Bioinspired surface modification of AZ31 Mg alloy with cellulose-derivative HPMC: Enhancing corrosion protection with biocompatibility

The application of magnesium alloys in cardiovascular stents exhibits a rapid corrosion rate and insufficient biocompatibility, resulting in significant morbidity and mortality. Achieving an appropriate corrosion rate and biocompatibility for magnesium alloys is still a key research priority. Hydroxypropyl methylcellulose (HPMC) is an environment-friendly cellulosic polymer with excellent biocompatibility and corrosion-inhibiting properties. Here we present a simple and controllable coating method to enhance the corrosion protection and biocompatibility of HPMC coatings on Mg alloy for the first time for cardiovascular applications. The various thicknesses of HPMC coatings were deposited in the present study using a dip-coating method, followed by evaluations of surface physicochemical characteristics, corrosion behavior, and immersion tests including Mg 2+ ion release, pH, and hydrogen evolution. Biocompatibility of the samples was assessed by hemolysis assay and endothelial cell cultures. HPMC coatings exhibit hydrophilic surfaces with strong tensile strength and robust adhesion to AZ31 Mg substrates. Electrochemical corrosion results reveal that at the high thickness of 3011.0 ± 100.0 nm, the HPMC coatings provide superior corrosion protection. In vitro cross-sectional and weight loss results revealed that the HPMC coatings reduce the corrosion rates, whilst immersion tests show reduced Mg 2+ ion release, pH values, and hydrogen evolution compared to bare Mg alloy. The HPMC samples show a significantly reduced hemolysis ratio and enhanced cell viability and adhesion ascribed to their superior corrosion protection and moderate wettability. This study of HPMC coatings on Mg alloys provides insights into their potential future application for cardiovascular stents.