Suzuki T, Yamamoto T, Toriyama M, Nishizawa K, Yokogawa Y, Mucalo M R, Kawamoto Y, Nagata F, Kameyama T
Bioceramics Laboratory, National Industrial Research Institute of Nagoya, Kita-ku, Japan.
J Biomed Mater Res. 1997 Mar 15;34(4):507-17. doi: 10.1002/(sici)1097-4636(19970315)34:4<507::aid-jbm11>3.0.co;2-9.
The surface of biocompatible ceramics made of synthesized hydroxyapatite (HAP) and beta-tricalcium phosphate (TCP) was found to be extremely active in tissue culture medium. Using mixed ceramics of HAP and TCP which had been prepared with different Ca/P molar ratios adjusted in stepwise fashion to values of 1.50, 1.55, 1.60, 1.64 and 1.67, the characteristics of the surface were investigated. The time-dependent variation of zeta potential of the TCP-HAP ceramics immersed in distilled water and in culture medium with and without addition of fetal bovine serum showed that the surface was unstable with significant changes in the charge being observed. Dry TCP powder had a zeta potential of -19 mV, which shifted to -7 mV after soaking in water and to -26 mV in culture medium. In contrast, HAP had a zeta potential of -11 mV in a dry state, -9 mV in water and -29 mV in culture medium. Concentrations of calcium and phosphate dissolved in distilled water showed the solubility was higher for TCP than for HAP. In comparison, it was found that dissolved calcium and phosphate in the medium were removed from the solution by deposition on immersed TCP-HAP ceramics. These results suggested that the stability of the surface was closely related to both reactions of association and dissociation of calcium and phosphate in tissue culture medium. The zeta potential analysis also suggested that Ca-deficient HAP, which has a similar crystal structure to HAP with a Ca/P ratio less than 1.67, was generated by degradation and reforming of the surface layer. The most stable structure which was the most suitable for adhesion of L-929 cells was obtained by the mixture of 20% TCP and 80% HAP ceramics. In conclusion, the stability of the surface structure was considered to be the dominant factor for the enhancement of the adhesiveness of cells on TCP-HAP ceramics.
研究发现，由合成羟基磷灰石（HAP）和β-磷酸三钙（TCP）制成的生物相容性陶瓷表面在组织培养基中具有极高的活性。使用以逐步方式将不同钙磷摩尔比调整为1.50、1.55、1.60、1.64和1.67而制备的HAP和TCP混合陶瓷，对其表面特性进行了研究。浸泡在蒸馏水以及添加和不添加胎牛血清的培养基中的TCP-HAP陶瓷的zeta电位随时间的变化表明，该表面不稳定，电荷发生了显著变化。干燥的TCP粉末的zeta电位为-19 mV，浸泡在水中后变为-7 mV，在培养基中变为-26 mV。相比之下，HAP在干燥状态下的zeta电位为-11 mV，在水中为-9 mV，在培养基中为-29 mV。溶解在蒸馏水中的钙和磷的浓度表明，TCP的溶解度高于HAP。相比之下，发现培养基中的溶解钙和磷通过沉积在浸泡的TCP-HAP陶瓷上而从溶液中去除。这些结果表明，表面的稳定性与组织培养基中钙和磷的缔合和解离反应密切相关。zeta电位分析还表明，钙磷比小于1.67且晶体结构与HAP相似的缺钙HAP是由表面层的降解和重整产生的。通过20% TCP和80% HAP陶瓷的混合物获得了最稳定的结构，该结构最适合L-929细胞的黏附。总之，表面结构的稳定性被认为是增强细胞在TCP-HAP陶瓷上黏附性的主导因素。
