热诱导白蛋白与壳聚糖在溶液中的自组装-He Naipu

80 ℃热诱导牛血清白蛋白(BSA)变性,BSA疏水残基暴露在分子表面,并进一步凝胶化.采用紫外-可见光光度仪(UV-Vis)和动态激光光散射仪(DLS)考察了热处理时间、溶液pH值、壳聚糖(CS)与BSA配比等因素对CS与BSA自组装行为的影响.加热时间介于15~20 min,BSA与CS发生自组装;BSA/CS混合体系pH大于BSA等电点(pI=4.7)时,BSA与壳聚糖静电作用增强,随着pH增大,出现沉淀.BSA浓度过高,变性BSA之间聚集作用增强,导致体系出现沉淀.研究结果显示,CS阻碍了BSA自身凝胶化进程,并与BSA发生自组装.在pH=5.4的溶液中制备了BSA-CS自组装体.采用透射电镜(TEM)观察了自组装体的形态,采用DLS对其粒径及其分布进行了测试.自组装体是以BSA聚集体为核、CS分子链为壳的核壳纳米结构.制备的自组装体室温贮存40天后,其粒径和分布无明显变化.

The unfolding of bovine serum albumin (BSA) was induced by heating at 80 ℃,and hydrophobic residues were exposed on the BSA surface,which caused the gelation of BSA.Influences of heating temperature and time,pH value and the ratio of BSA to chitosan on the self-assembly behavior between denatured BSA and chitosan (CS) in aqueous solutions were explored by the ultraviolet-visible spectroscopy (UV-Vis) and dynamic light scatter (DLS).The self-assembly behavior of BSA and chitosan occurred at 80 ℃ for 15-20 min.At pH> 4.7(the isoelectric point of BSA,pI=4.7),electrostatic interactions between BSA and chitosan enhanced,and as pH is increased,precipitates were formed in the mixture system.At high concentrations of BSA,aggregation of denatured BSA resulted in precipitation of the aggregates.The results indicated that chitosan hindered the gelation process of BSA and self-assembled with denatured BSA by heating at 80 ℃.BSA-CS self-assemblies were fabricated at pH 5.4 in aqueous solutions by heating at 80 ℃.The morphology of nanoparticles was observed by the transmission electron microscopy (TEM) and the size and it distribution were measured by DLS.BSA-CS self-assemblies were constituted by the core consisting of BSA aggregates and the shell consisting of chitosan chains.Self-assemblies were stored without any changes at room temperature for 40 days.

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