Characterization of hydroxyapatite films prepared by pulsed laser deposition

Hydroxyaptite (HA) films were prepared by pulsed laser deposition from two kinds of targets using a KrF excimer laser at a substrate temperature of 575 degrees C. The characterization of films was studied by an electron probe microanalyzer, scanning electron microscopy, atomic force microscopy, glancing angle X-ray diffraction, and Fourier transform infrared spectroscopy. In vitro tests were performed to study the biocompatibility of the films. The results showed that the films were crystalline and there was a substitution of CO32- for PO43-. In vitro tests showed that with increased immersion time, the crystallinity of films became low, and the Ca/P ratio of films decreased first and then stayed at a stable value which is lower than that of the theoretical value of hydroxyapatite. The bands of new precipitated bonelike apatite were the same as with the original HA films, which indicated that the films had a good biocompatibility. The sintered temperature of the target had a small effect on the microstructure, while the coarse film could increase the bonelike apatite formation rate, which indicated that the bioactivity of coarse film was better.