Direct nanocrystalline hydroxyapatite formation on titanium from ultrasonated electrochemical bath at physiological pH

An electrochemical method of producing nanocrystalline hydroxyapatite coatings on titanium surface is reported. The bath contained Ca(NO3)2 and NH4H2PO4 in the molar ratio 1.67:1. The electrolyte was maintained at physiological pH and was ultrasonically agitated throughout the time of electrolysis. Coatings were deposited for 30 min at 10 and 15 mA/cm2 and contained mono hydroxyapatite phase whose crystal sizes were lower than 30 nm. These sizes are comparable to the size of the bone hydroxyapatite crystals. Small globules of hydroxyapatite covered the coating surface completely. Fourier transformed infra-red spectroscopy (FT-IR) studies showed that the coatings contained large amounts of hydroxide and phosphate groups to enable the formation of hydroxyapatite. The coatings had a roughness (Ra) of about 0.3 μm and water contact angles of about 49°. Ultrasonic agitation promoted the formation of nanocrystalline structure which will help in better attachment of bone tissues to the implant surface.