Hydroxyapatite/ZnO-nanorod composite coatings with adjustable hydrophilicity and Zn release ability

• Preparation and characterization of hydroxyapatite/ZnO-nanorod composite coatings
• Adjustable wettability of the composite coatings through ultraviolet treatment
• A slow and sustained Zn release of the composite coating
• Amphiphilic and ultraviolet responsible protein adsorption behaviors

Hydroxyapatite (HA)/ZnO-nanorod composite coatings were fabricated on Si substrates in this work. ZnO nanorods were firstly grown on the substrate through a hydrothermal method, and then CaP precursor solution was spin-coated on the surface and fired to form HA/ZnO-nanorod composite coatings. The results showed that ZnO nanorods were grown on substrates and hydroxyapatite was deposited between nanorods, leading to a composite coating. The surface wettability of such coating could be adjusted through ultraviolet treatment, from rather hydrophobic to hydrophilic. Such coatings showed different protein adsorption property from both ZnO nanorod coating and HA coating. Also, a desirable Zn ion release ability was observed. Such coatings could be potentially applied as bioactive coatings on metallic bioimplant surface.