoparticles, and combinations thereof. In some embodiments, the metal-based nanoparticles are metal nanoparticles, metal oxide nanoparticles, semiconductor nanoparticles, or combinations thereof. In some embodiments, the metal-based nanoparticles comprise a metal selected from Au, Ag, Cu, Zn, Ti, Mg, and combinations thereof. In some embodiments, the semiconductor nanoparticles comprise a semiconductor selected from ZnO, CdS, ZnS and combinations thereof. In some embodiments, the metal oxide nanoparticles comprise a metal oxide selected from TiO2, ZnO, Ag2O, MgO, Fe2O3, CuO, CaO, CdO and combinations thereof. In some embodiments, the polymer nanoparticles are selected from poly(lactide-co-glycolide) (PLGA), polylactide (PLA), polyglycolide, polycaprolactone (PCL), poly(d.l-lactide), and PLGA-polyethylene glycol (PEG). In some embodiments, the insulator nanoparticles are selected from silica, titanium dioxide, aluminum oxide, and combinations thereof. In some embodiments, the nanoparticles are Au nanoparticles.

[0074] In some embodiments, the nanoparticles are bound to the shell through the one or more functionalised organosilane linkers. In some embodiments, the linker is selected based on the nature of the nanoparticles to be bound. In some embodiments, the one or more functionalised organosilane linkers are selected from APTES, EDC- functionalised organosilane, glutaraldehyde-functionalised organosilane, and thiol organosilane linkers. In some embodiments, the functionalised organosilane linker is a thiol organosilane linker for attachment of Au nanoparticles due to the affinity between sulfur and Au.

[0075] In some embodiments, each of the one or more functionalised organosilane linkers is attached to one of the nanoparticles at a reactive functional group of the functionalised organosilane linker. In some embodiments, each of the nanoparticles is attached to a plurality of the functionalised organosilane linkers; wherein the plurality of the functionalised organosilane linkers form a silanol layer around each of the nanoparticles; and wherein the silanol layer is attached to the shell. In some embodiments, the one or more functionalised organosilane linkers are one or more thiol organosilane linkers. In some embodiments, the thiol organosilane linker is formed using a reagent selected from (3-mercaptopropyl)trimethoxysiloxane, 3-mercaptopropionic acid (3-MPA), 11-mercaptoundecanoic acid (MUA), polyethylene glycol 2-mercaptoethyl methyl ether, polyethylene glycol) methyl ether thiol, 3-(trimethoxysilyl)-1 -propanethiol, and combinations thereof.

[0076] In some embodiments, the silanol layer is further functionalised with one or more hydrophobic fluoroorganosilane functionalities of a structure of Formula I as herein; or wherein the nanoparticles are functionalised with a thiofluorohydrocarbon of Formula II

*-S-(CH ₂ ) _r - (CF ₂ ) _q CF ₃

(H) wherein

* is the point of attachment to the nanoparticles, r is an integer of from 0 to 5; and q is an integer of from 0 to 12.

[0077] In some embodiments, r is 1 to 4, 1 to 3, 2 to 3, or 2. In some embodiments, q is 5 to 10, 5 to 9, or 7.

[0078] In some embodiments, the microparticle has a diameter of about 2 pm to about 30 pm, about 10 pm to about 30 pm, about 15 pm to about 25 pm, or about 20 pm.

[0079] In some embodiments, the microparticle has a modulus of elasticity of 250 kPa to 280 kPa. The elastic modulus E is calculated based on the equation E = 20 MPa/n, where n is the PDMS/curing agent weight ratio.

[0080] In another aspect, the present application includes an omniphobic and antimicrobial surface treatment composition comprising the omniphobic and antimicrobial microparticle of the present application or an omniphobic and antimicrobial microparticle prepared by a method of the present application; and a solvent.

[0081] In some embodiments, the solvent of the omniphobic and antimicrobial surface treatment composition is selected from an alcohol, tetrahydrofuran, water, and combinations thereof. In some embodiments, the alcohol is ethanol.

[0082] In some embodiments, the surface treatment composition comprises about 50 mg/mL to about 200 mg/mL, about 75 mg/mL to about 175 mg/mL, about 80 mg/mL to about 150 mg/mL, about 80 mg/mL to about 125 mg/mL, about 90 mg/mL to about 110 mg/mL, or about 100 mg/mL of the omniphobic and antimicrobial microparticle. [0083] In some embodiments, the composition is sprayable.

III. Method of Preparing Microparticles and Compositions of the Disclosure

[0084] In another aspect, the present application includes a method of preparing an omniphobic and antimicrobial microparticle comprising combining a polymer and a surfactant to obtain a polymer microparticle comprising a polymeric core and a shell covering at least a portion of the core, the shell comprising the surfactant; treating the polymer microparticle under conditions to wrinkle at least a portion of the shell; and coating the polymer microparticle with one or more hydrophobic molecular layers and one or more nanoparticle layers through attachment to the shell to obtain the omniphobic and antimicrobial microparticle.

[0085] In some embodiments, the treating of the polymer microparticle exerts a compressive stress o greater than a critical wrinkled stress o _c of the microparticle, thereby wrinkling at least a portion of the shell.

[0086] In some embodiments, the polymer comprises natural rubber, silicone elastomers, polyurethane, polybutadiene, PDMS, polylactic acid (PLA), or mixtures thereof. In some embodiments, the polymer comprises PDMS, PLA, or mixtures thereof. In some embodiments, the polymer is PDMS or PLA.

[0087] In some embodiments, the surfactant comprises a plurality of hydroxyl groups. In some embodiments, the surfactant is partially hydrolyzed to provide the plurality of hydroxyl groups. In some embodiments, the method further comprises partially hydrolyzing the surfactant. It can be understood that partial hydrolysis of the surfactant can be carried out by methods known in the art. For example, the partially hydrolyzing can be carried out by exposing the surfactant to water. For example, the combining of the polymer and the surfactant can be carried in the presence of water to partially hydrolyze the surfactant while obtaining the polymer microparticle. Alternatively or additionally, the partially hydrolyzing of the surfactant can be carried out prior to the combining of the polymer and the surfactant. In some embodiments, the surfactant is as described herein. In some embodiments, the surfactant is an anionic trisiloxane alkoxylate surfactant. In some embodiments, the surfactant is an anionic trisiloxane ethoxylate surfactant. In some embodiments, the surfactant is selected from 3-(2-methoxyethoxy)propyl-methyl- bis(trimethylsilyloxy)silane (e.g. Silwet L-77 ^TM ), ethane-1 ,2-diol; propane-1 , 2-diol (e.g. Pluronic F-68 ^TM ), polyoxyethylene (20) sorbitan monolaurate (e.g. Tween 20™), 3-(3- hydroxypropyl) -heptamethyltrisiloxane, ethoxylated, acetate (e.g. Sylgard ® 309 Silicone), and combinations thereof.

[0088] In some embodiments, the one or more hydrophobic molecular layers and the one or more nanoparticle layers are attached to the shell through the plurality of hydroxyl groups.

[0089] In some embodiments, the combining of the polymer and the surfactant is carried out under conditions to obtain a homogenous emulsion comprising the polymer microparticle. In some embodiments, the combining of the polymer and the surfactant is carried out in an organic solvent. In some embodiments, the organic solvent is selected from acetone, ethanol, dichloromethane, toluene, chloroform, and combinations thereof. In some embodiments, the organic solvent is acetone. In some embodiments, the combining of the polymer and the surfactant is carried out in the presence of water. In some embodiments, the conditions for combining the polymer and the surfactant comprise sonication. In some embodiments, the sonication is ultrasonication. In some embodiments, the ultrasonication is performed at about 30 to about 50 kHz, about 30 to about 40 kHz, or about 35 kHz.

[0090] In some embodiments, the shell covering at least a portion of the core is a rigid layer covering substantially all of the core.

[0091] In some embodiments, the one or more hydrophobic molecular layers comprise a fluorosilane. In some embodiments, the fluorosilane is as described herein. In some embodiments, the coating of the polymer microparticle comprises fluorosilanating the polymer microparticles using one or more fluorosilanation agents as described herein. In some embodiments, the fluorosilanation agents have the structure of Formula III as defined herein. In some embodiments, the one or more fluorosilanation agents are selected from trichloro(1 H,1 H,2H,2H-perfluorooctyl)silane, 1 H,1 H,2H,2H- perfluorooctyltriethoxysilane, and combinations thereof.

[0092] In some embodiments, the one or more nanoparticle layers comprise one or more nanoparticles as described herein. In some embodiments, the nanoparticles comprise one or more hydrophobic fluoroorganosilane functionalities attached thereto. In some embodiments, the hydrophobic fluoroorganosilane functionalities are as described herein. In some embodiments, the nanoparticles are as described herein.

