Antioxidant and multi-sensitive PNIPAAm/keratin double network gels for self-stripping wound dressing application

Current progress of protein-based dressing for wound healing applications - A review

Protein-based wound dressings have garnered increasing interest in recent years owing to their distinct physical, chemical, and biological characteristics. The intricate molecular composition of proteins gives rise to unique characteristics, such as exceptional biocompatibility, biodegradability, and responsiveness, which contribute to the promotion of wound healing. Wound healing is an intricate and ongoing process influenced by multiple causes, and it consists of four distinct phases. Various treatments have been developed to repair different types of skin wounds, thanks to advancements in medical technology and the recognition of the diverse nature of wounds. This review has literature reviewed within the last 3-5 years-the recent progress and development of protein in wound dressings and the fundamental properties of an ideal wound dressing. Herein, the recent strides in protein-based state-of-the-art wound dressing emphasize the significant challenges and summarize future perspectives for wound healing applications.

Keratin-PNIPAM Hybrid Microgels: Preparation, Morphology and Swelling Properties

Combinations of synthetic polymers, such as poly(N-isopropylacrylamide) (PNIPAM), with natural biomolecules, such as keratin, show potential in the field of biomedicine, since these hybrids merge the thermoresponsive properties of PNIPAM with the bioactive characteristics of keratin. This synergy aims to produce hybrids that can respond to environmental stimuli while maintaining biocompatibility and functionality, making them suitable for various medical and biotechnological uses. In this study, we exploit keratin derived from wool waste in the textile industry, extracted via sulfitolysis, to synthesize hybrids with PNIPAM microgel. Utilizing two distinct methods-polymerization of NIPAM with keratin (HYB-P) and mixing preformed PNIPAM microgels with keratin (HYB-M)-resulted in hybrids with 20% and 25% keratin content, respectively. Dynamic light scattering (DLS) and transmission electron microscopic (TEM) analyses indicated the formation of colloidal systems with particle sizes of around 110 nm for HYB-P and 518 nm for HYB-M. The presence of keratin in both systems, 20% and 25%, respectively, was confirmed by spectroscopic (FTIR and NMR) and elemental analyses. Distinct structural differences were observed between HYB-P and HYB-M, suggesting a graft copolymer configuration for the former hybrid and a complexation for the latter one. Furthermore, these hybrids demonstrated temperature responsiveness akin to PNIPAM microgels and pH responsiveness, underscoring their potential for diverse biomedical applications.

Bifunctional lignocellulose nanofiber hydrogel possessing intriguing pH-responsiveness and self-healing capability towards wound healing applications

Lignocellulose nanofibers (LCNF) obtained from agricultural waste are potential candidates for enhancing composite materials because of their excellent mechanical properties, abundant groups and high biocompatibility. However, the application of LCNF has received limited attention to date from researchers in the healthcare field. Herein, based on the bifunctional group (carboxyl and aldehyde groups) modified LCNF (DCLCNF) and chitosan (CS), we developed a multifunctional bio-based hydrogel (CS-DCLCNF). The addition of lignin-containing DCLCNF strengthened the internal crosslinking and the intermolecular interaction of hydrogels, and the presence of lignin and carboxyl groups increased the mechanical strength of the hydrogel and the adsorption of aromatic drugs. Results revealed that the hydrogels exhibited self-healing, injectable, and high swelling rates. The hydrogels had favorable mechanical strength (G'max of ~16.60 kPa), and the maximum compressive stress was 24 kPa. Moreover, the entire tetracycline hydrochloride (TH) release process was slow and pH-responsive, because of the rich noncovalent and π-π interactions between DCLCNF and TH. The hydrogels also exhibited excellent biocompatibility and antibacterial properties. Notably, the wound healing experiment showed that the hydrogels were beneficial in accelerating wounds healing, which could heal completely in 13 days. Therefore, CS-DCLCNF hydrogels may have promising applications in drug delivery for wound healing.

