Oxidative stress-mediated selective antimicrobial ability of nano-VO₂against Gram-positive bacteria for environmental and biomedical applications

Abstract

Vanadium dioxide (VO2) is a unique thermochromic material as a result of its semiconductor-metal transition, holding great promise for energy-saving intelligent windows. Herein, pure nano-VO2 from discrete nanoparticles to continuous films were successfully deposited on quartz glass by controlling the sputtering parameters. It was demonstrated that, for Gram-positive S. aureus and S. epidermidis, the nano-VO2 could effectively disrupt bacteria morphology and membrane integrity, and eventually cause death. By contrast, the nano-VO2 did not exhibit significant toxicity towards Gram-negative E. coli and P. aeruginosa. To our knowledge, this is the first report on a selective antimicrobial effect of nano-VO2 materials on Gram-positive bacteria. Based on the experimental results, a plausible mechanism was proposed for the antimicrobial selectivity, which might originate from the different sensitivity of Gram-positive and Gram-negative bacteria to intracellular reactive oxygen species (ROS) level. Elevated intracellular ROS levels exceed the threshold that bacteria can self-regulate to maintain cellular redox homeostasis and thus cause oxidative stress, which can be alleviated by the intervention of glutathione (GSH) antioxidant. In addition, nano-VO2 did not produce significant cytotoxicity (hemolysis) against human erythrocytes within 12 h. Meanwhile, potential cytotoxicity against HIBEpiC revealed a time- and dose-dependent behavior that might be controlled and balanced by careful design. The findings in the present work may contribute to understanding the antimicrobial behavior of nano-VO2, and to expanding the new applications of VO2-based nanomaterials in environmental and biomedical fields.

Valence State Manipulation of Cerium Oxide Nanoparticles on a Titanium Surface for Modulating Cell Fate and Bone Formation

“…Subsequent increases in the surface oxygen content revealed a decrease in the number of oxygen vacancies on the surface, which corresponded to the increase in surface Ce 4+ content and the decrease in surface Ce 3+ content in the CeONPs. The sampling depth of XPS analysis is ≈10 nm,35 so the measured Ce 4+ and Ce 3+ contents were derived from the outermost surface of the CeONPs. With regard to the bonding between CeNPs and titanium substrate, only the diffraction peaks of CeO 2 , TiO 2 , and Ti phases are detected in XRD (Figure 1e).…”

A functionalized surface modification with vanadium nanoparticles of various valences against implant-associated bloodstream infection

“…Therefore, according to a previous strategy, 20 we coincubated S. aureus and P. aeruginosa in TSB with 10 mM glutathione (GSH; reduced form), the primary endogenous antioxidant, to neutralize the function of oxidative stress when bacteria were exposed to our nanosamples. The bacterial viability of swimming and adhered cells was quantitatively assessed through using the aforementioned methods.…”

“…To investigate the antimicrobial behavior and mechanism of the vanadium-nanoparticle films, we adopted a comparative study method of using GSH antioxidant to evaluate antibacterial ability, with reference to in vitro antibacterial tests in previous studies, 20,35 which usually focused on exploring the effects that the materials exerted on planktonic and sessile bacteria. After 24 hours of culture on glass, V0, V3, V4, and V5 with/without GSH coincubation, the planktonic bacteria (MRSA and P. aeruginosa) were firstly collected and recultivated on SBA overnight.…”

“…In fact, previous works together with our recent study have observed the antibacterial activity of vanadium-coordination organic compounds and inorganic vanadium dioxide (VO 2 ). [19][20][21] The vanadium element has six natural oxidation states. Trivalence (+3), tetravalence (+4), and pentavalence (+5) are the most common forms.…”

“…20 Our experiments were approved by the ethics review committee of Shanghai Jiao Tong University Sixth People's Hospital. Volunteers whose blood was used provided informed consent to donate the blood.…”