[0093] In some embodiments, the treating of the polymer microparticle to obtain the wrinkled microparticle comprises stirring, particle drying, surface chemical modification such as wet surface chemical oxidation, or combinations thereof. In some embodiments, the treating of the polymer microparticles comprises mechanical tension, mechanical stretching, mechanical compression, heat or swelling induced stress, or a combination thereof. In some embodiments, the stirring is as described herein, for example the stirring is performed at about 8000 RPM to about 12000 RPM, about 9000 RPM to about 11000 RPM, about 9500 RPM to about 10500 RPM, or about 10000 RPM. In some embodiments, the stirring is carried out at about 60°C to about 100°C, about 70°C to about 90°C, or about 80°C. In some embodiments, the stirring is carried out for about 2 hours to about 5 hours, about 2.5 hour to about 4.5 hours, about 2 hours to about 4 hours, or about 2 hours. In some embodiments, the surface chemical modification is as described herein. In some embodiments, the surface chemical modification comprises wet chemical surface oxidation using for example acids (e.g. H2SO4 and/or HNO3).

[0094] In some embodiments, the coating of the wrinkled microparticle with the one or more nanoparticle layers comprises attaching the one or more nanoparticle layers to the shell through one or more functionalised organosilane linkers. In some embodiments, the functionalised organosilane linkers are as described herein. In some embodiments, the functionalised organosilane linkers are a compound of Formula IV as described herein.

[0095] In some embodiments, the antimicrobial and omniphobic microparticles have a diameter of about 2 pm to about 30 pm, about 15 pm to about 25 pm, or about 20 pm.

[0096] In some embodiments, each of the nanoparticles is attached to a plurality of the functionalised organosilane linkers; wherein the plurality of the functionalised organosilane linkers form a silanol shell around each of the nanoparticles; wherein the silanol shell comprises hydroxyl groups; and wherein at least a portion of the hydroxyl groups of the silanol shell is for attachment to the shell of the polymer microparticle. In some embodiments, another portion of the hydroxyl groups of the silanol shell around each of the nanoparticles is functionalised with fluorosilane functionalities. In some embodiments, the fluorosilane functionalities have a structure of Formula I as defined herein.

[0097] In some embodiments, the method further comprises combining naked nanoparticles and a coupling agent to obtain the nanoparticles attached to the plurality of the functionalised organosilane linkers.

[0098] In some embodiments, the functionalised organosilane linker is thiol organosilane linker and the coupling agent is of Formula IV:

R ⁷ „ i R ⁸ -Si-(CH ₂ ) _P -SH

R ⁹

(IV) wherein p is an integer of from 1 to 8 and

R ⁷ , R ⁸ and R ⁹ are each independently a hydrolysable group.

[0099] In some embodiments, p is 1 to 6, 1 to 4, 1 to 3, 2 to 3, or 3. In some embodiments, R ⁷ , R ⁸ and R ⁹ are each independently C1-3 alkoxy or halo. In some embodiments, R ⁷ , R ⁸ and R ⁹ are each independently methoxy, ethoxy, or Cl.

[00100] In some embodiments, the coupling agent is selected from (3- mercaptopropyl)trimethoxysilane, 3-mercaptopropionic acid (3-MPA), 11- mercaptoundecanoic acid (MUA), polyethylene glycol 2-mercaptoethyl methyl ether, polyethylene glycol) methyl ether thiol, and 3-(trimethoxysilyl)-1 -propanethiol.

[00101] In some embodiments, the functionalising of the wrinkled PDMS microparticles with the plurality of metal-based nanoparticles occurs prior to the fluorosilanating of the wrinkled PDMS microparticles.

[00102] In some embodiments, the naked nanoparticles are combined with the coupling agent in the presence of a thiol fluorohydrocarbon of Formula V

HS-(CH ₂ ) _t - (CF ₂ ) _S CF ₃ (V) wherein t is an integer of from 0 to 5; and s is an integer of from 0 to 12.

[00103] In some embodiments, t is 1 to 4, 1 to 3, 2 to 3, or 2. In some embodiments, s is 5 to 10, 5 to 9, or 7.

[00104] In some embodiments, the thiol fluorohydrocarbon is 1 H,1 H,2H,2H- perfluorodecanethiol.

[00105] In some embodiments, the method of preparing the omniphobic and antimicrobial microparticle further comprises washing and drying the omniphobic and antimicrobial microparticle.

[00106] In some embodiments, the omniphobic and antimicrobial microparticle is the omniphobic and antimicrobial microparticle of the present application as described herein.

IV. Methods and Use of the Microparticles and Compositions of the Disclosure [00107] In another aspect, the present application includes a method of surface treatment of a substrate to provide omniphobic and/or antimicrobial properties comprising applying a binder on a surface of the substrate; applying a layer of an omniphobic and antimicrobial surface treatment composition of the present application on the surface of the substrate; and drying the surface of the substrate applied with the binder and the surface treatment composition.

[00108] In another aspect, the present application includes a method of preventing, reducing, or delaying adhesion, or adsorption of a biological material onto a device in contact therewith, comprising: treating at least one surface of the device with an omniphobic and antimicrobial surface treatment composition of the present application, optionally by a surface treatment method of the present application.

[00109] In another aspect, the present application includes a use of an omniphobic and antimicrobial microparticle of the present application or a surface treatment composition of the present application in preventing, reducing, or delaying adhesion, or adsorption of a biological material onto a device in contact therewith.

[00110] In some embodiments, the method of surface treatment further comprises applying one or more additional layers of the surface treatment composition prior to the drying of the surface.

[00111] In some embodiments, the applying of the layer(s) of the surface treatment composition comprises spraying and/or painting the surface treatment composition. In some embodiments, the applying of the layer(s) of the surface treatment composition comprises dipping or immersing the surface of the substate in the surface treatment composition.

[00112] In some embodiments, the binder is an epoxy resin binder or aluminum phosphate. In some embodiments, the binder is the epoxy resin binder. In some embodiments, the epoxy resin binder is selected from polyacrylic acid (PAA), polyvinyl alcohol (PVA), PDMS, methylphenyl silicone resin, polyurethane, and mixtures thereof.

[00113] In some embodiments, the drying of the surface comprises heating at about 60°C to about 100°C, about 70°C to about 90°C, or about 80°C.

[00114] In some embodiments, the substrate is selected from glass, polystyrene, stainless steel, textile, paper, and combinations thereof.

[00115] In another aspect, the present application includes a substrate surface treated by a surface treatment method of the present application.

[00116] In another aspect, the present application includes a material comprising a substrate and the omniphobic and antimicrobial microparticles of the present application or omniphobic and antimicrobial microparticles prepared by a method of the present application, wherein the microparticle is present on a surface of the substrate.

[00117] In some embodiments, the material has a water static contact angle of 130° to about 190°, about 145° to about 175°, about 150° to about 170°, about 155° to about 165°, or about 160° as measured at room temperature using a goniometer.

[00118] In some embodiments, the material has a hexadecane static contact angle of about 90° to about 130°, about 100° to about 120°, about 110° to about 115°, about 112° to about 115°, or about 113° as measured at room temperature using a goniometer. [00119] In some embodiments, the material has a water sliding angles of about 8° to about 15°, about 10° to about 13°, or about 12°, as determined at room temperature using a digital angle level.

[00120] In some embodiments, the material has a surface roughness of about 5 pm to about 12 pm, or about 8 pm to about 10 pm, or about 9.6 pm as measured using vertical scanning interferometry.

[00121] In some embodiments, the material is stable to thermal treatment of about 100°C, about 150°C, about 200°C, about 250°C, about 300°C, about 350°C, or at least about 300°C, for about 30 minutes to about 2.5 hours, about 1 hour to about 2.5 hours, about 2 hours, or at least about 2hours.

[00122] In some embodiments, the material is stable to UV irradiation at 10 mW/cm ² at a wavelength of 340 nm for at least about 1 hour, at least about 2 hours, at least about 4 hours, or about 6 hours.

[00123] In some embodiments, the material is stable to sonication at 35 kHz for at least about 5 minutes, at least about 10 minutes, or at least about 15 minutes.

[00124] In some embodiments, the material exhibits repellency to liquids.

[00125] In some embodiments, the material exhibits repellency to biospecies. In some embodiments, the biospecies are selected from MRSA, P. aeruginosa, Phi6, SARS- CoV2, and combinations thereof.

[00126] In some embodiments, the material exhibits repellency to bacteria, virus, fungus, and biofilm formation. In some embodiments, the bacteria are selected from MRSA, P. aeruginosa, vancomycin-resistant Enterococcus, Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumanii, Salmonella Typhimurium, Enterobacter aerogenes, Burkholderia cenocepacia, and Proteus mirabilis, and combinations thereof. In some embodiments, the virus is selected from Phi6, SARS-CoV2, Middle East respiratory syndrome (MERS-CoV), Herpes simplex virus, and influenza A viruses, and combinations thereof.

[00127] In another aspect, the present application includes a device or an article comprising a material of the present application. [00128] In another aspect, the present application includes a device or article comprising a surface, wherein at least a portion of the surface comprises a material of the present application.