Vancomycin-loaded hydrogels with thermal-responsive, self-peeling, and sustainable antibacterial properties for wound dressing

Wound dressings play an important role in wound healing. However, many wound dressings lack antibacterial properties and are difficult to remove from newly grown tissues, causing secondary wound injuries and repeated medical treatment. This study reports a new type of thermal-responsive hydrogel dressing consisting of vancomycin-loaded gelatin nanospheres (GNs) and poly((N-isopropylacrylamide)-co-N-(methylol acrylamide)) functional components that could impart self-peeling and sustainable antibacterial properties. SEM images showed that the prepared hydrogel possessed a porous microstructure and the homogeneous distribution of GNs in its network. Excellent swelling ratios and thermal-induced self-peeling characteristics were confirmed by qualitative analysis. The GNs not only enhanced the strain at break of the hydrogel, but also acted as drug carriers to slow down the drug release from the hydrogel, achieving sustainable antibacterial properties and balanced biocompatibility. Therefore, this vancomycin-loaded hydrogel with self-peeling characteristics provides an effective way of preventing wound infection and can be used as a novel platform for wide-ranging applications of wound dressings.

Engineering pH responsive carboxyethyl chitosan and oxidized pectin -based hydrogels with self-healing, biodegradable and antibacterial properties for wound healing

As an important organ of the human body, effective protection of the skin during trauma is crucial. An ideal wound dressing should have adhesion, adsorption of wound secretions, and good antibacterial properties. Two kinds of natural polysaccharide-based hydrogels, carboxyethyl chitosan/oxidized pectin hydrogel (CEC/OP) and carboxyethyl chitosan/oxidized pectin/polyethyleneimine hydrogel (CEC/OP/PEI), were reported by using carboxyethyl chitosan as the matrix, and oxidized pectin and branched polyethyleneimine as the crosslinking agents. Both hydrogels could be formed in a short time and exhibited the pH responsively due to the presence of imine bond. Compared with carboxyethyl chitosan/oxidized pectin hydrogel, polyethyleneimine containing hydrogel can form gel quickly, a more compact and stable three-dimensional space network structure was formed, which exhibited better swelling performance, the swelling ration, rheology property, self-repair ability, and antibacterial performance. When the mass fractions of carboxyethyl chitosan and oxidized pectin solutions are 4 wt% and 9 wt%, respectively, the hydrogel exhibited an antibacterial efficiency of >96 % against both Staphylococcus aureus and Escherichia coli. After adding 0.75 wt% polyethyleneimine, the antibacterial efficiency of hydrogel could reach up to >98 %. More importantly, the polyethyleneimine containing hydrogel has a significant effect in the treatment of bacterially infected wounds.

Photopolymerized keratin-PGLa hydrogels for antibiotic resistance reversal and enhancement of infectious wound healing

Infectious wounds have become serious challenges for both treatment and management in clinical practice, so development of new antibiotics has been considered an increasingly difficult task. Here, we report the design and synthesis of keratin 31 (K31)-peptide glycine-leucine-amide (PGLa) photopolymerized hydrogels to rescue the antibiotic activity of antibiotics for infectious wound healing promotion. K31-PGLa displayed an outstanding synergistic effect with commercial antibiotics against drug-resistant bacteria by down-regulating the synthesis genes of efflux pump. Furthermore, the photopolymerized K31-PGLa/PEGDA hydrogels effectively suppressed drug-resistant bacteria growth and enhanced skin wound closure in murine. This study provided a promising alternative strategy for infectious wound treatment.

Recent advances in keratin for biomedical applications

The development of keratin-based biomaterials provides an approach to addressing related environmental pollutants and turns waste into wealth. Keratin possesses various merits, such as biocompatibility, biodegradability, hemostasis, non-immunogenicity, antibacterial activity, antioxidation, multi-responsiveness, and abundance in nature. Additionally, keratin biomaterials have been extensively employed in various biomedical applications such as drug delivery, wound healing, and tissue engineering. This review focuses on the properties and biomedical applications of keratin biomaterials. It is anticipated to provide valuable insights for the research and development of keratin biomaterials.

Phase transition and potential biomedical applications of thermoresponsive compositions based on polysaccharides, proteins and DNA: A review

Smart thermoresponsive polymers have long attracted attention as materials of a great potential for biomedical applications, mainly for drug delivery, tissue engineering and wound dressing, with a special interest to injectable hydrogels. Poly-N-isopropylacrylamide (PNIPAM) is the most important synthetic thermoresponsive polymer due to its physiologically relevant transition temperature. However, the use of unmodified PNIPAM encounters such problems as low biodegradability, low drug loading capacity, slow response to thermal stimuli, and insufficient mechanical robustness. The use of natural polysaccharides and proteins in combinations with PNIPAM, in the form of grafted copolymers, IPNs, microgels and physical mixtures, is aimed at overcoming these drawbacks and creating dual-functional materials with both synthetic and natural polymers' properties. When developing such compositions, special attention should be paid to preserving their key property, thermoresponsiveness. Addition of hydrophobic and hydrophilic fragments to PNIPAM is known to affect its transition temperature. This review covers various classes of natural polymers - polysaccharides, fibrous and non-fibrous proteins, DNA - used in combination with PNIPAM for the prospective biomedical purposes, with a focus on their phase transition temperatures and its relation to the natural polymer's structure.

