Antibacterial effects of titanium embedded with silver nanoparticles based on electron-transfer-induced reactive oxygen species

Although titanium embedded with silver nanoparticles (Ag-NPs@Ti) are suitab le for biomedical implantsbecause of the good cytocompatibility and antibacterial characteristics, the exact antibacterial mecha-nism is not well understood. In the present work, the antibacterial mechanisms of Ag-NPs@Ti preparedby plasma immersion ion implantation (PIII) are explored in details. The antibacterial effects of the Ag-NPs depend on the conductivity of the substrate revealing the importance of electron transfer in theantibacterial process. In addition, electron transfer between the Ag-NPs and titanium substrate producesbursts of reactive oxygen species (ROS) in both the bacteria cells and culture medium. ROS leads tobacteria death by inducing intracellular oxidation, membrane potential variation, and cellular contentsrelease and the antibacterial ability of Ag-NPs@Ti is inhibited appreciably after adding ROS scavengers.Even though ROS signals are detected from osteoblasts cultured on Ag-NPs@Ti , the cell compatibility isnot impaired. This electron-transfer-based antibacterial process which produces ROS provides insightsinto the design of biomaterials with both antibacterial properties and cytocompatibility