叶酸负载两亲嵌段聚合物与牛血清白蛋白结合作用的研究

Studies on the interaction between bovine serum album and folate-mediated PNIPAAm-PS-PNIPAAm

通过可逆加成断裂链转移聚合法(RAFT)合成了两亲三嵌段聚合物PNIPAAm-PS-PNIPAAm,通过GPC和1H NMR对聚合物的结构进行表征。TEM研究表明,PNIPAAm-PS-PNIPAAm在选择性溶剂中自组装形成半径约为200nm的球形胶束。通过非均相聚合,得到叶酸负载的嵌段聚合物FA/PNIPAAm-PS-PNIPAAm。采用荧光光谱技术研究叶酸负载的PNIPAAm-PS-PNIPAAm与牛血清白蛋白之间的结合作用,结果表明,叶酸负载的三嵌段聚合物PNIPAAm-PS-PNIPAAm对牛血清白蛋白的荧光猝灭机制为静态猝灭,通过计算得到结合反应的结合常数KA及热力学函数ΔGθ、ΔHθ和ΔSθ,确定了授受体之间的结合距离和能量转移效率,并确定了叶酸负载的PNIPAAm-PS-PNIPAAm与牛血清白蛋白之间是疏水相互作用。

An amphiphilic triblock copolymer PNIPAAm-PS-PNIPAAm was synthesized via reversible addition fragmentation chain transfer（RAFT） polymerization. The product was characterized by 1H-NMR and GPC. The triblock eopolymer self-assembled into spheres with the size of about 200nm in selective solution, Heterogeneous synthesis was used to prepare folate-mediated PNIPAAm- PS-PNIPAAm. The binding interaction of the folate-mediated PNIPAAm-PS-PNIPAAm colloidal spheres with bovine serum albumin （BSA） was investigated by fluorescence spectra and UV-vis spectra techniques. Mechanism discussion results indicated that the azo polymer colloidal spheres caused the fluorescence quenching of BSA by a static quenching procedure. Quenching constants and the number of binding sites were determined according to the Stern-Volmer equation. The equilibrium constant KA and the thermody- namic parameters △Gθ, AHθ and ASθ were calculated, indicating that hydrophobic forces play a major role in FA/PNIPAAm-PS- PNIPAAm colloidal spberes-BSA association. The binding distance between FA/PNIPAAm-PS-PNIPAAm and BSA and the energy transfer efficiency were also obtained.