Impact of TiO₂ nanoparticles on Vicia narbonensis L.: potential toxicity effects

This work was aimed to provide further information about toxicology of TiO2 nanoparticles (NPs) on Vicia narbonensis L., considering different endpoints. After exposure to TiO2 nanoparticle suspension (mixture of rutile and anatase, size <100 nm) at four different concentrations (0.2, 1.0, 2.0 and 4.0 ‰), the seeds of V. narbonensis were let to germinate in controlled environmental conditions. After 72 h, the extent of the success of the whole process (seed germination plus root elongation) was recorded as the vigour index, an indicator of possible phytotoxicity. After the characterisation of the hydric state of different materials, oxidative stress and enzymatic and nonenzymatic antioxidant responses were considered as indicators of possible cytotoxicity and to assess if damage induced by TiO2 NPs was oxidative stress-dependent. Cytohistochemical detection of in situ DNA fragmentation as genotoxicity endpoint was monitored by TUNEL reaction. The treatments with TiO2 NPs in our system induced phytotoxic effects, ROS production and DNA fragmentation. The nonenzymatic and enzymatic antioxidant responses were gradually and differentially activated and were able to maintain the oxidative damage to levels not significantly different from the control. On the other hand, the results of DNA fragmentation suggested that the mechanisms of DNA repair were not effective enough to eliminate early genotoxicity effects.