Novel fibrous collagen-based cream accelerates fibroblast growth for wound healing applications: in vitro and in vivo evaluation

Recombinant collagen for the repair of skin wounds and photo-aging damage

The skin, being the body's primary defense mechanism, is susceptible to various injuries such as epidermal wounds, natural aging, and ultraviolet-induced damage. As a result, there is growing interest in researching skin repair methods. Traditional animal-derived collagen, widely available on the market, poses risks due to its immunogenicity and potential for viral contamination. In contrast, recombinant collagen sourced from human genes offers a safer alternative. To investigate the potential of human recombinant collagen in skin repair, our research team applied two types, type I human collagen (Col I) and CF-1552(I), to two different skin injury models: a wound-healing model and a photo-aging model. Our findings indicate that both Col I and CF-1552(I) effectively enhance wound healing and repair skin damaged by ultraviolet exposure. Notably, CF-1552(I) showed effects comparable to Col I in promoting cell proliferation in the wound-healing model and increasing malondialdehyde content in the photo-aging model, suggesting that CF-1552(I) may offer greater potential for skin repair compared to the larger Col I molecule.

Physicochemical properties and cell proliferation and adhesive bioactivity of collagen-hyaluronate composite gradient membrane

Membrane materials were widely used in guided tissue regeneration (GTR) to prevent fibroblast invasion and form a confined area for preferentially growing of osteoblast. A novel collagen-hyaluronate composite gradient membrane was prepared by Tilapia (Oreochromis mossambicus) skin collagen and sodium hyaluronate for potential GTR applications and their bioactivities were investigated by cellular viability. SEM results indicated the membrane showed a dense outer and a porous inner surface for effectively guiding the growth of bone tissue. Physicochemical and biosafety experiments showed the tensile strength of membrane was 466.57 ± 44.31 KPa and contact angle was 74.11°, and the membrane showed perfect biocompatibility and cytocompatibility as well, which met the requirements of GTR material. Cell morphology revealed that the membrane could facilitate the adherence and proliferation of fibroblast and osteoblast. The results of qRT-PCR and ELISA demonstrated that the membrane could effectively activate TGF-β/Smad pathway in fibroblast, and promote the expressions of TGF-β1, FN1 and VEGF. Remarkably, RUNX2 was stimulated in BMP2 pathway by the membrane to regulate osteoblast differentiation. In summary, the collagen-hyaluronate composite gradient membrane not only fulfills the prerequisites for use as a GTR material but also demonstrates substantial potential for practical applications in the field.

Characterizing polyproline II conformational change of collagen superhelix unit on adsorption on gold surface

The dynamic process of protein binding onto a metal surface is a frequent occurrence as gold nanoparticles are increasingly being used in biomedical applications, including wound treatment and drug transport. Collagen, as a major component of the extracellular matrix, has potentially advantageous biomedical applications, due to its excellent biocompatibility and elasticity properties. Therefore, a mechanistic comprehension of how and which species in collagen interact with gold nanoparticles is a prerequisite for collagen-gold complexes in clinical application. However, the dynamic behavior of collagen with the polyproline II (PPII) conformation on gold sheets at the molecular level is too complex to capture under current experimental conditions. Here, using molecular dynamics simulations, we investigate the adsorption process and conformational behavior of the tripeptide Gly-Pro-Hyp with the repetitive unit of the collagen superhelix on the gold surface as a function of number of repeating units from 1 to 10. The different numbers of repeating units all prefer to approach the gold surface and adsorb via charged residues at the C-terminal or N-terminal ends, tending to form arch structures on the gold surface. Compared with the various tripeptide units in solution still retaining the native PPII conformation, the presence of the gold surface affects the formation of hydrogen bonds between the protein and water molecules, thus disrupting the PPII conformation of collagen. Specifically, the interaction between the gold surface and HYP limits the rotation of the dihedral angle of collagen, resulting in a tendency for the PPII conformation of the gold surface to transform to the β-sheet conformation. The results provide an indication of how to improve the interaction between the terminal groups and the gold surface for the design of a bioavailable protein-gold material for medicinal purposes.

