Authors: S. Nakamura, M. Ueshima, T. Kobayashi and K. Yamashita
Affilation: Tokyo Medical and Dental University, Japan
Pages: 372 - 375
Keywords: pseudo-biological environment, electret, HYDROXYAPATITE
A pseudo-biological environment using simulated body fluid (SBF) has been widely accepted as an osteobonding estimation of biomaterial surfaces. In the present study, the interactions at the interface of the polarized HA surface and the solution were investigated. The nano-scale activated field was discussed in view of the electrostatic effects of HA electrets. The HA crystals with the size of ca. 50 nm were overgrown on almost all the negative charge induced surface of HA ceramic surface. Almost of the particles were deposited on each of the ceramic substrate grain. The grain boundaries of the substrate clearly appeared as linear lacks of deposition. The majority of the overgrown crystals were spheroidal and uniformly orientated. On the non-polarized ceramic surfaces, neither the individual overgrowth on each of the substrate grain nor the orientation of the crystals was observed. The microstructural observation revealed that the negative surface charges accelerated overgrowth in initial stage but that the positive charge decelerated it, as described in the published data. Moreover, the induced surface charges of the HA electrets affected the overgrowth conductivities of the individual substrate grains. Therefore, the ~10 nanometer-scale modification was attributed to the electrostatic force generated by the HA electret.