A composite structure and related methods thereof

Abstract

There is provided a composite structure for promoting wound healing, the structure comprising, a compressible substrate; and a bioactive material disposed on said compressible substrate, wherein the bioactive material comprises a mixture of a synthetic homopolymer and a bioactive copolymer.

Description

[0001] A COMPOSITE STRUCTURE AND RELATED METHODS THEREOF

[0002] TECHNICAL FIELD

[0003] The present disclosure relates broadly to a composite structure, a method of preparing said composite structure, and related methods and uses thereof.

[0004] BACKGROUND

[0005] Chronic and acute partial thickness, full thickness wounds require extensive treatment and care to ensure that proper healing is attained with limited scarring. Most wounds are exudative either at the initial stage or when infected. For instance, partial-thickness burn wounds typically remain moist for the first 7 days, while full-thickness wounds can remain exudative for up to 21 days when uninfected and even longer if infection is present. Among the present therapeutic options, foam dressings are widely regarded as the standard of care for exudating wounds such as chronic wounds (e.g., diabetic foot ulcers, pressure ulcers, or venous ulcers), or as secondary dressings for paediatric burn patients. These dressings function by absorbing wound fluids either directly, or on top of the primary dressing which may be a dermal matrix.

[0006] Currently, conventional foam dressings are typically made of pure polyurethane (PU) foam with or without a silicone layer or silver impregnation such a silver-based dressing. However, such foam dressings present several disadvantages. Firstly, they are not biocompatible as PU is known to be mildly cytotoxic and can destroy the epidermis while silver is highly cytotoxic. Moreover, these materials generally lack tissue regenerative properties or stimulus to speed up the wound healing process. Other existing treatment methods, which include the use of collagen or even skin grafting, are associated with significant drawbacks such as requiring prior cell seeding, infection susceptibility, high cost, and prevalent scarring. In view of the above, there is a need to address or at least ameliorate the above-mentioned problems. In particular, there is a need to provide a wound dressing that is biocompatible, and capable of supporting skin tissue regeneration to improve wound healing outcome.

[0007] SUMMARY

[0008] In one aspect, there is provided a composite structure for promoting wound healing, the structure comprising, a compressible substrate; and a bioactive material disposed on said compressible substrate, wherein the bioactive material comprises a mixture of a synthetic homopolymer and a bioactive copolymer.

[0009] In one embodiment, the synthetic homopolymer comprises a base poly(lactic-co-glycolic acid) (PLGA) homopolymer, and the bioactive copolymer comprises a bioactive poly(lactic-co-glycolic acid) (PLGA) copolymer.

[0010] In one embodiment, the bioactive material comprises from 60.0 wt% to 99.9 wt% of the base PLGA and from 0.1 wt% to 40.0 wt% of the bioactive PLGA copolymer.

[0011] In one embodiment, the bioactive PLGA copolymer comprises a bioactive PLGA copolymer with a poly(norbornene-dicarboximide) backbone having one or more repeating units represented by general formula (I) and one or more repeating units represented by general formula (II):

[0012] wherein

[0013] R1is selected from a single bond, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted alkoxyalkyl, optionally substituted alkylcarbonyl, or optionally substituted alkylcarbonylalkyl;

[0014] R2is optionally substituted alkyl;

[0015] R3is selected from H, optionally substituted alkyl, optionally substituted alkenyl, or optionally substituted alkynyl;

[0016] L is heteroalkylene;

[0017] X comprises a bioactive moiety selected from the group consisting of proteins, peptides, oligopeptides, carbohydrates, oligosaccharides, sugar, collagen, hyaluronic acid (HA), therapeutic / drug molecules, and derivatives thereof;

[0018] Z1and Z2are each independently selected from CRaRb, O, NRC, SiRaRb, PRa, or S, wherein Ra, Rb, and Rcare each independently selected from the group consisting of H, optionally substituted alkyl, optionally substituted alkenyl, and optionally substituted alkynyl; p > 1 ; and q > 1.

[0019] In one embodiment, the bioactive moiety comprises no more than one carboxylic acid terminal group. In one embodiment, L is selected from the group consisting of polyethylene glycol (PEG), polypropylene glycol (PPG), polytetramethylene glycol (PTMG), polybutylene glycol (PBG), and combinations thereof.

[0020] In one embodiment, the bioactive moiety comprises hyaluronic acid (HA), arginine-glycine-aspartic acid (RGD), isoleucine-lysine-valine-alanine-valine (IKVAV), leucine-lysine-lysine-leucine-cysteine-arginine-isoleucine-leucine- lysine-lysine-leucine-cysteine-arginine-isoleucine (LKKLCRILKKLCRI), or combinations thereof.

[0021] In one embodiment, the compressible substrate comprises a compressible foam substrate.

[0022] In one embodiment, the compressible substrate comprises polyurethane.

[0023] In one embodiment, the bioactive material impregnates at least part of the substrate.

[0024] In one embodiment, the compressible substrate is capable of being compressed to less than 50 % of its original thickness.

[0025] In one embodiment, the structure is acellular and devoid of an extraneous drug.

[0026] In one aspect, there is provided a method of preparing a composite structure disclosed herein, the method comprising: providing the compressible substrate; and three-dimensionally (3D) printing the bioactive material on said compressible substrate with a 3D printing system.

[0027] In one embodiment, the 3D printing comprises a fused filament fabrication (FFF) printing method or a fused deposition modelling (FDM) printing method. In one embodiment, the method further comprises leveling the distance between print nozzle(s) of the 3D printing system and the compressible substrate by using a non-compressible reference substrate in lieu of the compressible substrate, prior to 3D printing.

[0028] In one embodiment, the method further comprises replacing the reference substrate with the compressible substrate after leveling is completed.

[0029] In one embodiment, the compressible substrate is provided on a support having a cut-out that is substantially complementary to the compressible substrate such that a top surface of the support and a printable top surface of the compressible substrate is capable of forming a substantially flat plane when the compressible substrate is fitted in the cut-out of the support.

[0030] In one embodiment, 3D printing the bioactive material on the compressible substrate comprises extruding flowable bioactive material onto the compressible substrate such that at least part of the bioactive material impregnates the compressible substrate.

[0031] In one embodiment, the flowable bioactive material is extruded at a temperature falling in the range of from 50 °C to 200 °C.

[0032] In one embodiment, the method further comprises solidifying the flowable bioactive material to anchor the bioactive material to the compressible substrate.

[0033] In one embodiment, the bioactive material is 3D printed with an infill density falling in the range of from 30 % to 90 %.

[0034] In one embodiment, the composite structure disclosed herein is for use in medicine. In one embodiment, the composite structure disclosed herein is for use in treating wounds.

[0035] In one aspect, there is provided use of the composite structure disclosed herein in the manufacture of a medicament for treating wounds.

[0036] In one aspect, there is provided a method of treating wounds comprising applying the composite structure disclosed herein to a wound.

[0037] DEFINITIONS

[0038] The term “bioactive” as used herein broadly refers to the property of having a biological effect, preferably a desirable or positive biological effect on a living organism, tissue, or cell.

[0039] The term “biocompatible” as used herein broadly refers to a property of being compatible with biological systems or parts of the biological systems without substantially or significantly eliciting an adverse physiological response such as a toxic reaction, an immune reaction, an injury, or the like. Such biological systems or parts include blood, cells, tissues, organs, or the like.

[0040] The term "polymer" as used herein refers to a chemical compound comprising repeating units and is created through a process of polymerization. The units composing the polymer are typically derived from monomers and / or macromonomers. A polymer typically comprises repetition of a number of constitutional units.

[0041] The terms “monomer” or “macromonomer” as used herein refer to a chemical entity that may be covalently linked to one or more of such entities to form a polymer. The term "bond" refers to a linkage between atoms in a compound or molecule. The bond may be a single bond, a double bond, or a triple bond.

[0042] In the definitions of a number of substituents below, it is stated that “the group may be a terminal group or a bridging group”. This is intended to signify that the use of the term is intended to encompass the situation where the group is a terminal group / moiety as well as the situation where the group is a linker between two other portions of the molecule. Using the term “alkyl” having 1 carbon atom as an example, it will be appreciated that when existing as a terminal group, the term “alkyl” having 1 carbon atom may mean -CHs and when existing as a bridging group, the term “alkyl” having 1 carbon atom may mean -CH2- or the like.

[0043] The term "alkyl" or “alkylene” as a group or part of a group refers to a straight or branched aliphatic hydrocarbon group having 1 to 20 carbon atoms, 1 to 10 carbon atoms, 1 to 6 carbon atoms, or 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 , 12, 13, 1 , 15, 16, 17, 18, 19 or 20 carbon atoms. Examples of suitable straight and branched alkyl substituents include methyl, ethyl, n-propyl, 2- propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, hexyl, amyl, 1 ,2- dimethylpropyl, 1 , 1 -dimethylpropyl, pentyl, isopentyl, hexyl, 4-methylpentyl, 1 -methylpentyl, 2-methylpentyl, 3-methylpentyl, 2,2-dimethylbutyl, 3,3- dimethylbutyl, 1 ,2-dimethylbutyl, 1 ,3-dimethylbutyl, 1 ,2,2-trimethylpropyl, 1 ,1 ,2-trimethylpropyl, 2-ethylpentyl, 3-ethylpentyl, heptyl, 1 -methylhexyl, 2,2- dimethylpentyl, 3,3-dimethylpentyl, 4,4-dimethylpentyl, 1 ,2-dimethylpentyl, 1 ,3-dimethylpentyl, 1 ,4-dimethylpentyl, 1 ,2,3-trimethylbutyl, 1 ,1 ,2- trimethylbutyl, 1 , 1 , 3-trimethylbutyl, 5-methylheptyl, 1 -methylheptyl, octyl, nonyl, decyl, and the like. The group may be a terminal group or a bridging group.

[0044] The term "alkenyl" or “alkenylene” as a group or part of a group denotes an aliphatic hydrocarbon group containing at least one carbon-carbon double bond and which may be straight or branched having 2 to 20 carbon atoms, 2 to 10 carbon atoms, 2 to 6 carbon atoms, or 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 , 12, 13, 14, 15, 16, 17, 18, 19 or 20 carbon atoms in the chain. The group may contain a plurality of double bonds and the orientation about each double bond is independently E or Z. Exemplary alkenyl groups include, but are not limited to, ethenyl, vinyl, allyl, 1 -methylvinyl, 1 -propenyl, 2-propenyl, 2-methyl-

[0045] 1 -propenyl, 2-methyl-1 -propenyl, 1 -butenyl, 2-butenyl, 3-butentyl, 1 ,3- butadienyl, 1 -pentenyl, 2-pententyl, 3-pentenyl, 4-pentenyl, 1 ,3-pentadienyl, 2,4-pentadienyl, 1 ,4-pentadienyl, 3-methyl-2-butenyl, 1 -hexenyl, 2-hexenyl, 3-hexenyl, 1 ,3-hexadienyl, 1 ,4-hexadienyl, 2-methylpentenyl, 1 -heptenyl, 2- heptentyl, 3-heptenyl, 1 -octenyl, 2-octenyl, 3-octenyl, 1 -nonenyl, 2-nonenyl, 3-nonenyl, 1 -decenyl, 2-decenyl, 3-decenyl, and the like. The group may be a terminal group or a bridging group.

[0046] The term "alkynyl" or “alkynylene” as a group or part of a group denotes an aliphatic hydrocarbon group containing at least one carbon-carbon triple bond and which may be straight or branched having 2 to 20 carbon atoms, 2 to 10 carbon atoms, 2 to 6 carbon atoms, or 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 , 12, 13, 14, 15, 16, 17, 18, 19 or 20 carbon atoms in the chain. The group may contain a plurality of triple bonds. Exemplary alkynyl groups include, but are not limited to, acetylenyl, propynyl, 1 -butynyl, 2-butynyl, 3-butynyl, 1 -pentynyl,

[0047] 2-pentynyl, 3-methyl-1 -butynyl, 4-pentynyl, 1 -hexynyl, 2-hexynyl, 5-hexynyl,

[0048] 1 -heptynyl, 2-heptynyl, 6-heptynyl, 1 -octynyl, 2-octynyl, 7-octynyl, 1 -nonynyl,

[0049] 2-nonynyl, 8-nonynyl, 1 -decynyl, 2-decynyl, 9-decynyl, and the like. The group may be a terminal group or a bridging group.

[0050] The term "heteroalkylene" as used herein refers to alkylene having one or more -CH2- replaced with a heteroatom selected from O, NR, Si, P or S, where R is hydrogen or alkyl as defined herein. The term "heteroalkylene" can be linear, branched, or cyclic and containing up to 500 carbon atoms. The term "alkoxy" as used herein refers to straight chain or branched alkyloxy groups. Examples include methoxy, ethoxy, n-propoxy, isopropoxy, tert-butoxy, and the like.

[0051] The term “cyclic” as used herein broadly refers to a structure where one or more series of atoms are connected to form at least one ring. The term includes, but is not limited to, both saturated and unsaturated 5-membered and saturated and unsaturated 6-membered rings. Examples of groups having a cyclic structure include, but are not limited to, cyclopentane, cyclopentene, cyclohexane, cyclohexene, benzene, and the like. The term “cyclic” as used herein includes “heterocyclic”.

[0052] The term “heterocyclic” as used herein broadly refers to a structure where two or more different kinds of atoms are connected to form at least one ring. For example, a heterocyclic ring may be formed by carbon atoms and at least another atom (i.e. heteroatom) selected from oxygen (O), nitrogen (N) or (NR) and sulfur (S), where R is independently a hydrogen or an organic group. The term also includes, but is not limited to, saturated and unsaturated 5-membered, and saturated and unsaturated 6-membered rings. Examples of groups having a heterocyclic structure include, but are not limited to furan, thiophene, 1 H-pyrrole, 2H-pyrrole, 1 -pyrroline, 2-pyrroline, 3-pyrroline, 1 - pyrazoline, 2-pyrazoline, 3-pyrazoline, 2-imidazoline, 3-imidazoline, 4- imidazoline, pyrazole, imidazole, oxazole, isoxazole, thiazole, isothiazole,

[0053] 1 .2.3-triazole, 1 ,2,4-triazole, 1 ,2,3-oxadiazole, disubstituted 1 ,2,4- oxadiazole, 1 ,2,5-oxadiazole, 1 ,3,4-oxadiazole, 1 ,2,3-thiadiazole, 1 ,2,4- thiadiazole, 1 ,2,5-thiadiazole, 1 ,3,4-thiadiazole, tetra hydrofuran, tetrahydrothiophene, pyrrolidine, 1 ,3-dioxolane, 1 ,2-oxathiolane, 1 ,3- oxathiolane, pyrazolidine, imidazolidine, pyridine, pyridazine, pyrimidine, pyrazine, 1 ,2-oxazine, 1 ,3-oxazine, 1 ,4-oxazine, thiazine, 1 ,2,3-triazine,

[0054] 1 .2.4-triazine, 1 ,3,5-triazine, 2H-pyran, 4H-pyran, 2-pyrone, 4-pyrone, 1 ,4- dioxin, 2H-thiopyran, 4H-thiopyran, tetrahydropyran, thiane, piperidine, 1 ,4- dioxane, 1 ,2-dithiane, 1 ,3-dithiane, 1 ,4-dithiane, 1 ,3,5-trithiane, piperazine, morpholine, thiomorpholine, and the like.

[0055] The term "alkoxyalkyl" as used herein is intended to broadly refer to a group containing -R-O-R’, where R and R’ are alkyl as defined herein. The group may be a terminal group or a bridging group.

[0056] The term "alkylcarbonyl" as used herein is intended to broadly refer to a group containing -R-C(=O)-, where R is alkyl as defined herein. The group may be a terminal group or a bridging group.

[0057] The term "alkylcarbonylalkyl" as used herein is intended to broadly refer to a group containing -R-C(=O)-R’, where R and R’ are alkyl as defined herein. The group may be a terminal group or a bridging group.

[0058] The term "carboxylalkyl" as used herein is intended to broadly refer to a group containing -C(=O)-O-R, where R is alkyl as defined herein. The group may be a terminal group or a bridging group.

[0059] The term "oxycarbonylalkyl" as used herein is intended to broadly refer to a group containing -O-C(=O)-R, where R is alkyl as defined herein. The group may be a terminal group or a bridging group.

[0060] The term "alkylcarboxylalkyl" as used herein is intended to broadly refer to a group containing -R-C(=O)-O-R’, where R and R’ are alkyl as defined herein. The group may be a terminal group or a bridging group.

[0061] The term "alkoxycarbonylalkyl" as used herein is intended to broadly refer to a group containing -R-O-C(=O)-R’, where R and R’ are alkyl as defined herein. The group may be a terminal group or a bridging group. The term "oxy" as used herein is intended to broadly refer to a group containing -O-.

[0062] The term "carbonyl" as used herein is intended to broadly refer to a group containing -C(=O)-.

[0063] The term "oxycarbonyl" as used herein is intended to broadly refer to a group containing -O-C(=O)-.

[0064] The term "carboxyl" as used herein is intended to broadly refer to a group containing -C(=O)-O-R, where R is hydrogen or an organic group.

[0065] The term “optionally substituted,” when used to describe a chemical structure or moiety, refers to the chemical structure or moiety wherein one or more of its hydrogen atoms is optionally substituted with a chemical moiety or functional group such as alcohol, alkoxy, alkanoyloxy, alkoxycarbonyl, alkenyl, alkyl (e.g., methyl, ethyl, propyl, t-butyl), alkynyl, alkylcarbonyloxy (- OC(O)alkyl), amide (-C(O)NH-alkyl- or -alkylNHC(O)alkyl), amine (such as alkylamino, arylamino, arylalkylamino), aryl, aryloxy, azo, carbamoyl (-NHC(O)O-alkyl- or -OC(O)NH-alkyl), carbamyl (e.g., CONH2, as well as CONH-alkyl, CONH-aryl, and CONH-arylalkyl), carboxyl, carboxylic acid, cyano, ester, ether (e.g., methoxy, ethoxy), halo, haloalkyl (e.g., -CCI3, -CF3, - C(CF3)3), heteroalkyl, isocyanate, isothiocyanate, nitrile, nitro, phosphodiester, sulfide, sulfonamide (e.g., SO2NH2), sulfone, sulfonyl (including alkylsulfonyl, arylsulfonyl and arylalkylsulfonyl), sulfoxide, thiol (e.g., sulfhydryl, thioether) or urea

[0066] (-NHCONH-alkyl-).

