Center of Eco-material and Green Chemistry, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, PR China.
Center of Eco-material and Green Chemistry, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, PR China.
Colloids Surf B Biointerfaces. 2014 Jan 1;113:51-8. doi: 10.1016/j.colsurfb.2013.08.036. Epub 2013 Aug 31.
Halloysite nanotube is an ideal vehicle of the controlled release of drugs. In this study, we systematically investigated the effects of acid- and heat-treatments on the physicochemical properties, structure and morphology of halloysite by XRD, FTIR, SEM and TEM. Afterwards, the adsorption and in vitro release properties of halloysite for cationic ofloxacin (OFL) were evaluated. The results indicate that HCl treatment has no influence on the crystal structure of halloysite, whereas it becomes amorphous after calcined at temperature higher than 500 °C. Both acid- and heat-treatments have no evident influence on the tubular structure of halloysite. OFL was adsorbed onto halloysite via electrostatic interaction between protonated OFL and negative halloysite surface, cation exchange as well as electrostatic interaction between the OFL-Al(3+) complexes and the negative halloysite surface. Acid-treatment facilitates the release of the adsorbed OFL compared with the natural halloysite in spite of a slight decrease of adsorption capacity. However, heat-treatment results in a sharp decrease of adsorption capacity for OFL owning to the OFL-promoted dissolution of aluminum and the disappearance of the porous structure. Although heat-treatment also facilitates release of the adsorbed OFL, the amount of OFL released is in fact less than the natural halloysite owing to the very low adsorption capacity. Thus, acid-activation is an effective protocol to improve the adsorption and release of halloysite for cationic drug molecules.
埃洛石纳米管是药物控制释放的理想载体。在这项研究中，我们通过 XRD、FTIR、SEM 和 TEM 系统地研究了酸处理和热处理对埃洛石的物理化学性质、结构和形态的影响。随后，评估了埃洛石对阳离子氧氟沙星（OFL）的吸附和体外释放性能。结果表明，HCl 处理对埃洛石的晶体结构没有影响，但在 500°C 以上煅烧时会变成无定形。酸处理和热处理对埃洛石的管状结构均无明显影响。OFL 通过质子化 OFL 与负埃洛石表面之间的静电相互作用、阳离子交换以及 OFL-Al（3+）配合物与负埃洛石表面之间的静电相互作用被吸附到埃洛石上。与天然埃洛石相比，酸处理有利于吸附的 OFL 的释放，尽管吸附容量略有下降。然而，热处理导致 OFL 的吸附容量急剧下降，这归因于 OFL 促进了铝的溶解和多孔结构的消失。尽管热处理也有利于吸附的 OFL 的释放，但由于吸附容量非常低，释放的 OFL 量实际上少于天然埃洛石。因此，酸活化是改善埃洛石对阳离子药物分子的吸附和释放的有效方法。