[00129] In another aspect, the present application includes a device or article comprising a surface, wherein at least a portion of the surface has been treated by a surface treatment method of the present application.

[00130] In some embodiments, the device or article is selected from:

- plastic material that is disposed of for fouling or contamination, including, but not limited to plastic shopping bags, shower curtains and children’s toys (such as blow up pools and slip and slides water toys);

- keyboards, mouse, public kiosks, ATMs, sunglasses, car windshields, camera lenses, solar panels, and architectural systems (knobs/latches, hospital bed rails, windows, handles), public trash handles, transportation articles (e.g. poles, seats, handles, buttons, airplane trays), food service items (cutting boards, countertops, food storage containers, handles, doors, refrigerator interior, upstream, downstream, consumer-targeted), restroom items (toilet seat, flush handle), and manufacturing equipment (e.g., surfaces, conduits, tanks); and

- wearable articles including, but not limited to, protective clothing such as gloves, scrubs, and face masks; consumable research equipment including, but not limited to, centrifuge tubes, micropipette tips and multiwell plates, a cannula, a connector, a catheter, a catheter, a clamp, a skin hook, a cuff, a retractor, a shunt, a needle, a capillary tube, an endotracheal tube, a ventilator, a ventilator tubing, a drug delivery vehicle, a syringe, a microscope slide, a plate, a film, a laboratory work surface, a well, a well plate, a Petri dish, a tile, a jar, a flask, a beaker, a vial, a test tube, a tubing connector, a column, a container, a cuvette, a bottle, a drum, a vat, a tank, a dental tool, a dental implant, a biosensor, a bioelectrode, an endoscope, a mesh and a wound dressing.

[00131] In some embodiments, the biological material is selected from the group consisting of whole blood, plasma, serum, sweat, feces, urine, saliva, tears, vaginal fluid, prostatic fluid, gingival fluid, amniotic fluid, intraocular fluid, cerebrospinal fluid, seminal fluid, sputum, ascites fluid, pus, nasopharengal fluid, wound exudate fluid, aqueous humour, vitreous humour, bile, cerumen, endolymph, perilymph, gastric juice, mucus, peritoneal fluid, pleural fluid, sebum, vomit, and combinations thereof.

EXAMPLES

[00132] The following non-limiting examples are illustrative of the present application.

General Methods

Synthesis of hierarchal Microparticles (hMPs)

[00133] A 10:1 weight ratio of polydimethylsiloxane (SYLGARD 184™) (Dow Corning, United States) to curing agent was prepared and degassed for 30 mins to remove any air bubbles. Silwet L-77™ (10 wt%) (PhytoTech Labs, Canada) was mixed thoroughly with (3 g) PDMS to produce a homogenous emulsion at room temperature. The emulsion was then sonicated in glass vials at 35 KHz in an ultrasonication bath (VWR, Canada) for 2 hours to produce 20 pm sized uniform microparticles. The microparticles were then collected and vigorously stirred at 10000 RPM for 2 hours using a pneumaticbased overhead stirrer (AP10, ThermoFisher Scientific, Canada) at 80°C to cure and dry the interfacial layer. According to a previously reported method ¹⁴²¹ , activation and hydrolysis of 1 H,1 H,2H,2H-perfluorooctyltriethoxysilane (FOTS) (Millipore Sigma, Canada) was conducted by incubating a mixture of FOTS-ethanol-1 M HCI H2O (1 :1 :0.4 weight ratio) at 40°C for 1 hour, followed by sonication for 20 minutes to reduce the formation of any aggregates. Subsequently, FOTS (45 mL) was added to PDMS- surfactant (20 mL) solution under magnetic stirring for 24 hours. Finally, to functionalise the gold nanoparticles with a fluorosilane and a coupling agent, a thiol-mixed silane solution of 1 H,1 H,2H,2H-perfluorodecanethiol (2 wt%) (Millipore Sigma, Canada) and (3- mercaptopropyl)trimethoxysilane (MPTMS, 5 wt%) (Millipore Sigma, Canada) was prepared and incubated with (30 mL) AuNPs for 24 hours. AuNP were synthesized according to the Tukevich method. ¹⁴³¹ After 24 hours, the functionalized AuNP solution was then added to the FOTS-treated PDMS microparticles and stirred for 2 hours. The resultant hMPs were then centrifugally washed with water (x4) and ethanol (x2). The microparticles were then incorporated in a spray consisting of absolute ethanol with a final concentration of 100 mg ml’ ¹ .

Preparation of Omniphobic Coatings [00134] All substrates were washed with ethanol and dried at 45 °C before use. To prepare the binder spray, commercial ArtResin™ epoxy resin (2 g) and hardener (1 g) were mixed with absolute ethanol (20 g) under magnetic stirring. Other suitable resins include polyacrylic acid (PAA), polyvinyl alcohol (PVA), PDMS, methylphenyl silicone resin, polyurethane and aluminum phosphate. As the pressure equalizes between the atmosphere and the airbrush propellent (air) of the spray, the epoxy solution (ArtResin, Canada) was sprayed out at a 10-15 cm distance perpendicular to the substrates, and subsequently the surfaces were sprayed with hMPs spray. They were left to dry at 80°C for 2 hours.

PLA Microparticles

[00135] PLA based microparticles were prepared. Briefly, 15 mg/mL of PLA was dissolved in acetone. Then, 15 mg/mL of Silwet L-77 was dissolved in water. The 2 solutions were mixed using an overhead stirrer at 10000 RPM and heated at 80°C for 2 hours. The particles were washed and collected through centrifugation in ethanol and water.

Contact and Sliding Angle Measurements

[00136] All contact and sliding angle measurements were conducted on a drop shape analyzer (DSA30, Kriiss Scientific, Hamburg, Germany). A pipette was used to dispense (3 pl) of hexadecane on all the substrates, while an automated syringe was used to dispense (2 pl) of distilled water. The mean value of 4 measurements on different parts of a surface were taken. Based on the uneven texture of the coating, manual baseline configurations were adjusted for each surface using an image processing software (Kriiss ADVANCE). For sliding angle measurements, a digital angle level (ROK, Exeter, UK) was used with distilled water droplet volumes of 5 pL.

Surface Roughness

[00137] A vertical scanning interferometric (VSI) analysis was performed to measure the surface roughness of a spray coated and uncoated glass slides using the Wyko NT1100 Optical Profiling System (Veeco, Tuscon AZ, USA), in addition a software known as Vision32 version 2.303 was used for data analysis. A minimum of 10 different observations were tested on the coated and uncoated surfaces.

Scanning Electron Microscopy [00138] To visualize the nano- and micro-/hierarchal structure of the PDMS microparticles, as well as the deposition of the gold nanoparticles, electron microscopy using the JEOL JSM-7000F and FEI Magellan 400 was conducted. The samples were mounted on a stub using carbon tape and silver paste, they were then coated using a sputter coater (Polaron model E1500, Polaron Equipment Ltd., Watford, Hertfordshire) with 5 nm of platinum for images taken with JEOL JSM-7000F and 3 nm of carbon for images taken with FEI Magellan 400. To visualize the bacteria-stained surfaces, SEM images were taken using the JEOL JSM-7000F. The samples were initially fixed with (4%) formalin solution for 24 hours, then the samples were stained with (1%) osmium tetraoxide in sodium cacodylate buffer (pH = 7.4). Subsequently, they were sequentially dehydrated with (100%) ethanol solutions from 25% to 100%, and finally critically point dried (Leica Microsystems, Wetzlar, Germany).

Durability and Stability Tests

[00139] To test durability of the coating under harsh environments, coated glass slides were subjected to 350°C on a hot plate for 2 hours. Next, the coated glass slides were irradiated under a UV lamp (approximately 10 mW cm ^-2 ) with a wavenumber of 340 nm for 6 hours at a perpendicular distance of 10 cm . A sonication test was also conducted, whereas a coated glass slide was fully immersed in a falcon tube containing ethanol and sonicated in an ultrasonic bath (VWR, Mississauga, Canada) at 35 kHz for 5, 10, 15 minutes. After the stability tests, contact angle measurements were examined.

Bacterial Adhesion (Stamp) Assay and Experimental Setup

[00140] Pseudomonas aeruginosa PA01 ^[441 and Staphylococcus aureus USA300 JE2 (MRSA) ^[451 were streaked onto LB agar from frozen and allowed to grow overnight at 37 °C. Overnight cultures were then diluted 1/100 into MOPS-minimal media supplemented with (0.4%) glucose and (0.5%) casamino acids (TekNova, United States) for P. aeruginosa, or tryptic soy broth supplemented with (0.4%) glucose and (3%) NaCI for MRSA ^[461 . Concentrated MRSA and P. aeruginosa bacterial suspensions were then prepared in small petri dishes. Agar plugs were fabricated from (3%) agar by dissolving (3 g) agarose in Milli-Q water (100 ml) under magnetic stirring at room temperature. The agarose was then heated in the microwave until no bubbles were seen, and then poured onto a petri dish to cool down at room temperature. Once the agarose cured, agar plugs were harvested by poking 15 mm tubes into the solidified agarose. The stamp assay was conducted by initially dipping the harvested agar plugs into the concentrated bacterial suspensions and immediately stamping the surfaces to transfer the bacteria. Surfaces were then incubated in petri dishes covered with a lid at room temperature for 1 , 2, 4, and 8 hours. Next, the stamped surfaces were incubated with shaking for 20 minutes in tubes containing equal volumes (2.5 mL) of bacteria growth media and recombinant trypsin solution (TrypLE Express, Gibco) to disperse biofilms, as well as adhered bacterial cells from the surfaces. From this solution, 100 pL of each sample was taken in order to run a CFU assay by plating serial dilutions on LB agar Petri dishes.

