Preparation and antimicrobial properties of Ag+/carboxymethyl chitosan/silk fibroin composite microspheres

The frequent occurrence of respiratory infectious diseases has made it difficult for traditional antibacterial materials to meet practical needs in recent years. There was an urgent need to develop new antimicrobial materials with stronger antimicrobial effects and biosafety. In this paper, the carboxymethyl chitosan (CMCTS)/silk fibroin (SF) composite microspheres were synthesized through self-assembly, and the Ag⁺/CMCTS/SF composite microspheres were prepared by loading the Ag⁺ onto their surface. It investigated the effect of CMCTS contents, SF on the size and secondary structure of CMCTS/SF composite microspheres, and the antibacterial activity and mechanism of Ag⁺/CMCTS/SF composite microspheres. The results showed that the average particle size distribution size of CMCTS/SF composite microspheres was ranged from approximately 593–1115 nm. When CMCTS was added at 50 wt%, the content of β-sheet structures in silk fibroin microspheres was the largest at 38.6%. And the CMCTS/SF composite microspheres loaded with Ag⁺ enhanced the bactericidal rate against Escherichia coli and Staphylococcus aureus by 27.51% and 36.39%, respectively. In addition, the Ag⁺/CMCTS/SF composite microspheres have high biological safety, providing a new method for designing an efficient, green, and safe composite antibacterial agent.