Zinc-doped hydroxyapatite-zeolite/polycaprolactone composites coating on magnesium substrate for enhancing in-vitro corrosion and antibacterial performance

This work is focused on developing zinc-doped hydroxyapatite-zeolite (ZnHA-Zeo) and polycaprolactone (PCL) composite coatings on magnesium (Mg) substrate to improve the corrosion resistance and antimicrobial properties. Dip-coating technique was used to coat ZnHA-Zeo/PCL on the Mg substrate at room temperature. The samples were subjected to field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR), energy dispersive X-ray spectroscopy (EDX) and antimicrobial potential. Results demonstrated that composite coatings consist of HA, scholzite, zeolite, and PCL phases. EDX spectra indicated the presence of calcium (Ca), silicon (Si), aluminum (Al), zinc (Zn), phosphorus (P) and oxygen (O). The composite surface appeared in spherical-like microstructure on coating with thickness ranging 226-260 mu m. Zinc-doped HA-Zeo composite coating had a high corrosion resistance and provided sufficient protection to the Mg surface against galvanic corrosion. Doped ZnHA-Zeo coating samples exhibited superior disc inhibition by confirming antimicrobial activity against the E. coli as compared to HA-Zeo sample. Altogether these results showed that the ZnHA-Zeo coatings not only improved the corrosion resistance, but also enhanced the antimicrobial property and hence they can be used as suitable candidates for implant applications.