Study of the mechanism of environmentally friendly translucent balsa-modified lysozyme dressing for facilitating wound healing

Multifunctional Adhesive Hydrogels: From Design to Biomedical Applications

Adhesive hydrogels characterized by structural properties similar to the extracellular matrix, excellent biocompatibility, controlled degradation, and tunable mechanical properties have demonstrated significant potential in biomedical applications, including tissue engineering, biosensors, and drug delivery systems. These hydrogels exhibit remarkable adhesion to target substrates and can be rationally engineered to meet specific requirements. In recent decades, adhesive hydrogels have experienced significant advancements driven by the introduction of numerous multifunctional design strategies. This review initially summarizes the chemical bond-based design strategies for tissue adhesion, encompassing static covalent bonds, dynamic covalent bonds, and non-covalent interactions. Subsequently, the multiple functionalities imparted by these diverse design strategies, including highly stretchable and tough performances, responsiveness to microenvironments, anti-freezing/heating properties, conductivity, antibacterial activity, and hemostatic properties are discussed. In addition, recent advances in the biomedical applications of adhesive hydrogels, focusing on tissue repair, drug delivery, medical devices, and wearable sensors are reviewed. Finally, the current challenges are highlighted and future trends in this rapidly evolving field are discussed.

Film-forming polymer solutions containing cholesterol myristate and berberine mediate pressure ulcer repair via the Wnt/β-catenin pathway

Pressure ulcer (PU) is a worldwide problem that is difficult to address because of the related inflammatory response, local hypoxia, and repeated ischaemia/reperfusion, causing great suffering and financial burden to patients. Traditional Chinese medicine turtle plate powder can treat skin trauma, but its composition is complex and inconvenient to use. Here, we combined cholesterol myristate (S8) with berberine (BBR), with anti-inflammatory and antibacterial effects, as a drug and used hydroxypropyl methylcellulose and polyvinylpyrrolidone K30 as carriers to construct a novel film-forming polymeric solution (S8 + BBR FFPS), comprehensively study its reparative effect on PU and explore the potential mechanism in rat PU models. The results showed that S8 + BBR FFPS inhibits excessive inflammatory response, promotes re-epithelialization, and promotes hair follicle growth during the healing process of PU, which may be related to the activation of the Wnt/β-catenin signalling pathway by S8 + BBR FFPS to mediate hair follicle stem cell proliferation and maintain skin homeostasis. Therefore, S8 + BBR FFPS may be a potential candidate for the treatment of chronic skin injury, and its association with the Wnt/β-catenin signalling pathway may provide new ideas to guide the design of biomaterial-based wound dressings for chronic wound repair.

Self-Adaptive Antibacterial Scaffold with Programmed Delivery of Osteogenic Peptide and Lysozyme for Infected Bone Defect Treatment

Bone defects caused by disease or trauma are often accompanied by infection, which severely disrupts the normal function of bone tissue at the defect site. Biomaterials that can simultaneously reduce inflammation and promote osteogenesis are effective tools for addressing this problem. In this study, we set up a programmed delivery platform based on a chitosan scaffold to enhance its osteogenic activity and prevent implant-related infections. In brief, the osteogenic peptide sequence (YGFGG) was modified onto the surface of cowpea chlorotic mottle virus (CCMV) to form CCMV-YGFGG nanoparticles. CCMV-YGFGG exhibited good biocompatibility and osteogenic ability in vitro. Then, CCMV-YGFGG and lysozyme were loaded on the chitosan scaffold, which exhibited a good antibacterial effect and promoted bone regeneration for infected bone defect treatment. As a delivery platform, the scaffold showed staged release of lysozyme and CCMV-YGFGG, which facilitates the regeneration of infected bone defects. Our study provides a novel and promising strategy for the treatment of infected bone defects.

