A study on the corrosion behavior and biological properties of polycaprolactone/ bredigite composite coating on biodegradable Mg-Zn-Ca-GNP nanocomposite

[Display omitted] •PCL layers contain bredigite particles were prepared on Mg-Zn-Ca-GNPs nanocomposite using the dip-coating method.•PCL-bredigite coatings could control the degradation rate and enhance the biocompatibility of Mg-Zn-Ca-GNPs nanocomposite.•Apatite formation can be motivated by the PCL coating containing bredigite, thus surface bioactivity is increased.•Corrosion mechanism of the PCL-bredigite-coated Mg-Zn-Ca-GNPs nanocomposite is proposed. In this study, biodegradable Mg-Zn-Ca-GNPs nanocomposite was chosen as substrate and was coated by polycaprolactone (PCL) with different amounts of bredigite particles (Br = 0, 2.5, 5, 10 wt.%). Morphology and chemical composition of the coating were investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and Fourier-transform infrared spectroscopy (FTIR). Polarization test and electrochemical impedance spectroscopy (EIS) in the SBF solution were performed in order to study the samples corrosion behavior. The degree of cell viability was evaluated by the MTT test via the extraction method. Morphology and cell adhesion were investigated by 4′,6-diamidino-2-phenylindole (DAPI) and SEM. In order to investigate the degree of calcium precipitation by bone cells, Alizarin red staining was performed. In order to define the level of differentiation of osteoblast cells, the level of alkaline phosphatase (ALP) enzyme activity was investigated. The results of corrosion test showed that the bredigite-embedded PLC coating has a considerable effect on improving the corrosion resistance and the highest resistance is related to the sample coated by PCL-10 wt.% bredigite. The results of 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test showed that during all the time ranges, by increasing the bredigite particles up to 10 wt.%, cell viability increases. Cell adhesion results showed that the amount of attached cells on the surface results in a significant growth of MG-63 osteoblast cells by increasing bredigite particles. Thus, PCL-10 wt.% bredigite coatings can be employed to reduce the degradation rate and to enhance the biocompatibility of Mg-Zn-Ca-GNPs nanocomposite for orthopedic applications.