窄分子量分布低聚壳聚糖CSn(n表示壳聚糖的聚合度, n=6, 8, 11)和对二甲氨基苯甲醛(DMABA)通过缩合反应得到了新型的基于壳聚糖的希夫碱化合物DMABA-CSn。 利用荧光光谱法, 同步荧光光谱法, 圆二色谱法(CD)和等温滴定微量热法(ITC)研究了DMABA-CSn与牛血清白蛋白 (BSA)之间的相互作用。 通过荧光光谱法探讨了DMABA-CSn对BSA的荧光猝灭机制。 结果表明, DMABA-CSn(n=6, 8, 11) 均能使BSA的荧光猝灭, 猝灭机制是形成DMABA-CSn/BSA复合物的静态猝灭。 利用同步荧光光谱法和圆二色谱法考察了DMABA-CSn对BSA构象的影响。 研究结果表明, BSA的构象在DMABA-CSn的溶液微环境中发生了变化。 另外, ITC热力学测定结果(ΔH<0, ΔS<0, ΔG<0)表明, BSA与DMABA-CSn的作用过程是自发进行的放热过程, 二者之间的作用力类型主要是氢键和疏水作用。 同时, 研究结果也说明在一定的分子量范围内, 随着CSn聚合度的增加, DMABA-CSn更容易与BSA结合。 研究结果为DMABA-CSn(n=6, 8, 11)作为潜在药物的药理作用机制研究提供了一定的理论参考。

The novel chitosan-based schiff bases DMABA-CSn were synthesized by the concentration reaction of narrow molecular distribution,low molecular weight chitosan CSn (n represents the degree of polymerization of chitosan, n=6, 8, 11) and 4-Dimethylaminobenzaldehyde (DMABA). The binding reaction between DMABA-CSn and bovine serum albumin (BSA) was studied with fluorescence spectroscopy, synchronous fluorescence spectropy, circular dichroism (CD) and isothermal tiration calorimetric (ITC). The fluoresonance quenching mechanism between DMABA-CSn and BSA was studied with fluorescence spectroscopy. The results indicated that DMABA-CSn (n=6, 8, 11) had the ability to quench the fluorescence from BSA and the quenching mechanism was a static quenching process with complex formation of DMABA-CSn/BSA. The effect of DMABA-CSn on the conformation of BSA was studied with synchronous fluorescence spectroscopy. The results suggested that the conformation of BSA was changed in the microenvironment of DMABA-CSn. Based on the thermodynamic results, the type of binding force was determined between DMABA-CSn and BSA. In addition, the thermodynamics results (ΔH<0, ΔS<0, ΔG<0) with ITC determination indicated that the binding process between DMABA-CSn and BSA was exothermic and spontaneous. What’s more, the main binding force was hydrogen bond and hydrophobic interaction. At the same time, with the increase of polymerization degree of CSn in a certain range of molecular weight, DMABA-CSn can be more easiliy combined with BSA. The research results have provided theoretical reference for the study on pharmacological mechanism of DMABA-CSn (n=6, 8, 11) as potential drugs.