Study On Fabrication Of The Functional Drug Release Coating On Magnesium Alloy

Due to the biodegradable properties,magnesium alloys have attracted more and more attention in the field of biological materials.The main degradation product in the physiological medium environment is magnesium ion,which is an essential element of the human body.Compared with the traditional implant materials,magnesium alloy implant materials not only avoid the second surgery to remove it,but also reduce the inflammatory problems which is caused by implant materials.The mechanical strength of magnesium alloy is more close to the natural bone,so as to avoid the stress-shielding effects caused by traditional implant materials.Nevertheless,over fast corrosion of Mg alloys under physiological conditions hinders their application in the implant material field.Besides,implant materials often involved in infection,inflammation,thrombosis and other issues.In order to resolve the above problems,we fabricated a drug delivery system on magnesium alloy surface to solve the rapid corrosion,infection,inflammation,thrombosis issues.(1)Infection remains one of the most serious complications associated with orthopaedic surgery,which can lead to prolonged hospitalisation,increasing the patient's economic burden.In this chapter,we synthesized HA-GS coatings on magnesium alloy through microwave aqueous chemical route and soaking method.In order to improve the corrosion resistance and drug release property,Mg/ HA-GS/PCL compound material was prepared by dip coating.The HA coating provides a larger surface area which is benefited for the attachment of GS,blocking effect of PCL provides the controlled release performance of GS,the porous structure of the surface forming the channel for drug delivery.Electrochemical tests showed that the composite had superior corrosion resistance and controlled the release of magnesium ions in the immersion test.(2)The major problems for magnesium alloy implant are the high degradation rate and easy inflammation associated with implantation.Herein,surface drug delivery system(Mg/Epoxy resin-ZnO/PCL-Ibuprofen)which can realize bi-directional controlled release of ibuprofen and Mg2+ was designed via a dip coating process followed by spraying.The phase compositions and microstructures of the composite coatings indicate the ibuprofen maintains drug activity and the tumor fibers have a pore blocking effect,which significantly decrease the porosity of the coating.EP-ZnO coating act as a physical layer against the ingress of iron and reduce the release of Mg2+.The in vitro test demonstrated that the ibuprofen in drug-eluting compound material showed sustained release profiles for 22 days,which can effectively solve the local inflammation during the early stage of implantation.Besides,the drug carrier also exhibited improved corrosion resistance due to the high combining strength between EP-Zn O coating and magnesium alloy.This approach may be suitable for coating other implant materials such as stainless steel,titanium alloy etc.(3)Bio-absorbable drug-eluting vascular scaffold were developed to overcome limitations of permanent bare metal or drug-eluting stents,most notably a chronic vessel wall inflammation and the risk of stent thrombosis.The development of biodegradable magnesium alloys scaffolds is a new approach that is designed to circumvent these drawbacks.Nevertheless,over fast corrosion of Mg alloys under physiological conditions hinders their application,furthermore,multifunctional drug-eluting stent needs more attention to fundamentally cure the coronary artery disease.Herein,a drug delivery system(Mg/MgO/PLA-FA)which can realize sustainable release of ferulaic acid was designed via anodic oxidation process followed by dip coating process.Electrochemical tests combined with long term immersion results suggested that the preferable in vitro anticorrosion behavior could be achieved by dense MgO-PLA barrier.The released ferulaic acid can decrease platelets adhesion and aggregation during the early stage of implantation.Besides,hemolysis tests showed that the composite coatings endowed the Mg alloy with a low hemolysis ratio.The Mg/MgO/PLA-FA composite materials may be appropriate for applications on biodegradable Mg alloys drug-eluting stents.