The present paper demonstrated a biomimetic method to coat calcium phosphate (Ca-P) on the surface of titanium induced by NaOH-treatment from a simple supersaturated hydroxyapatite solution (SHS). The in#uence of pH value and calcium ions concentration on the precipitation process was investigated. It is necessary for the solution to be supersaturated than the critical concentration of octacalcium phosphate (OCP) to get Ca-P coatings on titanium surface. In the precipitating process, it seems that amorphous calcium phosphate (ACP) precipitated first, then OCP, and finally hydroxyapatite (HA). The system was in continuous evolution and the phase transitions occurred in sequence.

The antimicrobial ceramics (AC) based on hydroxyapatite (HA) were made in a wet chemical process with additions of AgNO3, Cu(NO3)2

pitation from the 4 mM solution within the vesicles was amorphous calcium phosphate (ACp) and it remained stable at room temperature. The ACp was transformed into HAp crystals after treatment in hot water bath (60℃) for 24 h. As for the 0.03 mMsolution, which is nearly the critical saturation concentration of HAp, the precipitated crystals were small HAp. The role of the vesicle membrane in the controlled precipitation of calcium phosphate is discussed in terms of kinetic and spatial restrictions inherent in the reaction environment. The influence of concentration of calcium ion is also discussed.

Using a new and simple etching method to investigate the tablets of nacre, it is possible to observe a great deal of tablets in a large range. We found that most tablets have the same formal orientations after citric acid treatment. This phenomenon occurred not only in the same lamina but also along the direction perpendicular to nacreous plane. Based on the additional selected area diffraction patterns of transmission electron microscope, it is proposed that the formal orientations could indicate the crystal orientations of aragonite tablets.Statistical analyze shows that there is a main (type I tablets) and a secondary (type II tablets) preferred orientation with an angle of around 60 between them. Two possible modes of structural correspondence between protein sheets and aragonite lattice are assumed to interpret the orientation preference. On the other hand, the cluster character of type II tablets strongly supports that mineral bridges of the organic matrix have significant function in the crystal growth.At last, the mechanisms of structural correspondence and mineral bridges are combined to explain the formation process of nacreous layer in mussel.

The structure and crystallographic orientation of mineral phase in the oblique prismatic layer of Mytilus edulisshell were studied by SEM, XRD and TEM with selected area electron diffraction (SAED). A crystallographic orientation regulation, i.e. the adjacent 1-5 calcite prisms with the same three-dimensional orientation in the oblique prismatic layer, was found for the first time. It is observed that the calcite prisms in the oblique prismatic layer were grown with their (104) parallel to the shell surface.