XPS analysis

[00141] Elemental fraction percentages were measured from the XPS spectra of hMP-coated glass surfaces under different incubation parameters, i.e., submerged in water for 1 , 3, and 7 days. The XPS spectra were obtained using a Physical Electronics (PHI) Quantera-ll XPS Microprobe spectrometer. The survey spectra were produced with a monochromatic X-ray source at 25 W using a voltage of 15 kV and a pass energy of 26 eV. All spectra were obtained with a take-off angle of 45° and a step size of 0.8 eV for the survey and 0.1 eV for elemental data. Data is collected at 3 different locations.

Self-cleaning Test

[00142] The previously mentioned stamp test was conducted again to verify the selfcleaning ability of the coated-glass surfaces. Post stamping, the glass slides were tilted with a certain angle in a Petri dish and (500 pL) sterile water droplets were dropped (x3) using a pipette on the glass slides. A CFU assay was conducted as previously mentioned.

Virus Adhesion (Stamp) Assay and Experimental Setup

[00143] Pseudomonas Phi6 (DSM-21518) and its host bacterium Pseudomonas syringae van Hall 1902 (DSM-21482) were purchased from Leibniz Institute DSMZ, (Braunschweig Germany). The bacterial strains were stored at -80°C in 50% glycerol. All bacteria were grown in Tryptic soy broth (TSB) supplemented by (5 mM) Magnesium sulfate and (6 g L ^-1 ) yeast extract (VWR, Canada). Bacterial overnight culture was aseptically inoculated from a frozen stock in (3 mL) supplemented TSB media and was grown at 25°C for24 h with orbital shaking at 180 rpm. For Phi6 propagation, (50 pL) virus stock and (1 mL) P. syringae in the exponential growth phase were added to (30 mL) supplemented TSB media. The suspension was incubated in a shaking incubator at 25°C and 180 rpm for 12 hours. The viral lysate was centrifuged at 7000 ref at 4°C for 20 min and the supernatant was filtered with sterile 0.2 pm pore size syringe filters (Fisher Scientific, Canada). The titer of viral suspension was determined using the double-layer agar ^[47] method and was stored at 4°C until use.

[00144] PDMS stamps were fabricated by initially degassing a 10:1 weight ratio of PDMS: curing agent for 30 minutes followed by curing at 150°C for 1 hour. Square-like stamps with sizes identical to the samples were harvested by cutting the PDMS using a scalpel. The PDMS stamps were then plasma treated for 30 seconds and then inoculated with (5 pL) Phi6 solution with an initial concentration of 10 ⁶ PFU mL’ ¹ . The inoculated stamps were left to dry for around 5 minutes and then immediately stamped onto glass coated and uncoated samples. Surfaces were incubated for 2 hours in a humidity chamber with relative humidity of 80%. Next, the stamped surfaces were incubated in tubes containing (5 mL) TSB growth media with yeast for 20 minutes. From this solution, 20 pL of each vortexed sample was taken for serial dilutions and PFU plating on TSB agar Petri dishes containing a lawn of bacteria with 0.3% soft agar and 200 pL of P. syringae.

Bacterial Growth Assay and Experimental Setup

[00145] MRSA and P. aeruginosa were grown on spray coated 96-well plates, using uncoated 96-well plates and FOTS spray coated 96- well plates as controls. Each well was flooded with (500 pL) the bacterial suspensions containing around 10 ⁵ CFU ml’ ¹ of MRSA and 10 ⁶ CFU ml’ ¹ of P. aeruginosa. The plates were then incubated without shaking at 37°C. Post incubation based on the designated time, CFUs were quantified by taking 10 pL from each well and plating serial dilutions on LB agar Petri dishes.

Live/dead Assay

[00146] The stamped glass coated surfaces were stained with the Live/Dead BacLight™ kit (SYTO9 and propidium iodide (PI)) (Thermo Fisher Scientific, Canada). A mixture of (10 pmol I ^-1 ) SYTO9 and (60 pmol I ^-1 ) PI was added to each coated surface. Then, the samples were incubated for 30 min at room temperature in the dark. After gentle cleaning using (0.9% (w/v)) NaCI followed by phosphate buffered saline (PBS) (Bioshop) at pH 7.4, the surfaces were retrieved for examination under a fluorescence microscope (Eclipse™ Ti2 Series, Nikon®, Melville, New York) equipped with a 20x objective lens with filters appropriate for SYTO9 and PI. To quantify and compare the number of living cells relative to dead cells, image processing was carried out using Imaged software.

Pathogen Transfer on gloves, tweezers, and textile [00147] The index finger of a coated and uncoated gloved hand was initially dipped into a concentrated bacterial suspension of MRSA (10 ⁶ CFU ml ^-1 ) enough to cover the surface of the upper part of the gloved finger. Subsequently, the inoculated glove was touched with a clean glass surface to transfer the bacteria. A series of 10 consecutive touches were performed for the coated glove, while the uncoated glove underwent a series of 10 consecutive touches, followed by 20, 30, 40, and 50 touches. Each round of touches was performed on new sterile glass slides. The time difference between each set of touches was the same for the coated and uncoated glove during the first 10 touches. The contaminated gloves were then collected, suspended in bacteria media, and incubated in a shaking incubator for 40 minutes. 100 pL of each sample was taken to run a CFU assay by plating serial dilutions on LB agar Petri dishes. The same assay was performed using a suspension of Phi6 with initial concentration of 10 ⁶ PFU mL. Coated and uncoated gloves were similarly dipped into a suspension of virus and then contaminated secondary clean glass surfaces a series of 10 and 50 times, respectively. Contaminated glove surfaces were then collected and suspended in TSB media for 20 minutes. From each vortexed solution, 20 pL of solution was then taken for PFU plating on TSB agar Petri dishes containing a lawn of bacteria with (0.3%) soft agar and (200 pL) P. syringae.

[00148] A pair of tweezers with a coated and uncoated side were used for the glove transfer assay using MRSA. Post the assay, each side of the tweezers were fully immersed into bacteria media for 30 minutes, followed by incubation in a shaking incubator for 40 minutes. 100 pL of each sample was taken for CFU plating. Lastly, two equal sizes of textile were collected and initially sterilized, followed by spray-coating one of them. The two pieces of textile were taped using two-sided tape onto a lab coat, whereas the subject wearing the lab coat performed experiments wearing the lab coat for a series of 10 days. The surfaces were then suspended in bacteria media and incubated in a shaking incubator for 40 minutes. Post incubation, CFUs were quantified by taking 10 pL from each well and plating serial dilutions on LB agar Petri dishes.

16S ribosomal RNA (rRNA) gene sequencing

[00149] The 16s rRNA gene was amplified from each contaminant colony by PCR using the 8F (5’AGAGTTTGATCCTGGCTCAG 3’, SEQ ID NO:1) and 1492R (5’GGTTACCTTGTTACGACTT 3’, SEQ ID NO:2) primers. Amplicons from this reaction were PCR purified and sequenced by Sanger sequencing. Resulting sequences were run through NCBI Nucleotide BLAST to identify the bacterial colonies.

Example 1 Fabrication of Three-Tier Hierarchal Wrinkled PDMS Microparticles

[00150] To fabricate hierarchically structured PDMS microparticles, decorated with wrinkles and functionalized AuNPs, an emulsion-solvent evaporation process was employed, followed by fluorosilanization via a polymerization reaction and nanoparticle deposition using a mixed silane solution (exemplary process shown in Figure 1a). Specifically, uniform microparticles were first fabricated by subjecting a homogenous emulsion of PDMS and Silwet L-77 to ultrasonic waves, which generated a high yield of ~20 pm-sized, spherical microparticles. Silwet L-77 is an anionic trisiloxane ethoxylate surfactant with the chemical structure CH3Si(OsiMe3)2(CH2)3O(CH2)sCH3, whereby its hydrophobic tail is adsorbed by PDMS, resulting in the formation of a stiff siloxane oxidised shell around the microparticles. During sonication, the high frequency from the ultrasonic waves, paired with the resultant shear forces, were large enough to overcome the entropy-driven coalescence interactions between the oligomer chains, leading to mechanical shear and subdivision which in turn produces smooth uniform microparticles. Characterization of the microparticles via water (surface tension = 71.99 mN m ^-1 ) and hexadecane (surface tension = 27 mN m ^-1 ) contact angle (CA), as well as water sliding angle (SA) revealed that the microparticles were superhydrophilic, which can be attributed to the assembly of the hydroxyl groups from the surfactant around the PDMS microparticles.

