Study on the Protein Adsorption and Bacterial Attachment to Synthetic Hydroxyapatite

牙菌斑的原始形成是由蛋白质吸附和细菌附着在牙齿表面而引发的现象。本研究成功地测定了人工合成羟基磷灰石（HAp）、蛋白质和细菌的zeta电位（迁移率），并对蛋白质吸附在HAp表面的现象进行了物理化学分析。利用X射线光电子能谱仪定性分析了细菌表面存在的元素，利用原子力显微镜观察了细菌表面的形貌，并与细菌的电化学特性进行了探讨，得出以下结论：1）不仅可以测量HAp的zeta电位，而且可以测量蛋白质和细菌作为活胶体的zeta电位。关于zeta电位的测量装置，HAp方便地使用由Pen-Kem公司提供的Lazer Zee Model-501，对于蛋白质和细菌，使用由Otsuka Electronics Co.和马尔文Co.提供的LEZA 600和ZETASIZER-4。2）通过氟化物或含氟表面活性剂的处理来改变HAp和牙釉质的表面特性以影响蛋白质吸附。HAp表面疏水性的轻微变化会降低蛋白质的吸附，而HAp表面疏水性的极端变化会增强蛋白质的吸附。3)口腔细菌的zeta电位在pH 5.0和9.0之间没有变化。然而，根据zeta电位的数据，细菌被分为两组;一组为稳定的负zeta电位，另一组为zeta电位接近0的细菌。细菌表面Zeta电位不仅与细菌表面磷酸根离子的存在有关，还与细菌表面糖蛋白的长度和细菌表面嵴的光滑度有关。

It is well known that primitive formation of plaque is a phenomenon initiated by protein adsorption and bacterial attachment onto tooth surface. This phenomenon is significantly influenced by physicochemical characteristics of tooth, protein and bacterial surface, and by electrostatic interaction between tooth, protein and bacteria.We succeeded to measure zeta potentials (mobility) of synthetic hydroxyapatite (HAp), protein and bacteria, and to analyze physicochemically the phenomenon of protein adsorption onto HAp. We also analyzed qualitatively the elements existing on bacterial surface by using X-ray photoelectron spectroscope, moreover observed the surface morphology of bacteria by atomic force microscope to discuss with electrochemical characterization of bacteria.We concluded that; 1) It was possible to measure not only zeta potentials for HAp but also protein and bacteria as a living colloid. With regard measuring apparatus of zeta potential, it was convenient for HAp to employ Lazer Zee Model-501 provided by the Pen-Kem Co., and for protein and bacteria to use LEZA 600 and ZETASIZER-4 provided by the Otsuka Electronics Co. and the Malvern Co. 2) Surface characteristics of HAp and enamel were altered by treatments of fluoride or fluorosurfactant to affect protein adsorption. The protein adsorption is decreased by slight changes of hydrophobicity of HAp surface, while increased adsorption of protein is enhanced by extreme changes of hydrophobicity of HAp surface. 3) There were no changes of zeta potentials for oral bacteria between pH 5.0 and 9.0. However, the bacteria were divided two groups by the data of zeta potential; one group for stabilized negative zeta potential and another group for near the O of zeta potential. Zeta potential of bacterial surface was dependent on not only the presence of phosphate ion on the bacterial surface but also the length of glycoprotein and smoothness of ridge of bacterial surface.