[0067] The term "aryl" as a group or part of a group denotes (i) an optionally substituted monocyclic, or fused polycyclic, aromatic carbocycle (ring structure having ring atoms that are all carbon) preferably having from 5 to 20, or 5, 6, 7, 8, 9, 10, 11 , 12, 13, 14, 15, 16, 17, 18, 19 or 20 carbon atoms per ring. Examples of aryl groups include but are not limited to phenyl, tolyl, xylyl, naphthyl, anthracenyl, phenanthrenyl, fluorenyl, indenyl or indanyl, and the like.

[0068] The term "halogen" represents chlorine, fluorine, bromine or iodine. The term "halo" represents chloro, fluoro, bromo or iodo.

[0069] The term "amine group" or the like is intended to broadly refer to a group containing -NR2, where R is independently a hydrogen or an organic group. The group may be a terminal group or a bridging group.

[0070] The term "amide group" or the like is intended to broadly refer to a group containing -C(=O)NR2, where R is independently a hydrogen or an organic group. The group may be a terminal group or a bridging group.

[0071] The term “treatment", "treat" and “therapy”, and synonyms thereof as used herein refer to both therapeutic treatment and prophylactic or preventative measures, wherein the object is to prevent or slow down (lessen) a medical condition, which includes but is not limited to diseases, symptoms and disorders. A medical condition also includes a body’s response to a disease or disorder, e.g., inflammation. Those in need of such treatment include those already with a medical condition as well as those prone to getting the medical condition or those in whom a medical condition is to be prevented.

[0072] As used herein, the term "therapeutically effective amount" of a compound is intended to refer to an amount that is sufficient or capable of preventing or at least slowing down (lessening) a medical condition, such as wounds or infections / inflammations arising from wounds (e.g., acute wounds, burns, lacerations, incisions, excisions, abrasions, skin graft donor sites, superficial wounds, partial thickness wounds, full thickness wounds, chronic wounds, slow healing wounds, pressure sores, pressure ulcers, venous ulcers, diabetic ulcers, foot ulcers, bed sores, or the like). Dosages and administration of compounds, compositions and formulations of the present disclosure may be determined by one of ordinary skill in the art of clinical pharmacology or pharmacokinetics. An effective amount of the active agent of the present disclosure to be employed therapeutically will depend, for example, upon the therapeutic objectives, the route of administration, and the condition of the patient. Accordingly, it may be necessary for the therapist to titre the dosage and modify the route of administration as required to obtain the optimal therapeutic effect.

[0073] The term “subject” is intended to broadly refer to any animal, such as a mammal, and including humans. Exemplary subjects include but are not limited to humans and non-human primates. The term “subject” as used herein also includes patients and non-patients. The term “patient” refers to individuals suffering or are likely to suffer from a medical condition such as wounds (e.g., acute wounds, burns, lacerations, incisions, excisions, abrasions, skin graft donor sites, superficial wounds, partial thickness wounds, full thickness wounds, chronic wounds, slow healing wounds, pressure sores, pressure ulcers, venous ulcers, diabetic ulcers, foot ulcers, bed sores, or the like), while “non-patients” refer to individuals not suffering and are likely to not suffer from the medical condition. “Non-patients” include healthy individuals, non-diseased individuals and / or an individual free from the medical condition. As used herein, the term "mammal" includes vertebrate such as a human or a large veterinary mammal (e.g., horses, cattle, deer, sheep, llamas, goats, Pigs).

[0074] The terms "coupled" or "connected" as used in this description are intended to cover both directly connected or connected through one or more intermediate means, unless otherwise stated. The term "and / or", e.g., "X and / or Y" is understood to mean either "X and Y" or "X or Y" and should be taken to provide explicit support for both meanings or for either meaning.

[0075] Further, in the description herein, the word “substantially” whenever used is understood to include, but not restricted to, "entirely" or “completely” and the like. In addition, terms such as "comprising", "comprise", and the like whenever used, are intended to be non-restricting descriptive language in that they broadly include elements / components recited after such terms, in addition to other components not explicitly recited. For example, when “comprising” is used, reference to a “one” feature is also intended to be a reference to “at least one” of that feature. Terms such as “consisting”, “consist”, and the like, may in the appropriate context, be considered as a subset of terms such as "comprising", "comprise", and the like. Therefore, in embodiments disclosed herein using the terms such as "comprising", "comprise", and the like, it will be appreciated that these embodiments provide teaching for corresponding embodiments using terms such as “consisting”, “consist”, and the like. Further, terms such as "about", "approximately", and the like whenever used, typically means a reasonable variation, for example a variation of + / - 5% of the disclosed value, or a variance of 4% of the disclosed value, or a variance of 3% of the disclosed value, a variance of 2% of the disclosed value or a variance of 1 % of the disclosed value.

[0076] Furthermore, in the description herein, certain values may be disclosed in a range. The values showing the end points of a range are intended to illustrate a preferred range. Whenever a range has been described, it is intended that the range covers and teaches all possible sub-ranges as well as individual numerical values within that range. That is, the end points of a range should not be interpreted as inflexible limitations. For example, a description of a range of 1 % to 5% is intended to have specifically disclosed sub-ranges 1 % to 2%, 1 % to 3%, 1 % to 4%, 2% to 3% etc., as well as individually, values within that range such as 1 %, 2%, 3%, 4% and 5%. It is to be appreciated that the individual numerical values within the range also include integers, fractions and decimals. Furthermore, whenever a range has been described, it is also intended that the range covers and teaches values of up to 2 additional decimal places or significant figures (where appropriate) from the shown numerical end points. For example, a description of a range of 1 % to 5% is intended to have specifically disclosed the ranges 1.00% to 5.00% and also 1.0% to 5.0% and all their intermediate values (such as 1.01 %, 1.02% ... 4.98%, 4.99%, 5.00% and 1.1 %, 1.2% ... 4.8%, 4.9%, 5.0% etc.,) spanning the ranges. The intention of the above specific disclosure is applicable to any depth / breadth of a range.

[0077] Additionally, when describing some embodiments, the disclosure may have disclosed a method and / or process as a particular sequence of steps. However, unless otherwise required, it will be appreciated that the method or process should not be limited to the particular sequence of steps disclosed. Other sequences of steps may be possible. The particular order of the steps disclosed herein should not be construed as undue limitations. Unless otherwise required, a method and / or process disclosed herein should not be limited to the steps being carried out in the order written. The sequence of steps may be varied and still remain within the scope of the disclosure.

[0078] Furthermore, it will be appreciated that while the present disclosure provides embodiments having one or more of the features / characteristics discussed herein, one or more of these features / characteristics may also be disclaimed in other alternative embodiments and the present disclosure provides support for such disclaimers and these associated alternative embodiments.

[0079] It will also be appreciated that where priority is claimed to an earlier application, the full contents of the earlier application is also taken to form part of the present disclosure and may serve as support for embodiments disclosed herein.

[0080] DESCRIPTION OF EMBODIMENTS

[0081] Exemplary, non-limiting embodiments of a composite structure as well as its constituent components, a method of preparing said composite structure, and related methods / uses thereto are disclosed hereinafter.

[0082] COMPOSITE STRUCTURE

[0083] There is provided a composite structure for promoting / stimulating wound healing / closure. In various embodiments, the structure comprises a compressible substrate and a bioactive material disposed on said compressible substrate. In various embodiments, it will be appreciated that the composite structure is different from a pure bioactive material (e g., poly(lactic-co-glycolic acid) (PLGA)) sheet.

[0084] In various embodiments, the bioactive material is three-dimensional (3D) printed on the compressible substrate. In various embodiments, the bioactive material is 3D printed on the compressible substrate via a fused filament fabrication (FFF) / fused deposition modeling (FDM) process, or the like. In various embodiments, the bioactive material is obtained via FFF-based or FDM-based 3D printing. Advantageously, in various embodiments, filament extrusion and 3DP by FFF methods do not denature the biomolecules present in the bioactive material.

[0085] In various embodiments, the composite structure has a length of from about 20 mm to about 320 mm, from about 30 mm to about 310 mm, from about 40 mm to about 300 mm, from about 50 mm to about 290 mm, from about 60 mm to about 280 mm, from about 70 mm to about 270 mm, from about 80 mm to about 260 mm, from about 90 mm to about 250 mm, from about 100 mm to about 240 mm, from about 110 mm to about 230 mm, from about 120 mm to about 220 mm, from about 130 mm to about 210 mm, from about 140 mm to about 200 mm, from about 150 mm to about 190 mm, from about 160 mm to about 180 mm, or about 170 mm.

[0086] In various embodiments, the composite structure has a width of from about 20 mm to about 230 mm, from about 30 mm to about 220 mm, from about 40 mm to about 210 mm, from about 50 mm to about 200 mm, from about 60 mm to about 190 mm, from about 70 mm to about 180 mm, from about 80 mm to about 170 mm, from about 90 mm to about 160 mm, from about 100 mm to about 150 mm, from about 110 mm to about 140 mm, from about 120 mm to about 130 mm, or about 125 mm.

[0087] In various embodiments, the composite structure has a thickness / height / depth of from about 0.01 mm to about 12 mm, from about 0.05 mm to about 11.5 mm, from about 0.1 mm to about 11 mm, from about 0.2 mm to about 10.5 mm, from about 0.3 mm to about 10 mm, from about 0.4 mm to about 9.5 mm, from about 0.5 mm to about 9 mm, from about 0.6 mm to about

[0088] 8.5 mm, from about 0.7 mm to about 8 mm, from about 0.8 mm to about 7.5 mm, from about 0.9 mm to about 7 mm, from about 1 mm to about 6.5 mm, from about

[0089] 1 .5 mm to about 6 mm, from about 2 mm to about 5.5 mm, from about 2.5 mm to about 5 mm, from about 3 mm to about 4.5 mm, from about 3.5 mm to about 4 mm, or about 3.75 mm.

[0090] In various embodiments, the bioactive material and / or composite structure is an acellular material. In various embodiments, the bioactive material and / or composite structure is substantially devoid of cells. Accordingly, in various embodiments the composite structure does not require the additional incorporation of cells to enhance treatment outcomes.

[0091] In various embodiments, the composite structure is substantially devoid of a drug (e g., extraneous drug such as anti-inflammatory drug e g., steroidal drugs) or a pharmaceutically active ingredient e.g., that is releasable to the human or animal body.

[0092] In various embodiments, the composite structure has one or more of the following properties: at least partially oxygen permeable; moisture / fluid / water permeable; flexible (i.e., capable of conforming to surface / site that it is applied to / on); thermally stable (i.e., capable of undergoing high temperatures e.g., melt processing); mechanically stable (i.e., does not warp and / or thin substantially); biodegradable; bioresorbable; and / or biocompatible.

[0093] In various embodiments, at least part of the composite structure is biocompatible, i.e., the at least part of the composite structure is compatible with biological systems or parts of the biological systems without substantially or significantly eliciting an adverse physiological response such as a toxic reaction / response, an immune reaction / response, an injury, or the like when used on the human or animal body. In various embodiments, the composite structure is substantially devoid of substances that elicit an adverse physiological response.

[0094] In various embodiments, the composite structure has an apparent density ranging from about 50 kg / m3to about 250 kg / m3, from about 55 kg / m3to about 245 kg / m3, from about 60 kg / m3to about 240 kg / m3, from about 65 kg / m3to about

[0095] 235 kg / m3, from about 70 kg / m3to about 230 kg / m3, from about 75 kg / m3to about

[0096] 225 kg / m3, from about 80 kg / m3to about 220 kg / m3, from about 85 kg / m3to about

[0097] 215 kg / m3, from about 90 kg / m3to about 210 kg / m3, from about 95 kg / m3to about

[0098] 205 kg / m3, from about 100 kg / m3to about 200 kg / m3, from about 105 kg / m3to about 195 kg / m3, from about 110 kg / m3to about 190 kg / m3, from about 115 kg / m3to about 185 kg / m3, from about 120 kg / m3to about 180 kg / m3, from about 125 kg / m3to about 175 kg / m3, from about 130 kg / m3to about 170 kg / m3, from about 135 kg / m3to about 165 kg / m3, from about 140 kg / m3to about 160 kg / m3, from about 145 kg / m3to about 155 kg / m3, or about 150 kg / m3. It will be appreciated that apparent density of the composite structure is related its porosity, and hence the porosity values obtained (e.g., via the liquid displacement method) may be used to infer the apparent density of the composite structure.

[0099] In various embodiments, the compressive stress required to reduce the thickness of the composite structure to 25 % of its original value ranges from about 1 kPa to about 15 kPa, from about 2 kPa to about 14 kPa, from about 3 kPa to about 13 kPa, from about 4 kPa to about 12 kPa, from about 5 kPa to about 11 kPa, from about 6 kPa to about 10 kPa, from about 7 kPa to about 9 kPa, or about 8 kPa.

[0100] In various embodiments, the composite structure has a hardness ranging from about 10° to about 100°, from about 15° to about 95°, from about 20° to about 90°, from about 25° to about 85°, from about 30° to about 80°, from about 35° to about 75°, from about 40° to about 70°, from about 45° to about 65°, from about 50° to about 60°, or about 55°.

[0101] In various embodiments, the composite structure has a tensile strength ranging from about 100 kPa to about 500 kPa, from about 110 kPa to about 490 kPa, from about 120 kPa to about 480 kPa, from about 130 kPa to about 470 kPa, from about 140 kPa to about 460 kPa, from about 150 kPa to about 450 kPa, from about 160 kPa to about 440 kPa, from about 170 kPa to about 430 kPa, from about 180 kPa to about 420 kPa, from about 190 kPa to about 410 kPa, from about 200 kPa to about 400 kPa, from about 210 kPa to about 390 kPa, from about 220 kPa to about 380 kPa, from about 230 kPa to about 370 kPa, from about 240 kPa to about 360 kPa, from about 250 kPa to about 350 kPa, from about 260 kPa to about 340 kPa, from about 270 kPa to about 330 kPa, from about 280 kPa to about 320 kPa, from about 290 kPa to about 310 kPa, or about 300 kPa.

[0102] In various embodiments, the composite structure is capable of exhibiting an elongation of from about 100 % to about 500 %, from about 110 % to about 490 %, from about 120 % to about 480 %, from about 130 % to about 470 %, from about 140 % to about 460 %, from about 150 % to about 450 %, from about 160 % to about 440 %, from about 170 % to about 430 %, from about 180 % to about 420 %, from about 190 % to about 410 %, from about 200 % to about 400 %, from about 210 % to about 390 %, from about 220 % to about 380 %, from about 230 % to about 370 %, from about 240 % to about 360 %, from about 250 % to about 350 %, from about 260 % to about 340 %, from about 270 % to about 330 %, from about 280 % to about 320 %, from about 290 % to about 310 %, or about 300 % of its original length.

[0103] In various embodiments, the composite structure has a water resistance characterized by water absorption of less than about 10 %, less than about 9 %, less than about 8 %, less than about 7 %, less than about 6 %, less than about 5 %, less than about 4 %, less than about 3 %, less than about 2 %, less than about 1 % or less than about 0.5 %.

[0104] In various embodiments, the composite structure has an oil resistance characterized by absorption of a paraffin liquid / Escalol 557 mixture (9:1 ) of from about 1 % to about 10 %, from about 2 % to about 9 %, from about 3 % to about 8 %, from about 4 % to about 7 %, from about 5 % to about 6 %, or about 5.5 %.

[0105] In various embodiments, the composite structure has an oil resistance characterized by paraffin liquid absorption of less than about 10 %, less than about 9 %, less than about 8 %, less than about 7 %, less than about 6 %, less than about 5 %, less than about 4 %, less than about 3 %, less than about 2 %, less than about 1 % or less than about 0.5 %.

[0106] In various embodiments, the composite structure has a porosity of from about 50 % to about 95 %, from about 51 % to about 94 %, from about 52 % to about 93 %, from about 53 % to about 92 %, from about 54 % to about 91 %, from about 55 % to about 90 %, from about 56 % to about 89 %, from about 57 % to about 88 %, from about 58 % to about 87 %, from about 59 % to about 86 %, from about 60 % to about 85 %, from about 61 % to about 84 %, from about 62 % to about 83 %, from about 63 % to about 82 %, from about 64 % to about 81 %, from about 65 % to about 80 %, from about 66 % to about 79 %, from about 67 % to about 78 %, from about 68 % to about 77 %, from about 69 % to about 76 %, from about 70 % to about 75 %, from about 71 % to about 74 %, from about 72 % to about 73 %, or about 72.5 %. The porosity of the composite structure may be determined using a liquid displacement method.

[0107] In various embodiments, the composite structure can facilitate wound closure in from about 8 days to about 30 days, from about 9 days to about 29 days, from about 10 days to about 28 days, from about 11 days to about 27 days, from about 12 days to about 26 days, from about 13 days to about 25 days, from about 14 days to about 24 days, from about 15 days to about 23 days, from about 16 days to about 22 days, from about 17 days to about 21 days, from about 18 days to about 20 days, about 19 days, fewer than 31 days, fewer than about 30 days, fewer than about 28 days, fewer than about 26 days, fewer than about 24 days, fewer than about 22 days, fewer than about 20 days, fewer than about 18 days, fewer than about 16 days, fewer than about 15 days, fewer than about 14 days, fewer than about 13 days, fewer than about 12 days, fewer than about 11 days, fewer than about 10 days, or fewer than about 9 days. In various embodiments, the composite structure facilitates wound closure with complete re-epithelialisation.

[0108] In various embodiments, all of or some of the parts of the composite structure or the bioactive material is substantially or completely devoid of silver (e.g., silver nanoparticles), which are known to be cytotoxic. While the entire composite structure or the bioactive material may be substantially or completely devoid of silver, it will be appreciated that in some embodiments, it may be sufficient for the parts of the composite structure or the bioactive material that will be in direct contact with the wound to be substantially or completely devoid of silver.

