Biocompatible silk nanofibers with excellent antimicrobial and preservation properties by ε-polylysine grafting

Bacterial infections pose a major global threat to human health, which has been further exacerbated by the rise of antimicrobial resistance. In this study, we developed a novel strategy for producing non-antibiotic antimicrobial materials by grafting ε-polylysine (EPL) onto silk nanofibers (SNF). The obtained EPL-grafted SNF (ESNF) retained the inherent nanofibrous architecture, with a uniform diameter distribution below 100 nm. With increasing EPL content, ESNF exhibited an increase in the zeta potential value, confirming the successful graft of EPL onto SNF. Notably, the incorporation of EPL endowed SNF with strong antibacterial activity, achieving inhibition rates over 90% against Gram-positive Staphylococcus aureus (S. aureus), Gram-negative Escherichia coli (E. coli), and multidrug-resistant Staphylococcus aureus (MRSA), while maintaining good biocompatibility. Additionally, ESNF samples effectively extended the shelf life of peeled longans by significantly slowing decay, reducing weight loss, and delaying the increase in titratable acid content. Consequently, ESNF is a promising non-antibiotic antimicrobial material for food preservation.