Temperature-responsive tungsten doped vanadium dioxide thin film starves bacteria to death

The colonization of microorganisms on material surfaces, or namely biofouling, is a challenging matter in both the medical and marine industries. With the inspiration of the metabolism cascade of microorganisms, this study develops a new antifouling material surface that enables the drainage of extracellular electrons from the electron transfer chain in microbial metabolism, thereby interrupting the energy metabolism and subsequent microbial viability. This thought has been realized by tungsten-doped vanadium dioxide (VO₂) thin film using customized magnetron-sputtering deposition. The aim of tungsten doping is to tune the semiconductor-to-metal phase change of the VO₂ thin film and then endow the temperature-responsive electrical conductivity (band structure). While contacting with microorganisms, the electrically conductive VO₂ can disrupt the membrane respiration function of bacteria. This antifouling phenomenon can be explained by a three-step mechanism. The initial step is the microbial adhesion onto the metallic VO₂ film to form the direct microbe–VO₂ physical contact, which leads to the destructive extraction of electrons from the transmembrane protein complex of the respiratory chain (a discharge process); this induces oxidative stress and energy starvation and, eventually, interrupts the microbial membrane function. Finally, the microbial membrane integrity is destroyed, which leads to intracellular matter leakage (electrocution). This study demonstrates that the temperature-dependent VO₂ electrical conductivity or band structure serves as a key factor to modulate the antimicrobial capability of tungsten-doped VO₂ thin film. It is believed that the current findings can provide a new insight for the development of new antifouling surfaces.