In Vivo Skin Hydrating Efficacy of Fish Collagen from Greenland Halibut as a High-Value Active Ingredient for Cosmetic Applications

The industrial processing of fish for food purposes also generates a considerable number of by-products such as viscera, bones, scales, and skin. From a value-added perspective, fish by-products can act also as raw materials, especially because of their collagen content (particularly in fish skin). Interestingly, the potential of marine collagen for cosmetic applications is enormous and, remarkably, the extraction of this protein from fish skins has been established for different species. Using this approach, we investigated the integration of marine collagen (COLRp_I) extracted from the skin of the Greenland halibut as an active ingredient in a cosmetic hydrogel formulation. In this study, extracts of marine collagen at concentrations up to 10 mg/mL showed a non-cytotoxic effect when cultured with fibroblast cells for 3 days. In addition, marine collagen extract, when incorporated into a cosmetic hydrogel formulation, met criterion A of ISO 11930:2019 regarding the efficacy of the preservative system (challenge test). In addition, the cosmetic formulations based on marine collagen at dosages of 0.1, 0.25 and 0.5% were tested in a clinical study on the skin of the forearms of 23 healthy volunteers, showing a sightly hydration effect, suggesting its potential for beauty applications. Moreover, this work illustrates that the circular economy concept applied to the fish processing industry can represent important benefits, at innovation, environmental and economic levels.

Soft substrates promote direct chemical reprogramming of fibroblasts into neurons

Fibroblasts can be directly reprogrammed via a combination of small molecules to generate induced neurons (iNs), bypassing intermediate stages. This method holds great promise for regenerative medicine; however, it remains inefficient. Recently, studies have suggested that physical cues may improve the direct reprogramming of fibroblasts into neurons, but the underlying mechanisms remain to be further explored, and the physical factors reported to date do not exhibit the full properties of the extracellular matrix (ECM). Previous in vitro studies mainly used rigid polystyrene dishes, while one of the characteristics of the native in-vivo environment of neurons is the soft nature of brain ECM. The reported stiffness of brain tissue is very soft ranging between 100 Pa and 3 kPa, and the effect of substrate stiffness on direct neuronal reprogramming has not been explored. Here, we show for the first time that soft substrates substantially improved the production efficiency and quality of iNs, without needing to co-culture with glial cells during reprogramming, producing more glutamatergic neurons with electrophysiological functions in a shorter time. Transcriptome sequencing indicated that soft substrates might promote glutamatergic neuron reprogramming through integrins, actin cytoskeleton, Hippo signalling pathway, and regulation of mesenchymal-to-epithelial transition, and competing endogenous RNA network analysis provided new targets for neuronal reprogramming. We demonstrated that soft substrates may promote neuronal reprogramming by inhibiting microRNA-615-3p-targeting integrin subunit beta 4. Our findings can aid the development of regenerative therapies and help improve our understanding of neuronal reprogramming. STATEMENT OF SIGNIFICANCE: : First, we have shown that low stiffness promotes direct reprogramming on the basis of small molecule combinations. To the best of our knowledge, this is the first report on this type of method, which may greatly promote the progress of neural reprogramming. Second, we found that miR-615-3p may interact with ITGB4, and the soft substrates may promote neural reprogramming by inhibiting microRNA (miR)-615-3p targeting integrin subunit beta 4 (ITGB4). We are the first to report on this mechanism. Our findings will provide more functional neurons for subsequent basic and clinical research in neurological regenerative medicine, and will help to improve the overall understanding of neural reprogramming. This work also provides new ideas for the design of medical biomaterials for nerve regeneration.

In vitro and in vivo biocompatibility of decellularized cellulose scaffolds functionalized with chitosan and platelet rich plasma for tissue engineering applications