[0109] BIOACTIVE MATERIAL In various embodiments, the bioactive material has a thickness / height / depth of from about 0.05 mm to about 0.50 mm, from about 0.06 mm to about 0.49 mm, from about 0.07 mm to about 0.48 mm, from about 0.08 mm to about 0.47 mm, from about 0.09 mm to about 0.46 mm, from about 0.10 mm to about 0.45 mm, from about 0.11 mm to about 0.44 mm, from about 0.12 mm to about 0.43 mm, from about 0.13 mm to about 0.42 mm, from about 0.14 mm to about 0.41 mm, from about 0.15 mm to about 0.40 mm, from about 0.16 mm to about 0.39 mm, from about 0.17 mm to about 0.38 mm, from about 0.18 mm to about 0.37 mm, from about 0.19 mm to about 0.36 mm, from about 0.20 mm to about 0.35 mm, from about 0.21 mm to about 0.34 mm, from about 0.22 mm to about 0.33 mm, from about 0.23 mm to about 0.32 mm, from about 0.24 mm to about 0.31 mm, from about 0.25 mm to about 0.30 mm, from about 0.26 mm to about 0.29 mm, or from about 0.27 mm to about 0.28 mm.

[0110] In various embodiments, the bioactive material is part of a structure that has a length of from about 10 mm to about 310 mm, from about 20 mm to about 300 mm, from about 30 mm to about 290 mm, from about 40 mm to about 280 mm, from about 50 mm to about 270 mm, from about 60 mm to about 260 mm, from about 70 mm to about 250 mm, from about 80 mm to about 240 mm, from about 90 mm to about 230 mm, from about 100 mm to about 220 mm, from about 110 mm to about 210 mm, from about 120 mm to about 200 mm, from about 130 mm to about 190 mm, from about 140 mm to about 180 mm, from about 150 mm to about 170 mm, or about 160 mm.

[0111] In various embodiments, the bioactive material is part of a structure that has a width of from about 10 mm to about 220 mm, from about 20 mm to about 200 mm, from about 30 mm to about 190 mm, from about 40 mm to about 180 mm, from about 50 mm to about 170 mm, from about 60 mm to about 160 mm, from about 70 mm to about 150 mm, from about 80 mm to about 140 mm, from about 90 mm to about 130 mm, from about 100 mm to about 120 mm, or about 110 mm. In various embodiments, the dimensions of the bioactive material are determined by those of the compressible substrate. For example, the bioactive material may be smaller than the compressible substrate (e g., a PU foam). In various embodiments, a border is present between the periphery of the bioactive material and the outer edge of the compressible substrate, where the border has a width (e.g., distance between the periphery of the bioactive material and the outer edge of the compressible substrate) ranging from about 1.5 mm to about 10 mm, from about 2 mm to about 9.5 mm, from about 2.5 mm to about 9 mm, from about 3 mm to about 8.5 mm, from about 3.5 mm to about 8 mm, from about 4 mm to about 7.5 mm, from about 4.5 mm to about 7 mm, from about 5 mm to about 6.5 mm, from about 5.5 mm to about 6 mm, or about 5.75 mm.

[0112] In various embodiments, the bioactive material has an infill density in the range of from about 30 % to about 90 %, from about 30 % to about 90 %, from about 32 % to about 88 %, from about 34 % to about 86 %, from about 36 % to about 84 %, from about 38 % to about 82 %, from about 40 % to about 80 %, from about 42 % to about 78 %, from about 44 % to about 76 %, from about 46 % to about 74 %, from about 48 % to about 72 %, from about 50 % to about 70 %, from about 52 % to about 68 %, from about 54 % to about 66 %, from about 56 % to about 64 %, from about 58 % to about 62 %, or about 60 %.

[0113] In various embodiments, the bioactive material comprises a bioresorbable polymer. In various embodiments, the bioactive material comprises a mixture of a synthetic homopolymer and a bioactive copolymer. In various embodiments, the bioactive material comprises a base poly(lactic-co-glycolic acid) (PLGA) and a bioactive poly(lactic-co-glycolic acid) (PLGA) copolymer. Advantageously, poly(lactic-co-glycolic acid) (PLGA) is a thermoplastic polymer widely accepted in healthcare applications due to its tuneable degradation rate, tuneable mechanical properties, and biocompatibility. Furthermore, PLGA is useful in drug delivery and tissue engineering applications, owing to their low processing temperatures, which allow the incorporation of biomolecules and therapeutic agents without denaturation.

[0114] In various embodiments, the synthetic homopolymer comprises a base PLGA homopolymer, and the bioactive copolymer comprises a bioactive PLGA copolymer. In various embodiments, the bioactive PLGA copolymer may be blended / mixed with the base PLGA. Advantageously, in various embodiments, the material is suitable for promoting or stimulating connective tissue regeneration such as skin regeneration and / or tissue regeneration. Accordingly, in various embodiments, the material is a regenerative material. Advantageously, in various embodiments, the material is also suitable for promoting or stimulating wound healing / regeneration / regrowth / repair / closure / treatment / angiogenesis / infection management and / or providing antibacterial effects, and may also be used in methods of treating wounds. The material may also be a material that is suitable for use in controlling and / or reducing inflammation. In various embodiments, by controlling and / or reducing inflammation, embodiments of the material may also be suitable for use in reducing risk of scarring (which may result due to prolonged inflammation). In various embodiments, the material overcomes or at least ameliorates one or more of the inherent issues of conventional wound care products as described earlier above.

[0115] In various embodiments, the term “poly(lactic-co-glycolic acid)” comprise and / or may be used interchangeably with the terms “poly(lactide-co-glycolide)”, “poly(D-lactide-co-glycolide)”, “poly(L-lactide-co-glycolide)”, “poly(D,L-lactide-co- glycolide)”, or the like. In various embodiments, PLGA comprises medical grade PLGA.

[0116] In various embodiments, the ratio of the base PLGA to bioactive PLGA copolymer present in the bioactive material is from about 60.0 - 99.9 : 0.1 - 40.0, from about 70.0 - 99.9 : 10.0 - 40.0, from about 80.0 - 99.9 : 20.0 - 40.0, from about 90.0 - 99.9 : 30.0 - 40.0, from about 60.0 - 90.0 : 0.1 - 30.0, from about 60.0 - 80.0 : 0.1 - 20.0, or from about 60.0 - 70.0 : 0.1 - 10.0. In various embodiments, the bioactive material comprises from about 60.0 wt% to about 99.9 wt%, from about 61 .0 wt% to about 99.8 wt%, from about 62.0 wt% to about 99.7 wt%, from about 63.0 wt% to about 99.6 wt%, from about 64.0 wt% to about 99.5 wt%, from about 65.0 wt% to about 99.0 wt%, from about 66.0 wt% to about 98.5 wt%, from about 67.0 wt% to about 98.0 wt%, from about 68.0 wt% to about 97.0 wt%, from about 69.0 wt% to about 96.0 wt%, from about 70.0 wt% to about 95.0 wt%, from about 71.0 wt% to about 94.0 wt%, from about 72.0 wt% to about 93.0 wt%, from about 73.0 wt% to about 92.0 wt%, from about 74.0 wt% to about 91 .0 wt%, from about 75.0 wt% to about 90.0 wt%, from about 76.0 wt% to about 89.0 wt%, from about 77.0 wt% to about 88.0 wt%, from about 78.0 wt% to about 87.0 wt%, from about 79.0 wt% to about 86.0 wt%, from about 80.0 wt% to about 85.0 wt%, from about 81.0 wt% to about 84.0 wt%, or from about 82.0 wt% to about 83.0 wt% of the base PLGA.

[0117] In various embodiments, the bioactive material comprises from about 0.1 wt% to about 40.0 wt%, from about 0.2 wt% to about 39.0 wt%, from about 0.3 wt% to about 38.0 wt%, from about 0.4 wt% to about 37.0 wt%, from about 0.5 wt% to about 36.0 wt%, from about 1.0 wt% to about 35.0 wt%, from about 1.5 wt% to about 34.0 wt%, from about 2.0 wt% to about 33.0 wt%, from about 3.0 wt% to about 32.0 wt%, from about 4.0 wt% to about 31.0 wt%, from about 5.0 wt% to about 30.0 wt%, from about 6.0 wt% to about 29.0 wt%, from about 7.0 wt% to about 28.0 wt%, from about 8.0 wt% to about 27.0 wt%, from about 9.0 wt% to about 26.0 wt%, from about 10.0 wt% to about 25.0 wt%, from about 11 .0 wt% to about 24.0 wt%, from about 12.0 wt% to about 23.0 wt%, from about 13.0 wt% to about 22.0 wt%, from about 14.0 wt% to about 21 .0 wt%, from about 15.0 wt% to about 20.0 wt%, from about 16.0 wt% to about 19.0 wt%, or from about 17.0 wt% to about 18.0 wt% of the bioactive PLGA copolymer.

[0118] In various embodiments, the bioactive PLGA copolymer comprises a bioactive PLGA copolymer with a poly(norbornene-dicarboximide) backbone having one or more repeating units represented by general formula (I) and one or more repeating units represented by general formula (II): wherein

[0119] R1is selected from a single bond, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted alkoxyalkyl, optionally substituted alkylcarbonyl, or optionally substituted alkylcarbonylalkyl;

[0120] R2is optionally substituted alkyl;

[0121] R3is selected from H, optionally substituted alkyl, optionally substituted alkenyl, or optionally substituted alkynyl;

[0122] L is heteroalkylene;

[0123] X comprises a bioactive moiety selected from the group consisting of proteins, peptides, oligopeptides, carbohydrates, oligosaccharides, sugar, collagen, hyaluronic acid (HA), therapeutic / drug molecules, and derivatives thereof;

[0124] Z1and Z2are each independently selected from CRaRb, 0, NRC, SiRaRb, PRa, or S, wherein Ra, Rb, and Rcare each independently selected from the group consisting of H, optionally substituted alkyl, optionally substituted alkenyl, and optionally substituted alkynyl; p > 1 ; and q > 1. In various embodiments, the repeating unit(s) represented by general formula (I) possess good mechanical strength / hardness. In various embodiments, the repeating unit(s) represented by general formula (II) and / or moiety X possess bioactivity, biocompatibility and / or biodegradability. In various embodiments, the repeating unit represented by general formula (I) has a higher mechanical strength than the repeating unit represented by general formula (II) and / or moiety X. Advantageously, the presence of repeating units represented by general formulae (I) and (II) in the bioactive PLGA copolymer imparts both bioactivity and mechanical strength to the copolymer, leading to a mechanically strong bioactive copolymer. In various embodiments, the copolymer may also be biocompatible and / or biodegradable. Accordingly, in various embodiments, the copolymer is capable of being classified as a biomaterial. Advantageously, due to the presence of synthetic and bioactive side chains, the bioactive PLGA copolymer may also have a high thermal stability than conventional biomolecules such as peptides, proteins, carbohydrates or glycosaminoglycans. Even more advantageously, the thermal stability of the bioactive hyaluronic acid-based synthetic copolymer allows for embodiments of the copolymer to be suitable for processing at high temperatures or even harsh material processing such as melt processing / extrusion > 100 °C, making the copolymer ideal / attractive 3DP. In various embodiments, the repeating unit(s) represented by general formula (I) is substantially or completely non-bioactive, or at least less bioactive than the repeating unit(s) represented by general formula (II) and / or bioactive moiety X.

[0125] In various embodiments, the one or more repeating units represented by general formula (I) comprises two or more different types of bioactive moiety X. In various embodiments, the one or more repeating units represented by general formula (I) comprises 2, 3, 4, 5, 6, 7, or 8 different types of bioactive moiety X. For example, within a bioactive PLGA copolymer, there may be repeating units represented by general formula (I) comprising peptide as X and repeating units represented by general formula (I) comprising carbohydrate as X. Advantageously, in various embodiments, the bioactive PLGA copolymer imparts two or more different types of bioactivities. In various embodiments, X comprises a bioactive moiety selected from proteins, peptides, carbohydrates, therapeutic / drug molecules and derivatives thereof. In various embodiments, proteins, peptides, carbohydrates or therapeutic / drug molecules derivatives thereof include proteins, peptides, carbohydrates or therapeutic / drug molecules that are or have been optionally modified to contain one carboxylic acid terminal group. In some embodiments, the bioactive moiety contains only one carboxylic acid terminal group.

[0126] In various embodiments, the proteins, peptides, carbohydrates, or therapeutic / drug molecules derivatives thereof include proteins, peptides, carbohydrates, or therapeutic / drug molecules that are or have been optionally modified to contain one carboxylic acid terminal group. In some embodiments, the bioactive moiety contains only one carboxylic acid terminal group.

[0127] In various embodiments, the bioactive moiety comprises a monocarboxylic acid. Advantageously, in some embodiments, the use of a bioactive moiety having a monocarboxylic acid terminal group may reduce / avoid the possibility of an undesirable crosslinking as compared to the case of using more than one carboxylic acid. In some embodiments therefore, the bioactive moiety X is substantially devoid of more than one carboxylic acid terminal group, e.g., a dicarboxylic acid or tricarboxylic acid.

[0128] In various embodiments, X comprises protein or peptide. In various embodiments, X may be a peptide sequence, laminin-derived peptide, integrin binding peptide, cell-penetrating peptide, collagen mimics, or collagen fragments. In various embodiments, X comprises from 2 to 50 amino acid residues, from 2 to 40 amino acid residues, or from 2 to 20 amino acid residues in any sequence. In various embodiments, X comprises 50 amino acid residues, 40 amino acid residues, 30 amino acid residues, 25 amino acid residues, 20 amino acid residues, 15 amino acid residues, 10 amino acid residues, 9 amino acid residues, 8 amino acid residues, 7 amino acid residues, 6 amino acid residues, 5 amino acid residues, 4 amino acid residues, or 3 amino acid residues in any sequence. In various embodiments, the amino acid residues may be selected from the group consisting of glycine (G), alanine (A), valine (V), leucine (L), isoleucine (I), methionine (M), proline (P), phenylalanine (F), tryptophan (W), asparagine (N), glutamine (Q), glycine (G), serine (S), threonine (T), tyrosine (Y), cysteine (C), lysine (K), arginine (R), histidine (H), aspartic acid (D), and glutamic acid (E). In various embodiments, X is a peptide sequence comprising 3 to 20 natural amino acids. In various embodiments, X may be integrin binding peptide selected from the group consisting of arginine-glycine-aspartic acid (RGD), serine-arginine- glycine-aspartic acid-serine (SRGDS), and arginine-glycine-aspartic acid-serine (RGDS); laminin-derived peptide A5G81 (alanine-glycine-glutamine-tryptophan- histidine-arginine-valine-serine-valine-arginine-tryptophan-glycine-cysteine (AGQWHRVSVRWGC)), isoleucine-lysine-valine-alanine-valine (IKVAV); osteopontin derived peptides serine-valine-valine-tyrosine-glycine-leucine- arginine (SWYGLR); and cell-penetrating / antimicrobial peptide selected from leucine-lysine-lysine-leucine-cysteine-arginine-isoleucine-leucine-lysine-lysine- leucine-cysteine-arginine-isoleucine (LKKLCRILKKLCRI), isoleucine-arginine- isoleucine-lysine-isoleucine-arginine-isoleucine-lysine (IRIK)2, or isoleucine- lysine-lysine-isoleucine-isoleucine-lysine-lysine-isoleucine-isoleucine-lysine- lysine-isoleucine (IKKI)s. In various embodiments, X is a collagen sequence comprising 3 to 20 units of glycine (G), proline (P), and hydroxyproline (Hyp) in any sequence or permutation. In various embodiments, X may be collagen fragment having a (PHypG)n type sequence, (PGHyp)n type sequence, (HypGP)n type sequence, (HypPG)n type sequence, (GHypP)n type sequence, (GPHyp)ntype sequence, or collagen mimic aspartic acid-glycine-glutamic acid-alanine (DGEA).

[0129] In various embodiments, X comprises non-type I collagen. In various embodiments, the material is a non-animal derived material. Advantageously, by using non-type I collagen, the material reduces and / or eliminates risk of bacterial infection (which may otherwise result from the use of Type I collagen). In various embodiments, X comprises carbohydrate or sugar. In various embodiments, X comprises monosaccharide, disaccharide, oligosaccharide or polysaccharide. In various embodiments, X comprises from 2 to 50 saccharide units, from 2 to 40 saccharide units, from 2 to 20 saccharide units or from 10 to 1 saccharide units. In various embodiments, X comprises 50 saccharide units, 40 saccharide units, 30 saccharide units, 25 saccharide units, 20 saccharide units, 15 saccharide units, 14 saccharide units, 13 saccharide units, 12 saccharide units, 11 saccharide units, 10 saccharide units, 9 saccharide units, 8 saccharide units, 7 saccharide units, 6 saccharide units, 5 saccharide units, 4 saccharide units or 3 saccharide units or 2 saccharide units. In various embodiments, X may be heparin sulfate (HS) or glycosaminoglycans (GAGs). In various embodiments, X is heparin sulfate / oligosaccharide selected from the group consisting of DP8, DP10, DP12, DP14 and DP16. In various embodiments, X is hyaluronic acid which is the simplest form of glycosaminoglycan (GAG). For example, X may be hyaluronic acid comprising from 8 to 20 saccharide units, from 8 to 13 saccharide units, about 8 saccharide units, about 9 saccharide units, about 10 saccharide units, about 11 saccharide units, about 12 saccharide units, about 13 saccharide units, about 14 saccharide units, about 15 saccharide units, about 16 saccharide units, about 17 saccharide units, about 18 saccharide units, about 19 saccharide units, or about 20 saccharide units.

[0130] In various embodiments, the term “hyaluronic acid” comprises and / or may be used interchangeably with the term “hyaluronic acid and / or derivatives thereof”, “hyaluronic acid”, “hyaluronan”, “derivatives of hyaluronic acid”, “conjugate base of hyaluronic acid”, and “hyaluronate”.

