Corrosion Resistance,Antibacterial Property And Biocompatibility Of Self-Assembled And Its Biomineralized Composite Coating On Magnesium Alloy

Biomedical magnesium(Mg)alloys have become the most potential degradable bone-implant materials due to their unique mechanical properties,biocompatibility and complete biodegradablity.However,Mg alloys are extremely susceptible to corrode in the complex body fluid environment of the human body,and their excessively fast degradation rate cannot match the healing speed of human bones,which severely limits their application in the field of biomedicine.Hydroxyapatite(Ca10(PO4)6(OH)2,referred to as HAp)has the excellent biocompatibility and bone conductivity,which can be used as coatings to improve the corrosion resistance of Mg alloys.Nevertheless,proteins,amino acids,and other organics substances are easily adsorbed on the surface of HAp,favoring the adhesion and growth of the bacterial and thus resulting implant-associated infections.Therefore,in addition to improving the corrosion resistance and biocompatibility of Mg alloys,it is equally important to prevent inflammatory reactions at the implantation site.In this work,multilayer films were first prepared on the surface of Mg alloys by using layer-by-layer(LbL)assembly technology,and then HAp coating was induced by hydrothermal method.First,ciprofloxacin/polyacrylamine hydrochloride/SiO2/polyacrylamine hydrochloride(CIP/PAH/SiO2/PAH)multilayer films were assembled on the surface of Mg substrate by spin-spray method,which were successfully prepared by electrostatic forces,air shear forces and centrifugal forces between reagents with opposite charges.In this work,the addition of SiO2 nanoparticles could not only endow the self-healing properties for membrane layer,but also effectively improve the corrosion resistance of Mg alloys.Moreover,the presence of SiO2 nanoparticles prolonged the release of CIP,which ensured the long-term antibacterial effect of the samples.Then,polyacrylic acid/gentamicin sulfate(PAA/GS)and CIP/PAH multilayer films-induced HAp coatings were successfully fabricated on the surface of Mg alloys via LbL technique and hydrothermal method.The presence of GS and CIP could endow the excellent antibacterial properties to the Mg alloys.The multilayer films-induced HAp coating had the physical barrier effect,which could not only improve the corrosion resistance of Mg alloys,but also reduce the release rate of antibiotics.The release rate of CIP was slower than that of GS,which could be ascribed to the fact that the strong interaction between the carboxylate of CIP and Ca2+ions hindered the release of CIP.The slower release rate of CIP made the coating more biocompatible.