Biomimetic mineralized amorphous carbonated calcium phosphate-polycaprolactone bioadhesive composites as potential coatings on implant materials

Biomimetic mineralized (Mg, Zn, Sr) carbonated amorphous calcium phosphate (cACP) containing biodegradable polycaprolactone (PCL) coating was prepared via spin coating technology. The main role of PCL was to provide a controlled release of cACP for a prolonged period of time and to act as a bioadhesive, providing better adherence than that of pure cACP powder. The cACP and the cACP-PCL composite layers were optimized as very thin, noncontinuous films on the surface of a commercial titanium alloy, maintaining its surface roughness. The powder layer and the composite film were morphologically, chemically, and biologically tested. In vitro biocompatibility measurements were performed using MC3T3-E1 cells. The cell viability significantly increased when cACP coatings and cACP-PCL composite were applied to the pure Ti6Al4V substrate. The pure PCL coating and the titanium substrate indicated similar biocompatibility, however, adding cACP powders into the polymer solution resulted in increased cell viability. LDH and ALP measurements showed a large number of living cells on the surface of all samples. The cell morphology study by Calcein/DAPI staining as well as SEM measurements demonstrated a well-adhered and spread, confluent cell monolayer. The long-term release of bioactive ions in SBF solution indicated that the biodegradability of composite coating is slightly faster than the cACP powder layer. All in vitro measurements confirmed the suitability of the developed composite layer as a potential bone substitute and bioactive coating on middle- and long-term implants.