Antibacterial ability of black titania in dark: Via oxygen vacancies mediated electron transfer

Antibacterial ability is greatly demanded for biomedical implants to prevent after-surgery infections. Titania is the oxidative layer of the widely used Ti implants, and is well known to gain antibacterial ability via photocatalysis. However, to prevent the implant related infections, antibacterial ability in dark is required. In this work, we carry out a study on the in-dark antibacterial ability of black titania nanotube arrays (B-TNT) on Ti substrate, and the mechanisms are also deeply investigated. We discover that B-TNT have prominent bactericidal ability in dark, and the mechanisms lie on the electron transfer mediated by the oxygen vacancies (Vo) of B-TNT. With single-electron trapped in their sites, the Vo function as both electron donors and acceptors, generating superoxide anions, hydroxyl radicals and singlet oxygen to do bacteria killing. Moreover, the Vo have the ability to trigger unusual extracellular electron transfer (EET) from the bacteria on B-TNT, which eventually leads to bacteria death. The generation of the Reactive Oxygen Species (ROS) and the force EET mediated by Vo work together to enable the antibacterial ability of B-TNT in dark.