Evaluation of the deteriorating effects of microbial primary metabolites on silk fibres.

The silk biodegradation process remains unclear and requires elucidation with advanced analytical tools. To address this challenge, the role of microbial primary metabolites in the deterioration of ancient silk was investigated using metabolomics and proteomics techniques in this work. The oxalic and palmitic acids were separately identified as the most abundant organic and fatty acid metabolites for silk-fabric deterioration via metabolomics. Proteomics showed that oxalic acid accelerated the degradation of silk proteins, revealing changes at the molecular level in silk. A high concentration of oxalic acid promoted the dissolution of peptides by activating the cleavage activity of various amino acids on the molecular chain of silk protein. Palmitic acid formed sedimentary particulate matter with peptides solubilised from silk proteins, indicating the possibility that traces of ancient-silk proteins remained in the fatty acids. The work presented new techniques and concepts for studying the degradation of historical fabrics and contributed to the proposal of effective measures to prevent microbial attack on silk.

Silk fibroin biohydrogel composites for loading and ordered release of multiple active ingredients with enhanced bioactivity.

Bioactive hydrogels are currently receiving significant attention. In this study, silk fibroin tyramine-modified gelatin hydrogels (SF-TG) with varying degrees of tyramine root substitution were explored. The physicochemical property and biocompatibility of low degree of substitution tyramine-modified gelatin hydrogel (SF-LTG) and high degree of substitution tyramine-modified gelatin hydrogel (SF-HTG) were compared. The results showed that SF-LTG possessed better mechanical property and higher biocompatibility. Thus, SF-LTG was selected as a bioactive matrix and loaded with basic fibroblast growth factor (bFGF); subsequently, curcumin-coupled chitosan rods (CCCRs-EGF) enriched with epidermal growth factor (EGF) were added to obtain SF-LTG-bFGF@CCCRs-EGF hydrogels. The results showed that SF-LTG-bFGF@CCCRs-EGF retained the basic structural and mechanical properties of the SF-LTG matrix gel material and underwent multiple loading and orderly release with different activities while displaying antioxidant, anti-inflammatory, antimicrobial, and pro-cellular proliferation activities and orderly regulation of activity during wound healing. Therefore, the SF-LTG-bFGF@CCCRs-EGF hydrogel is of great value in healing complex wounds.