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An ideal wound dressing should have excellent antimicrobial properties and provide a suitable microenvironment for regenerating damaged skin tissue. In this study, we utilized sericin to biosynthesize silver nanoparticles in situ and introduced curcumin to obtain Sericin-AgNPs/Curcumin (Se-Ag/Cur) antimicrobial agent. The hybrid antimicrobial agent was then encapsulated in a physically double cross-linking 3D structure network (Sodium alginate-Chitosan, SC) to obtain the SC/Se-Ag/Cur composite sponge. The 3D structural networks were constructed through electrostatic interactions between sodium alginate and chitosan and ionic interactions between sodium alginate and calcium ions. The prepared composite sponges have excellent hygroscopicity (contact angle 51.3° ± 5.6°), moisture retention ability, porosity (67.32 % ± 3.37 %), and mechanical properties (>0.7 MPa) and exhibit good antibacterial ability against Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus). In addition, in vivo experiments have shown that the composite sponge promotes epithelial regeneration and collagen deposition in wounds infected with S. aureus or P. aeruginosa. Tissue immunofluorescence staining analysis confirmed that the SC/Se-Ag/Cur complex sponge stimulated upregulated expression of CD31 to promote angiogenesis while downregulating TNF-α expression to reduce inflammation. These advantages make it an ideal candidate for infectious wound repair materials, providing an effective repair strategy for clinical skin trauma infections., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)

Trade-off of high-strength and dynamic crosslinking of hydrogels remains an enormous challenge. Motivated by the self-healing property of biological tissues, the strategy of combining multiple dynamic bond mechanisms and a polysaccharide network is proposed to fabricate biomimetic hydrogels with sufficient mechanical strength, injectability, biodegradability, and self-healing property for bone reconstruction engineering. Stable acylhydrazone bonds endowed hydrogels with robust mechanical strength (>10 kPa). The integration of dynamic imine bonds and acylhydrazone bonds optimized the reversible characteristic to protect the cell during the injection and mimicked ECM microenvironment for cell differentiation as well as rapid adapting bone defect area. Furthermore, due to the slow enzymatic hydrolysis kinetics of chitosan and the self-healing properties of resulting networks, hydrogels exhibited a satisfactory biodegradation period (>8 weeks) that highly matches with bone regeneration. Additionally, rBMSC-laden hydrogels exhibited splendid osteogenic induction and bone reconstruction without prefabrication scaffolds and incubation, demonstrating tremendous potential for clinical application. This work proposes an efficient strategy for the construction of a low-cost multifunctional hydrogel, making polysaccharide-based hydrogels as the optimal carrier for enabling cellular functions in bone repair.

The development of wound dressings with hemostatic and antibacterial properties has attracted great attention. In this study, we prepared a multi-functional natural substance sponge (CMC/Ser-Ag/HNT) composed of carboxymethyl chitosan (CMC), sericin-silver nanoparticle (Ser-Ag), and halloysite (HNT). CMC/Ser-Ag/HNT sponge was demonstrated to bear desired hygroscopicity, porosity, compressive strength and compressive stability, cytocompatibility, and hemocompatibility. The mechanical properties (compressive strength of 100 kPa) and hemostatic capacity (hemostasis time of 15 ± 3 s in the liver injury model and 12 ± 3 s in the caudal injury model) were enhanced by introducing HNT into the CMC sponge. Ser-Ag was synthesized in situ via the redox nature of tyrosine residues in sericin in a "one-step, green" way to enhance the antibacterial activity of the hybrid sponge against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). In addition, the rat full-thickness skin defect model experiments demonstrated that the CMC/Ser-Ag/HNT4 sponge significantly promoted epithelialization and collagen formation. Immunofluorescence staining assays revealed that the composite sponge reduced inflammation by downregulating the expression of IL-6 and enhanced angiogenesis by upregulating VEGF expression. All the findings demonstrated the great potential of CMC/Ser-Ag/HNT sponge as versatile clinical wound dressing, especially for hemorrhagic and infected wounds., Competing Interests: Declaration of competing interest The authors declare no competing interests., (Copyright © 2023. Published by Elsevier B.V.)