功能化多壁碳纳米管对血管内皮细胞毒性的初步研究

目的:由于碳纳米管的广泛应用,其对人类及环境造成的影响日益受到人们的关注.血管是碳纳米管进入人体的首要通道之一,因此探讨功能化与原始状态的多壁碳纳米管对血管内皮细胞的细胞毒性作用具有重要意义.方法:自人脐静脉分离血管内皮细胞,免疫组化进行细胞鉴定.选择0.5～1 μm经羧基修饰的功能化多壁碳纳米管(f-CNTs)与同等长度未经修饰的多壁碳纳米管(p-CNTs)制备颗粒悬液,与血管内皮细胞共育后,利用噻唑蓝实验(MTT比色法)检测细胞活力,透射电镜进行细胞形态学观察;制备碳纳米管透析液,通过MTT实验检测其对细胞的毒性作用.结果:①2种纳米管均对原代脐静脉内皮细胞(HUVEC)产生一定的毒性作用,而且其细胞毒性随剂量递增呈上升趋势.与细胞共育24 h后,p-CNTs的毒性大于f-CNTs;而共育48 h及72 h后,f-CNTs毒性大于p-CNTs.②透射电镜实验表明,f-CNTs共育细胞内空腔明显多于p-CNTs,而空腔内f-CNTs聚集体紧密程度明显小于p-CNTs.③对2种多壁碳纳米管透析后的细胞培养基对细胞活力无明显影响.结论:根据上述结果笔者推测.p-CNTs细胞毒性的主导因素是聚集程度,f-CNTs对细胞毒性的主导因素为表面效应.进入细胞的碳纳米管数目增多,造成细胞损伤或阻断细胞内代谢通路,可能是共育后期f-CNTs细胞毒性大于p-CNTs的原因.

Study on the cytotoxicity of functionalized muitl-wailed carbon nanotubes against vascular endothelial cells

Objective The broad range of increasing applications for carbon nanotubes (CNTs) may bring hazardous exposure to humans and other biological systems. Modification of CNTs with different chemical groups was used to enhance solubility and was likely to result in different toxicity. The current study was designed to study the cytotoxicity of pristine CNTs (p-CNTs) and functionalized CNTs (f-CNTs) against vascular endothelial cells,which mediate many key biological processes in the body. Methods Vascular endothelial cells (VECs) were isolated from human umbilical veins and identified by immunochemical staining. MTT assay was employed to test the viability of the VECs exposed to different concentrations of p-CNTs or f-CNTs for up to 72 h. The mor-phology of the cells was observed under transmission electron microscope. Results It was demonstrated that both p-CNTs and f-CNTs induced decreased cell viability in a dose dependent manner, whereas neither of the medium dialyzed against p-CNTs or f-CNTs showed any cytotoxicity against the VECs. The eytotoxicity of p-CNTs was greater than that of f-CNTs after at 24 h of exposure. However, at 48 h and 72 h of exposure, f-CNTs resulted in greater decrease of cell viability as compared to p-CNTs. Transmission electron microscopic observation showed that there were much more CNT aggregates in the cytoplasm of f-CNTs treated cells than those of p-CNTs treated cells. It was also observed that the p-CNT aggregates are much more condensed than f-CNTs aggregates. Conclusion It is likely that the aggregation may play greater role in the cytotoxicity of p-CNTs, whereas the sur-face chemistry was the major factor responsible for that of f-CNTs. Increased number of f-CNTs enveloped by the cells may cause greater degree of cell damage or interfere the mass transportation in the cytoplasm, and hence in-duced increased loss of cell viability.