Mussel Inspired In Situ Preparation of Antibacterial Silver Nanoparticles by DOPA-Containing Silk Fibroin

Silver nanoparticles (AgNPs) attract a great deal of attention for potent antibacterial capacity, but their use is challenged by limited stability. Inspired by the adhesive and redox properties of the mussel foot proteins containing L-3,4-dihydroxyphenylalanine (DOPA), a facile strategy for in situ synthesis of AgNPs using DOPA-containing fibroin is developed. Tyrosine residues in fibroin are transformed into DOPA via biomimetic synthesis method with content of 0.55 mol%. In situ synthesis generates stable and small AgNPs through DOPA bound in fibroin as a reducing and stabilizing agent. Narrow size distribution with average diameter of 20 nm and excellent monodispersity are obtained. Cross-linking with lysine increases the content of β-sheet to form hydrogel and achieves gradual release of silver. The material exhibits excellent antibacterial properties against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli bacteria. It can be potentially applied in biological and medical fields to treat bacterial infections.