[0131] In various embodiments, X comprises a carbohydrate / saccharide that contained or has been modified to contain one carboxylic acid terminal group. In various embodiments, modification by one or more chemical reaction(s) such as oxidation may be performed on the carbohydrate / saccharide to create a carboxylic acid group. In various embodiments, modification is performed on a hydroxyl group that is originally present in the carbohydrate / saccharide. In various embodiments, -CH2OH on the carbohydrate / saccharide is oxidized completely to -C(=O)OH, which subsequently reacts with a -NH2 terminal on L to create a peptide linkage that links the carbohydrate / saccharide to the rest of general formula (II): X-C(=O)-NH-L- It will be appreciated, however, that no modification to the carbohydrate / saccharide may be required / necessary if a carboxylic acid is naturally present in the carbohydrate / saccharide.

[0132] In various embodiments, X comprises therapeutic / drug molecule. In various embodiments, X comprises antibiotic, antimicrobial, antibacterial, blood thinning agents or anti-inflammatory agents. X may be penicillin, amoxicillin, amphotericin, ciprofloxacin (GIF), atorvastatin, aspirin or aminoglycoside-based molecules selected from streptomycin, ribostamycin or gentamycin. It will be appreciated that X may be any therapeutic or drug molecule that contains a carboxylic acid group.

[0133] In various embodiments, X comprises a therapeutic / drug molecule that contained or has been modified to contain one carboxylic acid terminal group. Modification by one or more chemical reaction(s) such as oxidation may be performed on the therapeutic / drug molecule to create a carboxylic acid group. In various embodiments, modification is performed on a hydroxyl group that is originally present in the therapeutic / drug molecule. For example, in various embodiments when X is ribostamycin or gentamycin, -CH2OH on the drug molecule is oxidized completely to -C(=O)OH, which subsequently reacts with a -NH2 terminal on L to create a peptide linkage that links the drug molecule to the rest of general formula (II): X-C(=O)-NH-L- It will be appreciated, however, that no modification to the therapeutic / drug molecule may be required / necessary if a carboxylic acid is already present in the therapeutic / drug molecule.

[0134] In various embodiments, the bioactive moiety is or has been modified to contain one carboxylic acid terminal group. For example, if a carboxylic acid terminal group is absent in a carbohydrate or therapeutic / drug molecule, the carbohydrate or therapeutic / drug molecule may be modified to add a carboxylic acid at one of the carbohydrate or therapeutic / drug molecule terminals. The modification may comprise oxidation reaction(s) to convert a hydroxy group in the carbohydrate to carboxylic acid.

[0135] In various embodiments, X is chemically coupled / connected to the rest of general formula (I) via its hydroxy group. For example, when X is carbohydrate / saccharide, oxidation and / or reductive amination reactions may be performed on the carbohydrate’s hydroxy for linking X to general formula (I). In various embodiments, -CH2OH on the saccharide may be oxidised to -C(=O)H, which subsequently undergoes reductive amination using the -NH2 terminal on L to create a peptide linkage.

[0136] In various embodiments, X is coupled to the poly(norbornene dicarboximide) backbone through a carboxylic acid functionality in the following arrangement: -R1-L-NR3-C(=O)-X. Advantageously, by linking X through a carboxylic acid functionality, amine terminal group(s) in X is / are free up for delivering its bioactivity, therefore ensuring the bioavailability of X. It will be appreciated that as amine group(s) confer bioactivity, exhausting up amine groups in bioactive moieties for polymer binding may be undesirable.

[0137] In various embodiments, X is coupled to the poly(norbornene dicarboximide) backbone via peptide / amide linkage, i.e. , -NR3-C(=O)-. Advantageously, the bioactive PLGA copolymer disclosed herein is considerably stronger and / or stable than conventional polymers that contain ester linkages. Without being bound by theory, it is believed that amide linkages are stronger than ester linkages because ester linkages are more prone to hydrolysis, which may release bioactive moieties into the bloodstream, leading to a premature metabolism of bioactive moieties. Advantageously, the presence of an amide linkage prevents the bioactive moieties from breaking off from the polymer chain, therefore ensuring the bioavailability of the bioactive moieties. It will be appreciated that the active site for bioactivity (e.g., cell binding) is at bioactive moieties in general formula (II). In various embodiments, the one or more repeating units represented by general formula (I) and the one or more repeating units represented by general formula (II) are designed to link to the poly(norbornene) backbone via at least covalent interactions. In various embodiments, each repeating unit represented by general formula (I) is covalently bonded to the poly(norbornene) backbone and / or each repeating unit represented by general formula (II) is covalently bonded to the poly(norbornene) backbone. Advantageously, as bioactive moieties (in general formula (II)) are covalently bonded to the bioactive PLGA copolymer, bioactivity is localized. In various embodiments, the bioactive moieties do not leach out from the polymer, therefore preventing undesirable / unwanted side effects caused by biomolecules entering the circulatory system and / or reaching unintended parts of the body system.

[0138] In various embodiments, the ratio of the number of repeating units represented by general formula (I) to the number of repeating units represented by general formula (II) in the bioactive PLGA copolymer is from about 1 :1 to about 1 :100, from about 1 :2 to about 1 :99, from about 1 :3 to about 1 :98, from about 1 :4 to about 1 :97, from about 1 :5 to about 1 :96, from about 1 :6 to about 1 :95, from about 1 :7 to about 1 :90, from about 1 :8 to about 1 :85, from about 1 :9 to about 1 :80, from about 1 :10 to about 1 :75, from about 1 :15 to about 1 :70, from about 1 :20 to about 1 :65, from about 1 :25 to about 1 :60, from about 1 :30 to about 1 :55, from about 1 :35 to about 1 :50, or from about 1 :40 to about 1 :45.

[0139] In various embodiments, the molecular weight of general formula (I) is from about 100 to about 15,000, from about 200 to about 14,000, from about 300 to about 13,000, from about 400 to about 12,000, from about 500 to about 11 ,000, from about 1 ,000 to about 10,000, from about 1 ,500 to about 9,500, from about 2,000 to about 9,000, from about 2,500 to about 8,500, from about 3,000 to about 8,000, from about 3,500 to about 7,500, from about 4,000 to about 7,000, from about 4,500 to about 6,500, from about 5,000 to about 6,000, or about 5,500. In various embodiments, the molecular weight of general formula (II) is about 15,000, about 14,000, about 13,000 or at least about 12,000. In various embodiments, the molecular weight of general formula (II) is from about 100 to about 15,000, from about 200 to about 14,000, from about 300 to about 13,000, from about 400 to about 12,000, from about 500 to about 11 ,000, from about 1 ,000 to about 10,000, from about 1 ,500 to about 9,500, from about 2,000 to about 9,000, from about 2,500 to about 8,500, from about 3,000 to about 8,000, from about 3,500 to about 7,500, from about 4,000 to about 7,000, from about 4,500 to about 6,500, from about 5,000 to about 6,000 or about 5,500.

[0140] In various embodiments, the total molecular weight of general formula (I) and general formula (II) is kept to about 500,000, no more than about 500,000, no more than about 400,000, no more than about 300,000, no more than about 200,000, no more than about 100,000, no more than about 90,000, no more than about 80,000, no more than about 70,000, no more than about 60,000, no more than about 50,000, no more than about 45,000, no more than about 40,000, no more than about 35,000, no more than about 30,000, no more than about 25,000, no more than about 20,000, or no more than about 15,000 to facilitate copolymerisation.

[0141] In various embodiments, the molecular weight of general formula (I) is comparable / substantially similar with / to the molecular weight of general formula (II). In various embodiments, the molecular weight of general formula (I) does not differ from the molecular weight of general formula (II) by more than 30 % of the molecular weight of general formula (II) or vice versa. For example, the molecular weight of general formula (I) may be at most about 30 % more or at most 30 % less than the molecular weight of general formula (II) or vice versa. The molecular weight of general formula (I) may not differ from the molecular weight of general formula (II) by more than about 30 %, more than about 25 %, more than about 20 %, more than about 15 %, more about 10 %, more than about 5 %, more than about 4 %, more than about 3 %, more than about 2 %, or more than about 1 % of the molecular weight of general formula (II) or vice versa. In various embodiments, the molecular weight of general formula (I) does not differ from the molecular weight of general formula (II) by more than about 20 % of the molecular weight of general formula (II) or vice versa. For example, the molecular weight of general formula (I) may be at most about 20 % more or at most 20 % less than the molecular weight of general formula (II) or vice versa. Advantageously, as the bioactive moiety bearing repeating unit has a molecular size / weight / length that is similar to that of the synthetic polymer (i.e. , PLGA) bearing repeating unit, the length of the bioactive moiety X is extended, thereby allowing X to be “visible", available for binding to cells or accessible to its targeted physiological site for desired bioactivity, i.e., not buried in a sea / matrix of synthetic polymers (i.e. PLGA).

[0142] In various embodiments, p > 1. In various embodiments, p is 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 , 12, 13, 14, 15, 16, 17, 18, 19, 20, 21 , 22, 23, 24, 25, 26, 27, 28, 29, 30, 31 , 32, 33, 34, 35, 36, 37, 38, 39, 40, 41 , 42, 43, 44, 45, 46, 47, 48, 49,

[0143] 50, 51 , 52, 53, 54, 55, 56, 57, 58, 59, 60, 61 , 62, 63, 64, 65, 66, 67, 68, 69, 70,

[0144] 71 , 72, 73, 74, 75, 76, 77, 78, 79, 80, 81 , 82, 83, 84, 85, 86, 87, 88, 89, 90, 91 ,

[0145] 92, 93, 94, 95, 96, 97, 98, 99, 100, 101 , 102, 103, 104, 105, 106, 107, 108, 109,

[0146] 110, 111 , 112, 113, 114, 115, 116, 117, 118, 119, 120, 121 , 122, 123, 124, 125,

[0147] 126, 127, 128, 129, 130, 131 , 132, 133, 134, 135, 136, 137, 138, 139, 140, 141 ,

[0148] 142, 143, 144, 145, 146, 147, 148, 149 or 150. In various embodiments, q > 1. In various embodiments, q is 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 , 12, 13, 14, 15, 16, 17,

[0149] 18, 19, 20, 21 , 22, 23, 24, 25, 26, 27, 28, 29, 30, 31 , 32, 33, 34, 35, 36, 37, 38,

[0150] 39, 40, 41 , 42, 43, 44, 45, 46, 47, 48, 49, 50, 51 , 52, 53, 54, 55, 56, 57, 58, 59,

[0151] 60, 61 , 62, 63, 64, 65, 66, 67, 68, 69, 70, 71 , 72, 73, 74, 75, 76, 77, 78, 79, 80,

[0152] 81 , 82, 83, 84, 85, 86, 87, 88, 89, 90, 91 , 92, 93, 94, 95, 96, 97, 98, 99, 100, 101 ,

[0153] 102, 103, 104, 105, 106, 107, 108, 109, 110, 111 , 112, 113, 114, 115, 116, 117,

[0154] 118, 119, 120, 121 , 122, 123, 124, 125, 126, 127, 128, 129, 130, 131 , 132, 133,

[0155] 134, 135, 136, 137, 138, 139, 140, 141 , 142, 143, 144, 145, 146, 147, 148, 149 or 150. In various embodiments, the total molecular weight of general formula (I) is kept to no more than about 15,000 or no more than about 10,000. It will be appreciated that copolymerisation may become inefficient when the total molecular weight of general formula (I) and (II) is too high. In various embodiments, when the bioactive PLGA copolymer is used for applications which require fast biodegradation, the molecular weight of general formula (I) is kept low by adjusting the value of p and / or q.

[0156] In various embodiments, the number of repeating units represented by general formula (I) in the bioactive PLGA copolymer is from about 10 to about 1 ,000, from about 50 to about 950, from about 100 to about 900, from about 150 to about 850, from about 200 to about 800, from about 250 to about 750, from about 300 to about 700, from about 350 to about 650, from about 400 to about 600, from about 450 to about 550, or about 500.

[0157] In various embodiments, the number of repeating units represented by general formula (II) in the bioactive PLGA copolymer is from about 10 to about 1 ,000, from about 50 to about 950, from about 100 to about 900, from about 150 to about 850, from about 200 to about 800, from about 250 to about 750, from about 300 to about 700, from about 350 to about 650, from about 400 to about 600, from about 450 to about 550, or about 500.

[0158] In various embodiments, the repeating unit represented by general formula (II) is in an amount of from about 1 molar % to about 100 molar %, from about 2 molar % to about 99 molar %, from about 3 molar % to about 98 molar %, from about 4 molar % to about 97 molar %, from about 5 molar % to about 96 molar %, from about 10 molar % to about 95 molar %, from about 15 molar % to about 90 molar %, from about 20 molar % to about 85 molar %, from about 25 molar % to about 80 molar %, from about 30 molar % to about 75 molar %, from about 35 molar % to about 70 molar %, from about 40 molar % to about 65 molar %, from about 45 molar % to about 60 molar %, or from about 50 molar % to about 55 molar % relative to the copolymer. In various embodiments, the repeating unit represented by general formula (II) is in an amount of from about 1 molar % to about 10 molar % relative to the copolymer. In various embodiments, the bioactive moiety is about 2 molar %, about 3 molar %, about 4 molar %, about 5 molar %, about 6 molar %, about 7 molar %, about 8 molar %, about 9 molar %, or about 10 molar % of the bioactive PLGA copolymer.

[0159] In various embodiments, R1is selected from C1-C20 alkyl, C2-C20 alkenyl, C2-C20 alkynyl, C1-C20 alkoxyalkyl, C2-C20 alkylcarbonyl, or C3-C20 alkylcarbonylalkyl. The C1-C20 alkyl substituents may be straight or branched substituents selected from methyl, ethyl, n-propyl, 2-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, hexyl, amyl, 1 ,2-dimethylpropyl, 1 ,1 -dimethylpropyl, pentyl, isopentyl, hexyl, 4-methylpentyl, 1 -methylpentyl, 2-methylpentyl, 3-methylpentyl, 2,2-dimethylbutyl, 3,3-dimethylbutyl, 1 ,2-dimethylbutyl,

[0160] 1 .3-dimethylbutyl, 1 ,2,2-trimethylpropyl, 1 ,1 ,2-trimethylpropyl, 2-ethylpentyl, 3-ethylpentyl, heptyl, 1 -methyl hexyl, 2,2-dimethylpentyl, 3,3-dimethylpentyl,

[0161] 4.4-dimethylpentyl, 1 ,2-dimethylpentyl, 1 ,3-dimethylpentyl, 1 ,4-dimethylpentyl,

[0162] 1 .2.3-trimethylbutyl, 1 , 1 ,2-trimethylbutyl, 1 , 1 ,3-trimethylbutyl, 5-methylheptyl, 1 -methylheptyl, octyl, nonyl, decyl, the like or combinations thereof. Similarly, the, C2-C20 alkenyl, C2-C20 alkynyl, C1-C20 alkoxyalkyl, C2-C20 alkylcarbonyl, or C3-C20 alkylcarbonylalkyl may contain substituents that are analogous variants of the alkyl substituents described above.

[0163] In various embodiments, R2is selected from straight or branched C1-C20 alkyl. The C1-C20 alkyl substituents may be straight or branched substituents selected from methyl, ethyl, n-propyl, 2-propyl, isopropyl, n-butyl, isobutyl, secbutyl, t-butyl, hexyl, amyl, 1 ,2-dimethylpropyl, 1 ,1 -dimethylpropyl, pentyl, isopentyl, hexyl, 4-methylpentyl, 1 -methylpentyl, 2-methylpentyl, 3-methylpentyl, 2,2-dimethylbutyl, 3,3-dimethylbutyl, 1 ,2-dimethylbutyl,

[0164] 1 .3-dimethylbutyl, 1 ,2,2-trimethylpropyl, 1 ,1 ,2-trimethylpropyl, 2-ethylpentyl, 3-ethylpentyl, heptyl, 1 -methyl hexyl, 2,2-dimethylpentyl, 3,3-dimethylpentyl,

[0165] 4.4-dimethylpentyl, 1 ,2-dimethylpentyl, 1 ,3-dimethylpentyl, 1 ,4-dimethylpentyl,

[0166] 1 ,2,3-trimethylbutyl, 1 , 1 ,2-trimethylbutyl, 1 , 1 ,3-trimethylbutyl, 5-methylheptyl, 1 -methylheptyl, octyl, nonyl, decyl, the like or combinations thereof. R2may be straight or branched C1-C4 alkyl substituents. In various embodiments, the length of R2is the same as the length of a repeating unit in L. For example, if L is poly(butylene glycol), then R2is butyl. In another example, if L is polyethylene glycol), then R2is ethyl. It will be appreciated that in various embodiments, R2is carefully designed to match L.

[0167] In various embodiments, R3is selected from H, C1-C20 alkyl, C2-C20 alkenyl or C2-C20 alkynyl. The C1-C20 alkyl substituents may be straight or branched substituents selected from methyl, ethyl, n-propyl, 2-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, hexyl, amyl, 1 ,2-dimethylpropyl, 1 ,1 -dimethylpropyl, pentyl, isopentyl, hexyl, 4-methylpentyl, 1 -methylpentyl, 2-methylpentyl, 3-methylpentyl, 2,2-dimethylbutyl, 3,3-dimethylbutyl, 1 ,2-dimethylbutyl,

[0168] 1 .3-dimethylbutyl, 1 ,2,2-trimethylpropyl, 1 ,1 ,2-trimethylpropyl, 2-ethylpentyl, 3-ethylpentyl, heptyl, 1 -methyl hexyl, 2,2-dimethylpentyl, 3,3-dimethylpentyl,

[0169] 4.4-dimethylpentyl, 1 ,2-dimethylpentyl, 1 ,3-dimethylpentyl, 1 ,4-dimethylpentyl, 1 ,2,3-trimethylbutyl, 1 , 1 ,2-trimethylbutyl, 1 , 1 ,3-trimethylbutyl, 5-methylheptyl, 1 -methylheptyl, octyl, nonyl, decyl, the like or combinations thereof. Similarly, the, C2-C20 alkenyl, or C2-C20 alkynyl, may contain substituents that are analogous variants of the alkyl substituents described above.

