Bal Jayanta Kumar, Das Nilanjan, Mathur Tanmay, Plaisier Jasper R, Thomas Sabu
Abhedananda Mahavidyalaya, University of Burdwan, Sainthia, 731234, India.
Elettra - Sincrotrone Trieste S.C.p.A., S.S. 14 Km 163.5 in Area Science Park, Basovizza, Trieste 34149, Italy.
ACS Omega. 2022 Apr 14;7(16):14031-14044. doi: 10.1021/acsomega.2c00572. eCollection 2022 Apr 26.
The interaction of a heterocyclic azo compound with itself and with bovine serum albumin (BSA) is realized by probing the structural modifications in Langmuir (L) monolayers and Langmuir-Blodgett (LB) films. It was found from the pressure-area/molecule isotherms that the elastic, thermodynamic, and hysteretic properties of the pure azo L monolayer were strongly altered due to the variation of temperature and pH of subphase water. In addition to that, the modification of such properties of the azo L monolayer due to mixing with BSA was also studied. The incorporation of BSA within the azo molecular assembly reduced the elasticity of that assembly. Such reduction of in-plane elasticity of the pure azo monolayer can also be achieved by reducing the temperature and pH of subphase water without adding BSA. A reduction in area per molecule of the azo assembly at the air-water interface associated with the conformational change from horizontal to vertical orientation facilitating π-π interaction was observed with increase in temperature and pH of the subphase. Such parameters also affected the interactions between azo and BSA molecules within the azo/BSA binary system. The structures of pure azo and binary films can be determined after they are transferred to hydrophilic and hydrophobic Si surfaces using the LB technique. Their out-of-plane and in-plane structures, as extracted from two complementary surface sensitive techniques, X-ray reflectivity and atomic force microscopy, were found to be strongly dependent on mixing with BSA, subphase pH, temperature, and substrate nature.
通过探测朗缪尔（L）单分子层和朗缪尔-布洛杰特（LB）膜中的结构变化，实现了杂环偶氮化合物与其自身以及与牛血清白蛋白（BSA）之间的相互作用。从压力-面积/分子等温线发现，由于亚相水的温度和pH值变化，纯偶氮L单分子层的弹性、热力学和滞后特性发生了强烈改变。除此之外，还研究了由于与BSA混合而导致的偶氮L单分子层此类性质的改变。在偶氮分子组装体中加入BSA降低了该组装体的弹性。不添加BSA，通过降低亚相水的温度和pH值也能实现纯偶氮单分子层面内弹性的降低。随着亚相温度和pH值的升高，观察到气-水界面处偶氮组装体每分子面积的减小，这与从水平取向到垂直取向的构象变化促进了π-π相互作用有关。这些参数也影响了偶氮/BSA二元体系中偶氮分子与BSA分子之间的相互作用。使用LB技术将纯偶氮膜和二元膜转移到亲水和疏水硅表面后，可以确定它们的结构。从两种互补的表面敏感技术X射线反射率和原子力显微镜提取的它们的面外和面内结构，被发现强烈依赖于与BSA的混合、亚相pH值、温度和基底性质。
