LbL Bioactive Coatings On AZ31 Chelated With Phytic Acid For Improvement Of Both Corrosion Protection And Cytocompatibility

Since twenty-first Century, magnesium is playing an increasingly important role in the field of biodegradable implants. Magnesium has good biodegradability and its mechanical properties are similar to those of natural bone, showing a good development prospect. However, the degradation of magnesium would be too fast among the physiological environments in the body and would make against the functional expression of implant because of the local alkalization and local gas cavity after degradation. This paper talks about the progress in application of biodegradable magnesium alloy in the field of biomedical material for orthopedics, discusses the research aiming at the improvement of degradable magnesium alloy’s corrosion resistance and the existing problems for clinical application at home and abroad. It is clear that the biodegradable magnesium alloy is a promising bone substitute materials after some problems related to its degradation is solved.In this paper, the chelateing of phytic acid improves the bonding between self-assembly coats and substrate, so as to trigger the inhibition of deeper corrosion by forming a dynamic equilibrium process. Phytic acid (PA) can be chelated with magnesium to control its degradation rate by forming a dense coating and provides some useful groups. After that, we use the LbL-technique to implement multilayer coatings of alginate and poly-1-lysine on the chelated layer. The chelated layer exhibits a lower degradation rate and the surface bioactivity of magnesium can be improved by the LbL multilayer coatings.We used electrochemical experiments and the immersion experiments to evaluate corrosion resistant and in vitro degradation of material. The results show that the surface modified process has good corrosion resistance, especially the PA-LBL AZ31 alloy. The corrosion protection efficiency up to 74%. The indicators that weight loss rate and pH changes of PA-LBL-AZ31 are kept in a very small range. The results show the coatings after PA-LbL are thicker and combined with the matrix closer, more uniform formation.In the biocompatibility evaluation, the effects of various indexes of the system on cell adhesion and proliferation were discussed by direct culture, leaching liquor culture and titanium surface similarity culture. The results show that PA-LBL composite membrane has a good cell compatibility and no obvious cytotoxicity in that osteoblasts in the surface spread better with high activity. It can be speculated that the coating has good bone conduction and induction. PA-LBL composite coating can improve the corrosion resistance and biocompatibility of magnesium alloy. This process for the coatings of magnesium-based biodegradable material has a higher value for extending to clinical.