[0170] In various embodiments, L is a polymeric linker that links the bioactive moiety X to the poly(norbornene) backbone. Advantageously, L is designed to be adjustable and / or customizable based on the size of the bioactive moiety X and the size of the synthetic polymer (i.e. , PLGA). The molecular weight and / or length of the polymeric linker L may be customized to suit the molecular weight and / or length of the bioactive moiety X and the synthetic polymer (i.e., PLGA), depending on the application the copolymer is to be used for. In various embodiments, physical properties of the copolymer can be changed / tuned / customized depending on the length of L (e.g., PEG chain). In various embodiments, for applications in dressings, or particularly non- biodegradable non-woven fibers which require thermal stability and / or mechanical strength properties, low molecular weight may be preferred for PLGA due to its poor solubility in common solvents.

[0171] In various embodiments, the molecular weight and / or length of the polymeric linker L is selected such that the overall molecular size of the repeating unit represented by general formula (I) is similar / comparable to the molecular size of the repeating unit represented by general formula (II). For example, if PLGA having a molecular weight of 4,000 is selected and a peptide having a molecular weight of from about 400 to about 500 is selected as the choice of bioactive moiety X, then L may be designed to comprise a molecular weight of about 3,400. It will be appreciated that in various embodiments, it is the length of L that gets adjusted to match the molecular weight of general formula (I) to molecular weight of general formula (II).

[0172] In various embodiments, L is a heteroalkylene having at least 20 carbon atoms, at least 30 carbon atoms, at least 40 carbon atoms, at least 50 carbon atoms, at least 60 carbon atoms, at least 70 carbon atoms, at least 80 carbon atoms, at least 90 carbon atoms, at least 100 carbon atoms, at least 150 carbon atoms, at least 200 carbon atoms, at least 250 carbon atoms or at least 300 carbon atoms. In various embodiments, L is C20-C300 heteroalkylene or a heteroalkylene having from 20 carbon atoms to 300 carbon atoms.

[0173] In various embodiments, the heteroatom in L is O. In various embodiments, L is polyalkylene glycol, e.g., poly(C2-C4 alkylene glycol). In various embodiments, L is selected from the group consisting of polyethylene glycol (PEG), polypropylene glycol (PPG), polytetramethylene glycol (PTMG), polybutylene glycol (PBG), the like, and combinations thereof. Advantageously, the use of a polyalkylene glycol such as PEG can increase hydrophilicity of the copolymer. In various embodiments, polyalkylene glycol such as PEG are used as spacers, linkers or linking groups in the overall polymers, instead of as terminal groups. In various embodiments, L is polyalkylene glycol having at least about 10 repeating units, at least about 15 repeating units, at least about 20 repeating units, at least about 21 repeating units, at least about 22 repeating units, at least about 23 repeating units, at least about 24 repeating units, at least about 25 repeating units, at least about 30 repeating units, at least about 40 repeating units, at least about 50 repeating units, at least about 60 repeating units, at least about 70 repeating units, at least about 80 repeating units, at least about 90 repeating units, at least about 100 repeating units, at least about 150 repeating units, at least about 200 repeating units, or at least about 250 repeating units. Unlike conventional polymers which uses a short PEG chain, embodiments of the bioactive synthetic copolymer disclosed herein incorporate a long polyalkylene glycol chain of at least 21 repeating units at L.

[0174] In various embodiments, L comprises from about 10 monomers / repeating units to about 250 monomers / repeating units. For example, L is selected from the group consisting of PEGsoo, PEGeoo, PEG700, PEGsoo, PEG900, PEG1000, PEG1100, PEG1200, PEG1300, PEG1400, PEG1500, PEG2000, PEG2500, PEG3000, PEG3500, PEG4000, PEG4500, PEG5000, PEG5500, PEGeooo, PEG6600 and mixtures thereof.

[0175] In various embodiments, L has a number average molecular weight of between about 500 and about 7,000. For example, L may have a number average molecular weight of about 600, about 700, about 800, about 900, about 1 ,000, about 1 ,500, about 2,000, about 2,500, about 3,000, about 3,500, about 4,000, about 4,500, about 5,000, about 5,500, about 6,000, about 6,500 or about 7,000.

[0176] In various embodiments, L is hydrophilic. As L is adjustable, the hydrophilicity of the repeating unit represented by general formula (II) and also the overall hydrophilicity of the bioactive PLGA copolymer may be adjusted as desired. Advantageously, the presence of L increases the hydrophilicity of the repeating unit represented by general formula (II) and also the overall hydrophilicity of the bioactive synthetic copolymer. Even more advantageously, the presence of L increases the hydrophilicity of the bioactive synthetic copolymer, therefore softening the synthetic polymeric chains which are hydrophobic, making the copolymer less stiff after processing. It will be appreciated by a person skilled in the art that, bioactive moieties and synthetic polymers are typically mutually incompatible as the individual bioactive moiety is generally hydrophilic while synthetic polymer is generally hydrophobic. Advantageously, L in repeating unit represented by general formula (II) is also used to extend the chain length of the bioactive moiety X attached at the end of L.

[0177] In various embodiments, L is amorphous. Advantageously, the presence of L increases the amorphousness and / or decreases the crystallinity of the bioactive synthetic copolymer, making the copolymer useful for crafting softer, flexible or less stiff plastics.

[0178] In various embodiments, Z1and Z2are each independently selected from CH2, O, NH, SiRaRb, PRaor S. The poly(norbornene) backbone may be selected from the group consisting of poly(norbornene-imide), poly(norbornene- dicarboximide), poly(5-norbornene-2,3-dicarboximide), poly(7-oxanorbornene), poly(oxanorbornene-imide), poly(oxanorbornene-dicarboximide) and the like. In various embodiments, Z1and Z2are each independently selected from CRaRb, O, NRC, SiRaRb, PRaor S, wherein Ra, Rb, and Rcare each independently selected from the group consisting of H, C1-C20 alkyl, C1-C20 alkenyl and C1-C20 alkynyl. In various embodiments, Z1is CH2. In various embodiments, Z2is CH2.

[0179] In various embodiments, one or more of H atoms in alkyl, alkenyl, alkynyl, alkoxyalkyl, alkylcarbonyl and alkylcarbonylalkyl is / are optionally replaced by hydroxy, hydroxyalkyl, halogen, haloalkyl, cyano, cyanoalkyl and nitro.

[0180] In various embodiments, the bioactive PLGA copolymer is a random polymer or a block copolymer. In some embodiments, the block polymer is a diblock or a triblock polymer. For example, the copolymer may have or is made up of two or three different polymer blocks. In some embodiments, the multi-block copolymer comprises more than three polymeric blocks. The blocks may be randomly distributed / arranged within the polymer.

[0181] In various embodiments, the bioactive PLGA copolymer comprises a brush, bottlebrush, block, comb or graft-copolymer structure. In various embodiments, the repeating units may be randomly distributed / arranged within the polymer.

[0182] In various embodiments, the bioactive PLGA copolymer has a number average molecular weight (Mn) of from about 1 ,000 to about 300,000, 2,000 to about 250,000, from about 3,000 to about 200,000, from about 4,000 to about 150,000, from about 5,000 to about 100,000, from about 10,000 to about 90,000, from about 20,000 to about 80,000, from about 30,000 to about 70,000, from about 40,000 to about 60,000, or about 50,000.

[0183] In various embodiments, the bioactive PLGA copolymer has a polydispersity index (PDI) of from about 1.0 to about 10.0. In various embodiments, PDI of the bioactive PLGA copolymer is about 1.0, about 1.5, about 2.0, about 2.5, about 3.0, about 3.5, about 4.0, about 4.5, about 5.0, about 5.5, about 6.0, about 6.5, about 7.0, about 7.5, about 8.0, about 8.5, about 9.0, about 9.5 or about 10.0. In various embodiments, the bioactive PLGA copolymer has a polydispersity index (PDI) of from about 1 .0 to about 3.0, from about 1 .05 to about 2.95, from about 1 .1 to about 2.9, from about 1 .2 to about 2.8, from about 1 .4 to about 2.6, from about 1 .6 to about 2.4, from about 1 .8 to about 2.2 or about 2.0. In various embodiments, the PDI of the bioactive PLGA copolymer is no more than 1 .50.

[0184] In various embodiments, the one or more repeating units represented by general formula (I) and the one or more repeating units represented by general formula (II) are designed to link to the poly(norbornene) backbone via at least covalent interactions. In various embodiments, each repeating unit represented by general formula (I) is covalently bonded to the poly(norbornene) backbone and / or each repeating unit represented by general formula (II) is covalently bonded to the poly(norbornene) backbone. Advantageously, as bioactive moieties (in general formula (II)) are covalently bonded to the bioactive PLGA copolymer, bioactivity is localized. In various embodiments, the bioactive moieties do not leach out from the polymer, therefore preventing undesirable / unwanted side effects caused by biomolecules entering the circulatory system and / or reaching unintended parts of the body system. Embodiments of the bioactive synthetic copolymer therefore overcome problems faced by conventional biomolecules that are administered as drugs which may metabolized prematurely before therapeutic effects are achieved. In various embodiments, the bioactive moieties such as drug molecules do not leach out into media which can escape into the environment in the event that disposal is improperly managed. Accordingly, in various embodiments, the bioactive material used in the composite structure is distinguished from materials that are merely blended (e.g., PCL and chitosan blended during electrospinning and are not chemically linked).

[0185] It will be appreciated that other interactions such as Van der Waals interactions may also be present within the copolymer.

[0186] In various embodiments, the bioactive PLGA copolymer is selected from one of the following: PLGA-RGD copolymer comprising RGD in general formula (II) (Scheme 1), PLGA-HA copolymer comprising HA in general formula (II) (Scheme 2), PLGA-IKVAV copolymer comprising IKVAV in general formula (II), and PLGA-LKKLCRILKKLCRI copolymer comprising LKKLCRILKKLCRI in general formula (II)

[0187]

[0188] Scheme 1. Chemical structure of an example of PLGA-RGD copolymer.

[0189] 5

[0190]

[0191] Scheme 2. Chemical structure of an example of PLGA-HA copolymer.

[0192] In various embodiments, x > 1. In various embodiments, x is 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24,25, 26, 27, 28,

[0193] 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49,

[0194] 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70,

[0195] 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91,

[0196] 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125,

[0197] 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141,

[0198] 142, 143, 144, 145, 146, 147, 148, 149 or 150. In various embodiments, y > 1. In various embodiments, y is 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17,

[0199] 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59,

[0200] 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80,

[0201] 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141 , 142, 143, 144, 145, 146, 147, 148, 149 or 150. In various embodiments, n > 1 . In various embodiments, n is 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 , 12, 13, 14, 15, 16, 17, 18, 19, 20, 21 , 22, 23, 24, 25, 26, 27, 28, 29, 30, 31 , 32, 33, 34, 35, 36, 37, 38, 39, 40, 41 , 42, 43, 44, 45, 46, 47, 48, 49,

[0202] 50, 51 , 52, 53, 54, 55, 56, 57, 58, 59, 60, 61 , 62, 63, 64, 65, 66, 67, 68, 69, 70,

[0203] 71 , 72, 73, 74, 75, 76, 77, 78, 79, 80, 81 , 82, 83, 84, 85, 86, 87, 88, 89, 90, 91 ,

[0204] 92, 93, 94, 95, 96, 97, 98, 99, 100, 101 , 102, 103, 104, 105, 106, 107, 108, 109,

[0205] 110, 111 , 112, 113, 114, 115, 116, 117, 118, 119, 120, 121 , 122, 123, 124, 125, 126, 127, 128, 129, 130, 131 , 132, 133, 134, 135, 136, 137, 138, 139, 140, 141 , 142, 143, 144, 145, 146, 147, 148, 149 or 150.

[0206] Advantageously, the bioactive PLGA copolymer disclosed herein is highly customizable. Depending on the application that the bioactive PLGA copolymer is intended, X with the desired biological activity may be selected to match the synthetic polymer PLGA, to eventually obtain the bioactive PLGA copolymer with the desired repeating units represented by general formulae (I) and (II). For example, PLGA-IKVAV is intended to promote angiogenesis whereas PLGA- LKKLCRILKKLCRI is intended for antimicrobial applications (e.g., infection management).

[0207] In various embodiments, the bioactive material comprises a bioactive synthetic copolymer with a poly(norbornene) backbone having one or more properties or features disclosed in PCT / SG2020 / 050621 , PCT / SG2023 / 050288 and PCT / SG2024 / 050107, the contents of which are fully incorporated herein.

[0208] COMPRESSIBLE SUBSTRATE

[0209] In various embodiments, the compressible substrate is a porous substrate. In various embodiments, the compressible substrate is a foam. Advantageously, in various embodiments, the foam substrate is highly absorbent and suitable for use forexudating wounds (such as burns, lacerations, abrasions, skin graft donor sites, diabetic foot ulcers, pressure ulcers, or venous ulcers) to maintain dryness of wound bed for infection prevention. The substrate is suitable for use on acute, chronic, abrasions, partial and full thickness skin injuries, or the like. In various embodiments, the compressible substrate is an adhesive or non-adhesive foam pad. In various embodiments, it will be appreciated that the compressible substrate disclosed herein is soft and is different from hard substrates such as Styrofoam.

[0210] In various embodiments, the compressible substrate comprises / consists essentially of / consists of polyurethane (PU). In various embodiments, the compressible substrate is optionally coated with silicone. In various embodiments, the compressible substrate comprises silicone-coated PU.

[0211] In various embodiments, the bioactive material impregnates / infiltrates at least part of the porous substrate.

[0212] In various embodiments, the compressible substrate has a uncompressed thickness of from about 1 mm to about 10 mm, from about 1.5 mm to about 9.5 mm, from about 2 mm to about 9 mm, from about 2.5 mm to about 8.5 mm, from about 3 mm to about 8 mm, from about 3.5 mm to about 7.5 mm, from about 4 mm to about 7 mm, from about 4.5 mm to about 6.5 mm, from about 5 mm to about 6 mm, or about 5.5 mm.

[0213] In various embodiments, the compressible substrate has a compressed thickness of from about 0.1 mm to about 10 mm, from about 0.1 mm to about 9 mm, from about 0.1 mm to about 8 mm, from about 0.1 mm to about 7 mm, from about 0.1 mm to about 6 mm, from about 0.1 mm to about 5 mm, from about 0.1 mm to about 4 mm, from about 0.1 mm to about 3 mm, from about 0.1 mm to about 2 mm, from about 0.1 mm to about 1 mm, from about 0.1 mm to about 0.5 mm, from about 0.2 mm to about 0.4 mm, or about 0.3 mm.

[0214] In various embodiments, the compressible substrate is capable of being compressed to less than about 50 %, less than about 48 %, less than about 46 %, less than about 44 %, less than about 42 %, less than about 40 %, less than about 38 %, less than about 36 %, less than about 34 %, less than about 32 %, less than about 30 %, less than about 28 %, less than about 26 %, less than about 24 %, less than about 22 %, less than about 20 %, less than about 18 %, less than about 16 %, less than about 14 %, less than about 12 %, or less than about 10 % of its original thickness.

[0215] METHOD OF PREPARING COMPOSITE STRUCTURE

[0216] There is provided a method of preparing a composite structure as disclosed herein, the method comprising providing a compressible substrate; and disposing a bioactive material on said compressible substrate. In various embodiments, the disposing step is carried out by three-dimensionally (3D) printing of the bioactive material onto the compressible substrate with a 3D printing system. Advantageously, 3D printing allows incorporation of complex structures into products, thereby facilitating the creation of target-specific solutions.

[0217] In various embodiments, the 3D printing step comprises a fused filament fabrication (FFF) printing method / technique or a fused deposition modelling (FDM) printing method / technique. Advantageously, due to the simplicity, ease of use of these techniques, and compatibility of these techniques with a wide material portfolio, these techniques can be easily adopted across a large user base, including industry professionals, researchers, and hobbyists. These techniques require materials to be in filament form, which are fed into a heated nozzle and extruded as molten material onto a substrate along the x-y plane, while increasing the layer height in the z-direction to form the final 3D-printed object. The type of substrate used these techniques is of great significance as it determines the material adhesion strength during the printing process, which in turn directly affects the quality of the 3D-printed object. Furthermore, the wide compatible material portfolio offered by these printing techniques enables the possibility of utilising functional materials such as bioresorbable polymers as mentioned above, thereby widening the range of its applications to areas including tissue engineering, drug delivery, and implants.

[0218] It will be appreciated that the disposing method (e.g., 3D printing) disclosed herein is different from electrospinning of any material (e.g., polycaprolactone (PCL)) on a substrate (e g., a foam). Furthermore, the disposing of the bioactive material on the compressible substrate (soft substrate) disclosed herein (e.g., 3D printing) is different from disposing a material on a hard substrate (substantially non-compressible substrate) such as a Styrofoam as an entirely different set of considerations need to be taken account.

[0219] In various embodiments, the compressible substrate is provided on a support (e.g., active plate) having a cut-out / recess / depression that is substantially complementary or substantially fits / houses the compressible substrate. In various embodiments, the compressible substrate is disposed / fitted / housed in the cut-out / recess / depression of the support, the exposed top surface of the compressible substrate and the exposed top surface of the support form a substantially flat plane (e.g., are on substantially the same plane). In various embodiments, one or more spacers may be placed between the bottom surface of the compressible substrate and the top surface of the cut- out / recess / depression of the support so that the exposed top surface of the compressible substrate and the exposed top surface of the support form a substantially flat plane (e.g., are on substantially the same plane). In various embodiments, advantageously, the support (e.g., active plate) acts as a holder for the compressible substrate, preventing any movement during the printing process.

[0220] In various embodiments, the bioactive material is printed with a print nozzle having a diameter falling in the range of from about 0.1 mm to about 1 mm, from about 0.1 mm to about 0.95 mm, from about 0.1 mm to about 0.9 mm, from about 0.1 mm to about 0.85 mm, from about 0.1 mm to about 0.8 mm, from about 0.1 mm to about 0.75 mm, from about 0.1 mm to about 0.7 mm, from about 0.1 mm to about 0.65 mm, from about 0.1 mm to about 0.6 mm, from about 0.1 mm to about 0.55 mm, from about 0.1 mm to about 0.5 mm, from about 0.1 mm to about 0.45 mm, from about 0.1 mm to about 0.4 mm, from about 0.1 mm to about 0.35 mm, from about 0.1 mm to about 0.3 mm, from about 0.1 mm to about 0.25 mm, from about 0.1 mm to about 0.2 mm, or about 0.25 mm. In various embodiments, the print nozzle would be slightly embedded into the compressible substrate during printing to ensure the molten bioactive material deposited is adhered onto it.

