Multilayer self-assembled kappa carrageenan/ chitosan: Heparin coating on Mg alloys for improving blood compatibility

The study aims to develop a layer-by-layer (LbL) self-assembled coating of Kappa carrageenan (KC) and heparin -loaded chitosan nanoparticles on the AZ91 alloy modified using micro-arc oxidation (MAO) to control its high corrosion rate and improve the hemocompatibility. In this regard, after the MAO process, polyethylene imine (PEI) coating was initially coated on the AZ91 samples. Heparin was loaded on chitosan nanoparticles (chitosan: heparin) with an average size of 55-130 nm. Afterward LBL self-assembled process was performed to deposit subsequent Chitosan: heparin and KC layers on MAO modified AZ91 (KC/Chitosan: heparin). The LbL process was repeated for 10,20, and 30 layers to get a uniform coating with desired electrochemical and biological properties. The electrochemical performance of the samples in phosphate-buffered saline (PBS, pH= 7.4) showed a significant improvement in the corrosion resistance of AZ91 samples after a two-step MAO and 30-layer LbL coating. Moreover, the heparin release from the multilayered coated samples was enhanced by increasing the number of layers. Finally, the determination of blood cell count (red blood cells, white blood cells, and platelets) and platelet adhesion indicated that controlled release of heparin from the coating resulted in a significant improvement of hemocompatibility. Overall, this multilayer KC/Chitosan: heparin coating with significant corrosion resistivity and hemocompatibility could have the potential for cardiovascular stent applications.