Poly (dimethyl diallyl ammonium chloride) Incorporated Multilayer Coating on Biodegradable AZ31 Magnesium Alloy with Enhanced Resistance to Chloride Corrosion and Promoted Endothelialization

Abstract Controlled corrosion and proper biological response are key demands for biodegradable Mg-alloy based vascular stents. To achieve those properties, herein, a chemical conversion coating was fabricated through layer-by-layer (LBL) assembly via the sequential assembly of poly (dimethyl-diallyl ammonium chloride) (PDDA), epigallocatechin gallate (EGCG) and heparin (Hep). Each component in the coating played a unique role, in which EGCG chelates Mg ions and enhances the stability of the coating by introducing multiple intermolecular interactions, while PDDA effectively enhances the resistance against chloride corrosion, and Hep provides adequate hemocompatibility and promotes endothelialization. Electrochemical assay and immersion test demonstrated that the synergistic combination of PDDA and EGCG effectively suppressed the corrosion rate. A systematic in vitro and ex-vivo evaluation demonstrated an impressive antithrombotic performance, along with a selective promotion of endothelial cells (ECs) proliferation and inhibition of smooth muscle cells (SMCs) growth and macrophages (MAs) activation. More importantly, subcutaneous implantation and implantation in the abdominal aorta wall indicated that the PDDA/EGCG/Hep-modified implants displayed good corrosion resistance and mild tissue response, enhanced endothelialization and suppressed intima hyperplasia. These promising outcomes revealed the clinical potential of the PDDA/EGCG/Hep coating on AZ31 as biodegradable cardiovascular implants.