La^(3+)和Dy^(3+)壳聚糖配合物与牛血清白蛋白相互作用

Interaction between Complexes of Chitosan with La^(3+) and Dy^(3+) and Bovine Serum Albumin

在模拟人体生理条件下,利用荧光、紫外?可见吸收和同步荧光光谱法研究了水溶性壳聚糖(CS)及两种壳聚糖稀土配合物(CS-La和CS-Dy)与牛血清白蛋白(BSA)的相互作用.紫外吸收光谱分析表明,CS,CS-La和CS-Dy相互作用的最大吸收峰强度都增加.用Stern–Volmer方程分别对荧光光谱的实验数据进行分析,发现CS-La对BSA的荧光猝灭作用属于静态荧光猝灭,反应生成新的复合物.而CS和CS-Dy对BSA的荧光猝灭作用有静态荧光猝灭和动态猝灭,发生了分子内的非辐射能量转移.求得三种物质在室温和体温的情况下与BSA相互作用过程的结合常数KA[291 K,CS-BSA:1.807?104 L/(g·s),CS-La-BSA:3.065?104 L/(g·s),CS-Dy-BSA:2.193?104 L/(g·s);310 K,CS-BSA:2.665?104 L/(g·s),CS-La-BSA:2.022?104 L/(g·s),CS-Dy-BSA:7.246?104 L/(g·s)]和相关热力学参数;确定了CS和CS-Dy与BSA之间的主要作用力是静电和疏水作用力,而CS-La与BSA之间的作用力主要为范德华力和氢键等作用力.同步荧光光谱表明,CS,CS-La和CS-Dy均对牛血清白蛋白的构象和所处的微环境产生影响.

The interaction between chitosan（CS）, its complexes CS-La and CS-Dy, and bovine serum albumin（BSA） in vitro under simulative physiological conditions was studied by fluorescence, ultraviolet？visible absorption and synchronous fluorescence spectrometry. The results showed that CS, CS-La, CS-Dy had strong effects on quenching of the fluorescence launching and enhanced the UV absorption spectra of BSA. After the fluorescence quenching, the obtained data were analyzed by Stern？Volmer equation, the results indicated that the reactions between BSA and CS, CS-La and CS-Dy generated new complexes. The quenching belonged to static fluorescence quenching, with non-radiation energy transfer happening within single molecule, but the static and dynamic quenching coexisted in the reactions between CS and CS-Dy and BSA. The binding constant KA（291 K, CS-BSA： 1.807×10^4 [L/（g·s）], CS-La-BSA： 3.065×10^4 [L/（g·s）], CS-Dy-BSA： 2.193×10^4 [L/（g·s）]; 310 K, CS-BSA： 2.665×10^4 [L/（g·s）], CS-La-BSA： 2.022×10^4 [L/（g·s）], CS-Dy-BSA： 7.246×10^4 [L/（g·s）] and thermodynamics parameters（？H, ？S, ？G） were calculated, respectively according to the equation of fluorescence spectrometry at different temperatures. Based on thermodynamic data, the main reactions between CS and CS-Dy and BSA were electrostatic and hydrophobic forces, but those between CS-La and BSA van der Waals and hydrogen bond forces. The effects of CS, CS-La and CS-Dy on the conformation of BSA shown by synchronous fluorescence spectrometry indicated that they changed the micro-environment and conformation of BSA molecules.