纳米二氧化钛和纳米氧化锌对尾草履虫急性毒性效应的比较研究

Acute Toxicity of Nano-TiO2 and Nano-ZnO on Paramecium caudatum: A Comparative Study

为了探讨纳米材料生物毒性效应以及机制,并为纳米二氧化钛(TiO2)和纳米氧化锌(ZnO)的环境毒性监测与评价提供依据,本研究以原生动物尾草履虫(Paramecium caudatum)为实验对象,采用急性毒性实验方法,检测了TiO2和ZnO的24 h半数效应浓度(EC50)和最低效应浓度(LOEC),以EC50浓度胁迫尾草履虫24 h,比较3种抗氧化酶活性的变化,并结合扫描电镜观察两种纳米材料的形态,分析了两种纳米材料的生物毒性的机理。结果显示:尾草履虫的24 h半数效应浓度(24 h-EC50)分别为51.580 mg/L(TiO2)、0.444 mg/L(ZnO);最低效应浓度(24 h-LOEC)分别为1.712 mg/L(TiO2)、0.352 mg/L(ZnO)。抗氧化酶活性变化表现为:超氧化物歧化酶(SOD),过氧化氢酶(CAT)和过氧化物酶(POD)活性与对照组相比有不同程度的改变,经差异显著性分析,两种纳米材料对尾草履虫的POD酶表现出较为明显的抑制作用。说明纳米ZnO对草履虫的24 h急性毒性大于纳米TiO2,纳米材料对草履虫的毒性与其对抗氧化酶的抑制作用有关。

The objectives are to explore the toxic effect and mechanism of nanomaterials, and provide a basis for environmental toxicity monitoring and evaluation of nano titanium dioxide(TiO2) and nano zinc oxide(ZnO).Protozoa Paramecium caudatum was took as an experimental object, and the acute toxicity experiment method was used to test the 24 h half effect concentration(EC50) and the 24 h lowest effect concentration(LOEC) of TiO2 and ZnO. Under EC50 concentration stress of Paramecium caudatum for 24 h, the activity changes of the three kinds of antioxidant enzymes were compared, the morphology of the two kinds of nanomaterials was observed by SEM. The biotoxicity mechanisms of the two nanomaterials were analyzed. The results showed that the 24 h-EC50 was 51.580 mg/L(TiO2) and 0.444 mg/L(ZnO), respectively, and the lowest effect concentration(24 h-LOEC) was 1.712 mg/L(TiO2) and 0.352 mg/L(ZnO), respectively. The changes of antioxidant enzyme activities were as follows: superoxide dismutase(SOD), catalase(CAT) and peroxidase(POD) activities changed to different degrees compared with the control group. The difference significance analysis indicated that the two kinds of nanomaterials showed a more obvious inhibition on POD enzymes of Paramecium. These results suggest that the 24 h-acute toxicity of nano-ZnO on Paramecium is greater than that of nano-TiO2, and the toxicity of nanomaterials to Paramecium caudatum is related to its inhibitory effect on antioxidant enzymes.