Li Han Lin
National Cheng Kung University, Taiwan
Title: In vitro study in functional coatings of biodegradable magnesium-zinc-zirconium alloy for cardiovascular stents
Biography
Biography: Li Han Lin
Abstract
Vascular stents are important and successful medical device in treating coronary artery disease. Currently, titanium alloy with or without anti-thrombosis drug are the common product. [1] However, the inert metal inside blood vessel could elicit long term inflammation and higher potential of thrombosis. In addition, the drug usage is toxic to the cells in order to inhibit the inflammation caused by the tissue factors released by macrophages.
Degradable polymer PLA was used as the material for the stent fabrication, but the acid degradation product could cause local inflammation and increase the rate of thrombosis. Therefore, using an absorbable magnesium-based stent becomes an ideal solution to long-term endothelial dysfunction. Degradable magnesium alloy has better biocompatibility, mechanical and degradation properties than current PLA base bio-absorbable polymer to serve the stent material. [2] However, Mg alloy without modification cannot provide proper corrosion resistance. Moreover, it was demonstrated that Gallic acid promoted the growth of normal cells [3]. In this study, alkali-heat treatment with two main groups: (1) polymer PLGA (PLGA group)[4] and (2) Gallic acids loaded PLGA (GA group) coating was used to improve corrosion resistance and cell-adhesion.[5] The ZK60 Mg alloy plate samples treated with PLGA and/ or GA dip-coating then were tested by electrochemical test, cell cytotoxicity, and cell adhesion. The results showed GA group has good significant difference in cell vitality, cell adhesion and corrosion resistance compared to control PLGA group (4wt %). In biocompatibility tests, cell has significant vitality in GA group with 1wt% but toxicity with 10wt%, while PLGA group has more cell adhesion on the surface. In electrochemical test, GA group has lowest corrosion density: (1) 6.7474E-08 for 1wt% and (2) 4.989E-08 for 10wt%. It is important to maintain cell vitality and corrosion resistance simultaneously. Therefore, PLGA-4wt%-GA-1wt% dip-coating is an ideal modification applied in vascular stents.