Characterization and mineralization of strontium doped nano hydroxyapatite coating on titanium rods

Abstract

Pure nano hydroxyapatite (nHA) and strontium doped nano hydroxyapatite (Sr-nHA, Sr/(Ca+Sr) = 10 %, atomic ratio) were prepared by a one-step method involving homogeneous phase co-precipitation. Fourier transform infrared spectroscopy (FT-IR) revealed OH-, PO43- and CO32- groups in both powders. X-ray diffraction (XRD) showed that the peaks of Sr-nHA shifted to lower 2θ values compared with those of pure nHA. Both the pure nHA (39.5 ± 11.2 nm in length and 15.9 ± 3.7 nm in width) and Sr-nHA (33.0 ± 10.2 nm in length and 13.2 ± 3.2 nm in width) powders showed tiny nano-rod feature. Moreover, TC4 (Ti-6Al-4V) rods (1 mm in diameter and 20 mm in length) coated with pure nHA or Sr-nHA were prepared by high-energy plasma spraying. Elements of Ca, P, O and Sr were detected on the Sr-nHA coating surface by energy dispersive spectrometry (EDS). XRD result also indicated the nearly unchanged phase composition after spraying. By immersion in the simulated body fluid (SBF), in vitro mineralization ability was estimated and the surface layers were evaluated by scanning electron microscopy (SEM) and XRD. The results showed that Sr-nHA coating had better mineralization ability than the pure nHA coating. Therefore, the synthesized Sr-nHA and its sprayed coatings would have potential application for surface modification of biological prostheses and other implantable materials.