Preparation of photo-crosslinked aliphatic polycarbonate coatings with predictable degradation behavior on magnesium-alloy stents by electrophoretic deposition

Abstract

Magnesium-alloy stents (Mg-alloy stents), a new generation of bioabsorbable stents, are characterized by limited surface biocompatibility and premature loss of radial support due to rapid and inhomogeneous corrosion. While these disadvantages could be addressed by coating the stents with biodegradable polymeric material, most investigations have discussed the coating materials and coating technology separately without attempting to study their combined effect. Since Mg-alloy stents possess a complex mesh tube structure, the facile preparation of high-performance polymeric coatings without defects to control the excessive and inhomogeneous corrosion remains challenging. In this paper, we report the fabrication of aliphatic polycarbonate (APC) coatings by electrophoretic deposition (EPD) and subsequent photo-crosslinking to achieve corrosion resistance and surface biocompatibility enhancement of Mg-alloy stents. The EPD method enabled the facile preparation of APC coatings with a uniform surface, controllable thickness, and enhanced adhesion on AZ31 Mg stents. The photo-crosslinking further enhanced the mechanical properties and durability of the coatings. The prepared APC coating demonstrated a predictable surface-erosion behavior, resulting in homogeneous and slow corrosion of AZ31 Mg alloy both in vitro and in vivo. The APC coating could not only effectively promote the adhesion and proliferation of endothelial cells but also improve the hemocompatibility and histocompatibility of Mg alloy. This study may offer a feasible and promising strategy for maintaining mechanical integrity and enhancing surface biocompatibility of Mg-alloy stents and other Mg-alloy implants.