Corrosion protection and antibacterial performance of a chitosan/salicylate coating electrogenerated on a magnesium alloy

Abstract

In this work, chitosan and chitosan/salicylate coatings were prepared by EPD on AZ91D Mg alloy to improve the corrosion resistance of the substrate in a simulated physiological solution. The effect of two concentrations of salicylate on the morphology and anticorrosive behaviour of the coatings was evaluated. The results showed that the addition of 0.50 g/L sodium salicylate to the chitosan formulation decreased the corrosion rate of the chitosan coating from 0.0025 ± 0.0003 to 0.0007 ± 0.0004 mA cm−2. From the results of electrochemical impedance spectroscopy (EIS) and Fourier Transform Infrared (FTIR) analysis, it can be concluded that the presence of salicylate in the coating leads to a self-healing effect that contributes to an improved corrosion protection. In addition, the presence of salicylate in the coating has been shown to increase antibacterial activity against both Gram-positive and Gram-negative bacteria. It has been demonstrated that salicylate can be released from the coating, which has an anti-inflammatory effect. In this way, a novel chitosan/salicylate coating was developed for the first time on a Mg alloy for bactericidal effect, release of salicylate and corrosion protection in simulated physiological solution. So far, chitosan and salicylate have not been investigated as a combination for the development of multifunctional coatings on Mg alloys. In addition, the self-healing effect of salicylate ions in a chitosan coating was established for the first time.