Bilayer hydrogel dressing with lysozyme-enhanced photothermal therapy for biofilm eradication and accelerated chronic wound repair

Biofilms are closely associated with the tough healing and dysfunctional inflammation of chronic wounds. Photothermal therapy (PTT) emerged as a suitable alternative which could destroy the structure of biofilms with local physical heat. However, the efficacy of PTT is limited because the excessive hyperthermia could damage surrounding tissues. Besides, the difficult reserve and delivery of photothermal agents makes PTT hard to eradicate biofilms as expectation. Herein, we present a GelMA-EGF/Gelatin-MPDA-LZM bilayer hydrogel dressing to perform lysozyme-enhanced PTT for biofilms eradication and a further acceleration to the repair of chronic wounds. Gelatin was used as inner layer hydrogel to reserve lysozyme (LZM) loaded mesoporous polydopamine (MPDA) (MPDA-LZM) nanoparticles, which could rapidly liquefy while temperature rising so as to achieve a bulk release of nanoparticles. MPDA-LZM nanoparticles serve as photothermal agents with antibacterial capability, could deeply penetrate and destroy biofilms. In addition, the outer layer hydrogel consisted of gelatin methacryloyl (GelMA) and epidermal growth factor (EGF) promoted wound healing and tissue regeneration. It displayed remarkable efficacy on alleviating infection and accelerating wound healing in vivo. Overall, the innovative therapeutic strategy we came up with has significant effect on biofilms eradication and shows promising application in promoting the repair of clinical chronic wounds.

Antibacterial activity of lysozyme-loaded cream against MRSA and promotion of scalded wound healing

Staphylococcus aureus (S. aureus) infection, especially its drug-resistant bacterial infection, is a great challenge often faced by clinicians and patients, and it is also one of the most important threats to public health. Finding a safe and effective antibacterial agent is of great significance for the prevention and treatment of S. aureus infection. Lysozyme is known to have antibacterial effects against Gram-positive bacteria including S. aureus. Here, high-quality lysozyme with a purity of more than 99% and an activity of more than 60, 000 U/mg was prepared from egg white, which showed excellent antibacterial activity against three strains of S. aureus, especially against MRSA. Furthermore, an antibacterial cream loaded with lysozyme was prepared and tested in scald wound healing. The lysozyme-loaded cream exhibited the effect of preventing wound infection and promoting wound healing on scalds, and no toxicity was found in animal organs. Overall, lysozyme showed great application potential in the prevention and treatment of infections caused by S. aureus and scalded wound healing. The most remarkable discovery in this work is the unexpectedly powerful inhibitory effect of lysozyme on the drug-resistant bacterial, especially MRSA, which is usually very difficult to deal with using normal antibacterial drugs.

Protein-Based Systems for Topical Antibacterial Therapy

Recently, proteins are gaining attention as potential materials for antibacterial therapy. Proteins possess beneficial properties such as biocompatibility, biodegradability, low immunogenic response, ability to control drug release, and can act as protein-mimics in wound healing. Different plant- and animal-derived proteins can be developed into formulations (films, hydrogels, scaffolds, mats) for topical antibacterial therapy. The application areas for topical antibacterial therapy can be wide including bacterial infections in the skin (e.g., acne, wounds), eyelids, mouth, lips, etc. One of the major challenges of the healthcare system is chronic wound infections. Conventional treatment strategies for topical antibacterial therapy of infected wounds are inadequate, and the development of newer and optimized formulations is warranted. Therefore, this review focuses on recent advances in protein-based systems for topical antibacterial therapy in infected wounds. The opportunities and challenges of such protein-based systems along with their future prospects are discussed.

Applications of Lysozyme, an Innate Immune Defense Factor, as an Alternative Antibiotic

Lysozyme is a ~14 kDa protein present in many mucosal secretions (tears, saliva, and mucus) and tissues of animals and plants, and plays an important role in the innate immunity, providing protection against bacteria, viruses, and fungi. Three main different types of lysozymes are known: the c-type (chicken or conventional type), the g-type (goose type), and the i-type (invertebrate type). It has long been the subject of several applications due to its antimicrobial properties. The problem of antibiotic resistance has stimulated the search for new molecules or new applications of known compounds. The use of lysozyme as an alternative antibiotic is the subject of this review, which covers the results published over the past two decades. This review is focused on the applications of lysozyme in medicine, (the treatment of infectious diseases, wound healing, and anti-biofilm), veterinary, feed, food preservation, and crop protection. It is available from a wide range of sources, in addition to the well-known chicken egg white, and its synergism with other compounds, endowed with antimicrobial activity, are also summarized. An overview of the modified lysozyme applications is provided in the form of tables.