[00151] Following microparticle fabrication, an emulsion-based method was exploited here to trigger labyrinth patterns, dimples, and a series of curvature and overstress wrinkles on the surface of PDMS microparticles (Figure 1 b). Specifically, the emulsion was heated and stirred at high revolutions per minute (RPM), which cured the PDMS and triggered interfacial instability. Once the induced compressive stress o exceeded the critical wrinkling stress o _c , sinusoidal undulations formed to lower the potential energy of the system. Compressive stress o originated from the strain mismatch between the stiff siloxane shell and the adjacent PDMS soft matter. This mismatch was induced by the bending energy on the outside of the shell versus the stretching energy inside the shell. In-plane compression was achieved through heat-induced thermal expansion and stirring-induced mechanical stretching and solvent evaporation. This led to the formation of tens of microscale buckyball and dimple-like wrinkles on the surface of the PDMS microparticles (Figure 1 , c-e).

[00152] 1 H, 1 /7,2/7,2/7-Perfluorooctyltriethoxysilane (FOTS) was then used to enrich the surface of wrinkled microparticles with CF3 groups, thus lower their surface energy and inducing superhydrophobicity. The three ethoxy groups of the fluoroalkyl silane were hydrolyzed and replaced by the hydroxyl groups from the PDMS microparticles, leading to a polycondensation reaction between the Si-O-Si bonds. The resultant FOTS-treated microparticles were then coated with functionalized AuNPs using a mixed silane solution of 1 H,1 H,2H,2H-Perfluorodecanethiol (PFDT) - a thiol-based fluorosilane, and (3- mercaptopropyl)trimethoxysilane (MPTMS) to induce omniphobicity. MPTMS acted as a coupling agent, using its thiol head (-SH) to bind to AuNPs and its three methoxy (-OCH3) functional groups to bind to PDMS. The self-assembled AuNPs were closely packed within the wrinkles of the PDMS microparticles (Figure 1f). Energy-dispersive X-ray spectroscopy (EDS) analysis (Figure 3) was conducted on scanning electron microscopy (SEM) images at 5 different spectra to confirm the presence of AuNPs within the wrinkles. Maximum statistical elemental analysis of various elements is presented in Tables 1 and 2.

Table 1

Table 2 The maximum statistical analysis showed that the microparticles comprise Si (52.15%), Au (48.07%), C (27.61 %), O (20.25%), S (1.52%), and F (1.02%). These wrinkled, functionalized, and AuNP-decorated hierarchical microparticles were termed hMPs.

Example 2 Spray Coating hMPs onto Various Substrates and Subsequent Characterizations

[00153] Following fabrication, hMPs were washed and incorporated into a spray. Coatings were achieved by spraying an epoxy resin binder solution, followed by the hMP spray solution onto target substrates. Optical imaging confirmed full coverage of a spray- coated glass slide, through the presence of a uniform coating of hMPs across the surface. Without wishing to be bound by theory, it is hypothesized that the hierarchical texture and high fluorine surface content of spray-coated surfaces would be capable of trapping pockets of air, resulting in a stable solid-liquid-air interface against both high and low surface tension liquids. ¹²² ’ ^{31 321}

[00154] To understand the contributions of each structural tier to repellency, wettability was assessed following each of their additions (Figure 4). The wrinkled microparticles were hydrophilic, demonstrating a water CA of 60±2.1 °, which can be attributed to the presence of surfactant. Given that the hydrophobic group of the surfactant was adsorbed by PDMS, a monolayer of hydroxyl terminated groups remained, resulting in hydrophilicity. Following treatment with FOTS, the particles were rendered superhydrophobic with a water CA of 158±3.3°, a hexadecane CA of 113±1.5°, and a water SA of 12±1 °. Surfaces coated with hMPs demonstrated omniphobic behavior, showing a water CA of 161 ±2.7°, a hexadecane CA of 135±1 .3°, and a water SA of 7±1 °. The higher repellency of hMPs was credited their increased surface roughness and the spatial frequency from AuNPs. The developed omniphobic coating is substrateindependent and thus can be sprayed onto various substrates, regardless of their physical or chemical properties. Epoxy resin binder solution and the hMP spray solution were sprayed onto glass, polystyrene, stainless steel, textile, and paper. Given the low elastic modulus of PDMS and its siloxane linkages, ¹⁴⁸⁴⁹¹ the additional layers of coating did not affect the flexibility of the surfaces, but rather helped maintain the flexibility of the sprayed substrates after four layers. All coated substrates demonstrated omniphobicity, as would be expected given the structural hierarchy of the spray coating. Whereas blue-dyed water and hexadecane droplets rapidly spread on uncoated surfaces, they maintained their spherical shape on coated surfaces (Figure 4, c-d). This was quantitatively confirmed via high water and hexadecane CAs, along with low water SAs demonstrated by all coated substrates.

[00155] Contact angle hysteresis (CAH) was also quantified using liquids of various surface tensions such as water, glycerol, ethylene glycol, hexadecane, and acetone with surface tensions of 72.75 mN m ^-1 , 64 mN m ^-1 , 47.7 mN m ^-1 , 27.47 mN m ^-1 , and 25.2 mN _m -i [50] respectively. All liquids showed CAH< 10° as seen in Figure 4.

[00156] The thickness of the coating was quantified using an optical profilometry test to evaluate the thickness of h MPs coated glass surface. The thickness was measured using the vertical scanning interferometry mode of an optical profilometer. Based on the Rz value, the thickness of the coating is 27 / m as seen in Figure 5a. In addition, the surface roughness of a coated and uncoated glass slide was quantitatively assessed using vertical scanning interferometry. A significant difference of 99.8% was seen between coated glass slides relative to uncoated glass slides, whereby the average roughness of the coated and uncoated glass slides were 9.63 pm and 0.02 pm, respectively (Figure 5b). The homogeneity of the surface could also clearly be seen in the optical profilometry results, as well as the optical and SEM images of a coated glass surface. Optical imaging confirmed full coverage of a spray-coated glass slide, through the presence of a uniform coating of hMPs across the surface as seen in Figure 5c. Without wishing to be bound by theory, it is hypothesized that the hierarchical texture and high fluorine surface content of spray-coated surfaces would be capable of trapping pockets of air, resulting in a stable solid-liquid-air interface against both high and low surface tension liquids. ^[22 ’ ³¹ ’ ^32] A four-layered coating was selected to achieve extreme repellency with water CA 60° (Figure 5d). This multi-leveled coating exhibited firm adhesion to the underlying substrate and provided dense substrate coverage. Its improved repellency is attributed to the entrapment of a larger volume of air, due to the hollow voids present between the greater number of tightly packed hMPs.

[00157] The degree of wrinkling on the surface of the PDMS microparticles, as well as the size of the PDMS microparticles could contribute to the overall level of omniphobicity of the coating. Wrinkling occurs on the surface of the microparticles to minimize the system’s overall potential energy when the compressive stress is higher than a critical value. The compressive stress is induced during the in-plane compression as a consequence of a strain mismatch which is dependent on the swelling degree of the PDMS microspheres. The swelling is in turn dependent on the size and radius of the microparticles, the curing temperature and time, shell thickness, and the Young’s modulus of PDMS. ^151-531 The resultant wrinkling topography is determined by the competition between the bending stiffness of the thin siloxane shell around the microparticle (short wavelengths) and the bulk elastic energy of the core deformation (long wavelengths), which in turn determines the curvature, critical wrinkling stress, overstress, and the resulting wrinkling morphologies. ^154-561 Studies investigating the effect of temperature, curing time, weight ratio of PDMS: curing agent, and particle size on the omniphobicity of the coating are seen in Figure 6a-c. High curing temperature resulted in a higher degree of sinusoidal undulations. While a curing temperature of 80°C for 2 hours resulted in a higher number of narrower herringbone patterns consisting of more grooves, a curing temperature of 50°C for 2 hours led to thicker herringbone patterns arranged in a flatter staggered zig-zag pattern with larger microscale wrinkles as seen in Figure 6a, iv. A small decrease in water and hexadecane CAH was revealed for coating in Figure 6a, iv corresponding to 6° and 13.3°, respectively, relative to the coating in Figure 6a, i, corresponding to 4.7° and 7°, respectively. Thus, the decrease in the wrinkle size from micro to nanoscale length decreases the wettability of the coating due to the reduced solid-liquid interfacial layer and entrapment of air pockets in the underlying interface. Increasing the curing temperature to 6 hours led to a higher degree of wrinkling with the formation of more secondary wrinkles with nanoscale lengths for the particles fabricated at 80°C and 50°C as seen in Figures 7a, i (water and hexadecane CAH of 2.7° and 5.7°) and Figure 6a, iii (water and hexadecane CAH of 5.3° and 12.3°), corresponding to the increased water and hexadecane contact angles relative to shorter incubation times seen in coatings in figures 7a, ii and 7a, iv. This is due to the increase in hierarchal structures and air gaps with increased curing time. Namely, ordered dimples or triangular dent-like wrinkles preferentially appear on the spherical surfaces in the case of a larger radius of curvature and a smaller swelling degree with less defined wrinkles as seen in the -250 / m sized microparticle in Figure 6a, v, whereas typical herringbone or labyrinth morphologies are mainly self-assembled in the case of a smaller radius of curvature or a larger excess swelling degree. The shell thickness is determined by the type and concentration of surfactant, thus a 10% anionic surfactant results in a thick shell leading to an increase in the critical wrinkling stress and a final decrease in the overstress (applied stress/critical wrinkling stress) on a spherical core/shell resulting in a larger swelling extent. ¹⁴⁸⁵⁷¹ The Young’s modulus of PDMS can be tailored by the cross-linking density of PDMS. Using a high weight ratio of PDMS/ curing agent results in a stiffer microparticle with a higher degree of wrinkling, whereas the bridged dimples are favorable. This is due to the increase in the critical wrinkling compressive stress for more rigid spherical substrates and the decrease of the resultant overstress. ^{158 591} Therefore, a 5:1 weight ratio of PDMS/ curing agent results in less defined wrinkles with wider gaps between the wrinkles as seen in Figure 6a, vi compared with 10:1 which has more defined wrinkles. This can clearly be seen by the increased water and hexadecane CAH for coating in Figure 6a, vi (8.7° and 24°, respectively) relative to the rest of the coatings. ^154-561

