Papers by Author: Xiang Ge

Abstract: Percutaneous type of orthopedic and dental implants requires not only a good adhesion with bone, but also the ability to form good attachment and seal with connective tissues and skins. Currently, the skin-seal of such implants still remains as a problem to be resolved. Electrochemical processing was used to modify the surface of titanium implants in order to improve the ability of anti-bacteria infection and skin seal around the implants by synthesizing a fluoridated calcium phosphate thin film on titanium substrate. The surface of titanium was cathodically treated in an electrochemical cell. A thin film of about 80 nm thickness was deposited on the titanium surface by controlling the treatment parameters. The dense and gel-like film was composed of calcium phosphate and fluorine ions. Fluorine ion has the anti-bacteria property and could help to improve the skin seal around the percutaneous device. The electrochemical method of fluoridated calcium phosphate thin film synthesis will provide an alternative method for surface treatment of orthopedic and dental implants.

Abstract: Nanocrystalline Zn-substituted calcium hydroxyapatite (HA) powder was synthesized by wet chemical method. Detailed characterization was carried out with both experimental techniques and numerical simulation method. X-ray diffraction (XRD) patterns show the calcium phosphate maintains as the apatite phase when the atomic ratio of Zn/(Zn+Ca) is less than 17% Zn in aqueous solutions. The calcium phosphate crystallinility decreases with the Zn concentration increase. The morphological changes with Zn substitution in HA were investigated by TEM. Lattice parameters of the apatitic samples were determined by XRD Rietveld refinement method. A computational study using ab initio generalized gradient approximation density functional theory was performed on Zn-substituted HA. Comparison of the experimental and computer simulation results provides our insights of Zn substitution in apatite structure.