Keywords: electrohydrodynamic spraying, nano-hydroxyapatite coatings, heat treatment, morphology, in vitro study, nanomaterials, nanotechnology, biomedical implants, medical implants, surface morphology, surface roughness, osteoblast response, biomaterials
Effect of heat treatment of nano-hydroxyapatite coatings prepared using electrohydrodynamic deposition
Electrohydrodynamic spraying has recently emerged as a powerful method of producing nano-structured hydroxyapatite (nHA) coatings for biomedical implants. To enhance the mechanical properties of these coatings, a subsequent heat treatment is normally needed. However, whether this process significantly influences the coated surface morphology and cellular responses still needs to be systematically studied and documented. In this investigation, the morphology, composition and resultant surface roughness of the nHA coating surfaces were examined, prior to in vitro cytocompatibility, proliferation and cell morphological assessments using primary alveolar human osteoblast-like (aHOB) cells. After heat treatment of nHA coatings prepared using electrohydrodynamic spraying, it was found that the coated surface roughness reduced from a pre heat treated average of 4.2 μm to a post heat treated roughness of 2.9 μm, 2.5 μm and 2.1 μm at 500°C, 700°C and 900°C, respectively. The in vitro study determined a favourable osteoblast response to all substrates examined, with no statistical difference between the samples examined, as determined by the AlamarBlue proliferation assay over 21 days in culture. Confocal microscopy and scanning electron microscopy further demonstrated cell proliferation and adhesive adaptation on the experimental substrates.