表面活性剂对多壁碳纳米管-重金属复合细菌毒性的影响及机制

The ecological risks of carbon nanotubes are paid more attention with their wide application in every walk of life. Heavy metals and surfactants are two kinds of important pollutants, which may enter into the waters with carbon nanotubes and influence the migration, transformation and ecological effects of carbon nanotubes. Therefore, it has important scientific significance to investigate the influence and mechanisms of surfactants on the combined toxicity of carbon nanotubes and heavy metals. In this study, Escherichia coli bacterium is selected as the model microorganism, the effects of surfactants on the combined bacterial toxicity of multi-walled carbon nanotubes (MWCNTs)(pristine, carboxyl-, hydroxyl- functionalized), and heavy metals (Zn(II) and Cd(II)) are investigated, and then the effects of surfactants on the interaction between MWCNTs and heavy metals are clarified. Finally, the influence mechanisms of surfactants on the combined bacterial toxicity will be clarified on the base of illustrating the effects of surfactants on the bacterial characteristics, the interaction between MWCNTs and bacteria, the bioavailability of heavy metals. The results will provide some useful information for the ecological risks evaluation in the presence of MWCNTs, surfactants, and heavy metals.

碳纳米管（CNTs）的应用日益广泛，其生物效应及风险受到人们关注。重金属和表面活性剂是环境中两类常见的重要污染物，会与碳纳米管一起进入水体，并影响碳纳米管的迁移转化行为及生物效应。研究表面活性剂对碳纳米管-重金属复合生物效应的影响及机制具有重要的科学意义。本项目以大肠杆菌为模型微生物，研究不同类型表面活性剂对未修饰、羧基化及羟基化多壁碳纳米管（MWCNTs）和Zn(II)、Cd(II)等重金属复合细菌毒性的影响，明确复合毒性属于加和、协同还是拮抗作用；在阐明表面活性剂对MWCNTs与重金属相互作用影响及分子作用机制的基础上，研究表面活性剂对MWCNTs毒性相关性质、细菌性质、MWCNTs与细菌的相互作用、重金属形态及生物有效性等的影响，从宏观和分子作用水平上揭示表面活性剂对MWCNTs与重金属复合细菌毒性的影响机制，试图为表面活性剂、碳纳米管与重金属复合污染水体的生态风险评估提供科学依据。

碳纳米管（CNTs）的应用日益广泛，其生物效应及风险受到人们关注。重金属和表面活性剂是环境中两类常见的重要污染物，可能与碳纳米管一起进入水体，并影响碳纳米管的迁移转化行为及生物效应。本项目以大肠杆菌为模型微生物，主要研究了SDBS和Tween 80对无表面基团、羧基化及羟基化多壁碳纳米管（MWCNTs）和Cd2+的细菌毒性效应及影响机理。主要结果如下：（1）低于100 mg/L的表面活性剂和多壁碳纳米管对大肠杆菌生长均没有明显的生长抑制，表面活性剂、多壁碳纳米管和Cd2+复合体系中的毒性主要来自于Cd2+；（2）与SDBS结合后的Cd2+吸附到细菌表面后会增强细菌外膜渗透性，从而增强Cd2+毒性；而Tween 80对Cd2+毒性基本没有影响；（3）不同官能团多壁碳纳米管吸附Cd2+能力如下：羧基化多壁碳纳米管>羟基化多壁碳纳米管>无表面基团多壁碳纳米管，对Cd2+吸附性能越强，复合毒性越小，且复合毒性小于Cd2+的单独毒性；SDBS存在条件下，多壁碳纳米管与Cd2+复合毒性增强，而Tween 80对复合毒性影响较小。研究结果可为表面活性剂、碳纳米管与重金属复合污染水体的生态风险评估提供科学依据。