Biomineralization behavior of electrophoretic-deposited hydroxyapatite-tricalcalcium phosphate biphasic composite

Highlights: • TCP phase is synthesized by controlled heat treatment of HA phase at 700 °C. • Biphasic HA/TCP coating is successfully deposited via EPD method with 60 V for 5 min. • The biomineralization behaviors of these composite coatings are systematically investigated. • Most appreciable growth in SBF is taken place in HA:TCP ratio of 25:75 wt%. Hydroxyapatite (HA) and tricalcium phosphate (TCP) coatings have been widely used as bonding layers on implants in the medical applications. In this research, nano-powders of HA is synthesized via aqueous sol-gel route. TCP is obtained by controlled heat treatment of HA phase at 700 °C. After that, these nano-powders are electrophoretically deposited on stainless steel substrates by applying 60 V for 5 min. Also, biphasic composite of these nano-powders are prepared at various HA/TCP ratios. The phase purity of HA and TCP are confirmed by means of X-ray diffraction (XRD) and energy dispersive X-ray (EDX) analysis. Differential thermal analysis and thermogravimetry (DTA/TG) clearly demonstrate the thermolysis and phase formation for each phase. Fourier transformed infrared (FTIR) spectroscopy represents through elimination of unwanted ions. The electrophoretic deposition behavior of HA/TCP biphasic as well as single phase samples are compared and biomineralization test is performed by simulated blood fluid solution. The electrophoretic behavior of the samples dramatically changes by increasing the TCP content due to its larger particle. The HA films show higher thickness and lower porosity, which are gradually changes by increasing TCP content. In terms of biomineralization, suitable growth occurs in all samples. However, the most appreciable growth is taken place in HA:TCP ratio of 25:75 wt%. These results show that the biphasic HA/TCP coatings, if appropriately applied on implants by simply controlling the electrophoretic deposition parameters, can enormously improve the grafting process by combining the TCP reactivity to form porous structure and providing required species and the HA biocompatibility and strength to bond to adjacent tissues.