Key Laboratory of Colloid and Interface Chemistry of the Education Ministry of China, Shandong University, Jinan 250100, China.
Soft Matter. 2021 Sep 15;17(35):8086-8094. doi: 10.1039/d1sm00783a.
A Good's buffer ionic liquid (GB-IL) composed of quaternary ammonium cations and Good's buffer anions is first introduced into a microemulsion system as a self-buffering and biocompatible electrolyte. The effects of the constituting ions of a GB-IL and their concentrations on the phase behavior of the anionic surfactant SDBS stabilized -octane-HO microemulsion system were studied for the first time using the - fish-like phase diagram method. The result indicates that the phase behavior of the above microemulsion system is greatly affected by GB-IL cations with a longer alkyl chain on the cation being more favorable for phase inversion. Compared with NaCl, a GB-IL of the same concentration is more efficient for achieving phase inversion, due to the dual role of an electrolyte and a co-alcohol. In addition to the phase behavior, the stability of horseradish peroxidase (HRP) solubilized in an SDBS stabilized bicontinuous microemulsion is also affected by a GB-IL. It is found that the variation of the cationic alkyl chain has a negligible effect on the microemulsion microstructure, but has a significant influence on the stability of the solubilized HRP. At a fixed concentration of the GB-IL, the quaternary ammonium cation with a longer alkyl chain is better for the stabilization of the HRP activity. For a given GB-IL, a higher level of the GB-IL results in a better HRP stability. More importantly, the GB-IL-buffered microemulsion, at the same level of the buffering salt, is more advantageous than the phosphate-buffered one for the stabilization of the HRP activity. This advantage is more pronounced for higher concentrations of the GB-IL. This difference in the HRP stability, caused by the buffering salts, should be ascribed to the microemulsion microstructure effect as well as the Hofmeister effect. The present study provides a guideline for the construction of a bicontinuous microemulsion with a simplified composition and stabilizing effect on the solubilized enzyme.
首次将 Good's 缓冲离子液体（GB-IL）作为自缓冲和生物相容的电解质引入到微乳液体系中，该离子液体由季铵阳离子和 Good's 缓冲阴离子组成。首次采用“鱼状”相图法研究了 GB-IL 组成离子及其浓度对阴离子表面活性剂 SDBS 稳定的-辛烷-H2O 微乳液体系相行为的影响。结果表明，GB-IL 阳离子的烷基链越长，对相转变越有利。与 NaCl 相比，具有相同浓度的 GB-IL 更有利于实现相转变，这是由于其同时具有电解质和共醇的双重作用。除相行为外，GB-IL 还影响 HRP 在 SDBS 稳定的双连续微乳液中的溶解稳定性。结果表明，阳离子烷基链的变化对微乳液的微观结构几乎没有影响，但对溶解的 HRP 的稳定性有显著影响。在固定浓度的 GB-IL 下，具有较长烷基链的季铵阳离子更有利于稳定 HRP 活性。对于给定的 GB-IL，GB-IL 的浓度越高，HRP 的稳定性越好。更重要的是，在相同缓冲盐水平下，GB-IL 缓冲的微乳液比磷酸盐缓冲的微乳液更有利于稳定 HRP 活性。对于较高浓度的 GB-IL，这种 HRP 稳定性的差异更为明显。这种由缓冲盐引起的 HRP 稳定性差异，应归因于微乳液的微观结构效应和 Hofmeister 效应。本研究为构建组成简化且对溶解酶具有稳定作用的双连续微乳液提供了指导。
