氧化石墨烯对嗜热四膜虫的毒性效应

以嗜热四膜虫（Tetrahymena thermophila）作为受试生物，考察了纳米材料氧化石墨烯（GO）对其细胞生长率、乙酰胆碱酯酶（AchE）和氧化应激酶活性、生物膜损伤及细胞凋亡的影响，以探究GO的毒性效应.结果表明，GO浓度高于32mg/L时显著抑制嗜热四膜虫的细胞增殖（P<0.05），细胞存活率低于50%；在0~64mg/L实验范围内，随GO暴露浓度增加，细胞内活性氧自由基（ROS）和超氧化物歧化酶（SOD）水平呈先升后降的趋势，AchE活性受抑；GO抑制位于线粒体内膜的琥珀酸脱氢酶（SDH）活性，促进细胞质中乳酸脱氢酶（LDH）的释放；64mg/L GO导致四膜虫细胞出现明显凋亡现象.以上结果显示，中低浓度GO（0~8mg/L）暴露下，氧化应激机制对细胞毒性起主要贡献作用；高浓度GO（32和64mg/L）作用下，四膜虫凋亡现象的产生可能是GO抑制其生长作用导致的.

Toxicity effects of graphene oxide to Tetrahymena thermophila

Effects of graphene oxide (GO) on the growth, acetylcholinesterase (AchE) activity, oxidative stress, membrane damage and apoptosis of Tetrahymena thermophila were investigated. The results showed that the concentrations higher than 32mg/L GO significantly inhibited the growth of T. thermophila (P<0.05), and the cell survival rate was less than 50%. With the increase of GO concentration (0~64mg/L), the levels of reactive oxygen species (ROS) and superoxide dismutase (SOD) in T. thermophila cells initially also increased but then decreased while the activity of AchE decreased. GO inhibited the activity of succinate dehydrogenase (SDH) and promoted the release of lactate dehydrogenase (LDH). Highest concentration of GO (64mg/L) caused cell apoptosis. Based on the results, it can be concluded that oxidative stress contributed to cytotoxicity at low and medium concentrations of GO (0~8mg/L) while at higher concentrations (32 and 64mg/L) of GO, apoptosis of Tetrahymena may be caused by GO inhibiting its growth.