含硅羟基磷灰石粉体的合成及其与蛋白质的相互作用研究

Preparation of silicon-substituted hydroxyapatite powder and its interaction with bovine serum albumin

将硅掺入羟基磷灰石(HA)晶格中能有效地提高HA的生物相容性。采用湿法合成了含硅羟基磷灰石微粉(Si-HA),用X射线荧光光谱(XRF)、X射线衍射(XRD)、红外光谱(FTIR)、扫描电镜(TEM)和荧光光谱等对Si-HA的晶相、结构、化学组成、形貌及其与牛血清白蛋白(BSA)的相互作用进行了表征和分析。结果表明:Si元素溶入磷灰石晶格中,使HA晶胞参数和结构发生变化,随着Si含量的增加,HA中-OH和PO43-的吸收峰呈减弱趋势,表明SiO44-可能部分取代了PO43-。Si-HA与BSA作用后的PO43-吸收峰发生变化,在Si-HA图谱中出现了蛋白质的酰胺Ⅰ带和酰胺Ⅱ带吸收峰,随着Si-HA与BSA作用时间由2h^3d的变化,BSA溶液酰胺I带位置出现蓝移,半峰宽减小且峰型变得尖锐,酰胺II带则向低频区移动。Si-HA与BSA作用3d后,开始在1139处出现PO43-的吸收峰。荧光光谱显示:加入相同质量的HA和Si-HA后蛋白质内源荧光强度较纯BSA溶液下降,随着Si-HA中Si质量分数的增加BSA荧光强度下降幅度增大,发射峰也出现红移,且Si-HA与BSA作用较纯HA与BSA的作用强,说明Si-HA使蛋白质二级结构发生改变,Si-HA中的Ca、PO43-、SiO44-与BSA之间发生了相互溶解、吸附和键合等作用,证明了Si-HA与生命物质蛋白质之间具有较高的反应性能,对Si-HA的生物活性及其与BSA相互作用的机理进行了详尽的阐述。

The incorporation of silicon into the hydroxyapatite lattice can improve the bioactivity ofhydroxyapatite. Silicon-substituted hydroxyapatite （Si-HA） has been prepared by incorporating a small amount of silicon into the structure of hydroxyapatite via an aqueous precipitation reaction. The interaction between Si-HA and bovine serum albumin （BSA） were characterized by FTIR, fluorescence spectra and XRD. The results indicate that the XRD spectra of Si-HA have the characteristic diffraction peaks of HA, and the incorporation of silicon changes the lattice of the crystal. The most notable effect of silicon substitution in FTIR spectra is that the stretching vibration band of --OH groups and PO4^3- groups decrease with the silicon contents increase. Silicon substitution appeares to affect the FTIR spectra of Si-HA and BSA. The absorption peak of amide group （--CONH2） in BSA is observed in Si-HA powder by FTIR spectra and the absorption peak of amide group in BSA solution alters and gradually blue shift after adding Si-HA powder from 2h to 3d. The fluorescence intensity of BSA decreases and red shift with the increase amounts of Si in Si-HA. The change of the fluorescence intensity in Si-HA is greater than that in HA, which suggests that Si-HA-BSA complexes have been formed by positive ion Ca^2＋ in Si-HA binding to negative ion --COO^- in BSA and SiO4^4-, PO4^3- in Si-HA binding to --NH2 in BSA. It can be assumed that Si-HA can bind to BSA and alter the hydrophobic environment on the surface of BSA molecules. On the basis of the results the bioactivity mechanism of Si-HA is discussed.