Biodegradable poly(lactide-co-glycolide) coatings on magnesium alloys for orthopedic applications
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Polymeric film coatings were applied by dip coating on two magnesium alloy systems, AZ31 and Mg4Y, in an attempt to slow the degradation of these alloys under in vitro conditions. Poly(lactic-co-glycolic acid) polymer in solution was explored at various concentrations, yielding coatings of varying thicknesses on the alloy substrates. Electrochemical corrosion studies indicate that the coatings initially provide some corrosion protection. Degradation studies showed reduced degradation over 3 days, but beyond this time point however, do not maintain a reduction in corrosion rate. Scanning electron microscopy indicates inhomogeneous coating durability, with gas pocket formation in the polymer coating, resulting in eventual detachment from the alloy surface. In vitro studies of cell viability utilizing mouse osteoblast cells showed improved biocompatibility of polymer coated substrates over the bare AZ31 and Mg4Y substrates. Results demonstrate that while challenges remain for long term degradation control, the developed polymeric coatings nevertheless provide short term corrosion protection and improved biocompatibility of magnesium alloys for possible use in orthopedic applications.
KeywordsCorrosion Protection AZ31 Alloy Alloy Substrate Magnesium Hydroxide PLGA Polymer
The authors gratefully acknowledge the support of National Science Foundation, NSF (Grant # CBET-0933153) and the Engineering Research Center funded by the National Science Foundation, NSF-ERC (Grant # EEC-0812348). The authors also acknowledge the financial support of the Center for Complex Engineered Multifunctional Materials (CCEMM), University of Pittsburgh for support of equipment, supplies and reagents used in this research. PNK also acknowledges the support of the Edward R. Weidlein Chair Professorship funds for partial support of miscellaneous research related expenditures. Additionally, the authors would like to thank the Department of Mechanical Engineering and Materials Science for the provision of access to the electron microscopy instrumentation and for assistance with the execution of this part of our research.
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