Influence of surface pretreatment on the coating quantity and properties of nanostructured octacalcium phosphate on commercially pure titanium

The influence of surface pretreatment conditions including sodium hydroxide concentrations and cleaning methods on composition, microstructure and properties of the octacalcium phosphate (OCP) coating on commercially pure titanium by rapid biomimetic technique was studied. Layer of amorphous sodium trititanate (Na2Ti3O7) gel was found to form on the surface of alkali pretreated titanium. Using high NaOH concentration and rinsed cleaning method could produce more uniform, but thinner OCP coatings than using low NaOH concentration and rigorous ultrasonic cleaning which resulted in isolated spheroidal microstructure. Regardless of pretreatment conditions, the contents of all OCP coatings were not significantly different and all coatings similarly comprised nano-thick and plate-like OCP crystals vertically grown on the surface of titanium. Contact angles of all coatings similarly decreased to zero compared to value of 76 for uncoated titanium indicating high wettability of all coating surfaces.