Growth factors-loaded calcium phosphate/polymer hybrid coating with sequential release behavior prepared via electrochemical deposition method

In this study, the dicalcium phosphate dehydrate (DCPD)/carboxymethyl hexanoyl chitosan (CHC) hybrid coating layer with sequential release of BMP-2 and TGF-β1 was deposited onto Ti6Al4V substrate by electrochemical co-precipitation method. Different concentrations of amphiphatic chitosan derivative (carboxymethyl hexanoyl chitosan, CHC), BMP-2 and TGF-β1-loaded PLA microspheres (PLA/TGF-β1 MSs) were co-precipitated with the precursor of DCPD. The resulting DCPD/CHC hybrid coating incorporated with BMP-2 and PLA/TGF-β1 MSs was designed for improving the osteoconductive and osteoinductive functionalities of Ti6Al4V. FTIR spectroscopy and X-ray diffraction were used to characterize these hybrid coatings. The drug release profile, MC3T3-E1 cell proliferation and alkaline phosphatase activity were used to investigate the functionality of these hybrid coatings. It was found that the incorporation of CHC could be used as a mean to manipulate the release behavior of growth factor from the DCPD/CHC hybrid coating. In addition, the BMP-2- and PLA/TGF-β1 MSs-incorporated DCPD/CHC hybrid coating exhibited a sequential release of BMP-2 and TGF-β1 during the first and second two weeks, respectively. Importantly, the DCPD/CHC hybrid coating immersed in simulated body fluid gradually transformed to hydroxyapatite phase. Hence, the BMP-2 and PLA/TGF-β1 MSs-incorporated DCPD/CHC hybrid coating exhibited the best cell viability and the highest ALP activity after 14 days. The biocompatible hybrid coating with sequential release functionality proposed in the present study can enhance the osseointegration process and possess promising potential for clinical applications in bone implants and tissue engineering.