Electrospinning polycaprolactone/collagen fiber coatings for enhancing the corrosion resistance and biocompatibility of AZ31 Mg alloys

Magnesium (Mg) alloy is widely studied as a potential biodegradable implant material in clinical orthopedics. However, its uncontrollable corrosion rate under physiological conditions has severely limited its development. To enhance the corrosion resistance and biocompatibility of AZ31 Mg alloys substrate, the polycaprolactone/collagen/cerium-hydroxyapatite (PCL/Col/Ce-HA) fiber coating is prepared by employing the electrospinning technique. The scanning electron microscope reveals that the PCL/Col/Ce-HA fiber coating with 5 wt% of Ce-HA exhibits the densest surface with a uniform fiber size of 396 nm, which provides a firm physical barrier against the corrosive ions. Furthermore, the enhanced adhesion strength of the PCL/Col/Ce-HA fiber coating will prevent the coating from falling off from the Mg substrate during the long-term immersion periods, and therefore ensures their durability. Electrochemical tests indicate that the annual corrosion rate of PCL/Col/Ce-HA fiber coating with 5 wt% Ce-HA is almost 30 times lower than the bare AZ31 Mg alloy. The lowest hydrogen evolution volume and relatively stable pH variations of the solution also confirm their effective protective ability. In addition, the cell assay indicates that the PCL/Col/Ce-HA fiber coating is beneficial for cell adhesion and growth, reflecting its excellent cell biocompatibility. The lowest hemolysis rate (2.72%) of PCL/Col/Ce-HA fiber coating also meets the biomedical material application requirements.