A facile and universal strategy to endow implant materials with antibacterial ability via alkalinity disturbing bacterial respiration†
Multifarious strategies have been proposed to enhance the antibacterial ability of implant surfaces for preventing bacterial infection, however, developing facile and universal modification methods still remains extremely elusive. Herein, inspired by the fact that the electron transfer respiratory chain of bacteria is embedded in the membrane, we proposed a novel strategy of local alkalinity disturbing bacterial respiration to endow implant materials with antibacterial ability. As a demonstration, MgO was deposited on biomedical titanium via magnetron sputtering to regulate surface alkalinity. With the thickness of MgO films increasing, they exhibited an excellent antibacterial rate against both Gram-negative and positive bacteria. The antibacterial mechanism confirmed that the alkaline surface can disturb the bacterial respiration action via weakening the transmembrane proton concentration gradient, resulting in the blockage of energy metabolism and the increase of oxidative stress of bacteria. Cell experiments indicated that MgO films not only have no obvious cytotoxicity to osteoblast cells, but can also selectively kill bacteria and promote cell proliferation in the presence of both bacteria and cells. More importantly, the by-product of MgO was only the biocompatible Mg2+, reducing any concerns about potential toxic effects. Furthermore, sputtering alkaline MgO films was confirmed to work well on polyetheretherketone polymer and zirconia ceramic implants, which indicates that this strategy has broad prospects of clinical application for preventing implant-associated bacterial infection.