Smart and versatile biomaterials for cutaneous wound healing

The global increase of cutaneous wounds imposes huge health and financial burdens on patients and society. Despite improved wound healing outcomes, conventional wound dressings are far from ideal, owing to the complex healing process. Smart wound dressings, which are sensitive to or interact with changes in wound condition or environment, have been proposed as appealing therapeutic platforms to effectively facilitate wound healing. In this review, the wound healing processes and features of existing biomaterials are firstly introduced, followed by summarizing the mechanisms of smart responsive materials. Afterwards, recent advances and designs in smart and versatile materials of extensive applications for cutaneous wound healing were submarined. Finally, clinical progresses, challenges and future perspectives of the smart wound dressing are discussed. Overall, by mapping the composition and intrinsic structure of smart responsive materials to their individual needs of cutaneous wounds, with particular attention to the responsive mechanisms, this review is promising to advance further progress in designing smart responsive materials for wounds and drive clinical translation.

Modern Approaches in Wounds Management

Wound management represents a well-known continuous challenge and concern of the global healthcare systems worldwide. The challenge is on the one hand related to the accurate diagnosis, and on the other hand to establishing an effective treatment plan and choosing appropriate wound care products in order to maximize the healing outcome and minimize the financial cost. The market of wound dressings is a dynamic field which grows and evolves continuously as a result of extensive research on developing versatile formulations with innovative properties. Hydrogels are one of the most attractive wound care products which, in many aspects, are considered ideal for wound treatment and are widely exploited for extension of their advantages in healing process. Smart hydrogels (SHs) offer the opportunities of the modulation physico-chemical properties of hydrogels in response to external stimuli (light, pressure, pH variations, magnetic/electric field, etc.) in order to achieve innovative behavior of their three-dimensional matrix (gel-sol transitions, self-healing and self-adapting abilities, controlled release of drugs). The SHs response to different triggers depends on their composition, cross-linking method, and manufacturing process approach. Both native or functionalized natural and synthetic polymers may be used to develop stimuli-responsive matrices, while the mandatory characteristics of hydrogels (biocompatibility, water permeability, bioadhesion) are preserved. In this review, we briefly present the physiopathology and healing mechanisms of chronic wounds, as well as current therapeutic approaches. The rational of using traditional hydrogels and SHs in wound healing, as well as the current research directions for developing SHs with innovative features, are addressed and discussed along with their limitations and perspectives in industrial-scale manufacturing.

Functional drug-delivery hydrogels for oral and maxillofacial wound healing

The repair process for oral and maxillofacial injuries involves hemostasis, inflammation, proliferation, and remodeling. Injury repair involves a variety of cells, including platelets, immune cells, fibroblasts, and various cytokines. Rapid and adequate healing of oral and maxillofacial trauma is a major concern to patients. Functional drug-delivery hydrogels play an active role in promoting wound healing and have shown unique advantages in wound dressings. Functional hydrogels promote wound healing through their adhesive, anti-inflammatory, antioxidant, antibacterial, hemostatic, angiogenic, and re-epithelialization-promoting properties, effectively sealing wounds and reducing inflammation. In addition, functional hydrogels can respond to changes in temperature, light, magnetic fields, pH, and reactive oxygen species to release drugs, enabling precise treatment. Furthermore, hydrogels can deliver various cargos that promote healing, including nucleic acids, cytokines, small-molecule drugs, stem cells, exosomes, and nanomaterials. Therefore, functional drug-delivery hydrogels have a positive impact on the healing of oral and maxillofacial injuries. This review describes the oral mucosal structure and healing process and summarizes the currently available responsive hydrogels used to promote wound healing.

