Highly antibacterial and biocompatible polylysine-modified silk fibroin for potential food preservation and biomedical applications

Bacterial infection remains a thorny problem in food, medicine, and other fields. Due to the emergence of antibiotic-resistant bacteria, it is critical to develop an effective strategy to yield novel antibacterial agents. Herein, a new type of non-antibiotic antimicrobial material was successfully synthesized by grafting ε-polylysine (EPL) onto silk fibroin (SF). The resulting ε-polylysine-modified silk fibroin (SF-EPL) possessed the possibility to be processed into different formats. As the EPL content increased, SF-EPL exhibited higher positive charge levels, similar to those of EPL. Notably, the incorporation of 10 % EPL endowed superior antibacterial effects against E. coli and S. aureus (>90 %), while maintaining excellent biocompatibility. Furthermore, SF-10%EPL effectively extended the shelf life of cherry tomatoes, significantly delaying weight loss and the decline in titratable acidity content. The obtained SF-EPL may represent a promising substitute for food preservation and biomedical applications.