Atomic layer deposition coating titanium dioxide nano-thin film on magnesium-zinc alloy to enhance cytocompatibility for vascular stents

Abstract

Implantable medical devices are designed to replace missing or restore damaged biological structures. A coronary stent is a well-known cardiovascular medical device implanted to resolve disorder of the circulatory system due to bloodstream narrowing that occurs in coronary arteries. Since the implanted device interacts with surrounding biological environments, the surface structure of a typical implantable device plays a critical role. Cell adhesion and proliferation performances and protein adsorption are fundamental identifications for the success of a medical device. Metallic coronary stents are commonly used as biomaterial platforms in cardiovascular implants. As the new generation of coronary stents such as bioresorbable vascular scaffolds appears to attract attention among researchers, studies of bioresorbable materials such as magnesium and zinc remains a target for further optimizations. Additional surface modification is needed to control the biodegradation of the implant material while promoting biological reactions without the use of drug elution. Herein, precise temperature and thickness controlled atomic layer deposition (ALD) were utilized to provide a unique and conformal nanoscale TiO2 coating on a customized magnesium-zinc alloy. Impressively, results indicated that this TiO2 nano-thin film coating stimulated coronary arterial endothelial cell adhesion and proliferation with additional features like acting as a protective barrier. Data revealed that both surface morphology and surface hydrophilicity together contributed the ALD nanoscale coating, which acted as a protection layer inhibiting degradation of the magnesium-zinc substrate. Additionally, different surface properties and their influences on biological functions were also investigated. Overall, the outcome of this study provided a promising tissue regeneration platform with unique nano-structural surfaces to be bioresorbable to enhance biocompatibility, and as a result will be beneficial for numerous biomedical applications.