title: Interaction between a high purity magnesium surface and PCL and PLA coatings during dynamic degradation.
abstract: In this study, polycaprolactone (PCL) and polylactic acid (PLA) coatings were prepared on the surface of high purity magnesium (HPMs), respectively, and electrochemical and dynamic degradation tests were used to investigate the degradation behaviors of these polymer-coated HPMs. The experimental results indicated that two uniform and smooth polymer films with thicknesses between 15 and 20 µm were successfully prepared on the HPMs. Electrochemical tests showed that both PCL-coated and PLA-coated HPMs had higher free corrosion potentials (E(corr)) and smaller corrosion currents (I(corr)) in the modified simulated body fluid (m-SBF) at 37 °C, compared to those of the uncoated HPMs. Dynamic degradation tests simulating the flow conditions in coronary arteries were carried out on a specific test platform. The weight of the specimens and the pH over the tests were recorded to characterize the corrosion performance of those samples. The surfaces of the specimens after the dynamic degradation tests were also examined. The data implied that there was a special interaction between HPM and its polymer coatings during the dynamic degradation tests, which undermined the corrosion resistance of the coated HPMs. A model was proposed to illustrate the interaction between the polymer coatings and HPM. This study also suggested that this reciprocity may also exist on the implanted magnesium stents coated with biodegradable polymers, which is a potential obstacle for the further development of drug-eluting magnesium stents.
authors.affiliation: State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Chen
authors.forename: Yang
authors.initials: Y
authors.lastname: Song
authors.forename: Shaoxiang
authors.initials: S
authors.lastname: Zhang
authors.forename: Jianan
authors.initials: J
authors.lastname: Li
authors.forename: Changli
authors.initials: C
authors.lastname: Zhao
authors.forename: Xiaonong
authors.initials: X
authors.lastname: Zhang
mesh_terms: D001826:Body Fluids / Q000187:drug effects; D020099:Coated Materials, Biocompatible / Q000737:chemistry; D003198:Computer Simulation; D003331:Coronary Vessels / Q000473:pathology; D054855:Drug-Eluting Stents; D004563:Electrochemistry / Q000379:methods; D006801:Humans; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000737:chemistry*; D008274:Magnesium / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning / Q000379:methods; D011091:Polyesters / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D013314:Stress, Mechanical; D013499:Surface Properties
chemical_list: D020099:Coated Materials, Biocompatible; D011091:Polyesters; D011108:Polymers; C016240:polycaprolactone; D019344:Lactic Acid; C033616:poly(lactide); D008274:Magnesium