叶酸修饰嵌段聚合物与BSA相互作用研究

通过可逆加成断裂链转移聚合法(RAFT)合成了两亲性三嵌段聚合物聚苯乙烯-聚丙烯酸-聚苯乙烯(PS-PAA-PS),通过非均相合成法合成了叶酸修饰的聚苯乙烯-聚丙烯酸-聚苯乙烯聚合物FA/PS-PAA-PS,并用红外光谱证明其结构。采用荧光光谱法研究了FA/PS-PAA-PS与牛血清白蛋白(BSA)之间的相互作用。FA/PS-PAA-PS通过静态猝灭过程使得BSA荧光强度减弱,在22℃和30℃下,FA/PS-PAA-PS与BSA结合常数分别为1.2252×1014mol.L-1和1.0645×1014mol.L-1,结合位点数分别为1.4124和1.2573,通过计算反应热力学参数值,可推断FA/PS-PAA-PS与BSA之间的作用力主要为疏水作用。根据Frster非辐射能量转移理论计算得到FA/PS-PAA-PS与BSA的结合距离为r=3.75 nm,表明FA/PS-PAA-PS与BSA之间发生了能量转移,BSA在FA/PS-PAA-PS的作用下发生的荧光猝灭属于非辐射能量转移的静态猝灭过程。

Interaction between Folate-mediated PS-PAA-PS and Bovine Serum Albumin by Fluorescence Spectrometry

An amphiphilic triblock copolymer PS-PAA-PS was synthesized via reversible addition fragmentation chain transfer(RAFT) polymerization.Heterogeneous synthesis was used to prepare folate-mediated PS-PAA-PS.The product was characterized by FTIR.The binding interaction of the folate-mediated PS-PAA-PS colloidal spheres with bovine serum albumin(BSA) was investigated by fluorescence spectra.The binding constant(KA) and the number of binding sites(n) for FA/PS-PAA-PS with BSA were calculated as 1.2252×1014 mol·L-1 and 1.0645×1014mol·L-1,1.4124 and 1.2573,respectively.The main binding forces of FA/PS-PAA-PS to BSA were concluded as hydrophobic forces from the calculated values of the hermodynamic parameter.The binding distance between BSA and FA/PS-PAA-PS was determined to be about 3.75 nm based on Frster nonradiative energy theory.The results showed that FA/PS-PAA-PS quenched the intrinsic fluoreseence of BSA.The mechanism of fluorescence quenching was confirmed by static quenching and non-radiation energy transferring.