Layer by layer assembled chitosan (TiO2)-heparin composite coatings on MAO-coated Mg alloys

Magnesium based alloys are ideal biodegradable materials owing to their appropriate mechanical properties and good biocompatibility. However, the poor corrosion resistance of Mg alloy limits its wide application. We fabricated self-sealed antibacterial MAO coatings and layer by layer assembled (LBL) composite coatings on Mg-3Zn-0.5Sr alloy. Three layers of chitosan and 1, 3, 6 cycles of LBL films containing TiO2 were alternately immobilized on MAO coating. The effects of heparin and layer numbers on corrosion resistance, wettability and hemocompatibility of composite coatings were explored. The results showed that 3 cycles of LBL film possessed uniform, dense and adhesive morphology, excellent apparent anticoagulant ability. It could effectively seal the pores in MAO coating and prevent the samples from corroding too fast.