Epigallocatechin gallate (EGCG) induced chemical conversion coatings for corrosion protection of biomedical MgZnMn alloys

Abstract

Event Abstract Back to Event Epigallocatechin gallate (EGCG) induced chemical conversion coatings for corrosion protection of biomedical MgZnMn alloys Hao Zhang1 and Jin Wang1 1 Southwest Jiaotong University, Key Lab. of Advanced Technology for Materials of Education Ministry, Southwest Jiaotong University, China Introduction: Degradable biomaterials are supposed to support tissue healing and regeneration in a specific application by material degradation and concurrent replacement of the implant by the surrounding tissues. Magnesium and its alloys are generally known to degrade in aqueous environments via an electrochemical reaction by producing hydrogen gas and magnesium hydroxide. Unfortunately, the intrinsic drawback of magnesium and its alloys is the low control of the corrosion speed, which makes the degradation too quick and the implant loses its function before sufficient healing. Surface modification is one of the most straightforward and effective methods for corrosion protection. Desired coatings on Mg-based implants should be environmentally friendly, biodegradable and biocompatible in the local tissue environment, along with strong adhesion to the substrates. The present study aimed to provide a simple and effective epigallocatechin gallate (EGCG) conversion coating to control the rapid biodegradation of MgZnMn. Green tea, an extremely popular beverage worldwide, has long been associated with health benefits including antioxidant activity and chemo-preventive efficacy. EGCG, the major catechin in green tea, is known to possess strong antioxidant ability and can suppress the inflammatory processes. As an organic compound with phenol hydroxyl (OH) groups, it was speculated to chelate with metal ions and form EGCG–metal complexes in the conversion coating on MgZnMn alloys. Materials and Methods: As shown in Fig.1, the MgZnMn samples were immersed into the conversion solution of 0.1 mg/mL, 0.5 mg/mL and 2.5 mg/mL EGCG with a surface/volume ratio about 0.08 cm2/mL and incubated for 12 h at 22 °C. The physicochemical properties of the modified surfaces were characterized; the corrosion resistance was evaluated by electrochemical corrosion measurement (polarization measurement and electrochemical impedance spectroscopy (EIS)) and immersion tests. Results and Discussion: As shown in Fig.2, the EGCG conversion coating was successfully prepared on MgZnMn alloy and the composition of the coating might contain Mg(OH)2 and EGCG–metal complex. The EGCG modified MgZnMn exhibits substantially lower corrosion current icorr and slower degradation rate in the phosphate buffered saline (PBS) compared to the bare. The formation of EGCG conversion coating in this study could enhance the corrosion protection of MgZnMn alloy, mainly due to the EGCG–metal complex formation. The complex content depended on the EGCG concentration. Conclusion: In this work, an organic chemical conversion coating of MgZnMn–EGCG was successfully established. The result confirmed that the EGCG conversion coating showed apparently better protection ability than the bare sample and the corrosion resistances of the coated samples was depended on the different EGCG concentrations. This study offers a promising approach for the surface modification of biodegradable implants. Keywords: biomaterial, corrosion, Surface modification, Biodegradable metal Conference: 10th World Biomaterials Congress, Montréal, Canada, 17 May - 22 May, 2016. Presentation Type: Poster Topic: Surface and interfacial characterization Citation: Zhang H and Wang J (2016). Epigallocatechin gallate (EGCG) induced chemical conversion coatings for corrosion protection of biomedical MgZnMn alloys. Front. Bioeng. Biotechnol. Conference Abstract: 10th World Biomaterials Congress. doi: 10.3389/conf.FBIOE.2016.01.02356 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 27 Mar 2016; Published Online: 30 Mar 2016. 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