[0221] In various embodiments, the bioactive material is printed with a line width in the range of from about 70 % to about 100 %, from about 72 % to about 98 %, from about 74 % to about 96 %, from about 76 % to about 94 %, from about 78 % to about 92 %, from about 80 % to about 90 %, from about 82 % to about 88 %, from about 84 % to about 86 %, or about 85 % of the diameters of the print nozzles.

[0222] In various embodiments, the print temperature is in the range of from about 130 °C to about 200 °C, from about 135 °C to about 195 °C, from about 140 °C to about 190 °C, from about 145 °C to about 185 °C, from about 150 °C to about 180 °C, from about 155 °C to about 175 °C, from about 160 °C to about 170 °C, or about 165 °C. In various embodiments, the melt flow of the bioactive material (e.g., a thermoplastic polymer like bioactive PLGA) increases as temperature increases. However, too much or too little flow would result in over- or underextrusion respectively which affects print quality. It will be appreciated that, in various embodiments, appropriate control of the print temperature prevents any material oozing from occurring, which may otherwise disrupt the printing process or result in material blobs being deposited on the print area, affecting the print quality.

[0223] In various embodiments, the bioactive material is printed with a print speed in the range of from about 1 mm / s to about 20 mm / s, from about 2 mm / s to about 19 mm / s, from about 3 mm / s to about 18 mm / s, from about 4 mm / s to about 17 mm / s, from about 5 mm / s to about 16 mm / s, from about 6 mm / s to about 15 mm / s, from about 7 mm / s to about 14 mm / s, from about 8 mm / s to about 13 mm / s, from about 9 mm / s to about 12 mm / s, from about 10 mm / s to about 11 mm / s, or about 10.5 mm / s. It will be appreciated that, in various embodiments, the print speed primarily plays a role in regulating the deposition of a sufficient volume of material at a moderate flow rate, thereby minimizing the risk of over- or under-extrusion and preventing poor print quality.

[0224] It will be appreciated that the print temperature and print speed as disclosed above work together to ensure excellent material flow and sufficient adhesion between compressible substrate (e.g., foam) and the 3D-printed bioactive material (e.g., PLGA).

[0225] In various embodiments, the bioactive material is printed with a layer height in the range of from about 0.01 mm to about 0.3 mm, from about 0.02 mm to about 0.29 mm, from about 0.03 mm to about 0.28 mm, from about 0.04 mm to about 0.27 mm, from about 0.05 mm to about 0.26 mm, from about 0.06 mm to about 0.25 mm, from about 0.07 mm to about 0.24 mm, from about 0.08 mm to about 0.23 mm, from about 0.09 mm to about 0.22 mm, from about 0.1 mm to about 0.21 mm, from about 0.11 mm to about 0.2 mm, from about 0.12 mm to about 0.19 mm, from about 0.13 mm to about 0.18 mm, from about 0.14 mm to about 0.17 mm, from about 0.15 mm to about 0.16 mm, or about 0.155 mm.

[0226] In various embodiments, the bioactive material is printed with a speed of the cooling fan in the range of from about 5 % to about 100 %, from about 10 % to about 95 %, from about 15 % to about 90 %, from about 20 % to about 85 %, from about 25 % to about 80 %, from about 30 % to about 75 %, from about 35 % to about 70 %, from about 40 % to about 65 %, from about 45 % to about 60 %, from about 50 % to about 55 %, or about 52.5 % of the maximum speed, from about 10 RPM to about 300 RPM, from about 20 RPM to about 290 RPM, from about 30 RPM to about 280 RPM, from about 40 RPM to about 270 RPM, from about 50 RPM to about 260 RPM, from about 60 RPM to about 250 RPM, from about 70 RPM to about 240 RPM, from about 80 RPM to about 230 RPM, from about 90 RPM to about 220 RPM, from about 100 RPM to about 210 RPM, from about 110 RPM to about 200 RPM, from about 120 RPM to about 190 RPM, from about 130 RPM to about 180 RPM, from about 140 RPM to about 170 RPM, from about 150 RPM to about 160 RPM, or about 155 RPM. In various embodiments, 100 % of the maximum fan speed is 255 RPM, 5 % of the maximum fan speed is 12.75 RPM, and 90 % of the maximum fan speed is 229.5 RPM.

[0227] In various embodiments, the bioactive material is printed with a wall line count in the range of from about 1 to about 5, from about 2 to about 5, from about 2 to about 4, or about 3.

[0228] In various embodiments, the method does not have an initial layer horizontal expansion. In various embodiments, the method comprises a step of deliberately setting the “initial layer horizontal expansion” parameter to 0 mm as the slicer software may otherwise apply a value by default.

[0229] In various embodiments, there is bed adhesion in the 3D printing process, and the bed adhesion type is skirt, brim, raft, the like, or combinations thereof. In various embodiments, there is substantially no bed adhesion in the 3D printing process.

[0230] In various embodiments, the bioactive material may be printed in any infill pattern or shape and size as desired in order to suit a particular application. In various embodiments, the infill pattern may be triangular, grid, lines, the like, or combinations thereof.

[0231] In various embodiments, the bioactive material is printed with an infill density in the range of from about 30 % to about 90 %, from about 32 % to about 88 %, from about 34 % to about 86 %, from about 36 % to about 84 %, from about 38 % to about 82 %, from about 40 % to about 80 %, from about 42 % to about 78 %, from about 44 % to about 76 %, from about 46 % to about 74 %, from about 48 % to about 72 %, from about 50 % to about 70 %, from about 52 % to about

[0232] 68 %, from about 54 % to about 66 %, from about 56 % to about 64 %, from about 58 % to about 62 %, or about 60 %.

[0233] In various embodiments, the parameter “number of top layer’’ is set to zero. In various embodiments, it will be appreciated that the parameter “number of top layer” should be set to zero otherwise the printed product may have one or more solid filled layer(s) instead of a porous layer with an infill density as disclosed above.

[0234] In various embodiments, the parameter “number of bottom layer” is set to zero. In various embodiments, it will be appreciated that the parameter “number of bottom layer” should be set to zero otherwise the printed product may have one or more solid filled layer(s) instead of a porous layer with an infill density as disclosed above.

[0235] In various embodiments, the bioactive material is printed with an infill overlap in the range of from about 0.01 mm to about 1 mm, from about 0.05 mm to about 0.95 mm, from about 0.1 mm to about 0.9 mm, from about 0.1 mm to about 0.85 mm, from about 0.1 mm to about 0.8 mm, from about 0.1 mm to about 0.75 mm, from about 0.1 mm to about 0.7 mm, from about 0.1 mm to about 0.65 mm, from about 0.1 mm to about 0.6 mm, from about 0.1 mm to about 0.55 mm, from about 0.1 mm to about 0.5 mm, from about 0.1 mm to about 0.45 mm, from about 0.1 mm to about 0.4 mm, from about 0.1 mm to about 0.35 mm, from about 0.1 mm to about 0.3 mm, from about 0.1 mm to about 0.25 mm, from about 0.1 mm to about 0.2 mm, or about 0.15 mm.

[0236] In various embodiments, the method further comprises using a non- compressible reference substrate in lieu of the compressible substrate to level / configure the distance between print nozzles of the 3D printing system and the substrate, prior to 3D printing. In various embodiments, the non-compressible reference substrate may be used during the bed / build plate levelling procedure prior to the start of printing process for the printing system to identify the zero point on the Z-axis. In various embodiments, the non-com pressible reference substrate comprises a reference plate, which may be entirely swapped out to be replaced with a support plate containing / housing the compressible substrate. In other embodiments, the non-compressible reference comprises a sample reference substrate that may be used to replace the compressible substrate housed on the support plate. In other words, during levelling, the sample reference substrate instead of the compressible substrate, is housed on the support plate for levelling and is only replaced with the compressible substrate after levelling is completed and deposition of the bioactive material on the compressible substrate is about to begin.

[0237] In various embodiments, the support / support plate comprises a cut- out / recess / depression. In various embodiments, when the support / support plate is fitted with a 3D printing system and the compressible substrate is disposed / fitted / housed in the cut-out / recess / depression of the support, the exposed top surface of the compressible substrate is at substantially the same Z level (i.e., vertical distance with respect to the ground) as a reference substrate / reference plate used for a levelling procedure (e.g., auto-levelling procedure) of the 3D printing process.

[0238] In various embodiments, the method comprises use of both a reference substrate / reference plate and an active plate (e g., the support plate) as a workaround to the mandatory auto-levelling / configuring feature of the 3D printing process, thereby enabling the use of a compressible substrate (e.g., foam) without compromising print quality. It will be appreciated that the use of both a reference substrate (e.g., a reference plate) and a support (e.g., an active plate) allows a compressible substrate (e.g., foam) to be printed using the FFF method. In various embodiments, both reference substrate and support are of substantially the same thickness with minimal deviation to ensure no significant difference to layer height accuracy when swapped later. It will be appreciated that a person skilled in the art may not easily conceive the methodology as described in accordance with various embodiments disclosed herein since using a soft / compressible substrate with FFF printing is non-existent or rare due to the nature of the FFF printer hardware. In various embodiments, FFF printers would perform build plate / bed levelling using the nozzle through its embedded capacitive sensor over multiple points across the build plate area. Hence, using a soft / compressible substrate such as a foam substrate would disable the FFF printer from performing the levelling procedure which risks the layer height accuracy of the printing process. It will also be appreciated that, while certain FFF printers may offer auto-levelling procedure bypass, it is still not easy to adapt these printers to arrive at the methodology as described in accordance with various embodiments disclosed herein in an obvious manner. This is because there is no suggestion that, firstly, the soft / compressible substrate (e.g., a foam substrate) should be held inside the support (e.g., an active plate) to prevent movements, ensuring accuracy with respect to the coordinate system of the FFF printer; and secondly, specific FFF print parameters may be needed for printing bioactive material (e.g., PLGA) on the soft / compressible substrate (e.g., a foam substrate).

[0239] It will be appreciated that references to electrospinning also do not render embodiments disclosed herein obvious, as electrospinning is a totally different method that creates totally different types of surfaces. It will also be appreciated that, even if electrospinning on compressible dressings (e.g., foam) is achievable, it does not automatically follow that 3D printing on a compressible dressing is easily possible. It will also be appreciated that a person skilled in the art would not even consider using a compressible substrate as a build plate for an FFF printing process as the FFF printer’s auto-levelling procedure, which relies on feedback from the nozzle via an embedded capacitive sensor, naturally prevents the use of compressible substrates. Without the benefit of the methodology as described in accordance with various embodiments herein, errors will occur prior to the start of the printing process. Furthermore, if the printing somehow proceeds with material deposition, it will likely result in a failed print due to nozzle embedment within the foam substrate, causing damage from the nozzle shearing the foam.

[0240] Similarly, it will be appreciated that any suggestion and demonstration of 3D printing on compressible substrates (e.g., foam) amongst other materials may likewise not be sufficient to render embodiments disclosed herein obvious. This is because known 3D printing techniques require preparation of the first layer to make it adhesive for subsequent layers (e.g., ethylene-vinyl acetate (EVA) coating) and employ a rotary positional coordinate system as opposed to the cartesian coordinate system used in accordance with various embodiments disclosed herein.

[0241] In various embodiments, the step of levelling / configuring the distance between print nozzles of the 3D printing system comprises setting a Z-offset (i.e. , distance between the nozzle to the substrate) to a suitable value. In various embodiments, it will be appreciated that the maximum positive Z-offset value (i.e., greater than 0 mm) may be any feasible value within the 3D printer’s maximum allowable printing height, wherein a positive value moves the nozzle away from the compressible substrate while a negative value moves the nozzle closer to the compressible substrate. In various embodiments, the Z-offset is set to a value that falls in the range of between about -0.5 mm to about 5 mm, about -0.45 mm to about 4.5 mm, about -0.4 mm to about 4 mm, about -0.35 mm to about 3.5 mm, about -0.3 mm to about 3 mm, about -0.25 mm to about 2.5 mm, about -0.2 mm to about 2 mm, about -0.15 mm to about 1.5 mm, about -0.1 mm to about 1 mm, about -0.05 mm to about 0.5 mm, about 0 mm to about 0.25 mm, about 0.05 mm to about 0.2 mm, about O.1 mm to about 0.2 mm, or about 0.15 mm. In various embodiments, the Z-offset value affects the thickness of the plates (e.g., the active plate and reference plate) used in the 3D printing process, which in turn affects the thickness of the compressible substrate that can be accommodated. In various embodiments, the thicknesses of the active and reference plates are selected to match that of the standard glass build plate used in 3D printing. Advantageously, this approach allows for the use of widely available, easy-to- source, and cost-effective plates. For example, when a 4-mm plate is used and the Z-offset parameter of the printer preferably ranges from about -0.35 mm to about 2 mm, the compatible foam thickness preferably ranges from about 3.65 mm to about 6 mm. In various embodiments, foam substrates with a thickness outside this range may require alternative active and reference plates of suitable thickness to ensure proper alignment with the 3D printer’s Z-offset limitations. In various embodiments, the maximum positive Z-offset value may be any feasible value within the 3D printer’s maximum allowable printing height, though in the provided example, a maximum Z-offset of 2 mm was chosen when using a 4-mm plate, as larger Z-offsets may negatively affect the nozzle's printing precision in terms of its planar accuracy, resulting in poor print quality. In various embodiments, the maximum compatible foam thickness may be any physically feasible value within the 3D printer’s maximum allowable printing height, while the minimum thickness is set to be 0.35 mm less than the thickness of the reference plate used. In various embodiments, the method comprises selecting the thickness of one or more plates (e.g., an active plate and a reference plate) based on the Z-offset parameter of the 3D printer, such that the combined height of the plate and a compressible substrate falls within a permissible Z-offset range. In various embodiments, the thickness of the substrate depends on the Z-offset tolerance of the 3D printer. For example, if the nozzle can tolerate a maximum Z- offset distance of 1 mm away from the substrate, then the maximum allowable substrate thickness may be ((thickness of the printing bed / reference plate / active plate) + 1 mm). Similarly, if the nozzle can tolerate a maximum Z-offset distance of 1 mm towards the substrate, then the maximum allowable substrate thickness may be ((thickness of the printing bed / reference plate / active plate) - 1 mm).

[0242] In various embodiments, the method further comprises swapping / replacing the reference substrate / reference plate after levelling / configuration of the distance between print nozzles of the 3D printing system has been completed with the non-compressible reference substrate with the support (e.g., active plate) having a cut-out / recess / depression that is substantially complementary or substantially fits / houses the compressible substrate. In various embodiments, the non-compressible reference substrate is a reference plate, which may be entirely swapped out to be replaced with a support plate containing / housing the compressible substrate in its cut- out / recess / depression. In other embodiments, the non-compressible reference comprises a sample reference substrate that may be used to replace the compressible substrate housed in cut-out / recess / depression of the support plate. In other words, during levelling, the sample reference substrate instead of the compressible substrate, is housed in the cut-out / recess / depression of the support plate for levelling and is replaced with the compressible substrate in the cut- out / recess / depression of the support plate after levelling is completed and when deposition of the bioactive material on the compressible substrate is about to begin. In various embodiments, the 3D printing process is temporarily paused / stopped to allow swapping / replacement of the non-compressible reference substrate with the support / support plate before the bioactive material is extruded from the print nozzles and deposited on the compressible substrate. In various embodiments, the support comprises the compressible substrate prior to extruding the bioactive material. The method may comprise additionally disposing / fitting / housing the non-compressible reference substrate in the cut- out / recess / depression of the support / support plate, removing the non- compressible reference substrate from the cut-out / recess / depression of the support / support plate, and / or disposing / fitting / housing the compressible substrate in the cut-out / recess / depression of the support.

[0243] In various embodiments, the method comprises use of a post-processing script to introduce a pause during the printing process before material deposition starts, enabling a swap of the reference substrate (e.g., reference plate) to the compressible substrate and / or support (e.g., active plate). It will be appreciated that, with this script, the compressible substrate may advantageously be easily inserted into the printing area since the printer will not continue with the printing process like it normally would. In various embodiments, the 3D printing techniques employed herein may also include one or more features of the 3D printing techniques disclosed in PCT / SG2022 / 050620 and PCT / SG2024 / 050107, the contents of which are fully incorporated herein.

[0244] In various embodiments, the method further comprises, prior to step (i), the method of preparing the bioactive material and thus may comprise one or more steps of the method disclosed in PCT / SG2020 / 050621 and PCT / SG2023 / 050288, the contents of which are fully incorporated herein. In various embodiments, the method of preparing the bioactive material comprises a step of ring-opening metathesis polymerization (ROMP).

[0245] In various embodiments, the method further comprises, prior to step (ii), the method of producing filaments of the bioactive material and thus may comprise one or more steps of the filament producing method disclosed in PCT / SG2022 / 050620 and PCT / SG2024 / 050107, the contents of which are fully incorporated herein.

[0246] In various embodiments, the method of producing filaments of the bioactive material comprises:

[0247] (i-a) providing a base PLGA powder and a bioactive PLGA copolymer;

[0248] (i-b) mixing / blending the base PLGA powder with the bioactive PLGA copolymer to obtain a bioactive PLGA formulation / mixture / blend; and

[0249] (i-c) extruding a bioactive PLGA filament from the formulation / mixture / blend.

