In Vitro and In Vivo Surface Reactivity of Various Calcium Phosphate Coatings Deposited Using Electrostatic Spray Deposition (ESD)

摘要

The dissolution and precipitation behavior of various porous, ESD-derived calcium phosphate coatings was investigated a) in vitro after soaking in Simulated Body Fluid (SBF) for several time periods (2, 4, 8, and 12 weeks), and b) in vivo after subcutaneous implantation in the back of goats for identical time periods. At the end of these studies, the physicochemical properties of the coated substrates were characterized by means of Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Fourier-Transform InfraRed spectroscopy (FTIR) and Energy Dispersive Spectroscopy (EDS). Moreover, part of the implants was prepared for light microscopical evaluation of the tissue response. In vitro, a highly bioactive behavior was observed for all ESD-coatings, characterized by the deposition of a thick and homogeneous carbonate hydroxyapatite precipitation layer on top of the porous coatings. Regarding the in vivo study, no adverse tissue reactions (toxic effects/inflammatory cells) were observed using light microscopy, and all coatings became surrounded by a thin, dense fibrous tissue capsule after implantation. The ESD-coatings degraded gradually at a dissolution rate depending on the specific chemical phase, thereby enabling synthesis of CaP coatings with a tailored degradation rate.