Study on the Protein Adsorption and Bacterial Attachment to Synthetic Hydroxyapatite

众所周知，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引起的现象。这一现象受牙齿、蛋白质和细菌表面的理化特性以及牙齿、蛋白质和细菌之间的静电相互作用的显著影响。我们成功地测量了合成羟基磷灰石（HAp）、蛋白质和细菌的zeta电位（迁移率），并分析了蛋白质在羟基磷灰石（HAp）上吸附的物理化学现象。利用x射线光电子能谱对细菌表面存在的元素进行定性分析，并利用原子力显微镜对细菌表面形貌进行观察，与细菌的电化学表征进行探讨。我们的结论是；1)不仅可以测量HAp的zeta电位，还可以测量作为活胶体的蛋白质和细菌的zeta电位。对于zeta电位的测量仪器，HAp采用Pen-Kem公司提供的Lazer Zee型号-501比较方便，蛋白质和细菌采用大suka Electronics公司和Malvern公司提供的LEZA 600和ZETASIZER-4比较方便。2)氟或氟表面活性剂处理改变HAp和牙釉质的表面特性，影响蛋白质的吸附。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则会增强蛋白质的吸附。3) pH 5.0 ~ 9.0范围内口腔细菌zeta电位无明显变化。然而，根据zeta电位的数据，细菌被分为两组；一组为稳定的负电位，另一组为接近0的电位。细菌表面的Zeta电位不仅与细菌表面磷酸离子的存在有关，还与糖蛋白的长度和细菌表面脊的平整度有关。

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.