[00158] To investigate the effect of the PDMS particle size on the level of omniphobicity of the coating, three different sizes were tested as follows: A) ~20 / m, B) ~60 / m, and c) -100 / m as seen in Figure 6d-e. The coating consisting of -20 / m sized PDMS microparticles demonstrated the highest degree of omniphobicity with water and hexadecane CAH of 4±1 ° and 6±1 °, respectively, relative to the coating consisting of -60 / msized particles with water and hexadecane CAH of 6±1.5° and 10±2°, as well as the coating with -100 fim sized particles with water and hexadecane CAH of 13±3° and 18±2°, respectively. This could be attributed to excess aggregation of the 20 / m particles resulting in a more porous and rougher surface, in addition to establishing a robust wetting stability due to fine capillary air pockets filled out by the smaller sized particles. ¹⁶⁰ ’ ⁶¹¹ Based on Cassie’s theory, air pockets are trapped in the voids of the rough surface of the coating where the droplets of water are suspended on a layer of air, contributing to the reduced CAH and small wrinkling wavelength. Thus, as the particle size gets smaller the aggregation of the particles changes the surface roughness of the coatings from being dependent on the size of the particles to a combination of the primary and aggregated particles, leading to hierarchical or multiscale roughness. Larger particles, i.e., 60 fim and 100 fim, provide larger pores and wrinkle wavelength, less roughness, and less capillary air pressure, hence the observed decrease in contact angles and increased CAH. ¹⁵⁹ ’ ⁶² ’ ⁶³¹ It should also be noted that changing the diameter of the PDMS microparticles affects the surface morphology and wavelength of the wrinkles. Under the same conditions, the wrinkling wavelength increases from 0.25 fim to 0.80 fim as the radius of the particle is increased from 20 fim to 100 ,um, which consequentially results in a reduction in the wettability of the surfaces. ¹⁵³ ’ ⁶⁴⁶⁵¹ Example 3 Robustness, Durability, and Self-Cleaning Properties of the Omniphobic Coatings

[00159] The poor stability of common omniphobic spray coatings - largely due to the mechanical fragility of micro-/nano-hierarchical structures in response to external abrasion, has severely limited their practical applications. ¹⁶³⁶⁶¹ To test the stability of the developed surface treatment composition of the present application, its response to harsh environmental conditions as well as abrasion tests. Initially, the coating’s mechanical stability was assessed using the Elcometer™ 1542 Cross Hatch Adhesion Tester kit. ^[67] The mechanical stability of four glass coated substrates were tested using the ASTM procedures found in the Elcometer’s user’s manual. The samples were first taped to the workbench using double-sided tape to ensure that the surfaces will remain secured during the scratch test. The surfaces were then scratched perpendicularly using the provided scratching tool. They were then cleaned using a brush and tape to remove any debris. The surfaces were then optically imaged on a Nikon Eclipse™ Ti2 Series at low magnification as seen in Figure 7f. The scratch patterns were compared with the ASTM classifications. Based on the ASTM classifications provided in the Elcometer’s user’s manual, the surfaces clearly belong to ASTM class 5B exhibiting a high level of stability. Cross hatch pattern shows no deterioration, especially at the intersections between scratches.

[00160] The viscoelastic behaviour of the coating essentially determines the flexibility of the coating. This is mainly defined by the coating thickness, coating material, and the adhesion between the binder and the coating. Given the extremely low elasticity of the individual chain of the PDMS, its large cross-sectional area, and the weak intra/interchain noncovalent interactions, the PDMS-based coating is highly flexible as seen on a coated textile in Figure 7g. Flattening or bending a coated substrate in any direction does not affect omniphobicity of the coating neither does it compromise its physical or mechanical properties. ¹³¹¹ Moreover, the use of epoxy resin glue as a binder between the substrate and the coating further ensures the strong adhesive strength of the coating and permits the flexibility of any coated substrate, given the substrate is flexible.

[00161] To further test the durability of a coated surface, a wear-test was performed involving rubbing a flat solid abradant, rubber, against the coated surface under a normal load. The coated surface was securely taped using double-sided tape on the lab bench. A piece of rubber abradant was placed between the coated glass surface and the rectangular load. A normal pressure was applied on the load and the abradant starting from the far-left side of the coated surface all the way to the right-end of the coated surface. The coating was then cleaned from debris using tape and a brush. Characterization of the wear in terms of change in CAH was performed before and after abrasion with liquids of various surface tension. There was a negligible increase in the CAH for all liquids, particularly the CAH remained below 10° for all liquids as seen in Figure 7e.

[00162] Additional stability tests were conducted on a coated glass surfaces under high temperatures and ultraviolet light. First, coated glass surfaces were incubated at 350°C for 2 hours, to test thermal stability. Following heat exposure, the structure of the coating and the wettability of the surface were assessed, demonstrating no change (Figure 7a). Coated glass surfaces were also irradiated with ultraviolet light for 6 hours, upon which slight changes in hexadecane CA (131 ±2°) and water SA (9±1 °) were observed. Nonetheless, the coating retained its omniphobic properties.

[00163] The durability of coated glass surfaces was also examined after 30 and 60 days, which revealed a negligible decrease in water and hexadecane CA measurements of 4.2° and 8.1 °, respectively, and a slight increase of 1.5° in water SA (Figure 7b). To further test the stability of the coating and whether the hMPs were strongly adhered to the underlying substrate, a sonication test was performed wherein a coated glass surface was fully immersed in ethanol and sonicated at 35 kHz for 15 mins (Figure 7c). There was a slight, non-significant decrease in water CA of 2°, that may have been due to the detachment of poorly attached hMPs. Finally, a stamp test, in which a PDMS stamp was repetitively stamped onto a coated glass surface, showed a very small decrease in water CA (Figure 7d). Despite slight changes in wettability, the coating maintained its repellency upon exposure to various environmental conditions. The excellent stability of the coating is attributed to its multi-leveled micro-/nano- hierarchal structures, excellent adhesive bonding strength, and high fluorine content.

[00164] Next, the self-cleaning properties of hMPs-coated glass substrates were evaluated. In this assay, coated and uncoated glass surfaces were stamped using agar plugs inoculated with dense bacterial suspensions of MRSA. After stamping, the surfaces were rinsed with water at an inclined angle. Water droplets seamlessly rolled across the omniphobic hMP coating, picking up any adhered bacteria along the way. This left the coated surfaces free of bacteria at both 0 hour and 2-hour time points (Figure 8). Contrarily, uncoated surfaces showed significant bacterial adhesion to the order of 10 ² and 10 ⁵ CFU ml ^-1 at 0 hours and 2 hours, respectively. The self-cleaning properties of the hMP coating is attributed to its small sliding angle and low adhesion force to water. ¹⁶⁸¹ In contrast, uncoated glass surfaces possess a high adhesion force to water, resulting in minimal removal of adhered bacteria.