This study describes the fabrication of cellulose scaffold (CS) and cellulose-chitosan (CS/CHI) scaffolds from the immature endosperm of Borassus flabellifer (Linn.) (BF) loaded with platelet rich plasma (PRP). Thus, developed scaffolds were evaluated for their physicochemical and mechanical behavior, growth factor release and biological performance. Additionally, in vivo response was assessed in a sub cutaneous rat model to study vascularization, host inflammatory response and macrophage polarization. The results of this study demonstrated that CS and CS/CHI scaffolds with PRP demonstrated favorable physiochemical and morphogical properties. The scaffold groups CS-PRP and CS/CHI-PRP were able to release growth factors in a well sustained manner under physiological conditions. The presence of PRP in cellulosic scaffolds did show significant differences in their behavior when investigated under in vitro studies, where the release of diverse cytokines improved the cellular proliferation and differentiation of osteoblasts. Finally, the PRP enriched scaffolds when studied under in vivo conditions showed increased angiogenesis and re-epithelialization with adequate collagen deposition and tissue remodeling. Our results suggest that besides the conventional carrier systems, this new-generation of plant-based cellulosic scaffolds with/without any modification can serve as a suitable carrier for PRP encapsulation and release, which can be used in numerous tissue regenerative therapies.

Anticancer effect of locally applicable aptamer-conjugated gemcitabine-loaded atelocollagen patch in pancreatic cancer patient-derived xenograft models

We investigated the anticancer effect of the aptamer-conjugated gemcitabine-loaded atelocollagen patch in a pancreatic cancer patient-derived xenograft (PDX) model to propose a future potential adjuvant surgical strategy during curative pancreatic resection for pancreatic cancer. A pancreatic cancer PDX model was established. Animals were grouped randomly into a no-treatment control group; treatment group treated with intraperitoneal gemcitabine injection (IP-GEM) or aptamer-conjugated gemcitabine (APT:GEM); and transplant with three kinds of patches: atelocollagen-aptamer-gemcitabine (patch I), atelocollagen-inactive aptamer-gemcitabine (patch II), and atelocollagen-gemcitabine (patch III). Tumor volumes and response were evaluated based on histological analysis by H&E staining and Immunohistochemistry (IHC) was performed. Anticancer therapy-related toxicity was evaluated by hematologic findings. The patch I group showed the most significant reduction of tumor growth rate, compared with the no-treatment group (p < 0.05). However, other treatment groups were not found to show significant reduction in tumor growth rate (0.05 < p < 0.1). There was no microscopic evidence suggesting potential toxicity, such as inflammation, nor necrotic changes in liver, lung, kidney, and spleen tissue. In addition, no leukopenia, anemia, or neutropenia was observed in the patch I group. This implantable aptamer-drug conjugate system is thought to be a new surgical strategy to augment the oncologic significance of margin-negative resection in treating pancreatic cancer in near future.

Safety and Efficacy of Collagen-Based Biological Dressings in the Management of Chronic Superficial Skin Wounds in Non-Complex Trauma: A Post-Marketing Surveillance Study

Biological dressings such as collagen and hyaluronic acid represent the main advanced tools that plastic surgeons, dermatologists and vulnologists use today to treat chronic wounds or ulcers that do not tend to heal. These types of dressings are important because they create a moist and physiological interface at the wound level, are of natural origin, easy to use, hypo-allergenic, economical and do not create discomfort for the patient during dressing changes. We treated 128 patients (divided into four groups based on type of dressing) with non-complex superficial chronic wounds in comparison with a traditional dressing (fitostimoline gauze or polyurethane foam). We analyzed wound characteristics, healing time, and operator and patient satisfaction. A significantly higher recovery rate was observed in the “Collagen-coated plates” treatment group compared to Standard Treatment. Additionally, a significantly higher probability of recovery was observed compared to the alternative two experimental devices (Collagen-coated plates + HA and Collagen-based spray). However, the main limitation of the randomization of this study is the presence in the “Collagen-based spray” group of localized wounds, mainly in the fingers and hand. No side effects were reported in relation to the procedures or the experimental products. Collagen may be considered as a valuable therapeutic tool in non-complex chronic wounds by virtue of its low immunogenicity, flexibility and applicability in biocompatible scaffolds, and represents driving force toward enhanced wound care.

