Fabrication and evaluation of Zn containing fluoridated hydroxyapatite layer with Zn release ability

A biphasic layer with a Zn-containing β-tricalcium phosphate (ZnTCP) phase and a fluoridated hydroxyapatite (FHA) phase on titanium alloy substrate was prepared by the sol–gel technique. Scanning electron microscopy and energy-dispersive X-ray analysis results showed the ZnTCP/FHA layer to have a heterogeneous surface with microscaled gibbous structures originating from ZnTCP particle agglomeration. This layer had a slow and sustained Zn release behavior. The scratch test result of the ZnTCP/FHA layer was 489 ± 4 mN, indicating good interface bonding between the layer and substrate. The ZnTCP/FHA layer supported cell growth, and showed a statistically significant increase in cell viability in comparison with another biphasic layer (TCP/FHA) without Zn. This work demonstrates that the present biphasic ZnTCP/FHA layer has the potential to play a significant role in enhancing bone growth when used as the outermost part of bioactive coatings on metallic implants.