Hydroxyapatite hybridized with metal oxides for biomedical applications

Zn-substituted apatites with homogeneous Zn distribution in the particles (Zn·HAp) and those with graded distribution (Zn/HAp) were prepared via a conventional wet chemical synthesis and soaking the Zn-free apatite particles in zinc nitrate solutions: X-ray photoelectron spectra of the apatites confirmed such Zn distribution. Physical and chemical properties such as particle size, specific surface area, or zeta-potential and were correlated to adsorption of β 2 -microglobulin (β 2 -MG) and bovine serum albumin (BSA). Adsorption of β 2 -MG on both apatites increased with the Zn content, whereas more β 2 -MG was adsorbed on Zn/HAp than on Zn-HAp. The amount of BSA adsorbed on Zn·HAp reached a maximum at about 1.5%, while it remained constant for Zn/HAp. From the results, it was suggested that Zn-substituted sites had better affinity against β 2 -MG and favored β 2 -MG adsorption. Surface charge on the particles was one of the factors to explain the suppressed adsorption of BSA by both apatites.