Decellularized natural 3D cellulose scaffold derived from Borassus flabellifer (Linn.) as extracellular matrix for tissue engineering applications

In this study, Borassus flabellifer (Linn.) (BF) immature endosperm was decellularized to produce three dimensional (3D) cellulose scaffolds that can support mammalian 3D cell culture. To this regard, we first evaluated the chemical composition, nutritive profile and pharmacological activities of BF endosperm. The results demonstrated that the BF tissue represented a complex concoction of polysaccharides with intrinsic phyto-ingredients which provide excellent pharmacological properties. Furthermore cellulosic scaffolds (CS) obtained from BF was treated with chitosan to produce cellulose-chitosan (CS/CHI) hybrid scaffolds. The comparative investigation on both scaffolds exhibited adequate swelling with controlled porosity and pore-size distribution. The physiochemical characterization showed reduced biodegradation, improved thermal stability and enhanced compressive strength in CS/CHI group. Biological studies reported favorable adhesion and proliferation of fibroblasts with evident cellular penetration and colonization on the both scaffolds. Taken together, plant derived cellulosic scaffolds could be used as an alternative scaffolding material in regenerative medicine.

Collagen-based formulations for wound healing: A literature review

Wounds have always been the point of concern owing to the involvement of infections and the level of severity. Therefore, the management of wounds always requires additional effort for comprehensive healing and subsequent removal of the scar from the wound site. The role of biomaterials in the management of chronic wounds has been well established. One of such biomaterials is collagen (Col) that is considered to be the crucial component of most of the formulations being developed for wound healing. The role of Col extracted from marine invertebrates remains an unmarked origin of the proteinaceous constituent in the evolution of innovative pharmaceuticals. Col is a promising, immiscible, fibrous amino acid of indigenous origin that is ubiquitously present in extracellular matrices and connective tissues. There are different types of Col present in the body such as type I, II, III, IV, and V however the natural sources of Col are vegetables and marine animals. Its physical properties like high tensile strength, adherence nature, elasticity, and remodeling contribute significantly in the wound healing process. Col containing formulations such as hydrogels, sponges, creams, peptides, and composite nanofibers have been utilized widely in wound healing and tissue engineering purposes truly as the first line of defense. Here we present the recent advancements in Col based dosage forms for wound healing. The Col based market of topical preparations and the published reports identify Colas a useful biomaterial for the delivery of pharmaceuticals and a platform for tissue engineering.

Self-Assembled Nanofibrous Marine Collagen Matrix Accelerates Healing of Full-Thickness Wounds

There is an urgent clinical need for wound dressings to treat skin injuries, particularly full-thickness wounds caused by acute and chronic wounds. Marine collagen has emerged as an attractive and safer alternative due to its biocompatibility, diversity, and sustainability. It has minimum risk of zoonotic diseases and less religious constraints as compared to mammalian collagen. In this study, we reported the development of a self-assembled nanofibrous barramundi (Lates calcarifer) collagen matrix (Nano-BCM), which showed good biocompatibility for full-thickness wound-healing applications. The collagen was extracted and purified from barramundi scales and skin. Thereafter, the physicochemical properties of collagen were systematically evaluated. The process to extract barramundi skin collagen (BC) gave an excellent 45% yield and superior purity (∼100%). More importantly, BC demonstrated structural integrity, native triple helix structure, and good thermal stability. BC demonstrated its efficacy in promoting human primary dermal fibroblast (HDF) and immortalized human keratinocytes (HaCaT) proliferation and migration. Nano-BCM has been prepared via self-assembly of collagen molecules in physiological conditions, which resembled the native extracellular matrix (ECM). The clinical therapeutic efficacy of the Nano-BCM was further evaluated in a full-thickness splinted skin wound mice model. In comparison to a clinically used wound dressing (DuoDerm), the Nano-BCM demonstrated significantly accelerated wound closure and re-epithelization. Moreover, Nano-BCM nanofibrous architecture and its ability to facilitate early inflammatory response significantly promoted angiogenesis and differentiated myofibroblast, leading to enhanced wound healing. Consequently, Nano-BCM demonstrates great potential as an economical and effective nonmammalian substitute to achieve skin regeneration.

