多壁碳纳米管对水稻幼苗的植物毒性研究

Comprehensive Phytotoxicity Assessment of Multi-wall Carbon Nanotubes on Rice Seedlings

考察了浓度为10、50和100 mg·L^(-1)的多壁碳纳米管(MWCNTs)的植物毒性,通过测量水稻生长指数、根系氧化应激反应、细胞膜损伤和生理功能的变化,探索了其具体的毒性机制。将水稻幼苗暴露于不同浓度的MWCNTs悬浮液中培养10 d后,高浓度处理组(100 mg·L^(-1))中水稻幼苗地上部分和根系鲜重分别降低至对照组的87.6%±1.1%和69.2%±7.8%。对根系深入研究发现氧化应激反应和细胞膜的损伤主要出现在高浓度处理组,此时过氧化氢酶(CAT)活性由对照组的(8.8±1.6)U·mg-1prot(protein,蛋白质)增加至(16.3±2.8)U·mg-1prot,丙二醛(MDA)含量由对照组的(8.0±0.3)μmol·g-1FW(fresh weight,鲜重)增加至(15.1±1.4)μmol·g-1FW。然而,水稻根系的生化酶活性在低浓度(10 mg·L^(-1))时就开始明显降低。通过透射电镜(TEM)观察发现,MWCNTs颗粒分布在水稻幼苗根系细胞内,从而证实了MWCNTs能被植物细胞吸收。

This study investigated the phytoxicity of multi-wall carbon nanotubes（ MWCNTs） of various concentrations（ 10,50,100 mg·L^-1） on rice seedlings. Detailed toxic mechanisms were explored by measuring the growth index of seedlings,oxidative stress,cell membrane damage,and the variation of physiological functions in roots. It was observed that a significant loss was detected in fresh weights of shoots and roots at 100 mg·L^-1of MWCNTs,which were decreased to 87. 6% ± 1. 1% and 69. 2% ± 7. 8% of the control,respectively. Based on the deep insights into root tests,the results demonstrated that the oxidative stress and cell membrane damage mainly took place at higher concentrations of MWCNTs（ i. e.,100 mg·L^-1）. Compared with the control sample,the catalase（ CAT）activity was increased from（ 8. 8 ± 1. 6） to（ 16. 3 ± 2. 8） U·mg^-1prot（ protein）. Simultaneously,the same in-creasing trend was found for malondialdehyde（ MDA） content,which changed from（ 8. 0 ± 0. 3）（ the control） to（ 15. 1 ± 1. 4） μmol·g^-1FW（ fresh weight）. Nevertheless,the physiological enzyme activities decreased to a greater level even after exposure to the lowest MWCNTs concentration（ 10 mg·L^-1）. Transmission electron microscope（ TEM） analysis was carried out for the observation of the root cells. It was found that the MWCNTs were distributed in the root cells,which further verified the uptake of MWCNT by the root cells.