[0250] In various embodiments, the step of 3D printing a bioactive material from the bioactive PLGA filament onto a compressible substrate comprises: (ii-a) feeding the bioactive PLGA filament into a printing apparatus;

[0251] (ii-b) applying heat to the bioactive PLGA filament to obtain a molten form of the bioactive PLGA; and

[0252] (ii-c) depositing the molten bioactive PLGA on a print bed to form a printed part or structure. Accordingly, there is also provided a FFF or FDM based three-dimensional printing method using the bioactive polymer filament disclosed herein as a feedstock. In various embodiments, the method comprises feeding a bioactive polymer filament disclosed herein into a FFF or FDM based three-dimensional printing apparatus (e g., fed to the print head of the apparatus); applying heat to bioactive polymer filament to obtain a molten / melted form of the bioactive polymer; and depositing the molten / melted bioactive polymer on a print bed to form a printed three-dimensional part or structure. Advantageously, FFF or FDM 3D printing / printers have great advantages such as low cost, shortened time to market and part customisation which are significantly beneficial for medical technology.

[0253] In various embodiments, 3D printing the bioactive material on the compressible substrate comprises extruding flowable bioactive material onto the compressible substrate such that at least part of the bioactive material impregnates the compressible substrate.

[0254] In various embodiments, the extruding step is performed using an extruder having one or more rotating screws. In various embodiments, the screw speed is in the range of from about 10 RPM to about 400 RPM, from about 20 RPM to about 380 RPM, from about 40 RPM to about 360 RPM, from about 60 RPM to about 340 RPM, from about 80 RPM to about 320 RPM, from about 100 RPM to about 300 RPM, from about 120 RPM to about 280 RPM, from about 140 RPM to about 260 RPM, from about 160 RPM to about 260 RPM, from about 160 RPM to about 240 RPM, from about 160 RPM to about 220 RPM, from about 160 RPM to about 200 RPM, from about 180 RPM to about 200 RPM, or about 190 RPM.

[0255] In various embodiments, the extruding step which is performed using an extruder having a melt pump. In various embodiments, the melt pump speed is in the range of from about 3 RPM to about 10 RPM, from about 3.5 RPM to about 9.5 RPM, from about 4 RPM to about 9 RPM, from about 4.5 RPM to about 8.5 RPM, from about 4.5 RPM to about 8 RPM, from about 4.5 RPM to about 7.5

[0256] RPM, from about 4.5 RPM to about 7 RPM, from about 4.5 RPM to about 6.5

[0257] RPM, from about 4.5 RPM to about 6 RPM, from about 4.5 RPM to about 5.5

[0258] RPM, from about 4.5 RPM to about 5 RPM, or about 4.75 RPM.

[0259] In various embodiments, the extruding step which is performed using an extruder having a spool. In various embodiments, the spool speed is in the range of from about 0.1 mm / min to about 1 mm / min, from about 0.2 mm / min to about 0.9 mm / min, from about 0.3 mm / min to about 0.8 mm / min, from about 0.4 mm / min to about 0.7 mm / min, from about 0.5 mm / min to about 0.6 mm / min, or about 0.55 mm / min.

[0260] In various embodiments, the bioactive material is printed with an extrusion flow in the range of from about 100 % to about 130 %, from about 101 % to about 129 %, from about 102 % to about 128 %, from about 103 % to about 127 %, from about 104 % to about 126 %, from about 105 % to about 125 %, from about 106 % to about 124 %, from about 107 % to about 123 %, from about 108 % to about 122 %, from about 109 % to about 121 %, from about 110 % to about 120 %, from about 111 % to about 119 %, from about 112 % to about 118 %, from about 113 % to about 117 %, from about 114 % to about 116 %, or about 115 %.

[0261] In various embodiments, feeding step (ii-a) comprises feeding the bioactive material into the extruder. In various embodiments, the feed rate is in the range of from about 5 % to about 30 %, from about 6 % to about 29 %, from about 7 % to about 28 %, from about 8 % to about 27 %, from about 9 % to about 26 %, from about 10 % to about 25 %, from about 11 % to about 24 %, from about 12 % to about 23 %, from about 13 % to about 22 %, from about 14 % to about 21 %, from about 15 % to about 20 %, from about 16 % to about 19 %, from about 17 % to about 18 %, or about 17.5 %.

[0262] In various embodiments, heating step (ii-b) comprises heating the bioactive PLGA filament at an extrusion temperature profile based on a predetermined melt / softening temperature and a predetermined onset degradation temperature of the bioactive material. In various embodiments, the heating zone temperature is in the range of from about 50 °C to about 200 °C, from about 60 °C to about 190 °C, from about 70 °C to about 180 °C, from about 80 °C to about 170 °C, from about 90 °C to about 160 °C, from about 100 °C to about 150 °C, from about 110 °C to about 140 °C, from about 120 °C to about 130 °C, or about 125 °C. In various embodiments, the flowable bioactive material is extruded at a temperature falling in the range of the heating zone temperature as disclosed above.

[0263] In various embodiments, the method further comprises solidifying the flowable bioactive material to anchor the bioactive material to the compressible substrate. In various embodiments, the solidifying step comprises cooling down / lower the temperature of the molten extruded bioactive material. In various embodiments, the bioactive material (e.g., PLGA) and the compressible substrate (e.g., a foam substrate) adhere thermally, whereby the molten bioactive material clings on the porous structure of the compressible substrate and subsequently cools down to create adhesion between the two materials. In various embodiments, the cooling medium is compressed air or water. In various embodiments, the compressible substrate and the bioactive material are structurally integrated in the composite structure.

[0264] In various embodiments, the method comprises configuring / designing / custom izing / optimizing one or more of the following parameters: print temperature; fan cooling speed; retraction speed; and retraction distance, to reduce material oozing. In various embodiments, the method comprises designing / customizing / optimizing one or more of the following parameters: printing speeds and post-processing scripts, to prevent over-extrusion. In various embodiments, the method comprises configuring / designing / customizing / optimizing one or more of the following parameters: layer height and line width, to ensure precise printing. RELATED METHODS / USES OF COMPOSITE STRUCTURE

[0265] There is provided a composite structure as disclosed herein for use as a skin patch, wound dressing, bandage, temporary wound coverage, wound care, personal care, and / or beauty product.

[0266] There is provided a composite structure as disclosed herein for use in medicine. In various embodiments, the composite structure as disclosed herein is a composite structure for use in promoting / stimulating wound healing / regeneration / regrowth / repair / closure / treatment / angiogenesis / infection management and / or providing antibacterial effects. In various embodiments, the wound is an ulcerative wound (e.g., diabetic foot ulcers, pressure ulcers, or venous ulcers), partial or full thickness burn wound, skin graft donor site, abrasion, laceration, or the like. In various embodiments, the composite structure as disclosed herein is a composite structure for use in preventing / reducing or lowering risk of scarring / scar formation of an ulcerative wound (e g., diabetic foot ulcers, pressure ulcers, or venous ulcers), bum wound, laceration or abrasion wound, skin graft donor site, or the like. The substrate is suitable for use on acute, chronic, abrasions, partial or full thickness skin injuries, or the like. Advantageously, in various embodiments, the composite structure is capable of preventing / reducing scarring / scar formation of a wound without substantially causing breakage in or injury to the skin. In various embodiments, the composite structure as disclosed herein is a composite structure for use in the prophylaxis or treatment of an ulcerative wound (e.g., diabetic foot ulcers, pressure ulcers, or venous ulcers), full or partial thickness burn wound, laceration, abrasion, skin graft donor site, or the like. The substrate is suitable for use on acute, chronic, abrasions, partial and full thickness skin injuries. In various embodiments, the composite structure as disclosed herein is a composite structure for use in wound infection management.

[0267] There is provided use of a composite structure as disclosed herein in the manufacture of a medicament for promoting / stimulating wound healing / regeneration / regrowth / repair / closure / treatment / angiogenesis / infection management of and / or providing antibacterial effects to an excisional wound, ulcerative wounds (e.g., diabetic foot ulcers, pressure ulcers, or venous ulcers), burn wound, trauma wounds (e g., abrasions, lacerations), skin graft donor sites, or the like. The foam substrate helps to absorb wound exudates whilst the bioactive PLGA layer promotes skin regeneration. In various embodiments, there is also provided use of a composite structure as disclosed herein in the manufacture of a medicament for infection management of an ulcerative wound (e.g., diabetic foot ulcers, pressure ulcers, or venous ulcers), burn wound, or the like. In various embodiments, there is also provided use of a composite structure as disclosed herein in the manufacture of a medicament for the prophylaxis or treatment of an ulcerative wound (e.g., diabetic foot ulcers, pressure ulcers, or venous ulcers), burn wound, trauma wound, skin graft donor site, or the like. The substrate is suitable for use on acute, chronic, abrasions, partial or full thickness skin injuries, or the like.

[0268] There is provided a method of promoting / stimulating wound healing / regeneration / regrowth / repair / closure / treatment / angiogenesis / infection management of a wound and / or providing antibacterial effects to a wound. The wound may be an excisional wound, ulcerative wounds (e.g. , diabetic foot ulcers, pressure ulcers or venous ulcers), burn wound, trauma wounds, skin graft donor site, or the like. In various embodiments, the method further comprises evaluating one or more wound characteristic(s); determining a treatment needed; three- dimensionally printing a bioactive material that is / are responsive to the treatment needed onto a compressible substrate to form a composite structure; preparing and / or administering / applying said composite structure to the wound. In various embodiments, there is also provided a method of preventing / reducing or lowering risk of infection of a wound. The wound may be an ulcerative wound (e.g., diabetic foot ulcers, pressure ulcers or venous ulcers), burn wound, trauma wound, skin graft donor site, or the like. The wound may be acute, chronic, abrasions, partial or full thickness skin injuries, or the like. In various embodiments, the method further comprises evaluating one or more wound characteristic(s); determining a treatment needed; three-dimensionally printing a bioactive material that is / are responsive to the treatment needed onto a compressible substrate to form a composite structure; preparing and / or administering / applying said composite structure to the wound. In various embodiments, there is also provided a method of treating and / or reducing inflammation of a wound, the method comprising administering / applying the composite structure disclosed herein to the wound. The wound may be an ulcerative wound (e g., diabetic foot ulcers, pressure ulcers, or venous ulcers), bum wound, trauma wound, skin graft donor site, or the like. The wound may be acute, chronic, abrasions, partial or full thickness skin injuries, or the like. In various embodiments, the method further comprises evaluating one or more wound characteristic(s); determining a treatment needed; three-dimensionally printing a bioactive material that is / are responsive to the treatment needed onto a compressible substrate to form a composite structure; preparing and / or administering / applying said composite structure to the wound.

[0269] BRIEF DESCRIPTION OF FIGURES

[0270] FIG. 1 shows the cell viability of the cells treated with commercial Allevyn and Acticoat wound dressings at the 24- and 48-hour time points, as determined by cytotoxicity testing carried out.

[0271] FIG. 2 shows the cell viability of the cells treated with commercial Allevyn and Acticoat wound dressings compared to untreated cells, as determined by biocompatibility testing carried out.

[0272] FIG. 3A shows the original equipment manufacturer (OEM) polyurethane (PU) adhesive foam pad with an uncompressed thickness of 3 mm and a total compressed thickness below 1 mm. FIG. 3B shows OEM PU non-adhesive foam pad A with an uncompressed thickness of 5 mm and a total compressed thickness of 2 mm. FIG. 3C shows OEM PU non-adhesive foam pad B with an uncompressed thickness of 4 mm and a total compressed thickness of 1 mm. These PU foam pads were used as the substrate in the three-dimensional (3D) printing process to print poly(lactic-co-glycolic acid) (PLGA) onto the substrates in accordance with various embodiments disclosed herein.

[0273] FIG. 4 shows the images illustrating the progression of in vivo porcine wound healing observed on Days 0, 3, 7, 14, and 21 , comparing bioactive foam dressings comprising 5 wt% PLGA-RGD and 5 wt% PLGA-HA, each 3D-printed onto OEM PU foam substrates sourced from medical foam manufacturers, in accordance with various embodiments disclosed herein.

[0274] FIG. 5 shows the images illustrating the progression of in vivo porcine wound healing observed on Days 0, 3, 7, 14, and 21 , comparing the commercial Suprathel dressing as the positive control with the bioactive foam dressing comprising 5 wt% PLGA-RGD 3D-printed onto an OEM PU foam substrate sourced from Mitsui Chemicals Inc. (MIC), in accordance with various embodiments disclosed herein.

[0275] FIG. 6 shows the images illustrating the progression of in vivo porcine wound healing observed on Days 0, 3, 7, 10, 14, 21 , and 32, comparing the commercial Allevyn dressing with the bioactive foam dressing comprising 5 wt% PLGA-RGD 3D-printed onto an OEM PU foam substrate, in accordance with various embodiments disclosed herein.

[0276] FIG. 7 shows the images illustrating the progression of in vivo porcine wound healing observed on Days 0, 3, 7, 10, 14, 21 , and 32, comparing the commercial Allevyn dressing with the bioactive dressing comprising PLGA- IKVAV 3D-printed onto a silicone backing material.

[0277] EXAMPLES

[0278] Example embodiments of the disclosure will be better understood and readily apparent to one of ordinary skill in the art from the following examples, tables and if applicable, in conjunction with the figures. It should be appreciated that other modifications related to structural, biological, and / or chemical changes may be made without deviating from the scope of the invention. Example embodiments are not necessarily mutually exclusive as some may be combined with one or more embodiments to form new example embodiments. The example embodiments should not be construed as limiting the scope of the disclosure.

[0279] The following examples describe the methodology of preparing an alternative wound dressing using three-dimensional printing, more specifically fused filament fabrication (FFF) technology, and bioactive material in the form of bioactive poly(lactic-co-glycolic acid) (PLGA) materials on compressible substrates in the form of foam pads, for the treatment of excisional and burn wounds. Traditionally, substrates used in FFF or fused deposition modelling (FDM) processes have been selected for their ability to maximise filament adhesion and minimise warpage, thereby reducing the risk of print failure. In contrast, the examples below utilise unconventional substrates such as adhesive and non-adhesive foam pads made of polyurethane (PU), which form part of the completed product that is ready for direct application. Advantageously, PU foams are capable for use to offload pressure in ulcer wounds due to its soft and compressible nature, and they also maintain dryness for the wound bed due to their highly absorbent nature. Thus, PU foams are useful not only for deep, exudating wounds but also in burn wound treatment where they may be used as secondary dressings on top of dermal matrices or skin substitutes. The examples below detail an unprecedented methodology that includes the process workflow and parameterisation of the FFF process tailored for using bioactive PLGA and standard PU foam pads as the printing substrate.

[0280] The examples also demonstrated the fabrication of alternative bioactive foam dressings by incorporating bioactive PLGA materials onto existing standard PU foam pads from various original equipment manufacturers (OEMs). Advantageously, by combining advancements in biomaterials with FFF technology, the resulting wound dressings exhibit improved biocompatibility and improved wound healing outcomes. More importantly, the following examples also demonstrate the inventive application of an unconventional substrate, i.e. , foam pads, within the FFF process, transforming standard foam materials into bioactive foam dressings suitable for treating exudative wounds such as ulcers or trauma-related injuries. This is despite the technically challenging task of applying PLGA in FFF-based 3D printing due to the polymer's low melt viscosity and high melting point, which limit the range of biomaterials that can be used effectively.

[0281] Notwithstanding the above, the challenges typically associated with printing PLGA for tissue engineering applications, such as its low melt viscosity and high melting point, were successfully circumvented through careful selection of printing parameters, adjustment of the lactide-to-glycolide ratio, and the use of PLGA-peptide brush polymers. Consequently, the developed bioactive foam wound dressings in accordance with various embodiments disclosed herein offer significant improvements in both biocompatibility and wound healing capability.

[0282] The examples below also show how the embodiments of the composite structure disclosed herein perform in comparison with commercial foam dressings, which are considered the clinical gold standard for chronic wounds such as diabetic foot ulcers, pressure ulcers or venous ulcers.

[0283] Example 1 : Biocompatibility and cell viability tests for commercial polyurethane (PU) foams with silicon or silver top layer

[0284] Commercial polyurethane (PU) foams with silicone top cover for non-skin adhesion such as Allevyn and silver-based dressings such as Acticoat, were tested for biocompatibility.

[0285] Firstly, cytotoxicity testing was conducted using human skin models seeded with epidermal skin cells (i.e., keratinocyte) for a total of 9 samples. FIG.1 shows the cell viability of Allevyn and Acticoat wound dressing samples over 24- and 48-hour time periods. It was demonstrated that Allevyn and Acticoat samples respectively had only 52.7 % and 34.3 % of viable keratinocytes after 48 hours, indicating their skin cytotoxicity.

[0286] Biocompatibility test using Hs27 skin fibroblasts was also carried out on Allevyn and Acticoat samples. FIG.2 shows the cell viability of each sample compared to untreated cells. It can be observed that Allevyn had less than 50 % viable fibroblast cells, while Acticoat showed no cell viability at all, further demonstrating that these samples are not biocompatible with human skin.

[0287] Hence, these results show that regular PU foams with silicone or silver top layer are not best suited for wound treatment and there is a need for better wound dressings to be developed.

[0288] Example 2: 3D printing of poly(lactic-co-glycolic acid) (PLGA) onto polyurethane (PU) foam pads via fused filament fabrication (FFF)

[0289] The following example describes the methodology for developing bioactive foam pads using both pure and bioactive poly(lactic-co-glycolic acid) (PLGA) on original equipment manufacturer (OEM) polyurethane (PU) foam pads as the fused filament fabrication (FFF) substrate.

[0290] Two types of OEM foam pads were used in the following example: one has an adhesive side which securely attaches on the wound, while the other one is a non-adhesive foam pad. Both types of pads are soft and compressible under small loads with a degree of conformity around rigid structures.

[0291] The adhesive foam pad (FIG 3A), was measured with an uncompressed thickness of 3 mm and a total compressed thickness below 1 mm. Non-adhesive foam pad A (FIG 3B), has an uncompressed thickness of 5 mm and a total compressed thickness of 2 mm while non-adhesive foam pad B (FIG 3C), has an uncompressed thickness of 4 mm and a compressed thickness of 1 mm. These thickness values were considered during the optimisation of the FFF process as shown in Table 1 below.

