Development of high strength bonding between polymer and magnesium with micro/nano structures and chemical treatment for bioresorbable stent

The adhesion of polymer coatings to magnesium (Mg) alloys poses a critical challenge in the development of biodegradable drug- or gene-eluting stents. WE43, an Mg-based alloy, offers promising properties such as biocompatibility and biodegradability; however, its rapid corrosion and inadequate polymer-substrate adhesion hinder its application in cardiovascular stents. This research addresses these challenges by employing advanced surface modification techniques to improve polymer adhesion and enhance the overall performance of WE43 stents. Different modification techniques such as anodization, plasma electrolytic oxidation (PEO), and laser ablation—were employed to enhance polymer adhesion and maintain the mechanical integrity and stability of the WE43. The treated surfaces were further coated with polycaprolactone (PCL) using ultrasonic atomization spray techniques to create a biocompatible, hydrophobic barrier that prevents corrosion. The study optimizes spray-coating parameters, such as solution concentration, number of passes, and atomizing power, to achieve uniform coatings with superior mechanical and corrosion properties. Comprehensive characterization techniques, such as scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), hydrogen evolution tests, and scratch tests, were used to evaluate the surface morphology, chemical composition, corrosion resistance, and adhesion of PCL to the treated alloys. Modified WE43 showed up to 6 times lower corrosion and more than ten times higher adhesion strength for polymer coating. In vitro, biocompatibility tests with human aortic endothelial cells (HAoECs) demonstrated that the surface modifications and coatings enhanced cell viability and adhesion. The findings of this thesis show that the combination of surface treatments and polymer coatings significantly improves the mechanical integrity, corrosion resistance, and biological performance of WE43, advancing its potential as a biodegradable, drug-eluting stent material. This work contributes to the broader field of biomaterials engineering by providing scalable, efficient methods for the development of next-generation cardiovascular devices.