Phytotoxicity of VO nanoparticles with different sizes to pea seedlings.

Vanadium dioxide nanoparticles (VO NPs) have been massively produced due to their excellent metal-insulator transition characteristics for various applications. Pilot studies indicated the toxicity of VO NPs to bacteria and mammalian cells, but the environmental hazards of VO NPs to plants have been unrevealed to date. In this study, we reported the inhibitive effects of VO NPs to the growth and photosynthesis of pea seedlings. Laboratory synthesized monoclinic VO NPs (N-VO), commercial nanosized VO NPs (S-VO), and commercial microsized VO particles (M-VO) were carefully characterized for environmental toxicity evaluations. VO particles were supplemented to culture medium for seed germination and seedling growth. All three VO samples did not affect the germination rates of pee seeds, while serious growth inhibition of pea seedlings was observed at 10 mg/L for S-VO and N-VO, and 100 mg/L for M-VO. VO particles had no impact on the chlorophyll contents, but the photosynthesis of leaf was significantly decreased following the consequence of N-VO > S-VO > M-VO. The inhibition of photosynthesis was attributed to the damage of acceptor side of photosystem II by VO particles at high concentrations. Abundant bioaccumulations of vanadium in roots aroused oxidative damage and changed the root structure. Our results collectively indicated that the phytotoxicity of VO NPs was related to the concentration, size and crystalline degree.