Abundant tannic acid modified gelatin/sodium alginate biocomposite hydrogels with high toughness, antifreezing, antioxidant and antibacterial properties

The acidity of high tannic acid (TA) content solution can destroy the structure of protein, such as gelatin (G). This causes a big challenge to introduce abundant TA into the G-based hydrogels. Here, the G-based hydrogel system with abundant TA as hydrogen bonds provider was constructed by a "protective film" strategy. The protective film around the composite hydrogel was first formed by the chelation of sodium alginate (SA) and Ca2+. Subsequently, abundant TA and Ca2+ were successively introduced into the hydrogel system by immersing method. This strategy effectively protected the structure of the designed hydrogel. After treatment with 0.3 w/v TA and 0.06 w/v Ca2+ solutions, the tensile modulus, elongation at break and toughness of G/SA hydrogel increased about 4-, 2-, and 6-fold, respectively. Besides, G/SA-TA/Ca2+ hydrogels exhibited good water retention, anti-freezing, antioxidant, antibacterial properties and low hemolysis ratio. Cell experiments showed that G/SA-TA/Ca2+ hydrogels possessed good biocompatibility and could promote cell migration. Therefore, G/SA-TA/Ca2+ hydrogels are expected to be used in the field of biomedical engineering. The strategy proposed in this work also provides a new idea for improving the properties of other protein-based hydrogels.

Chlorhexidine-loaded polysulfobetaine/keratin hydrogels with antioxidant and antibacterial activity for infected wound healing

Multifunctional hydrogel dressings are promising for wound healing. In the study, chlorhexidine(CHX) loaded double network hydrogels were prepared by free radical polymerization of sulfobetaine and oxidative self-crosslinking of reduced keratin. The introduced keratin and CHX endowed hydrogels with cytocompatibility, antioxidant capability as well as enhanced antibacterial activity due to the antifouling property of polysulfobetaine. These hydrogels exhibited acidity, glutathione(GSH), and trypsin triple-responsive release behaviors, resulting in the accelerated release of CHX under wound microenvironments. Intriguingly, the freeze-drying hydrogels could be ground to powders and sprinkled on the irregular wound bed, followed by absorbing wound fluid to reform hydrogel in situ. These aerogel powders were more convenient for sterilization, formulation, and storage. Further, these aerogel powders could be rejected after being mixed with an appropriate amount of water. In vivo infected wound healing confirmed that the aerogel powder dressing significantly promoted collagen deposition and reduced inflammation, thereby accelerating the closure and regeneration of skin wounds. Taken together, these degradable aerogel powders have great potential applications for wound healing.

Construction of chitosan-based supramolecular biofilm material for wound dressing based on natural deep eutectic solvents

Bacterial infection is still one of the main problems observed in the clinical process of wound healing, so the development of new multifunctional biocompatible materials is an urgent clinical need. A kind of supramolecular biofilm crosslinked by hydrogen bond between natural deep eutectic solvent and chitosan was studied and successfully prepared to reduce bacterial infection. Its killing rates of Staphylococcus aureus and Escherichia coli can reach 98.86 % ± 1.90 % and 99.69 % ± 0.53 %, and it can be degraded in both soil and water, showing excellent biocompatibility and biodegradability. In addition, the supramolecular biofilm material also has the UV barrier property, which can effectively avoid the secondary injury of UV to the wound. Interestingly, the cross-linking effect of hydrogen bond makes the biofilm have a more compact structure and rough surface, and gives the biofilm strong tensile properties. Overall, owing to these unique advantages, NADES-CS supramolecular biofilm has great potential for medical applications, laying the foundation for the realization of sustainable polysaccharide materials.

Bioinspired Processing of Keratin into Upcycled Fibers through pH-Induced Coacervation

Keratin is an important byproduct of the animal industry, but almost all of it ends up in landfills due to a lack of efficient recycling methods. To make better use of keratin-based natural resources, the current extraction and processing strategies need to be improved or replaced by more sustainable and cost-effective processes. Here, we developed a simple and environmentally benign method to process extracted keratin, using HCl to induce the formation of a coacervate, a separate aqueous phase with a very high protein concentration. Remarkably, this pH-induced coacervation did not result in the denaturation of keratin, and we could even observe an increase in the amount of ordered secondary structures. The low-pH coacervates could be extruded and wet-spun into high-performance keratin fibers, without requiring heating or any organic solvents. The secondary structure of keratin was largely conserved in these regenerated fibers, which exhibited excellent mechanical performance. The process developed in this study represents a simple and environmentally friendly strategy to upcycle waste keratin into high-performance materials.