Natural-Based Biomaterial for Skin Wound Healing (Gelatin vs. Collagen): Expert Review

Collagen (Col) and gelatin are most extensively used in various fields, particularly in pharmaceuticals and therapeutics. Numerous researchers have proven that they are highly biocompatible to human tissues, exhibit low antigenicity and are easy to degrade. Despite their different sources both Col and gelatin have almost the same effects when it comes to wound healing mechanisms. Considering this, the bioactivity and biological effects of both Col and gelatin have been, and are being, constantly investigated through in vitro and in vivo assays to obtain maximum outcomes in the future. With regard to their proven nutritional values as sources of protein, Col and gelatin products exert various possible biological activities on cells in the extracellular matrix (ECM). In addition, a vast number of novel Col and gelatin applications have been discovered. This review compared Col and gelatin in terms of their structures, sources of derivatives, physicochemical properties, results of in vitro and in vivo studies, their roles in wound healing and the current challenges in wound healing. Thus, this review provides the current insights and the latest discoveries on both Col and gelatin in their wound healing mechanisms.

Curcumin Loading on Alginate Nano-Micelle for Anti-Infection and Colonic Wound Healing

Despite the antibacterial, and anti-inflammatory properties of curcumin (C), its effect on wound healing, especially in the colorectal, is ambiguous. Moreover, due to the hydrophobic properties of C, its use is limited. Therefore, to reduce the bioavailability challenge and improve the transfer to colon area, we designed a C-alginate-based nano-micelle (C-A-NM). After fabrication of C-A-NM (55.5 nm) and physicochemical studies with the TEM, DLS and XRD, the C release rate based on gastrointestinal state was evaluated. Furthermore, the effects of C-A-NM on the survival of HCT-8 cells at 24 and 48 hours by MTT method and its antibacterial effects were also evaluated. To explain the effects of wound healing in rats, in addition to colonoscopy on the 14th-day, the repaired tissue on the 7th and 14th days were examined by Hematoxylin and Eosin method. Also, for evaluating wound healing in the colon, the protein/collagen concentration, and TGFβ1/NFκB gene expression were determined. The results of C cumulative release showed that the NM allows the drug to be loaded in the colon in a favourable manner. Also, the toxicity outputs revealed that C-A-NM at a concentration of 7.5 mg had no negative effects on cell viability. While the activity of Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli, bacteria decreased based on the minimum inhibitory concentration value with 153, 245 and 319 (μg/mL). The use of C-A-NM not only increases protein and collagen in damaged sites, but also increases TGFβ1 expression in contrast to NFκB. Based on these results, and the results of histopathology and colonoscopy, it was found that C-A-NM accelerates the healing of damaged areas. Overall, the results show that the use of C-A-NM can significantly accelerate the healing of wounds in the gastrointestinal tract based on collagen induction and reduced bacterial activity.

Effectiveness of Aqueous Extract of Marine Baitworm Marphysa moribidii Idris, Hutchings and Arshad, 2014 (Annelida, Polychaeta), on Acute Wound Healing Using Sprague Dawley Rats

Wound healing is a well-coordinated process that restores skin integrity upon injury. However, some wound treatment poses harmful effects on the skin, which delay the normal wound healing process. Marphysa moribidii, a marine baitworm or polychaete, represents unique ability to regenerate posterior segment after injury, which may be beneficial in the wound healing treatment. The effectiveness of the polychaete as wound healing treatment was discovered through skin irritation, microbial testing, animal wound model, and chemical identifications. Three polychaete extracts (PE) emulsifying ointment (0.1%, 0.5%, and 1.0%) were topically applied to the full thickness wound model once daily for 14 days. Interestingly, PE 1.0% revealed the most rapid wound healing effects as compared to other treatments, including gamat (sea cucumber) oil (15% w/v) and acriflavine (0.1% w/v). Histopathological analysis using Masson's trichrome staining further confirms that PE treated wound exhibited minimal scar, high collagen deposition, and the emergence of neovascularisation. The extract also displayed a minimum inhibitory concentration (MIC) of 0.4 g/ml against Escherichia coli and absence of skin irritation, infectious bacteria, and heavy metals from the extract. Moreover, chemical compounds such as alkaloid, flavonoid, amino acids, and organic acid were detected in M. moribidii extracts, which could contribute to wound healing activity. In conclusion, this study further justifies the beneficial use of polychaete in treating wound healing and could be developed as a novel bioactive agent in nutraceuticals and pharmaceutical drugs.

