Characterizations of hydroxyapatite (HA), biphasic calcium phosphate (BCP) and beta tricalcium phosphate (beta-TCP) ceramic particles were carried out using X-ray diffusion (XRD), Scanning electron micrograph (SEM), Particle Sizer and Zeta potential analyzer. Competitive adsorption of bovine serum albumin (BSA) and lysozyme (LSZ) on the three calcium phosphates were investigated by polyacrylamide gel electrophoresis (PAGE) method. The results showed that HA, BCP and beta-TCP ceramic particles with irregular shapes and similar size distributions all had negative surface net charges in pH7.4 phosphate buffered saline (PBS) solution and exhibited alike behaviors of BSA and LSZ adsorption. LSZ had higher affinity for calcium phosphate ceramics than BSA and its adsorption on them didn't be almost influenced by the increasing of BSA concentration in the solution. Electrostatic interaction played an important role on the competitive adsorption of BSA and LSZ on the surface of calcium phosphate ceramic particles.

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Studying on the interaction between proteins and calcium phosphate implants is one of the basic subjects in biomaterials science and engineering. In this work, zeta potentials and contact angles of hydroxyapatite (HA) and biphasic calcium phosphate (BCP) ceramics were measured, and the adsorption behaviors of bovine serum albumin (BSA) on the surfaces were investigated. The adsorption isotherms of BSA on both ceramics follow the Langmuir type, however, BCP shows higher BSA adsorption ability. The differences of contact angles and zeta potentials in HA and BCP are the key factors to determine their ability to bind BSA molecules.

This study was carried out to investigate the effect of acid-alkali treatment and alkaliheat treatment on the push-out strength and tissue response of the porous titanium in vivo. Porous titanium with different treatment was implanted in dog bony site for 2 months and 5 months and the push-out strength was tested. At 2 months, the mean push-out strengths of the acid-alkali treated and alkali-heat treated porous titanium were 11.3 and 15 MPa, respectively. At 5 months, the values reached 29.8 and 35 MPa, respectively. Histological observation showed a close contact between implants and bone, and more bone tissue filled inside the pores of porous titanium increasing with implantation time. The results indicated higher bonding strength between bone and porous titanium in alkali-heat treated samples. Therefore, alkali-heat treatment can provide porous titanium implants with better fixation as a bone substitute for clinical use under load-bearing conditions.

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