Preparation And Characterization Of Hydroxyapatite Coating On AZ31 Magnesium Alloy Induced By Carboxymethyl Cellulose-dopamine

As a medical implant material,magnesium alloys has excellent mechanical properties and biodegradability in physiological environment,so it has a broad application prospect in the future.However,the biggest obstacle to the application of magnesium alloy is the rapid corrosion and degradation without making full use of the alloys,especially in the environment containing chloride ion.Therefore,coating technology and other methods to improve the corrosion resistance of magnesium alloy and ensure good biocompatibility is the main focus of the current research.Objective:Hydroxyapatite coating was prepared on the surface of magnesium alloy using carboxymethyl cellulose-dopamine hydrogel as template to improve its corrosion resistance and biocompatibility.Methods:Using carboxymethyl cellulose-dopamine composite hydrogel as the nucleation center,Ca-P growth was induced to form HA coating.The coating was characterized by Scanning electron microscopy（SEM）、Fourier transformed infrared spectroscopy（FTIR）and so on.The corrosion resistance of each group of samples was studied by potentiodynamic polarization test and hydrogen collection test,and the biocompatibility was evaluated by CCK8 method and living/dead cell staining method.Results:The HA coating was induced by using carboxymethyl cellulose-dopamine as template.The surface of the coating is uniform,regular three-dimensional leaf-like structure.The thickness of the coating is about 15μm.The EDS results show that the Ca/P ratio of the coating is 1.66,which is close to the ratio of HA.The electrochemical test results show that the I_corrvalue of AZ31/CMC-DA/HA coating is the lowest(1.25±0.003×10^-7A/cm²),E_corris the highest（1.35±0.012 V）.Compared with the AZ31 group,the E_corrvalue of AZ31/CMC-DA/HA moved about 180 m V in the positive direction,and the I_corrvalue was reduced by 13.5 times.The hydrogen collection test show that the total amount of hydrogen released and the corrosion rate of AZ31/CMC-DA/HA samples are lower than those of other groups.The results of CCK8 suggest that with the increase of culture time,HA coating can promote cell proliferation.The living/dead cell staining method also verified this hypothesis.Conclusion:In this experiment,the HA coating was formed by using carboxymethyl cellulose-dopamine as the induction template.In addition,the corrosion resistance and biocompatibility of magnesium alloys with surface coating technology have been improved to a certain extent,which will provide a theoretical basis for the clinical application of magnesium alloys.