Bilayer dressing based on aerogel/electrospun mats with self-catalytic hydrogen sulfide generation and enhanced antioxidant ability

Hydrogen sulfide (H₂S) releasing wound dressings have attracted much attention for their ability to promote cell proliferation, stimulate angiogenesis, and resist inflammation. Mimicking the skin structure, a bilayer wound dressing based on aerogel/mats with H₂S release capability was designed and fabricated. A bio-macromolecular H₂S donor based on a keratin-TA conjugate (KTC) was first synthesized through a thiol-disulfide exchange reaction. As an inner layer, KTC was then loaded into a gelatin hydrogel with large pores to absorb the wound exudates and generate H₂S self-catalytically. Subsequently, polyurethane was electrospun with glutathione (GSH) to be used as an outer layer with small pores, which provided mechanical support, supplied GSH, and prevented bacterial invasion. The bilayer dressing was capable of generating H₂S self-catalytically, achieving a controlled and sustained release. The dressing could also promote cell proliferation and migration. In addition, the dress possessed enhanced antioxidant ability and reactive oxygen species (ROS) scavenging capability. The bilayer dressing on promoting wound healing was investigated in a full-thickness excisional cutaneous wound model in rats. The results demonstrated that it could reduce inflammation, promote vascularization, and facilitate hair follicle regeneration, thereby accelerating wound healing. Overall, the bilayer dressing has great potential applications in the field of the wound dressing.

Recent advances in responsive antibacterial materials: design and application scenarios

Bacterial infection is one of the leading causes of death globally, although modern medicine has made considerable strides in the past century. As traditional antibiotics are suffering from the emergence of drug resistance, new antibacterial strategies are of great interest. Responsive materials are appealing alternatives that have shown great potential in combating resistant bacteria and avoiding the side effects of traditional antibiotics. In this review, the responsive antibacterial materials are introduced in terms of stimulus signals including intrinsic (pH, enzyme, ROS, etc.) and extrinsic (light, temperature, magnetic fields, etc.) stimuli. Their biomedical applications in therapeutics and medical devices are then discussed. Finally, the author's perspective of the challenge and the future of such a system is provided.

Hydrogen sulfide-releasing polyurethane/gelatin/keratin-TA conjugate mats for wound healing

Hydrogen sulfide (H₂S) has indispensable effects on wound healing promotion, such as anti-inflammatory, cell proliferation enhancement, and angiogenesis improvement. However, small-molecular donors have drawbacks of burst release and low biocompatibility. In this study, a novel bio-macromolecular donor of H₂S based on a keratin-thiobenzoic acid conjugate (KTC) was first synthesized by a thiol-disulfide exchange reaction. Then, the KTC was incorporated into polyurethane and gelatin to fabricate nanofibrous mats by electrospinning. Interestingly, both the KTC donor and biocomposite mats were capable of releasing H₂S triggered by glutathione (GSH) under physiological conditions. These mats had excellent water absorption capacity, demonstrating their great ability to absorb tissue exudate. In addition, these mats possessed a notable antioxidant ability, thereby protecting cell membranes from oxidation. Cell assays in vitro demonstrated that these mats could promote cell proliferation and migration. Furthermore, the in vivo full-thickness defect model verified that these H₂S-releasing wound dressing mats could accelerate granulation tissue formation, enhance collagen deposition, and promote angiogenesis. Based on these advantages, these wound dressing mats had great potential applications for wound healing.

Fabrication of Thermo-Responsive Controllable Shape-Changing Hydrogel

Temperature response double network (DN) hydrogels comprising a network formed by polymerization of methacrylic acid (MA) modified PVA, N,N'-methylene bis(acrylamide), N-isopropylacryl amide (NIPAM), and one formed from crystalline polyvinyl alcohol (PVA) are prepared in a 3D printed tailor-made mold. The (PVA-MA)-g-PNIPAAm thermoset intermediate is formed in water by a radical, photo-initiated process, and in the presence of dissolved PVA polymers. A subsequent freezing-thawing sequence induces the crystallization of the PVA network, which forms a second network inside the thermoset NIPAM polymer. The prepared hydrogel is thermoresponsive by the phase transition of PNIPAAm segments (T ≈ 32 °C) and has good mechanical properties (tensile strength 1.23 MPa, compressive strength 1.47 MPa). Thermal cycling between room temperature at 40 or 50 °C shows the product converses from a virgin-state to a steady-state, which most likely involves the reorganization of PVA crystals. The swelling-deswelling cycles remain clear at a length change of about 13%.

