Abstract: Bloodstream infection, especially with implants involved, is an often life-threatening condition with high mortality rates, imposing a heavy burden on patients and medical systems. Herein, we firstly deposited homogeneous vanadium metal, V₂O₃, VO₂, and V₂O₅ nanofilms on quartz glass by magnetron sputtering. Using these platforms, we further investigated the potential antimicrobial efficiency of these nano-VO_x films and the interactions of human erythrocytes and bacteria (methicillin-resistant Staphylococcus aureus  and Pseudomonas aeruginosa ) with our samples in a novel cell–bacteria coculture model. It was demonstrated that these nano-VO_x precipitated favorable antibacterial activity on both bacteria, especially on S. aureus , and this effect increased with higher vanadium valence. A possible mechanism accountable for these results might be elevated levels of vanadium-induced intracellular reactive oxygen species. More importantly, based on hemolysis assays, our nano-VO_x films were found to be able to kill prokaryotic cells but were not toxic to mammalian cells, holding the potential for the prevention of implant-related hematogenous infections. As far as we know, this is the first report wherein such nano-VO_x films have assisted human erythrocytes to combat bacteria in a valence-dependent manner. Additionally, vanadium ions were released from these nano-VO_x films in a sustained manner, and low-valence films possessed better biocompatibility with human fibroblasts. This work may provide new insights for biomedical applications of inorganic vanadium compounds and attract growing attention in this field. From the perspective of surface modification and functionalization, this study holds promise to avail the prophylaxis of bloodstream infections involving implantable biomedical devices.
Keywords: surface modification, red blood cell, antibacterial activities, vanadium, nano­materials