Potent antibacterial fibers with the functional “triad” of photothermal, silver, and Dex for bone infections

Abstract

Bacteria-induced bone infections disrupt the healing and repair ability of bone tissue, posing a serious challenge to the treatment of clinical bone defects. In this study, novel composite fibers (PLLA/Dex/Ag fibers) with light-responsive rapid antibiosis and osteogenesis were obtained by mixing the photothermal agent silver nanoparticles (Ag-NPs) and the osteogenic drug dexamethasone (Dex) in polylactic acid (PLLA) using electrospinning, which can simultaneously kill multidrug-resistant bacteria and accelerate bone tissue healing due to the photothermal effect and release of Dex. Ag-NPs can act as antimicrobial agents released from the fibers and as photothermal agents to generate local high temperature and singlet state oxygen (1O2) under 808 nm light radiation, thereby killing the bacteria. The antimicrobial tests in vitro showed that PLLA/Dex/Ag fibers had an excellent antimicrobial effect on Escherichia coli and Staphylococcus aureus under NIR light radiation, shortening the effective antimicrobial time from 24 h to 6 h and achieving light-responsive antibiosis rapidly. Meanwhile, the released Dex could induce the differentiation of bone marrow mesenchymal stem cells into osteoblasts, thus promoting the healing of bone defects. In conclusion, this study provided a simple and effective strategy for the clinical treatment of bone infections.