单壁碳纳米角的氧化、修饰及分散性

研究了影响单壁碳纳米角(SWNHs)分散性的因素, 并初步探讨了其分散机制, 通过氧化及表面修饰等方法增强了SWNHs在水和盐溶液中的分散性. 考察了溶液酸碱度和电解质浓度对SWNHs在水中的分散性以及吐温80对SWNHs在磷酸盐缓冲液(PBS)中的分散性的影响. 结果表明, pH值为6~10时, SWNHs分散良好; 电解质浓度越大, SWNHs的分散性越差; 吐温80能有效改善SWNHs在PBS中的分散性. 比较了3种SWNHs的氧化方法, 红外光谱、 X射线光电子能谱、 透射电镜、 粒度分析及Zeta电位分析结果表明, 氙灯催化过氧化氢氧化SWNHs的方法可引入大量含氧官能团, 显著提高了SWNHs在水中的分散性. 选择两亲性和生物相容性极好的羧基化磷脂聚乙二醇(DSPE-PEG-COOH)修饰氧化处理后的碳纳米角(SWNHox), 并从分散稳定性和Zeta电位两个方面进行了表征, 发现用DSPE-PEG-COOH修饰的SWNHox在PBS中的分散性良好. 该研究为SWNHs应用于药物转运和生物传感奠定了实验基础.

Oxidation, Modification and Dispersibility of Single-walled Carbon Nanohorns

Single-walled carbon nanohorns(SWNHs) are new materials that are similar to single-walled carbon nanotubes(SWNTs) but have more comparative advantages than SWNTs. The size of SWNHs matches the condition for achieving enhanced permeability and retention(EPR) effect. The non-cytotoxicity makes SWNHs potentially applicable in drug delivery and electrochemical biosensing. However, it's hard to apply SWNHs in water since the surface of SWNHs is hydrophobic. In this article, we carried out systematic research to improve the dispersibility and biocompatibility of SWNHs. The effects of pH value, salt concentration and Tween 80 on the dispersion of SWNHs were investigated. The results showed that SWNHs dispersed well in water at the pH values of 6—10 and high salt concentration had substantial obstacle to their dispersion. It can be deduced that surface Zeta potential is an important factor on the dispersion of SWNHs. Tween 80 helped SWNHs well dispersed in buffers. These results are important for us to understand the dispersion of SWNHs mechanism in aqueous solution. In order to find the best way to improve the dispersion and biocompatibility of SWNHs, three oxidation methods of SWNHs were studied including concentrated nitric acid refluxing, H2O2 oxidation assisted by Hg lamp and H2O2 oxidation assisted by Xe lamp. As a result, H2O2 oxidation assisted by Xe lamp in 1 h is the most effective method because it generats large amount of oxygenated groups on the surface of SWNHs which are of great help for their dispersion. In order to improve the biocompatibility of SWNHox, we chose carboxyl polyethylene glycol distearoyl phosphatidylethanolamine(DSPE-PEG-COOH) to modify SWNHox. Different concentrations of DSPE-PEG-COOH were used in water and phosphate buffer solution(PBS) followed by determining the Zeta potentials and monitoring the coagulation times. The result showed that 0.25 mg/mL was the optimal concentration of DSPE-PEG-COOH to achieve the best dispersion in PBS. Our study lays an important experimental basis for carbon nanohorns to be used in drug delivery systems and biosensors in the future.