Thin Apatite Coating on Titanium Using Molecular Precursor Method

Abstract

The molecular precursor method is a new technology for producing a thin apatite coating on titanium. In the present study, we prepared two precursor solutions differing in Ca²⁺ concentration and examined their efficiency for apatite coating on titanium. Molecular precursor solution was prepared by adding dibutylammonium diphosphate salt to calcium-ethylenediamine-N, N, N ', N '-tetraacetic acid (Ca-EDTA) complex/amine ethanol solution by adjusting it to Ca/P=1.67. At that time, the Ca ion concentration was adjusted to 0.1 and 0.2 mmol/g.
Precursor solution was applied by drops to the titanium surface, which was then heated at 600℃for 2 h. Both precursor solutions produced a thin film on the titanium. X-ray diffraction (XRD) and Fouriertransform infrared spectroscopy revealed a coating of crystalline apatite on the titanium and the coatedapatite film contained the carbonate group in the apatite structure. There were no distinct differences in the coated apatite in the structure between the two precursor solutions, although the peak intensity in XRD patterns for the coated apatite using precursor solution with 0.2 mmol/g of Ca²⁺ ion was greater than that for the coated apatite with 0.1 mmol/g of Ca²⁺ ion. After the immersion of uncoated and apatite-coated titanium in simulated body fluid, hydroxyapatite crystals were precipitated on each surface. Greater apatite precipitation was observed on the apatite-coated titanium compared with the uncoated titanium. The apatitecoated titanium is expected to have biological properties superior to those of uncoated titanium. It is concluded that the difference in Ca²⁺ concentration in the precursor solution did not significantly influence the formation of apatite coating on the titanium.