Example 4 Role of the Omniphobic Spray in Reducing Pathogen Adhesion

[00165] Next, the performance of the hMP spray in preventing the adhesion and subsequent biofilm formation of MRSA and P. aeruginosa was tested. MRSA and P. aeruginosa are two multidrug-resistant pathogens, which have been identified by the World Health Organization as priority pathogens. ¹⁶⁹¹ Based on the topographical features, roughness, and wettability of the PDMS microparticles, the repellency or killing of bacteria can vary (Figure 9a). Wrinkled superhydrophobic microparticles possess a hierarchal structure with microscale roughness capable of repelling bacteria using steric or electrostatic repulsion techniques, compared to smooth hydrophilic microparticles. The entrapped air layer on the wrinkled hydrophobic microparticles causes the bacterial suspension to partially rest on air cushion and low energy protrusions. ¹⁷⁰ ’ ⁷¹¹ Incorporating bactericidal gold nanoparticles on the wrinkled microparticles further promotes the repellency of the microparticles by increasing the nanoscale roughness and hierarchy, thus further restricting the surface area available for bacterial attachment; as well as activates the bacterial killing effect. ^{172 731} A stamp assay was conducted to evaluate the bacteria repellency of hMP spray-coated glass surfaces relative to uncoated glass surfaces. Surfaces were stamped with agar plugs inoculated with MRSA and P. aeruginosa. After stamping, a CFU assay was conducted at various time points to quantitatively compare bacterial adhesion on hMP-coated glass surfaces versus uncoated glass surfaces. With MRSA, hMP-coated surfaces showed a relative reduction of 92% (P<0.01 ) and 94% (P<0.01 ) at 0 hours and 1 hour, respectively, compared to uncoated surfaces (Figure 9b). This decrease in bacterial adhesion reached 99% (P<0.0001 ) by 2 hours. At 8 hours, the hMP-coated surfaces demonstrated an over 99.9% (P<0.0001 ) reduction in bacterial adhesion relative to the uncoated surfaces - a three-log reduction. Against P. aeruginosa, hMP-coated surfaces revealed superior bacterial repellency (Figure 9c). At 0 hours, the hMP spray-coated surfaces showed a 97% (P<0.001) reduction in bacterial adhesion relative to uncoated surfaces. Between 2 to 8 hours post-stamping, further reduction in bacterial adhesion was subtle. By 8 hours, the hMP coating-mediated reduction in bacterial adhesion had surpassed 99.9% (P<0.0001 ), relative to uncoated surfaces. The immediate reduction in bacterial adhesion exhibited by hMP-coated surfaces at 0 hours demonstrates the bacterial repellency of the coating. The subsequent decrease in bacterial counts observed by these coated surfaces over an 8- hour timeframe points to their bactericidal capabilities. This clearly demonstrates the dual “repel and kill” properties of the developed spray.

[00166] Similarly, a stamp assay was conducted using the bacterial virus Phi6, to evaluate the repellency of the hMP coating towards enveloped viruses (Figure 9d). ^[411 Surfaces incubated for 2 hours were placed in a humidity chamber to avoid any potential drying or inactivation of the viral particles. hMP spray-coated surfaces revealed 1 -log and 2-log reductions in viral adhesion at 0 hours and 2 hours, respectively, relative to uncoated glass surfaces. Such a significant display of anti-viral properties holds promise in combating the spread of viral diseases.

[00167] SEM images were captured to visualize the interaction of MRSA and P. aeruginosa with hMP-coated and uncoated glass surfaces under conditions where mature biofilm formation was possible. After stamping the surfaces with agar plugs inoculated with bacteria, the coated and uncoated surfaces were imaged and compared. The uncoated glass surface revealed an abundance of MRSA bacteria, whereas the hMP spray-coated surfaces showed a significantly reduced number of adhered bacteria. Similarly, with P. aeruginosa, uncoated surfaces suffered from an abundance of adhered bacteria along with the formation of a biofilm matrix. However, no bacteria were visually identified on the hMP-coated surfaces. The improved performance against P. aeruginosa was attributed to its rod-like shape, compared to the coccoid-like shape of MRSA, the latter of which allows for some degree of entrapment on the microscale structures (Figure 9e) - a finding in line with previous studies. ^{121 281} Based on these observations, it was concluded that the spray-coated hMPs are capable of sterically hindering the attachment and subsequent biofilm formation of both Gram-negative and Gram-positive bacteria.

[00168] To further investigate the bacteria repellency and antimicrobial properties of the surfaces, a live/dead assay was conducted, with surfaces being monitored over 8 hours (Figure 9f). Viable cells (live) with integral membranes were stained green, while non-viable (dead) cells with disrupted membranes were stained red. A gradual decrease in green fluorescence for both MRSA and P. aeruginosa was observed over the 8-hour period, thus aligning well with our results presented above.

[00169] To quantify the effect of AuNPs in inducing bactericidal properties, a growth assay in liquid media was conducted across different time points. Specifically, uncoated wells and FOTS-treated microparticle-coated wells were compared with wells coated with hMPs. Liquid MRSA culture with a concentration of 10 ⁵ CFU ml ^-1 was added to the wells, and a CFU assay was used to quantify the bacterial density within wells over time (Figure 9). After 2 hours, the uncoated and FOTS microparticle-coated wells showed similar bacterial presence, with 3x10 ⁶ CFU ml ^-1 and 1.5x10 ⁶ CFU ml ^-1 of bacteria, respectively. Contrarily, hMP-coated wells showed a significant decrease in bacteria to the order of 4 x10 ⁴ CFU ml ^-1 , corresponding to a 98.7% (P<0.001) reduction in bacteria relative to uncoated wells, a 97.2% (P<0.001 ) reduction relative to FOTS microparticle-coated wells, and a 96.9% (P<0.001) reduction relative to the initial inoculum of bacteria. After 8 hours, a substantial amount of bacterial growth was seen within the uncoated wells, reaching 7.8x10 ⁸ CFU ml ^-1 , while FOTS microparticle-coated wells showed 2.2x10 ⁷ CFU ml ^-1 bacteria. While the hMP-coated wells showed an increase in bacteria after 2 hours, they still exhibited a significant decrease in bacterial presence relative to the uncoated wells, corresponding to a reduction factor of 99.7% (P<0.0001). A similar trend was seen at 24 hours, whereby hMPs treated surfaces exhibited the same reduction factor of 99.7% (P<0.0001) relative to uncoated wells. Relative to FOTS microparticle-treated wells, hMP- coated wells exhibited a relative bacteria reduction factor of 91 % (P<0.01 ) at 8 hours and 97.2% (P<0.001) after 24 hours.

[00170] To investigate whether AuNPs plays a similar role with Gram-negative P. aeruginosa, the well-plates were similarly prepared and incubated with 10 ⁶ CFU ml ^-1 of P. aeruginosa diluted in culture media (Figure 9j). After 2 hours, wells coated with hMPs showed significant bacterial reduction by a factor of 99.8% (P<0.0001) relative to uncoated wells, 98.6% (P<0.0001 ) relative to FOTS microparticle-coated wells, and 97.2% (P<0.001) relative to the initial inoculum of bacteria. After 8 hours, a 99.9% (P<0.0001) reduction in the number of bacteria was observed within wells coated with hMPs relative to FOTS-treated surfaces and a 99.99% (P<0.0001) reduction relative to uncoated wells. After 24 hours, hMPs demonstrated a 98.9% (P<0.0001) reduction in bacteria compared to FOTS microparticle-coated wells and a 99.9% (P<0.0001 ) reduction relative to uncoated wells. This growth assay clearly highlights the role of AuNPs in killing bacteria. The antimicrobial activity of AuNPs is attributed to their direct contact with bacterial cell walls, which induces cellular deformation, initiation of intracellular effects via interactions with DNA and proteins, an increase in the concentration of intracellular reactive oxygen species, and inhibition of biofilm formation through the application of mechanical stretch on their cell membrane of bacteria. ¹¹² ’ ^74-761 As such, surfaces coated with hMPs were capable of remarkable bactericidal activity against both Gram- negative and Gram-positive bacteria.

[00171 ] To validate the antimicrobial effect of functionalized gold nanoparticles, we conducted a bacterial growth assay using MRSA for 2 and 24 hours seen in Figure 10. A 10 ⁶ CFU/mL bacterial suspension diluted in TSB was used as the initial bacterial concentration. The control used was only TSB media. Whereas pure gold nanoparticles showed a bacterial growth of 8.0x10 ⁵ CFU/mL after 2 hours, the MPTMS-functionalized gold nanoparticles showed no bacterial growth. Modification with mercaptopyrimidine increases the positive charge on the gold nanoparticles which increases their affinity to negatively charged bacteria, hence the eradication of bacteria. ¹⁷⁵ ’ ⁷⁷ ’ ⁷⁸¹ Interestingly, after 24 hours a 2-log reduction in bacterial growth was seen for pure gold nanoparticles compared to the control. The reduction in bacterial growth seen for the pure gold nanoparticles is attributed to chemicals coexisting in gold nanoparticles such as gold ions, surface coating agents, and chemicals involved in synthesis. ¹⁷⁴ ’ ⁷⁵ ’ ^{77 791} Due to the increased affinity of the positive MPTMS-functionalized gold nanoparticles to the negatively charged MRSA, significant reduction in bacteria growth was seen, which validates the superior antimicrobial activity of the coating using functionalized gold nanoparticles.

