Green Tea Polyphenol Induced Mg2+-rich Multilayer Conversion Coating: Toward Enhanced Corrosion Resistance and Promoted in Situ Endothelialization of AZ31 for Potential Cardiovascular Applications.
As a promising biodegradable metallic material, magnesium (Mg) and its alloys have attracted special attention in the recent decade. However, challenges still remain due to its high corrosion rate and insufficient biocompatibility after implantation. In this work, we prepare a simple and versatile green tea phenol-metal induced multilayer conversion coating (Mg2+ incorporated epigallocatechin gallate (EGCG) coating) on magnesium alloys' (AZ31) substrate by layer-by-layer (LBL) method. The surface morphology results revealed that, with the incorporation of Mg2+, the as-formed EGCG/Mg coating was rich in phenol-Mg complex and presented more homogeneous and dense morphology, with far less cracks than the pure EGCG coating. The in vitro degradation rate and corrosion resistance were studied by electrochemical corrosion tests and monitoring of the changed pH value and hydrogen evolution, respectively, which revealed that the corrosion rate was effectively decreased compared to that of bare AZ31 after it was protected by EGCG/Mg coating. In vitro and ex vivo thrombogenicity test demonstrated the EGCG/Mg coatings presented an impressive improvement in decreasing the adhesion and activation of platelets and erythrocytes, in activated partial thromboplastin time (APTT), and in antithrombogenicity compared to those of bare AZ31. Owing to the mild degradation rate, in combination with the biological function of EGCG, enhanced endothelial cells' (ECs') adhesion and proliferation, suppressed smooth muscle cells' (SMCs') adhesion/proliferation, and inhibited cytokine release were observed on EGCG/Mg coated AZ31 alloy. Besides, the in vivo subcutaneous embedding experiment suggested that the EGCG/Mg coating performed more mild tissue response due to the improved corrosion resistance to the surrounding microenvironment. Moreover, for in vivo abdominal aorta assay, the EGCG/Mg coated AZ31 wire presented better corrosion resistance and enhanced re-endothelialization compared to bare AZ31 wire. These results suggested the potential of using green tea polyphenol induced Mg2+-rich multilayer conversion coating for enhanced corrosion protection and desired biocompatibility of biodegradable cardiovascular implants.
['Zhang|Bo|B|', 'Yao|Ruijuan|R|', 'Li|Linhua|L|', 'Wang|Yanan|Y|', 'Luo|Rifang|R|http://orcid.org/0000-0002-8998-9948', 'Yang|Li|L|', 'Wang|Yunbing|Y|http://orcid.org/0000-0002-2412-6762']
D000497:Alloys D000818:Animals D001012:Aorta, Abdominal D001792:Blood Platelets D002392:Catechin D002448:Cell Adhesion D049109:Cell Proliferation D020099:Coated Materials, Biocompatible D003343:Corrosion D042783:Endothelial Cells D004912:Erythrocytes D005343:Fibrinolytic Agents D006801:Humans D008274:Magnesium D015539:Platelet Activation D019736:Prostheses and Implants D051381:Rats D017207:Rats, Sprague-Dawley D013499:Surface Properties D013662:Tea
in situ endothelialization biocompatible corrosion protection biodegradable vascular implants polyphenol/Mg ions complex