School of Biosciences and Technology, VIT, Vellore, 632014, India.
Centre for Nanobiotechnology, VIT, Vellore, 632014, India.
Environ Sci Pollut Res Int. 2018 Jun;25(17):16729-16742. doi: 10.1007/s11356-018-1860-2. Epub 2018 Apr 2.
There has recently been an increase in the usage of TiO nanoparticles (NPs). P25 TiO NPs, a mixture of anatase and rutile phase in 3:1 ratio, are generally used for photocatalytic applications because both phases exhibit a synergistic effect on the photocatalytic activity of the TiO NPs. In the present study, increased toxicity of UVA-pre-irradiated P25 TiO NPs on freshwater algae Scenedesmus obliquus was assessed under visible light and dark exposure conditions at actual low concentrations (0.3, 3 and 35 μM of Ti). Photocatalytic property of P25 TiO NPs caused disaggregation of UVA-pre-irradiated NPs, thus significantly decreasing the mean hydrodynamic diameter (MHD) (188.74 ± 0.54 nm) than that of non-irradiated NPs (232.26 ± 0.44). This decrease in diameter of UVA-pre-irradiated NPs may increase its biological activity towards algal samples. All concentrations of pre-irradiated NPs, under both light and dark conditions, showed a significantly lesser cell viability (p < 0.001) when compared with non-irradiated NPs. Increased production of ROS, antioxidant enzymes and lipid peroxidation supported the viability data. Higher exopolysaccharide production and more nuclear damage were observed for pre-irradiated NPs. NP uptake was also more for the pre-irradiated NPs on treated samples when compared with non-irradiated NPs on treated samples, which, in turn, established the higher toxic potential of UVA-pre-irradiated TiO NPs. This study improves our understanding of the toxic effects of UVA-pre-irradiated TiO NPs on freshwater algae, thereby emphasising the need for ecological risk assessments of metal oxide nanoparticles in a natural experimental medium.
近年来，TiO2纳米粒子（NPs）的使用有所增加。P25 TiO2 NPs 是锐钛矿和金红石相的 3:1 混合物，通常用于光催化应用，因为两种相都对 TiO2 NPs 的光催化活性具有协同作用。在本研究中，在实际低浓度（0.3、3 和 35 μM 的 Ti）下，在可见光和黑暗暴露条件下，评估了 UVA 预辐照 P25 TiO2 NPs 对淡水藻类斜生栅藻的毒性增加。P25 TiO2 NPs 的光催化特性导致 UVA 预辐照 NPs 的解团聚，从而显著降低其平均水动力直径（MHD）（188.74 ± 0.54nm），低于未辐照 NPs 的 MHD（232.26 ± 0.44nm）。UVA 预辐照 NPs 的直径减小可能会增加其对藻类样品的生物活性。与未辐照 NPs 相比，所有浓度的预辐照 NPs 在光照和黑暗条件下的细胞活力均显著降低（p<0.001）。ROS、抗氧化酶和脂质过氧化产物的增加支持了存活数据。与未辐照 NPs 相比，预辐照 NPs 产生了更高的胞外多糖和更多的核损伤。与未辐照 NPs 相比，处理后的样品中预辐照 NPs 的摄取量也更高，这反过来又确立了 UVA 预辐照 TiO2 NPs 的更高毒性潜力。这项研究提高了我们对 UVA 预辐照 TiO2 NPs 对淡水藻类的毒性作用的理解，从而强调了在自然实验介质中对金属氧化物纳米颗粒进行生态风险评估的必要性。
