季铵盐型阳离子表面活性剂与牛血清白蛋白的相互作用

本文合成并表征了三种不同烷基链长度的季铵盐型阳离子表面活性剂：N-十二烷基-N-（2-羟乙基）-N，N-二甲基溴化铵（DHDAB）、N-十四烷基-N-（2-羟乙基）-N，N-二甲基溴化铵（THDAB）、N-十六烷基-N-（2-羟乙基）-N，N-二甲基溴化铵（CHDAB）。采用荧光光谱法、紫外-可见光谱法、动态光散射法和等温滴定量热法对三种表面活性剂与牛血清白蛋白（BSA）的相互作用进行研究。荧光光谱研究表明，三种表面活性剂主要与BSA分子内的色氨酸残基发生相互作用，导致蛋白质的构象发生变化，且表面活性剂烷基链越长，与BSA的相互作用就越强。BSA荧光猝灭的主要原因是静态猝灭，紫外光谱实验同样验证了静态猝灭的存在。等温滴定量热法结果表明低浓度的表面活性剂与BSA主要发生静电作用和疏水作用而放热。动态光散射结果表明高浓度的表面活性剂会使BSA结构被破坏。本文揭示了表面活性剂与BSA相互作用的机理，为表面活性剂的广泛应用提供了理论基础。

The Interactions between Quaternary Ammonium Cationic Surfactants and Bovine Serum Albumin

UV-visible (UV-Vis) absorption spectroscopy, fluorescence spectroscopy (FL), dynamic light scattering (DLS) and isothermal titration calorimetry (ITC) were used to study the interactions between bovine serum albumin (BSA) and the three quaternary ammonium surfactants N-dodecyl-N-(2-hydroxyethyl)-N, Ndimethyl ammonium bromide (DHDAB), N-tetradecyl-N-(2-hydroxyethyl)-N, N-dimethyl ammonium bromide (THDAB) and N-cetyl-N-(2-hydroxyethyl)-N, N-dimethyl ammonium bromide (CHDAB). These surfactants quenched the intrinsic fluorescence of BSA, with longer alkyl chains resulting in more significant quenching. This was attributed to static quenching. Further evidence of static quenching was provided by UV-Vis absorption spectroscopy. The particle size of BSA was found to initially increase and then decrease with increasing surfactant concentration. The concentration of surfactant changed the type of interaction mode. This work revealed the mechanism and binding characteristics between surfactants and protein, and provides the basis for further applications of surfactants.