Characterization of calcium phosphate layers grown on polycaprolactone for tissue engineering purposes

Composites fabricated by biomimetic mineral precipitation on polymeric substrates are of interest for tissue engineering. As biological properties of such mineral layers vary with slight changes in composition, a good physical characterization is necessary in order to study their biological activity. In this work polycaprolactone sheets were subjected to air plasma treatment followed by nucleation of calcium phosphate seeds to activate the growth of an apatite-like coating when immersing in simulated body fluid. Two compositions of the SBF were prepared, one of them highly carbonated and the other with no carbonate or magnesium ions. Immersion of PCL in the high carbonate composition produced a low-crystallinity apatite-like layer while the absence of carbonate and magnesium ions yielded a high crystallinity apatite with low Ca/P ratio that is likely partially hydrolyzed octacalciumphosphate (OCP). The morphology, crystal structure and composition of both types of coatings were characterized; osteoblast-like cell adhesion behaviour on different surfaces was observed by fluorescence and electron microscopy.