Evolution of calcium phosphate crystallization on three functional group surfaces with the same surface density

Detailed investigations of the biomineralization process of hydroxyapatite on the functional group surfaces of carboxyl, amino and methyl are performed. The three surface densities of the functional groups and their patterns were measured to be the same by XPS and AFM respectively. Crystallization was carried out in simulated body fluid in this study. Significantly different features of the crystallization process on the three surfaces were observed. Such differences in the process of nucleation and crystal growth are discussed according to the classical ion-based mechanism of the biomineralization pathways, as well as with the newly accepted mechanism of cluster-based biomineralization. This study indicates that both mechanisms work in suitable environments.