[00172] The possibility of AuNPs detaching from hMPs and leaching into the solution during the growth assay was a concern, as the spray coated wells were immersed with bacterial suspension for several hours. Therefore, the growth assay was repeated on the same spray-coated 96-well plate from the previous experiment, after extensively washing the treated wells. The well plate was washed with sterile water three times every 3 days for 4 weeks to ensure the stable deposition of AuNPs within the wrinkles of hMPs in the spray-coated wells. The growth assay was conducted again on the washed well-plate with MRSA. Upon running the second assay, a negligible difference was observed (Figure 1 1 ) in bacterial growth after 2 hours. Hence, it was shown that the deposition of AuNPs is stable.

[00173] To study whether the size of AuNPs affects the antimicrobial effect of the coating, a bacterial growth assay was conducted to compare hMPs coated with 5 nm, 10 nm, and 40 nm sized AuNPs. Liquid MRSA culture with a concentration of 10 ⁷ CFU ml ^-1 was added to the coated wells, and a CFU assay was used to quantify the bacterial density within wells over 2 hours (Figure S13d). A negligible difference was seen between coatings consisting of 10 nm sized AuNPs relative to 40 nm sized AuNPs, corresponding to a 99.5% (P<0.0001 ) and 99% (P<0.0001 ) reduction in bacterial growth, respectively. This small difference could be attributed to the similar cumulative stretching effect of the aggregated nanoparticles to the bacterial membrane, however the superior performance of the 10 nm sized AuNPs is because smaller-diameter nanoparticles provide surface effects and a larger surface-to-volume ratio and more effective contact with the bacteria surface, which allows the binding of a large number of high affinity ligands, equipping nanoparticles with a multivalency in eradicating bacterial cells. Coating consisting of 5 nm sized AuNPs showed the least reduction in bacterial growth, corresponding to a 94.5% (P<0.01 ) reduction relative to the initial concentration of bacteria. This highlights the superior antimicrobial activity of 10 nm-sized nanoparticles, whereby an increase in AuNP size increases the adhesion energy resulting in a greater area of contact and overall stretching of the bacterial membrane. ¹¹² ’ ⁷⁷ ’ ⁸⁰¹ This can be further explained by the different antimicrobial mechanisms of action of AuNPs as reported by Mironava et al., whereas 45- nm AuNPs penetrated cells via clathrin-mediated endocytosis, whereas 13-nm AuNPs entered mostly via phagocytosis. ¹⁸¹¹

[00174] Furthermore, the effect of AuNP concentration on the coating’s antimicrobial activity was investigated by testing a concentration of 5 ^g/mL, 50 ^g/mL, and 100 ^g/mL seen in the SEM images in Figure 12a-c. Similarly, liquid MRSA culture with a a concentration of 10 ⁷ CFU ml ^-1 was added to the coated wells, and a CFU assay was used to quantify the bacterial density within wells over 2 hours (Figure 12e). A concentration of 100 ^g/mL revealed the most significant reduction in bacterial growth, corresponding to a 98.8% (P<0.0001 ) reduction in bacterial growth relative to the initial concentration of bacteria. AuNPs concentrations of 5 ^g/mL and 50 ^g/mL revealed a 95% (P<0.01 ) and 97.9% (P<0.0001 ) reduction in bacterial growth, respectively. Higher concentrations of AuNPs leads to an increase in the stretching and subsequent rupturing of the bacterial cell membrane, as the diameter of the aggregated nanoparticles or cluster diameter is increased. Furthermore, the attractive forces between the AuNPs and the bacterial membrane are mediated by inherent characteristics such as nanoparticle surface charge, hydrophobicity, and roughness which are increased. ^[81-83] To conclude, a minor difference in bacterial growth reduction for coatings consisting of 50 ^g/mL and 100 ng/ml_ was seen, thus validating our use of 50 ^g/mL AuNP concentration.

Example 5 Assessing the Performance of Different Spray Coated Surfaces in a Practical Environment

[00175] To investigate whether the developed spray coating can reduce the transfer of pathogens, latex gloves, stainless steel tweezers, and a lab coat were spray-coated and subjected to real-world environmental conditions. The adhesion of pathogens and their subsequent transfer from contaminated to clean surfaces was used to assess the functionality of the coated surfaces.

[00176] To assess the transfer of bacteria via gloves, the index finger of a gloved hand was dipped in a bacterial suspension of MRSA with a concentration of 10 ⁷ CFU ml ^-1 , to mimic a contaminated surface (Figure 13a). Subsequently, this contaminated gloved finger was used to touch up to 50 clean glass surfaces. Quantification of bacterial adhesion on these surfaces revealed that the coated glove significantly outperformed an uncoated, contaminated glove, such that after only one touch, a 10 ⁴ CFU ml ^-1 reduction (P<0.0001 ) in bacterial transfer was shown on the coated glove relative to the uncoated one. While the surfaces touched by the uncoated glove showed a substantial amount of bacterial transfer (10 ⁵ CFU ml ^-1 ) even after 50 touches, no bacterial transfer was observed on the surfaces touched by the coated glove after the initial three touches (Figure 13b). Furthermore, the transfer of viruses on gloves was also assessed in a similar manner. Similarly, the coated gloves exhibited superior virus repellency, revealing a 10 ⁶ PFU ml ^-1 (P<0.0001 ) reduction in virus adhesion after only the first touch, relative to the uncoated gloves. In addition, no virus transfer was revealed on the surfaces touched by the coated glove after two touches, while uncoated gloves showed up to 10 ³ PFU ml ^-1 of active viral particles’ transfer even after 50 touches (Figure 13c). This highlights the role of the coating in reducing the adhesion and subsequent transfer of various pathogens onto other surfaces, thus showing promise for the reduction of cross-contamination and surfacebased transmission. [00177] Next, a pair of tweezers with a coated and uncoated side were evaluated (Figure 13d). CFU plating on both sides of the tweezers revealed a 10 ⁴ reduction (P<0.0001) in bacterial adhesion of MRSA on the coated side, further highlighting the outstanding performance of the coating.

[00178] Finally, two pieces of textile (coated and uncoated) were taped onto a lab coat for 10 days, following which the lab coat was used to perform experiments every day. After the 10-day period, CFU measurements showed higher bacterial adhesion on the uncoated textile relative to the coated textile, corresponding to a one-log reduction. To identify the nature of the colonies formed on agar plates upon textile culturing, 16S ribosomal RNA (rRNA) sequencing was performed using a PCR-based technique. Sequencing on the uncoated textile revealed three different organisms: Micrococcus luteus, Bacillus lichenformis, and Bacillus safensis. In contrast, 16s rRNA amplification of the colony found on the coated textile failed, likely because the adhered microbe was not a bacterium (Figure 13e). Ultimately, the effectiveness of this spray coating in real-world applications substantiates its potential for the reduction of surface contamination and pathogen transmission.

Conclusion

[00179] The fabrication and assessment of a dual action “repel and kill” spray, for the reduction of pathogens on surfaces were shown herein. Through a combination of microparticles, surface wrinkling, nanoparticle decoration, and functionalization with low surface energy molecules, an omniphobic, substrate-independent surface treatment composition was developed. The coating’s unique material architecture results in the repulsion of both high and low surface tension liquids. The high-performance repellency works synergistically with the bactericidal ability of AuNPs to repel the majority of present pathogens, while killing the few that adhere to the coating. An instant reduction was demonstrated in bacterial adhesion by 99.9% for both MRSA and P. aeruginosa and a 99.7% and 99.9% reduction in bacterial growth after 8 hours for MRSA and P. aeruginosa, respectively. Furthermore, the antiviral effect of the coating was confirmed by demonstrating a 95.4% reduction in the transfer of the bacterial virus Phi6, which is a surrogate for SARS-CoV-2. Finally, the spray coated surfaces were demonstrated to effectively reduce the transfer of pathogens under real-world conditions. The adhesion of bacteria was reduced by 99.7%, 99.9%, and 100% on coated tweezers, gloves, and textiles relative to uncoated controls. Additionally, while uncoated plastic gloves transferred contamination to 50 secondary surfaces, coated gloves transferred significantly less amount of MRSA and Phi6 to only three and two other surfaces, respectively. This spray coating strategy has the potential to be applied to packaging, biomedical devices, and high touch surfaces to reduce the spread of infectious pathogens.

[00180] While the present disclosure has been described with reference to examples, it is to be understood that the scope of the claims should not be limited by the embodiments set forth in the examples, but should be given the broadest interpretation consistent with the description as a whole. [00181 ] All publications, patents and patent applications are herein incorporated by reference in their entirety to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated by reference in its entirety. Where a term in the present disclosure is found to be defined differently in a document incorporated herein by reference, the definition provided herein is to serve as the definition for the term.

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