A nano-silver composite based on the ion-exchange response for the intelligent antibacterial applications

As a kind of antimicrobial agent, nano-silver composites have attracted a great deal of interest in biomedical applications. However, the typical loadings of silver nanoparticles (AgNPs) in such composites could result in dose-related cytotoxicity. In this study, a nano-silver composite leading to antimicrobial activity without cytotoxicity was fabricated by loading AgNPs into a dried alginate hydrogel. The biological performance of this composite mainly depended on the release of AgNPs, which needed to be triggered by the ion-exchange response and was further influenced by the loadings of AgNPs in the composite. The antimicrobial activity against E. coli and S. aureus demonstrated that the released silver no less than 678 ppb in the medium caused a reduction of 7log10CFU/mL (100%) bacteria. Significantly, the dose (~1.10×10(3) ppb) of released silver was not toxic and allowed attachment, and growth of MC3T3-E1 pre-osteoblast cells. These results supported that the composite was compatible with in vitro mammalian cells yet exhibited antimicrobial activity by carefully designing the loadings of AgNPs within the alginate. Thus, it indicated that the performance of this composite might permit management of bacterial infection in wound beds without impairment of wound healing.