钠基与钙基蒙脱石插层牛血清白蛋白的比较研究

Comparative study of BSA intercalated into Na-MMT and Ca-MMT

蒙脱石负载蛋白质的研究为纳米复合材料开发、药物的负载与缓释等方面研究奠定基础。为了进一步分析蒙脱石不同结构对蛋白质插层蒙脱石的影响,作者根据离子交换的原理,研究了在不同pH值条件下,牛血清白蛋白(BSA)插层钠、钙基蒙脱石的插层效果。研究发现,在pH值低于等电点时,钙基蒙脱石(Ca-MMT)与钠基蒙脱石(Na-MMT)插层效果差异明显;相同pH值下,Na-MMT插入的蛋白质比例高。FT-IR和UV-vis分析都显示蒙脱石颗粒的存在改变了蛋白质的结构;UV-vis分析显示,由于蒙脱石表面助色基作用,共轭效应加强,上清液中的蛋白质214nm吸收峰,产生了明显的红移;氢键等的破坏则导致蛋白质部分螺旋结构消失而使蒙脱石层间缓释出来的蛋白质吸收峰发生明显的蓝移。Ca-MMT与Na-MMT对牛血清白蛋白结构变化的作用程度存在差别。

Our research on the protein loading into montmorillonite may lay afoundation on the development of nanocomposites and drug loading and release. In order to further analyze the effects of different montmoriUonite structure on the protein intercalation, the authors studied the BSA intercalated into Na-MMT and Ca-MMT under different pH according to the principle of ion exchanging. It shows that the intercalation effects of Na-MMT and Ca-MMT are different at pH values lower than the isoeleetric point of protein and content of protein interacted into Na-MMT are more than that of Ca-MMT at the same pH value. FT-IR and UV-vis analysis show the existence of montmorillonite particles changes the structure of the protein. Analysis of the UV-vis spectra finds that a bathochromie shift happens at the 214nm absorption wavenumber of protein in solution because of the conjugated effect intensified which is caused by the function of the auxochrome at the surface of montmorillonite layer. While hypsochromic shift of the protein released from the interlayer of montmorillonite is induced by the partly disappearance of spiral structure as a result of the hydrogen bond break and so on. UV-vis analysis also shows that the effects of Ca-MMT and Na-MMT on BSA are different in degree.