Key Laboratory of Colloid, Interface and Chemical Thermodynamics, Beijing National Laboratory for Molecular Sciences (BNLMS), CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China.
Soft Matter. 2017 Nov 1;13(42):7804-7812. doi: 10.1039/c7sm01940h.
This work involved the construction of pH-responsive self-assembly systems from a pH-sensitive four-arm carboxylate acid (4EOCOOH) and either the cationic single chain surfactant dodecyl trimethyl ammonium bromide (DTAB) or the cationic gemini surfactant hexamethylene-1,6-bis(dodecyldimethylammonium bromide) (12-6-12). It was found that the constructed oligomeric-like structures from the mixtures of 4EOCOOH with DTAB or 12-6-12 greatly enhance the aggregation ability of the mixtures, thus improving the pH-responsivity. In particular, surfactant concentrations significantly affect the pH-responsivity at a fixed 4EOCOOH concentration. At higher surfactant concentrations, the pH-responsivity is suppressed, while at lower surfactant concentrations, the mixed aggregates gradually change from micelles to unstable large spherical aggregates or vesicles, and then to stable spherical aggregates, with decreasing pH. Moreover, the surfactant/4EOCOOH systems have different solubilization abilities for three hydrophobic drugs. For quercetin and baicalein, the systems support much better solubilization at lower pH values, while for indomethacin, the systems show better solubilization at higher pH values. In particular, compared with DTAB, 12-6-12 is more efficient in constructing pH-responsive systems, and the 12-6-12/4EOCOOH mixture shows better ability for solubilizing hydrophobic drugs. This work will be helpful in the design of high-efficiency, pH-responsive surfactant systems for solubilizing hydrophobic drugs by simply mixing pH-sensitive molecules with surfactants.
这项工作涉及从 pH 敏感的四臂羧酸（4EOCOOH）和阳离子单链表面活性剂十二烷基三甲基溴化铵（DTAB）或阳离子双子表面活性剂十六烷-1,6-双（十二烷基二甲基溴化铵）（12-6-12）构建 pH 响应自组装系统。结果发现，混合物中的 4EOCOOH 与 DTAB 或 12-6-12 构建的类似寡聚物结构极大地增强了混合物的聚集能力，从而提高了 pH 响应性。特别是，在固定的 4EOCOOH 浓度下，表面活性剂浓度显著影响 pH 响应性。在较高的表面活性剂浓度下，pH 响应性受到抑制，而在较低的表面活性剂浓度下，混合聚集物逐渐从胶束变为不稳定的大球形聚集物或囊泡，然后随着 pH 值的降低变为稳定的球形聚集物。此外，表面活性剂/4EOCOOH 体系对三种疏水性药物具有不同的增溶能力。对于槲皮素和黄芩素，体系在较低的 pH 值下具有更好的增溶能力，而对于吲哚美辛，体系在较高的 pH 值下具有更好的增溶能力。特别是，与 DTAB 相比，12-6-12 更有效地构建 pH 响应体系，并且 12-6-12/4EOCOOH 混合物具有更好的增溶疏水性药物的能力。这项工作将有助于通过简单地将 pH 敏感分子与表面活性剂混合来设计高效的 pH 响应表面活性剂体系，以增溶疏水性药物。
