Investigating Electrochemical Behavior of Antibacterial Polyele-ctrolyte-Coated Magnesium Alloys for Biomedical Applications

Abstract

This study presents corrosion rates of layer-by-layer (LBL) and self-assembled monolayer (SAM) coated magnesium (Mg) alloys, and their antibacterial properties. Mg alloy samples were coated with cationic (chitosan - CHI) and anionic polyelectrolyte (carboxymethyl cellulose-CMC) LBL coating, and phosphonic acid self-assembled monolayer (SAM) coating methods. Electrochemical impedance spectroscopy (EIS) was employed for analyzing these samples in order to detect their corrosion properties. During the electrochemical analysis, a corrosion rate of 72 milli inch per year (mpy) was found for the sample coated with a 12 deionized phosphonic acid SAM and 9 CHI/CMC multilayers. During the antibacterial tests, gentamicin was investigated about how it would adhere on the Mg substrate surface and how it would be an antibacterial agent against Escherichia coli (E. coli) bacteria. From a coating point of view, a bare layer, self-assembly monolayer, polyelectrolyte layer, and combination of LBL and SAM were analyzed. From an antibacterial treatment point of view, samples with no antibacterial treatment, 10% gentamicin sulfate, UV treatment and 0% gentamicin sulfate, anti-anti and 10% gentamicin sulfate, and 70% ethanol and 10% gentamicin sulfate were individually studied. Duration of the incubation was 7 days at 35°C. Antibacterial sensitivity was tested using the disk diffusion method in Petridish. Based on the standard diameter of the zone of inhibition chart, the growth of bacteria was inhibited relatively with those Mg substrates. The largest recorded diameter of the zone of inhibition was 50 mm for the pre-UV treated and gentamicin-loaded sample, which is more than the standard inhibition diameter.