COLLAGEN: STRUCTURE, METABOLISM, PRODUCTION AND INDUSTRIAL APPLICATION

This review presents the current scientific literature data about structure, properties, and functions of collagen, which is known as one of the most abundant human and animal proteins. The building of collagen molecule from the primary structure to submolecular formations, the main stages of its synthesis and biodegradation are briefly described. The information about collagen diversity, its features and metabolic ways in various tissues, including skin, tendons, bones, etc. is presented. The problems of pathologies caused by collagen synthesis and breakdown disorders as well as age-related changes in collagen properties and their causes are discussed. A comparative analysis of the advantages and disadvantages of collagen and its derivatives obtaining from various sources (animals, marine, and recombinant) is given. The most productive methods for collagen extraction from various tissues are shown. The concept of collagen hydrolysis conditions influence on the physicochemical properties and biological activity of the obtained products is described. The applications of collagen and its products in various fields of industrial activity, such as pharmaceutical, cosmetic industry and medicine, are discussed. Further prospective directions of fundamental and applied investigations in this area of research are outlined.

Sustainability of food waste biorefinery: A review on valorisation pathways, techno-economic constraints, and environmental assessment

The need to increase circularity of industrial systems to address limited resources availability and climate change has triggered the development of the food waste biorefinery concept. However, for the development of future sustainable industrial processes focused on the valorisation of food waste, critical aspects such as (i) the technical feasibility of the processes at industrial scale, (ii) the analysis of their techno-economic potential, including available quantities of waste, and (iii) a life cycle-based environmental assessment of benefits and burdens need to be considered. The goal of this review is to provide an overview of food waste valorisation pathways and to analyse to which extent these aspects have been considered in the literature. Although a plethora of food waste valorisation pathways exist, they are mainly developed at lab-scale. Further research is necessary to assess upscaled performance, feedstock security, and economic and environmental assessment of food waste valorisation processes.

The immunologic changes during different phases of intestinal anastomotic healing

Intestinal anatomosis is a complex and multicellular process that involving three overlapped phases: exudative phase, proliferative phase, and reparative phase. Undisturbed anastomotic healings are crucial for the recovery of patients after operations but unsuccessful healings are linked with a considerable mortality. This time, we concentrate on the immunologic changes during different phases of intestinal anastomotic healing and select several major immune cells and cytokines of each phase to get a better understanding of these immunologic changes in different phases, which will be significant for more precise therapy strategies in anastomoses.

Hybrid Freeze-Dried Dressings Composed of Epidermal Growth Factor and Recombinant Human-Like Collagen Enhance Cutaneous Wound Healing in Rats

Epidermal growth factor (EGF) is important for promoting skin repair and remodeling. Native collagen is also widely used as a scaffold for skin tissue engineering. The limitations of EGF include easy decomposition or inactivation, whereas native collagen is immunogenic and has poor solubility. Therefore, we constructed a freeze-dried dressing based on the recombinant human-like collagen (RHC) to act as a carrier for EGF (RHC/EGF freeze-dried dressing) and promote skin wound closure. Here, the freeze-dried dressing that combined EGF and RHC significantly enhanced the proliferation, adhesion, and spreading of NIH/3T3 fibroblasts and migration of HaCaT keratinocytes at the wound site. The physicochemical characteristics of the RHC/EGF freeze-dried dressing investigated using scanning electron microscopy, Fourier transform infrared (FTIR) spectroscopy, and differential scanning calorimetry revealed that it was a loose and porous cake that redissolved quickly. The molecular mechanisms involved in cell proliferation and angiogenesis were also assessed. The expression levels of the markers Ki-67, proliferating cell nuclear antigen, vascular endothelial growth factor, and cluster of differentiation 31 were significantly increased after treatment with the RHC/EGF freeze-dried dressing (P < 0.01, vs. RHC or EGF alone). This increase indicated that the RHC/EGF freeze-dried dressing significantly accelerated wound closure, re-epithelialization, and the orderly arrangement and deposition of collagen in the Sprague–Dawley rats with full-thickness skin defects. This work describes a significant step toward the development of wound environments conducive to healing, and the RHC/EGF freeze-dried dressing is a potential therapeutic strategy in wound management.

