Biomimetic deposition of hydroxyapatite on titanium with help of sol-gel grown calcium pyrophosphate prelayer
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Date
2011
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MATERIALS RESEARCH INNOVATIONS
Abstract
The biomimetic method is a cost effective, low temperature route for coating hydroxyapatite on titanium bone implants so as to provide an osteointegrating interface. However, biomimetic coatings have the limitations of poor adhesion and lower growth rates. This work investigates the role of a prelayer of calcium pyrophosphate made through sol-gel technique in growing adherent and thick layer of biomimetic hydroxyapatite over titanium surface. Cleaned titanium substrates were dip coated in a calcium-phosphate-citrate sol and calcined at 650 degrees C to form an adherent calcium phosphate layer. These were then subjected to biomimetic processing in 1.5 simulated body fluid for 7-14 days. The prelayer and the biomimetic layer were analysed for micromorphology (using SEM) and chemical phase (using X-ray diffraction, Fourier transform infrared spectroscopy and energy dispersive X-ray spectroscopy). Thickness measurements were performed on an optical profilometer and the adhesion was assessed through a microcombi scratch tester. The prelayer showed petal-like morphology, whereas globular particles were seen in the biomimetic growth. The prelayer had a thickness of 3.6 mu m and was found to contain calcium pyrophosphate, with calcium titanate at the interface. The phase in the biomimetic layer was identified to be hydroxyapatite, with a growth rate of 5.3 mu m/day. The scratch test gave the delamination load for this layer to be 6.23 N. Results show that it is possible to obtain adherent hydroxyapatite layer on the titanium surface at a faster rate by combining the sol-gel coating and the biomimetic growth technique.
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Materials Science
Citation
15 ,3;178-184