Synthesis and electrophoretic deposition of zinc oxide and zinc oxide-bioactive glass composite nanoparticles on AZ31 Mg Alloy for biomedical applications

Abstract

In the present study, zinc oxide-bioactive glass composite nanoparticles were synthesized through a sonochemical/sol-gel method. The results revealed that the composite nanoparticles consisted of zinc oxide (ZnO) cores (259 ± 9 nm) surrounded by a thin bioactive glass (BG) shell with 26 ± 3 nm thickness. The zinc oxide and zinc oxide-bioactive glass composite nanoparticles were electrophoretically deposited on the AZ31 substrate involving an intermediate oxide layer applied using plasma electrolytic oxidation. The composite nature of the zinc oxide-bioactive glass nanoparticles facilitated the application of lower voltages during electrophoretic deposition compared to simultaneous deposition of individual zinc oxide particles. Dopamine was used in the bath as a surfactant and polyethyleneimine as a binder to ensure complete adhesion between coating and substrate. Microscopic examinations confirmed more uniformity in the coatings constituted of composite nanoparticles. Electrochemical impedance spectroscopy in a phosphate-buffered saline solution revealed a significant improvement in barrier performance of the composite coatings compared to the zinc oxide coating. According to the short-term bioactivity evaluations in simulated body fluid, more Ca–P deposits were formed on the composite coating. Furthermore, the adhesion between the coating and substrate increased significantly in this coating, mainly due to the rough surface of the nanoparticles.