A moisture balanced antibacterial dressing loaded with lysozyme possesses antibacterial activity and promotes wound healing

Wound moisture management is very important in wound healing. Previous wound management has included dry healing and moist healing, and the theory of wound moisture balance is currently generally accepted. However, current studies have not reported which humidity is suitable for wound healing and how to appropriately use antibacterial compounds when the humidity is suitable. Our study explored the moisture balance of polyurethane foam dressings through a moisture balance test and constructed a safe and effective moisture balanced antibacterial dressing by loading lysozyme onto a polyurethane foam dressing. Wound healing experiments showed that the wound healing speed was the fastest when the humidity was 25%. In vivo and in vitro antibacterial experiments showed the superior antibacterial performance of the dressing after lysozyme loading. We loaded lysozyme on moisture balanced polyurethane dressings by means of dopamine adsorption, and the modified dressings were named PU/DA-LYS (polyurethane/dopamine-lysozyme). Experiments on wound healing in infected mice indicated that PU/DA-LYS helps fight infection while promoting wound healing. Cytotoxicity experiments and in vivo biological safety experiments indicated that PU/DA-LYS was safe for use. Our study found that the lysozyme loaded polyurethane dressing can provide appropriate wound moisture and prevent bacterial infection, which is a future developmental direction for wound dressings.

Graphene Oxide/Copper Nanoderivatives-Modified Chitosan/Hyaluronic Acid Dressings for Facilitating Wound Healing in Infected Full-Thickness Skin Defects

PURPOSE

Wound healing, especially of infected wounds, remains a clinical challenge in plastic surgery. This study aimed to manufacture a novel and multifunctional wound dressing by combining graphene oxide/copper nanocomposites (GO/Cu) with chitosan/hyaluronic acid, providing significant opportunities for the therapy of wound repair in wounds with a high risk of bacterial infection.

METHODS

In this study, GO/Cu-decorated chitosan/hyaluronic acid dressings (C/H/GO/Cu) were prepared using sodium trimetaphosphate (STMP) crosslinking and the vacuum freeze-drying method, and chitosan/hyaluronic acid dressings (C/H) and GO-incorporated chitosan/hyaluronic acid dressings (C/H/GO) served as controls. The surface characterization, in vitro degradation under various pH values, antimicrobial potential, cytocompatibility and in vivo therapeutic efficacy in a bacteria-infected full-thickness skin defect model were systematically evaluated.

RESULTS

Our experimental results indicated that the acidic environment facilitated the release of copper (CuNPs and Cu2+) from the dressings, and prepared C/H/GO/Cu dressings exhibited significant in vitro antimicrobial activities against the two tested bacterial strains (ATCC35984 and ATCC25923). All three dressings showed satisfactory cytocompatibility with mouse fibroblasts (NIH/3T3-L1). Moreover, remarkably accelerated wound healing was found in the C/H/GO/Cu group, with controlled inflammatory infiltration and improved angiogenesis in granulation tissues. In addition, no pathological damage was noted in the tissue structures of the tested organs (heart, lung, liver and kidney) in any of the four groups.

CONCLUSION

Collectively, GO/Cu-incorporated chitosan/hyaluronic acid dressings suggested a synergistic antimicrobial efficacy and acceptable biocompatibility both in vitro and in vivo, as well as a significantly accelerated healing process of bacteria-infected wounds. Thus, the multifunctional C/H/GO/Cu composite is expected to be a potential alternative for wound dressings, especially for the management of intractable wounds caused by bacterial infection.

Hyaluronic acid/lysozyme self-assembled coacervate to promote cutaneous wound healing

Traditional hydrogel dressings are limited in practical applications due to the complexity of the preparation and low biocompatibility. So, there is an urgent need to design wound dressing with simple preparation method, higher biocompatibility, and superior therapeutic effect. Additionally, using a polysaccharide/protein mixture system is an attractive method to prepare the gel. In this study, a simple mixture of hyaluronic acid/lysozyme (HL) was used to obtain the HL coacervate gel. HL coacervate has suitable viscoelasticity and excellent adhesion on the skin tissue. We demonstrated its highly efficient self-healing property to overcome fracture or deformation. HL coacervate showed a significant effect on promoting wound healing in a full-thickness skin defect model. Compared to the commercial 3M dressing, it has faster epithelial tissue regeneration and stronger collagen deposition. In addition, cytotoxicity and organ toxicity tests indicated its high safety. In summary, HL coacervate has broad clinical application prospects as a wound dressing material.