Electrochemical analysis of antibacterial polyelectrolyte-coated magnesium alloys for cardiovascular applications
This project involves two separate biomedical issues: corrosion rates of polyelectrolyte-coated magnesium (Mg) alloys, mainly used for biomedical purposes, and antibacterial properties of these alloys. Electrochemical impedance spectroscopy (EIS) was employed for analyzing these samples in order to detect their corrosion properties. In the electrochemical analysis section (GAMRY potentiostat), a corrosion rate of 72 milli inch per year was found for the sample coated with a 12 deionized phosphonic acid (Di-PA) self-assembled monolayer (SAM) and 9 chitosan/carboxymethyl cellulose (CHI/CMC) multilayers. The Mg alloy samples were coated with cationic polyelectrolyte (chitosan) and anionic polyelectrolyte (CMC) using a layer-by-layer (LBL) coating method. Both polymer solutions were 0.0015 gm. /liter. In the antibacterial test section, gentamicin was investigated for how it would adhere on the Mg substrate surface and how it would be an antibacterial agent against Escherichia coli (E. coli) bacteria. This experiment involved different sets of samples. From a coating point of view, a bare layer, self-assembly monolayer, polyelectrolyte layer, and combination of self-assembly monolayer and polyelectrolyte layer were analyzed. From an antibacterial treatment point of view, samples with no antibacterial treatment, 10% gentamicin sulfate, ultraviolet (UV) treatment and 0% gentamicin sulfate, anti-anti and 10% gentamicin sulfate, and 70% ethanol (EtOH) and 10% gentamicin sulfate were analyzed. Duration and temperature of incubation were 7 days at 35 degree C, respectively. Antibacterial sensitivity was tested using the disk diffusion method. Based on the standard diameter of the zone of inhibition chart, the antibacterial diffusion was found to be in the susceptible category, meaning that the growth of bacteria was inhibited strongly. 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 three times the standard diameter.
Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering