不同粒径TiO_2颗粒对海洋微藻的毒性效应

Toxic effects of TiO_2 particles with different size on the marine microalga

本实验以新月菱形藻为受试生物,研究了低浓度不同粒径TiO2颗粒(21nm、60nm和400nm)对海洋微藻生长、抗氧化酶活性(超氧化物歧化酶SOD、过氧化氢酶CAT和过氧化物酶POD)、脂质过氧化产物(MDA)含量的影响,并测定了相应的活性氧自由基(ROS)的含量,初步探讨了TiO2颗粒对海洋微藻的作用机制。结果表明,1mg/L TiO2颗粒对新月菱形藻生长的抑制作用随着粒径的减小而逐渐增强,第48h、72h、96h呈现出显著的纳米效应。TiO2颗粒可以诱导藻细胞内ROS的含量增加,对藻细胞产生氧化胁迫,新月菱形藻的抗氧化酶活性发生应激响应,以清除过量的ROS,但剩余的ROS对藻细胞产生氧化损伤,导致MDA含量升高,并且纳米级TiO2颗粒对新月菱形藻的氧化损伤大于微米级颗粒。在不同粒径TiO2颗粒的胁迫下,藻细胞SOD和CAT活性的响应也存在差异。本研究将为开展人工纳米材料对海洋生态系统影响的潜在风险评估提供科学依据。

With the increasing application of nanotechnologies,it is no doubt that more and more engineered nanop-articles end up in marine environment.The toxicity of TiO2 particles with different sizes （21 nm,60 nm and 400 nm）to the marine microalga Nitzschia closterium was investigated in this study,including the growth inhibition and oxidative stress.The results showed that the toxicity of 1 mg/L TiO2 particles to N.closterium cells increased with the decrease of particle size,indicating significant nano-effects at 48 h,72 h and 96h exposure,respectively. TiO2 particles induced excessive reactive oxygen species （ROS）which led to oxidative stress on the algal cells.The antioxidant enzyme activities of N.closterium cells could eliminate some ROS in order to protect algae cells.How-ever,the rest could cause oxidative damage and increase malondialdehyde （MDA）levels concomitantly.In addition, the oxidative damage caused by nano-sized TiO2 particles （21nm and 60nm）was greater than micro-sized particles. Superoxide dismutase （SOD）and catalase （CAT ）activities of the algal cells had different response under the stress of TiO2 particle with different size.This study shed new light on the assessment of ecological toxicity of engineered nanomaterials.