[0292] In addition, to accommodate the printing of pure and bioactive PLGA onto these unconventional compressible PU foam pads, the standard FFF workflow was revised to integrate additional components into the existing hardware setup. Briefly, the additional parts consisted of an aluminium (Al) foam mould (known as active plate) and another Al plate (known as the reference plate). The active plate (i.e. , an Al foam pad mould) and the reference plate (i.e. , a regular Al plate) were fabricated with dimensions in accordance with various embodiments disclosed herein, with the exception that the active plate included a 12 * 12 cm cut-out. In this example, the aluminium reference plate and active plate are both about 4 mm in thickness to match the thickness of the glass build plate used. Advantageously, this allows the use of readily available, easy-to-source, and inexpensive aluminium plates. The active plate serves to secure the foam pads during FFF process while the reference plate is used during the auto-levelling procedure of the FFF process, where the nozzle probes the surface of the reference plate to determine the initial z-distance between the nozzle and the substrate. The Z-offset distance refers to the distance between the nozzle to the substrate, with positive values moving the nozzle away from the substrate while negative values moving nozzle closer to the substrate.

[0293] Levelling cannot be performed directly on the foam pad or the active plate as the compressible nature of the foam pad will result in levelling errors. In this regard, a 4-mm reference plate was used for the Ultimaker’s auto-levelling procedure, where the Z-offset value was ascertained to range between -0.35 to 2 mm depending on the foam pad type being used. Thus, a spacer would be used for foam substrates with thicknesses of 4 mm or less.

[0294] It was determined that this parameter had a significant influence on the print quality of the printed part on the substrate: a narrow gap between the nozzle and foam pad will result in under-extrusion, while a wider gap will result in poor material adhesion on the foam pad. As the foam pads comprise varying structures and porosities, a slow print speed coupled with a high print temperature were necessary for excellent material flow and sufficient adhesion between the foam pad and the PLGA materials. Hence, a print speed ranging from 1 to 10 mm / s and a print temperature ranging from 150 to 170 °C were established to be ideal in achieving the print outcome.

[0295] To accommodate the use of a reference plate during the auto-levelling process, a post-processing script was introduced to the software setup by modifying the FFF sequence. Incorporated through Ultimaker Cura, the postprocessing script forced a pause in the printing process. This allows for the user to swap out the reference plate with the active plate before the printing begins, when the material gets extruded onto the substrate.

[0296] Accordingly, the workflow associated with the FFF process was modified for embodiments of the present disclosure: while the normal workflow consists of 4 steps, the modified workflow consists of 6 steps.

[0297] FFF normal workflow:

[0298] 1 . Slicing of 3D model and set print parameters on slicing software.

[0299] 2. Transfer G-code file to FFF printer.

[0300] 3. Start printing process.

[0301] 4. End of printing process.

[0302] FFF modified workflow:

[0303] 1 . Slicing of 3D model and set print parameters on slicing software.

[0304] 2. Transfer G-code file to FFF printer.

[0305] 3. Start printing process.

[0306] 4. Printing process is paused automatically after auto-levelling procedure. To swap out reference plate with active plate consisting of foam pad.

[0307] 5. Continue printing process.

[0308] 6. End of printing process. The FFF printing process was performed using Ultimaker S5 dual nozzle 3D printer fitted with AA 0.4mm print core. Ultimaker Cura slicing software was used to convert 3D model into multiple G-code commands for the FFF printer. Herewith, the printing parameters can be defined which is then exported as a file for uploading to the FFF printer. In addition, the dermal matrix 3D model used in this example was designed on Ultimaker Cura which measured at 50 x 50 x 0.1 mm (length x width x thickness). Upon completion of the 3D printing process, the completed FFF printed wound dressing can be removed from the active plate and is ready for use.

[0309] Table 1. FFF parameters used for printing PLGA on PU foam pads.

[0310] Example 3: Preparation of pure and bioactive PLGA filaments for 3D FFF printing

[0311] Pure and bioactive PLGA materials used in this example is a composition of pure PLGA blended with PLGA bioadditive at varying content ranging from 0 to 20 wt%. Pure PLGA used were PLGA 75-100 and PLGA 85-65 provided by Mitsui Chemicals Inc. (MCI).

[0312] The methodology of synthesising PLGA bioadditive can be found in PCT / SG2020 / 050621 , the contents of which are fully incorporated herein. The methodology of creating pure and bioactive PLGA filaments for FFF process can be found in PCT / SG2022 / 050620, the contents of which are fully incorporated herein.

[0313] Briefly, raw pure PLGA resins were converted into powder using cryogenic mill with liquid nitrogen. Both pure PLGA and PLGA bioadditive powders were dried in a vacuum oven at 40 °C for 6 hours prior to the filament extrusion process. The filament extrusion process was performed to obtain filaments with an average diameter of 2.85 mm using a twin-screw extruder (TSE) with a melt pump fitted with a nozzle of 03 mm. Compressed air was used as the cooling medium. Table 2 below shows the extrusion parameters used.

[0314] Table 2. Extrusion parameters used for producing PLGA filaments.

[0315] Example 4: Characterization of compressible PU substrate.

[0316] Physical data analysis was conducted to characterize a compressible PU substrate which may be suitable for use in a composite structure comprising the compressible PU substrate and 3D-printed PLGA in accordance with various embodiments disclosed herein. The testing was carried out by the Product Development Department of Yukigaya Chemical Industry Co., Ltd. Table 3 below presents the physical analysis data along with the testing methods used for each parameter.

[0317] Table 3. Physical properties and testing methods for the PU foam structure (JIS

[0318] K 6400: Japanese Industrial Standard K 6400).

[0319] The values presented above are representative data and are not the exact specifications.

[0320] The method for determining open-cell foam porosity using liquid displacement is described in further detail below. This method is used for quantifying the porosity of open-cell, flexible foams based on isopropanol (IPA) or ethanol absorption, and it provides the foam porosity in percentage for ease of reference.

[0321] Required Apparatus: a. An analytical balance with a resolution of at least 0.001 g. b. A graduated cylinder or volumetric flask for volume determination. c. Isopropanol or ethanol, preferably of high purity (~99 %), as the displacement liquid. d. A vacuum chamber (optional), for enhancing liquid penetration into internal pores.

[0322] Method Steps: a. Dry Weight Measurement: The foam sample is first dried, and its mass is recorded using the analytical balance to obtain the dry weight (Wdry). b. Liquid Saturation: The sample is then fully immersed in the selected liquid until saturation is achieved. Optionally, a vacuum may be applied to facilitate the removal of entrapped air and ensure complete liquid penetration into the pore structure. c. Surface Blotting and Wet Weight Measurement: Upon saturation, the sample is carefully removed from the selected liquid (e g., ethanol), and excess surface liquid is gently blotted using a lint-free absorbent material. The saturated mass (Wwet) is then immediately measured. d. Absorbed Liquid Volume Calculation: The volume of liquid absorbed into the foam is calculated as: where piiquid is the density of liquid used at the room temperature. e. External Volume Determination: The external volume (Vext) of the foam sample is determined based on its dimensions (length x width x height), or by fluid displacement if dimensional measurement is impractical. f. Porosity Calculation: The open-cell porosity (P) is computed using the equation:

[0323] Example 5: In vivo evaluation of bioactive foam dressings comprising PLGA-RGD or PLGA-HA 3D-printed on PU foam substrates in a porcine wound model

[0324] An in vivo study of full-thickness wound healing using a porcine excisional wound model was conducted to evaluate the wound healing performance of bioactive foam dressings comprising PLGA blended with bioadditives such as RGD peptide (Scheme 1) and hyaluronic acid (HA) (Scheme 2). The dressings were fabricated by FFF 3D printing of pure or bioactive PLGA filaments onto OEM PU foam substrates, as described in the preceding examples.

[0325] In one comparative study, PU foam dressings printed with 5 wt% PLGA- RGD and 5 wt% PLGA-HA in accordance with various embodiments disclosed herein were applied to wounds, with wound healing progress documented on Days 0, 3, 7, 14, and 21. As illustrated in FIG. 4, the dressing with PLGA-RGD exhibited superior healing, with effective wound closure and minimal inflammation observed by Day 21. These dressings were prepared using a PU foam substrate supplied by an OEM manufacturer based in China.

[0326] Another comparison involved PLGA-RGD dressings printed on PU foam supplied by Mitsui Chemicals Inc. (MCI) in accordance with various embodiments disclosed herein and a positive control dressing which is commercially available (Suprathel®), with wound healing progress documented on Days 0, 3, 7, 14, and 21. As illustrated in FIG. 5, both groups demonstrated equally effective wound closure; however, the PLGA-RGD-treated group exhibited minimal inflammation, whereas inflammation was observed in the Suprathel-treated wounds.

[0327] A third evaluation compared bioactive foam dressings containing PLGA- RGD in accordance with various embodiments disclosed herein with a commercial foam dressing (Allevyn™, by Smith & Nephew). Observations were recorded on Days 0, 3, 7, 10, 14, 21 , and 32. As illustrated in FIG. 6, wounds treated with the bioactive foam with a PLGA-RGD layer exhibited rapid wound closure, with full re-epithelialisation achieved by Day 14. In contrast, wounds treated with the Allevyn dressing remained visibly raw on Day 21 and were not fully closed even by Day 32.

[0328] These results demonstrate that the PU foam dressings in accordance with various embodiments disclosed herein enhanced with bioactive PLGA formulations, especially those incorporating RGD peptides, offer accelerated wound healing and reduced inflammation when compared to commercially available foam dressings which are bioinert.

[0329] Example 6: In vivo evaluation of bioactive dressings comprising PLGA- IKVAV 3D-printed on silicone backing in a porcine wound model

[0330] An in vivo porcine full-thickness wound healing study was conducted to evaluate the wound healing performance of PLGA-IKVAV 3D-printed on a silicone backing material, compared to Allevyn, a commercial foam dressing. Observations were recorded on Days 0, 3, 7, 10, 14, 21 , and 32. As illustrated in FIG. 7, rapid reepithelization was observed by Day 7 for PLGA-lKVAV-treated wound but Al levyn -treated wound was still visibly raw on Day 7. The PLGA-IKVAV product was left on the wound until Day 10, without prior removal. However, the tissue growth was too fast in PLGA-lKVAV-treated wound due to the presence of angiogenic peptide, and hence the PLGA-IKVAV product was buried under the rapidly growing skin tissues. Consequently, this resulted in the need to excise the wound to remove the product on Day 10, explaining the slow and delayed healing of the wound. This finding suggests that the PLGA-IKVAV needs to be printed on a backing that facilitates regular product changes, such as a foam backing (e.g., a PU substrate). With regular dressing changes and the presence of an angiogenic peptide, wound healing is expected to be rapid while preventing tissues from growing into the substrate or backing.

[0331] On the other hand, Allevyn was changed on Days 3, 7, 10, 14, and 21. Although the regular dressing change helped maintain wound hygiene, the wound was nevertheless infected with Pseudomonas bacteria. In contrast, no bacterial infection was observed in the PLGA-lKVAV-treated wound, despite the pig being infected by Pseudomonas bacteria in the neighbouring Allevyn-treated wound.

[0332] APPLICATIONS

[0333] Embodiments of the present disclosure provide a FFF 3D printing system capable of accommodating unconventional substrates, including both highly compressible porous adhesive and non-adhesive foam pads, which are typically incompatible with standard 3D printing platforms. Specifically, embodiments of the system disclosed herein provide a unique hardware setup involving the use of a reference plate for an auto-levelling procedure, alongside an active plate to secure a foam substrate during the printing process. Advantageously, such a setup addresses variations in substrate thickness by enabling Z-offset optimization, thereby ensuring consistent / accurate layer height throughout the print. Besides, embodiments of the system disclosed herein further integrate a post-processing script within the software configuration to allow for active plate swapping midprocess, facilitating greater flexibility in the printing workflow. Advantageously, such a system overcomes challenges associated with the compressibility of foam substrates, which can interfere with bed / build plate levelling, cause nozzle embedment that limits material flow and adhesion, and complicate the FFF process workflow.

[0334] Embodiments of the present disclosure provide a new methodology for lamination of acellular bioactive PLGA onto a PU foam pad via FFF 3D printing, thereby offering a bioactive composite structure suitable for the treatment of acute, chronic, partial and full thickness skin injuries, exudative wounds such as burns, trauma (e.g., lacerations, abrasions, or the like), skin graft donor sites, and ulcers (e.g., diabetic foot ulcers, pressure ulcers, venous ulcers, or the like). Advantageously, the use of the resulting bioactive foam dressing simplifies clinical application by eliminating an additional procedural step for healthcare providers.

[0335] Embodiments of the present disclosure provides an alternative wound dressing incorporating a layer of bioactive component prepared via the FFF 3D printing process. Advantageously, the resulting bioactive foam dressing promotes skin tissue regeneration with minimal scarring. Even more advantageously, the resulting bioactive foam dressing is both tissue- regenerative and absorbent, addressing the limitations of current foam dressings which are often cytotoxic (e.g., silver-containing foam) or poorly biocompatible (e.g., standard foam dressing).

[0336] It will be appreciated by a person skilled in the art that other variations and / or modifications may be made to the embodiments disclosed herein without departing from the spirit or scope of the disclosure as broadly described. For example, in the description herein, features of different exemplary embodiments may be mixed, combined, interchanged, incorporated, adopted, modified, included, etc. or the like across different exemplary embodiments. The present embodiments are, therefore, to be considered in all respects to be illustrative and not restrictive.

Claims

CLAIMS1. A composite structure for promoting wound healing, the structure comprising, a compressible substrate; and a bioactive material disposed on said compressible substrate, wherein the bioactive material comprises a mixture of a synthetic homopolymer and a bioactive copolymer.

2. The composite structure of claim 1 , wherein the synthetic homopolymer comprises a base poly(lactic-co-glycolic acid) (PLGA) homopolymer, and the bioactive copolymer comprises a bioactive poly(lactic-co-glycolic acid) (PLGA) copolymer.

3. The composite structure of claim 2 or 3, wherein the bioactive material comprises from 60.0 wt% to 99.9 wt% of the base PLGA and from 0.1 wt% to 40.0 wt% of the bioactive PLGA copolymer.

4. The composite structure of any one of claims 2 to 4, wherein the bioactive PLGA copolymer comprises a bioactive PLGA copolymer with a poly(norbornene-dicarboximide) backbone having one or more repeating units represented by general formula (I) and one or more repeating units represented by general formula (II):whereinR1is selected from a single bond, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted alkoxyalkyl, optionally substituted alkylcarbonyl, or optionally substituted alkylcarbonylalkyl;R2is optionally substituted alkyl;R3is selected from H, optionally substituted alkyl, optionally substituted alkenyl, or optionally substituted alkynyl;L is heteroalkylene;X comprises a bioactive moiety selected from the group consisting of proteins, peptides, oligopeptides, carbohydrates, oligosaccharides, sugar, collagen, hyaluronic acid (HA), therapeutic / drug molecules, and derivatives thereof;Z1and Z2are each independently selected from CRaRb, 0, NRC, SiRaRb, PRa, or S, wherein Ra, Rb, and Rcare each independently selected from the group consisting of H, optionally substituted alkyl, optionally substituted alkenyl, and optionally substituted alkynyl; p > 1 ; and q > 1.

5. The composite structure of claim 4, wherein the bioactive moiety comprises no more than one carboxylic acid terminal group.

6. The composite structure of claim 4 or 5, wherein L is selected from the group consisting of polyethylene glycol (PEG), polypropylene glycol (PPG), polytetramethylene glycol (PTMG), polybutylene glycol (PBG), and combinations thereof.

7. The composite structure of any one of claims 4 to 6, wherein the bioactive moiety comprises hyaluronic acid (HA), arginine-glycine-aspartic acid (RGD), isoleucine-lysine-valine-alanine-valine (IKVAV), leucine-lysine- lysine-leucine-cysteine-arginine-isoleucine-leucine-lysine-lysine-leucine- cysteine-arginine-isoleucine (LKKLCRILKKLCRI), or combinations thereof.

8. The composite structure of any one of the preceding claims, wherein the compressible substrate comprises a compressible foam substrate.

9. The composite structure of any one of the preceding claims, wherein the compressible substrate comprises polyurethane.

10. The composite structure of any one of the preceding claims, wherein the bioactive material impregnates at least part of the substrate.11 . The composite structure of any one of the preceding claims, wherein the compressible substrate is capable of being compressed to less than 50 % of its original thickness.

12. The composite structure of any one of the preceding claims, wherein the structure is acellular and devoid of an extraneous drug.

13. A method of preparing a composite structure of any one of the preceding claims, the method comprising: providing the compressible substrate; andthree-dimensionally (3D) printing the bioactive material on said compressible substrate with a 3D printing system.

14. The method of claim 13, wherein the 3D printing comprises a fused filament fabrication (FFF) printing method or a fused deposition modelling (FDM) printing method.

15. The method of claim 13 or 14, wherein the method further comprises leveling the distance between print nozzle(s) of the 3D printing system and the compressible substrate by using a non-compressible reference substrate in lieu of the compressible substrate, prior to 3D printing.

16. The method of claim 15, wherein the method further comprises replacing the reference substrate with the compressible substrate after leveling is completed.

17. The method of any one of claims 13 to 16, wherein the compressible substrate is provided on a support having a cut-out that is substantially complementary to the compressible substrate such that a top surface of the support and a printable top surface of the compressible substrate is capable of forming a substantially flat plane when the compressible substrate is fitted in the cut-out of the support.

18. The method of any one of claims 13 to 17, wherein 3D printing the bioactive material on the compressible substrate comprises extruding flowable bioactive material onto the compressible substrate such that at least part of the bioactive material impregnates the compressible substrate.

19. The method of claim 18, wherein the flowable bioactive material is extruded at a temperature falling in the range of from 50 °C to 200 °C.

20. The method of claim 18 or 19, further comprising solidifying the flowable bioactive material to anchor the bioactive material to the compressible substrate.

21. The method of any one of claims 13 to 20, wherein the bioactive material is 3D printed with an infill density falling in the range of from 30 % to 90 %.

22. The composite structure of any one of claims 1 to 12 for use in medicine.

23. The composite structure of any one of claims 1 to 12 for use in treating wounds.

24. Use of the composite structure of any one of claims 1 to 12, in the manufacture of a medicament for treating wounds.

25. A method of treating wounds comprising applying the composite structure of any one of claims 1 to 12 to a wound.

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