Multifunctional hydrogels for wound dressings using xanthan gum and polyacrylamide

Developing advanced dressings that integrate multiple functions is one of the major challenges in current clinical wound treatment. In this study, Xanthan gum (XG) and polyacrylamide (PAAm) materials were used to prepare hydrogel dressings by one-pot method. With the combination of the PAAm network and the XG network, the PAAm-XG hydrogels showed the tensile strength of 0.36 MPa and the stretchability as large as 2078 %. The prepared PAAm-XG hydrogels had excellent water uptake efficiency with the swelling ratio of 1200 %. Besides, the developed dressings possessed outstanding biocompatibility, universal adhesion and self-healing ability. More importantly, the PAAm-XG hydrogels can be successfully loaded with Cefixime and human recombinant epidermal growth factor, and these loaded hydrogels released these bioactive molecules in sustained ways. As a result, both E. coli and S. aureus bacteria were inactivated after contacting with the Cefixime-loaded hydrogels for 24 h. Furthermore, in vivo data demonstrated that the PAAm-XG hydrogel dressings significantly accelerated the wound healing in a mouse model. All of these indicate that the multifunctional PAAm-XG hydrogels are promising candidates for wound treatment.

Keratin-based wound dressings: From waste to wealth

Keratin is a natural protein with a high content of cysteine residues (7-13%) and is widely found in hair, wool, horns, hooves, and nails. Keratin possesses abundant cell-binding motifs such as leucine-aspartate-valine (LDV), glutamate-aspartate-serine (EDS), and arginine-glycine-aspartate (RGD), which benefit cell attachment and proliferation. It has been confirmed that keratin plays important roles in every stage of wound healing, including hemostasis, inflammation, proliferation, and remodeling, making keratin-based materials good candidates for wound dressings. In combination with synthetic and natural polymers, keratin-based wound dressings in the forms of films, hydrogels, and nanofibers can be achieved with improved mechanical properties. This review focuses on the recent development of keratin-based wound dressings. Firstly, the physicochemical and biological properties of keratin, are systematically discussed. Secondly, the role of keratin in wound healing is proposed. Thirdly, the applications of keratin-based wound dressings are summarized, in terms of the forms and functionalization. Finally, the current challenges and future development of keratin-based wound dressings are presented.

Alginate/gelatin-based hybrid hydrogels with function of injecting and encapsulating cells in situ

Multi-network hydrogels with high strength and toughness have attracted increasing attention. Herein, a hybrid hydrogel consisting of alginate, gelatin, and polyacrylamide was constructed with the combination of advantages of natural and synthetic polymers. Alginate grafted with host-guest complex of βCD/Ad-AAm was first prepared, namely Alg-βCD/Ad-AAm, then further crosslink with gelatin methacryloyl (GelMA) to form hydrogel via one-step UV light initiation. The hydrogel produced by this method has more uniform and well-crosslinked networks. The hydrogels demonstrated uniform porosity, adjustable hydrophilicity (water contact angle within 32.7-91.5°), and desired mechanical properties (maximum tensile strain of 242.8%, tensile strength of 75.9 kPa, and Young's modulus of 28.5 kPa). The hydrogel also possessed self-healing ability and pH sensitivity, showing higher mechanical tensile strength at lower pH. The temperature-adjustable viscosity of pre-gel solution (sol-gel transition point of 20.4 °C) endowed it to be 3D printed as a bioink, and the printed scaffold exhibited good resilience and toughness. Moreover, HUVEC, L929, and 3T3 cells were cultured on hydrogel surfaces for 28 days and were enveloped within the hydrogels for 3D culture, indicating excellent cytocompatibility of the hydrogels. Therefore, this hybrid hydrogel system can be used potentially in 3D cell culture and tissue engineering.

Sustainable Applications of Animal Waste Proteins

Currently, the growth of the global population leads to an increase in demand for agricultural products. Expanding the obtaining and consumption of food products results in a scale up in the amount of by-products formed, the development of processing methods for which is becoming an urgent task of modern science. Collagen and keratin make up a significant part of the animal origin protein waste, and the potential for their biotechnological application is almost inexhaustible. The specific fibrillar structure allows collagen and keratin to be in demand in bioengineering in various forms and formats, as a basis for obtaining hydrogels, nanoparticles and scaffolds for regenerative medicine and targeted drug delivery, films for the development of biodegradable packaging materials, etc. This review describes the variety of sustainable sources of collagen and keratin and the beneficial application multiformity of these proteins.