Bioactivity of strontium-monetite coatings for biomedical applications

Abstract

The bioactivity of calcium phosphate (CaP) coatings can be controlled by different CaP phase precipitation and/or addition of foreign ions to their crystal lattice. Cationic substitution of strontium (Sr) into CaP coatings has gained a great attention due to the unique potential of Sr ions on stimulating new bone formation while inhibiting bone resorption. In this study, a novel route was used for producing Sr-substituted calcium phosphate coating on metallic substrates, containing 5 mol%, 10 mol% and 15 mol% Sr concentration, by chemical deposition method. The obtained Sr-substituted calcium phosphate coatings were structurally characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analyses. The presence of strontium ions into calcium phosphate phase fostered monetite precipitation, instead of brushite, and this cationic substitution was investigated by Rietveld refinement method. FEG-SEM analysis showed the bioactivity behavior by the precipitation of characteristic bone-like apatite on the 5% Sr-monetite and HA coatings after 14 days of incubation, using McCoy culture medium. The biological performance of the coated surfaces showed that hDPSCs viability was enhanced in the presence of Sr2+ ion concentration up to 10 mol% (p < 0.05) when compared to the uncoated titanium substrates and hydroxyapatite coatings. The results suggested the 5% Sr-monetite as a potential alternative for hydroxyapatite coatings, because of the improved biological responses in this study.