Interaction Mechanism of Doxorubicin and SWCNT: Protonation and Diameter Effects on the Drug Loading and Releasing.
Interaction Mechanism of Doxorubicin and SWCNT: Protonation and Diameter Effects on the Drug Loading and Releasing.
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作者：
Wang Y;Xu Z
本文采用OMIOM方案中的PM6-DH2和M06-2X理论方法，系统研究了阿霉素（DOX）在单壁碳纳米管（SWCNT）表面的吸附及其在SWCNT中的包封，以及它们对DOX的NH2基团质子化、溶剂和armchair (n,n) SWCNT直径的依赖关系。研究发现，碳纳米管侧壁吸附和碳纳米管包封两种负载方式对溶剂、质子化和直径有明显的依赖性。这种包封性比DOX在碳纳米管侧壁上的吸附强得多，并且前者的溶剂化和质子化效应也明显高于后者。吸附主要通过π-π堆积发生，随着碳纳米管直径的增加，吸附强度略强，而除了π-π堆积外，额外的C- h /N-H/O- h…π和C=O…π也有助于DOX在碳纳米管中的封装。从能量上看，（8,8）碳纳米管（直径~ 11Å）是包封的开始，当直径大于约11Å时，包封由吸热转为放热，而（10,10）碳纳米管的最佳包封直径为14Å。因此，对于厚碳纳米管，包封也可能在DOX基于碳纳米管的药物传递系统的装载和释放中发挥重要作用。
In the present work the adsorption of doxorubicin (DOX) on the surface of single-walled carbon nanotube (SWCNT) as well as its encapsulation in SWCNT, and their dependence on the protonation of NH2 group of DOX, solvent, and the diameter of armchair (n,n) SWCNT were systematically investigated using theoretical methods such as PM6-DH2 and M06-2X in the scheme of OMIOM. It was found that the two loadings, adsorption on the sidewall of CNT and the encapsulation in CNT, have distinct solvent, protonation and diameter dependences. The encapsulation is much stronger than the adsorption of DOX on the sidewall of CNT, and the former also has significantly higher solvent and protonation effects than the latter. The adsorption primarily occurs through π-π stacking and just becomes slightly stronger as the diameter of CNT increases, while besides π-π stacking the additional C-H/N-H/O-H…π and C=O…π also contribute to the encapsulation of DOX in CNT. It seems that (8,8) CNT (diameter ~ 11Å) energetically is an onset for the encapsulation since the encapsulation turns from endothermic to exothermic as the diameter is larger than approximately 11 Å, and the optimal diameter for the encapsulation is 14Å corresponding to (10,10) CNT. Thus for the thick CNT the encapsulation may also play an important role in the loading and releasing for the CNT-based drug delivery system of the DOX.