Formation and in vitro induction ability of apatite nanobelt coating on silicon

Apatite coating with nanobelt structure was fabricated on single crystal silicon by a two-step method of electrodeposition at 1.0-2.0 mA/cm2 with DC power and vapor-thermal treatment (VTT) at 150–180 °C for 6 h over alkali medium. Scanning electron microscopy (SEM), X-ray diffractometry (XRD), and electron diffraction spectrometry (EDS) were employed to investigate the compositions and morphologies of specimens before or after vapor-thermal treatment. The results demonstrate that nanobelt crystals of coating, 0.5-2 μm in width, 100 nm in thickness, and 6-10 μm in length, are Ca-deficient apatite (CDA) with a mole ratio of Ca to P approximately of 1.60, which shows similarity of the nanobelt coating to inorganic phase in composition and to collagen in dimension appearing in human hard tissue. Induced nucleation and growth of bone-like apatite were observed on the nanobelt after soaking in a simulated body fluid (SBF) for 6 h and for 3 d, respectively, identifying that nanobelt has good ability for induction of bone-like apatite in SBF.