Fabrication of electroactive poly(gamma-glutamic acid) coating for improving corrosion resistance and cytocompatibility of magnesium alloy

Although magnesium (Mg) and its alloys are promising biodegradable materials for orthopedic implants, rapid and uncontrollable degradation of Mg is still a challenge for clinical applications. In this work, electroactive polymer coatings were prepared to improve the corrosion resistance and cytocompatibility of Mg alloys. Amphiphilic electroactive tetraaniline (TANi)-conjugated poly(gamma-glutamic acid) (gamma-PGA) with various TANi modification rates (gamma-PGA-TANi(10), gamma-PGA-TANi(20), gamma-PGA-TANi(27)) were first synthesized. gamma-PGA-TANi colloidal particles, prepared by a self-assembly method, were then coated on Mg alloys by electrophoretic deposition. The prepared gamma-PGA-TANi coatings showed a homogeneous surface and good adhesion on AZ31 Mg alloys. Electrochemical analysis and in vitro immersion tests revealed that gamma-PGA-TANi-coated Mg exhibited superior corrosion resistance, which was mainly attributed to the electroactivity of the gamma-PGA-TANi coatings, leading to the rapid formation of a passivation layer to prevent the further corrosion of Mg alloys. Furthermore, the gamma-PGA-TANi alloy coatings efficiently regulated Mg2+ release and pH value of coated Mg alloy during immersion for 40 days. In comparison with bare Mg alloy, the coated Mg alloy also showed better cytocompatibility, where L929 cells emerged with a good cell adhesion and viability. These results indicate that electroactive gamma-PGA-TANi coatings have promising potential for corrosion resistance of Mg alloys. (c) 2022 Society of Industrial Chemistry.