Abstract
Bioactive coatings on metallic ‘titanium’ or ceramic ‘sapphire’ implants
are known for their potential to promote bone biocompatibility,
osseointegration, and long-term survival. In this study, we have
investigated the effect of the surface topography of titanium and
sapphire at different temperatures on the chemistry, morphology,
organization, and coverage of the synthesized apatite coatings. We use a
wet chemical method with a fluoride rich calcium-phosphate solution, to
induce bioactive coatings onto etched titanium, non-etched titanium,
polished and unpolished sapphire at 37, 70, and 90˚C. Fluoridated
hydroxyapatite formation is detected across all temperatures using FTIR,
synchrotron XRD, and MAS-NMR. Surface topography and temperature changes
play a crucial role in the organization and coverage of the apatite
crystals. Well-defined hexagonal nanocrystals are observed across each
of the conditions, in the range between 35-81 nm. At lower temperatures,
self-assembled organized nanocrystals appear to grow out from spherical
structures, creating highly-ordered apatite architectures. However, at
90˚C, the nanocrystals seem to lack the hierarchical organization and
appear to be arranged randomly. This work demonstrates a promising
avenue for modifying implant surfaces with highly-ordered apatite-based
coatings at physiological conditions.