Processing, Characterization and In-Vitro Biodegradation of AE42 Magnesium Alloy Coated With Silane-PMMA for Cardiovascular Stent Application

Abstract

In the present study, AE42 Mg alloy was squeeze-cast and its microstructural analysis was performed using optical and field emission scanning electron microscope (FESEM). The casted AE42 Mg alloy was alkali pre-treated (NaOH 3M, for 10 days) before coating. The alkali pre-treated specimen was coated with silane and silane-polymethylmethacrylate (PMMA) by sol-gel technique. The coatings were characterized using FESEM, energy dispersive spectroscopy (EDS) and Fourier transform infrared (FTIR) spectroscopy. The adhesion strength and the hardness of the coatings on the substrates were evaluated using ASTM standards. The in-vitro biodegradation of the uncoated and coated specimens in simulated body fluid (SBF) were studied under static and dynamic conditions for 7 days. The variation in pH and the ionic concentrations of the SBF were measured during this period. The corrosion resistance of coated and uncoated specimens were investigated in SBF using hydrogen evolution, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) analyses. In addition, contact angle, protein adsorption and hemocompatibility of all the specimens were also studied to establish its significance for cardiovascular stent application. The results confirmed that the silane-PMMA coating showed less in-vitro biodegradation with improved corrosion resistance and also enhanced hemocompatibility of the material making it favourable candidate for biodegradable stent applications.