Biogenic silver nanoparticles as a more efficient contrivance for wound healing acceleration than common antiseptic medicine

A simple and facile way of using biogenic silver nanoparticles (BSNP) (10-20 nm) was developed for wound healing acceleration and suppression of wound infections. The BSNP were formulated in an ointment base, and the study to accelerate the wound healing process was conducted in a rat. The pH of the BSNP ointment, pH 6.8 ± 0.5, lies in normal pH range of the human skin, with good spreadability and diffusibility. The wound closure rate, as a percentage, was highest at day 3 for a BSNP ointment-treated wound at 22.77 ± 1.60%, while in an untreated control the rate was 10.99 ± 1.74%, for Betadine 14.73 ± 2.36% and for Soframycin 18.55 ± 1.37%, compared with day 0. A similar pattern of wound closure rate was found at days 7 and 11. The antibacterial activity of BSNP was evaluated against wound-infection-causing bacteria Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli by the agar diffusion method. The total bacterial counts in the wound area were enumerated by the colony forming unit method. The lowest number of bacterial counts was found in the BSNP-treated wound compared with the other groups. BSNP treatment at 7.5% concentration enhanced migration of fibroblasts in a scratch assay. These findings reveal BSNP as an efficient contrivance for wound healing acceleration and as an eco-friendly alternative therapeutic antimicrobial agent.

Biofunctions of antimicrobial peptide-conjugated alginate/hyaluronic acid/collagen wound dressings promote wound healing of a mixed-bacteria-infected wound

The increase in severe infections caused by antibiotic drug resistance and the decrease in the number of new antibacterial drugs approved for use in the last few decades are driving the need for the development of new antimicrobial strategies. Antimicrobial peptides (AMPs) are a potential new class of antimicrobial drugs that are expected to solve the problem of global antibiotic drug resistance. Herein, the AMP Tet213 was immobilised onto the substrates of alginate (ALG), hyaluronic acid (HA), and collagen (COL) to form the ALG/HA/COL-AMP wound dressing. This wound dressing exhibited a high degree of swelling and the appropriate porosity, mechanical properties, and biodegradability. The Tet213-immobilised ALG/HA/COL dressings exhibited antimicrobial activity against three pathogenic bacterial strains (Gram-negative E. coli and Gram-positive MRSA and S. aureus) and facilitated the proliferation of NIH 3T3 fibroblast cells. In addition, the ALG/HA/COL-AMP antimicrobial dressings promoted wound healing, re-epithelialisation, collagen deposition, and angiogenesis. Moreover, the wound-healing effects of ALG/HA/COL-AMP surpassed the gauze and ALG/HA/COL compared to commercially available silver-based dressings (Aguacel Ag). These results suggest that the Tet213-conjugated ALG/HA/COL wound dressing, with its multiple biological activities, is a promising wound-dressing material.

Physicochemical, antioxidant properties of giant croaker (Nibea japonica) swim bladders collagen and wound healing evaluation

Acid-solubilized collagen (ASC) and pepsin-solubilized collagen (PSC) were obtained from Nibea japonica swim bladders. The denaturation temperature (Td) of ASC and PSC was approximately 33.8 °C. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Fourier transform infrared spectroscopy (FTIR) analyses indicated that ASC and PSC contained triple-helical type I collagen when compared to rat tail collagen type I. Moreover, the microstructure of collagen sponges was uniform and porous. In addition, ASC and PSC exhibited antioxidant properties and in vitro scratch assays showed that PSC at various concentrations (0, 12.5, 25, and 50 μg/mL) had significant effects on the scratch closure rate. Furthermore, collagen sponge from Nibea japonica swim bladders exhibited an increased efficacy of wound healing when compared to the control mice. The levels of interleukin (IL)-1β, IL-6 and tumor necrosis factor (TNF)-α in the collagen sponge treated mice were significantly decreased when compared to the control group. Thus, our results suggested that collagen sponge from Nibea japonica swim bladders has potential wound healing applications.

Interaction of gold nanosurfaces/nanoparticles with collagen-like peptides

Nanotechnology has quickly emerged as a promising research field with potential effects in disease treatments. For example, gold nanoparticles (AuNPs) have been extensively used in diagnostics and therapeutics. When administrated into human tissues, AuNPs first encounter extracellular matrix (ECM) molecules. Amongst all the ECM components, collagen is the main tension-resisting constituent, whose biofunctional and mechanical properties are strongly dependent on its hierarchical structure. Therefore, an in-depth understanding of the structural response of collagen to the presence of gold nanosurfaces (AuNS) and AuNPs is crucial in terms of clinical applications of AuNPs. However, detailed understanding of the molecular-level and atomic-level interaction between AuNS/AuNPs and collagen in the ECM is elusive. In this study, comprehensive molecular dynamics (MD) simulations have been performed to investigate the molecular behaviour of a collagen molecule segment (CMS) in the presence of AuNS/AuNPs in explicit water, aiming to explore the interaction of AuNS/AuNPs with collagen triple helices at the molecular and atomic levels. The results show that the CMS forms a rapid association with AuNS/AuNPs and undergoes a severe unfolding upon adsorption on AuNS/AuNPs, indicating an unfolding propensity of gold surfaces. We conclude that collagen triple helices unfold readily on AuNS and bare AuNPs, due to the interaction of gold surfaces with the protein backbone. The revealed clear unfolding nature and the unravelled atomic-level unfolding mechanism of collagen triple helices onto AuNPs contribute to the development of AuNPs for biomedical and therapeutic applications, and the design of gold-binding proteins.

Hybrid cellulose nanocrystal/alginate/gelatin scaffold with improved mechanical properties and guided wound healing

Nature derived biopolymers such as polysaccharides and collagen have attracted considerable attention in biomedical applications. Despite excellent biocompatibility and bioactivity, their poor mechanical properties could not meet the requirement for skin regeneration. In this study, cellulose nanocrystal (CNC) was incorporated into the calcium cross-linked sodium alginate/gelatin (SA/Ge) scaffold to reinforce its physicochemical properties. A novel sodium alginate/gelatin/cellulose nanocrystal (SA/Ge/CNC) scaffold was successfully prepared through electrostatic interaction of sodium alginate and gelatin, ionic cross-linking of calcium ions with sodium alginate, and incorporation of CNC. Afterwards, the SA/Ge and SA/Ge/CNC scaffolds were fully characterized and compared with scanning electron microscopy images, swelling behaviors, tensile strengths and contact angles. The involvement of CNC produces a hybrid SA/Ge/CNC scaffold with desired porous network, moderate swelling behavior, and superior mechanical strength (from 18 MPa to 45 MPa). Furthermore, in vitro cytotoxicity and cell growth assay using mouse embryonic fibroblast cells validated that SA/Ge/CNC scaffold was non-toxic and can prompt cell adhesion and proliferation. The in vivo skin regeneration experiments using the SA/Ge/CNC scaffold group showed an improved skin wound healing process with accelerated re-epithelialization, increased collagen deposition and faster extracellular matrix remodeling. Overall, the results suggested that the SA/Ge/CNC hybrid scaffold with enhanced mechanical performance and wound healing efficacy was a promising biomaterial for skin defect regeneration.

Cellulose nanocrystal (CNC) is incorporated into Ca²⁺ cross-linked alginate/gelatin (SA/Ge) scaffold to improve physical, chemical and biological aspects. The SA/Ge/CNC scaffold with enhanced wound healing efficacy is a promising biomaterial for skin defect regeneration.

A novel microporous oxidized bacterial cellulose/arginine composite and its effect on behavior of fibroblast/endothelial cell

The bacterial cellulose (BC) has been reported widely. Although there are many methods to modify BC, such as the oxidized BC, which is biodegradable and can be used as wound dressing. However, the nanostructure of BC makes it difficult to be oxidized. Importantly, high oxidation degree makes the content of aldehyde high, which make the cell biocompatibility poor. Herein, we fabricated a novel bio-composite based on microporous oxidized BC (MOBC) and in-situ grafted with Arg. The micropores can increase the contact area between BC and oxidizing agent and the reaction between MOBC and Arg, which will enhance the biocompatibility. The roughness and surface energy of MOBC/68.68%Arg are 1.5 and 1.16 times than that of BC respectively. We applied a microfluidic chip to evaluate the cell migration. Comparing with BC, MOBC/Arg promoted proliferation, migration and expression of Collagen-I of fibroblasts and endothelial cells. It prospects the MOBC/Arg can be used as wound dressing.