The corrosion and biological behavior of 3D-printed polycaprolactone/chitosan scaffolds as protective coating for Mg alloy implants

Magnesium (Mg) and its alloys have gained attention for use in orthopedic implants and bone tissue engineering. However, the corrosion of these materials, which results in toxic by-products, reduces their mechanical strength and limits their use. Here, fused deposition modeling 3D printing was used to fabricate polycaprolactone (PCL)/chitosan composite scaffolds on the surface of AZ31 Mg alloy to improve its corrosion resistance and bioactivity. Physiochemical characterization of the composite scaffold was performed. Corrosion behavior of the coatings was investigated by potentiodynamic polarization and electrochemical impedance spectroscopy, indicating higher corrosion resistance of 3D-printed PCL/chitosan scaffold-coated AZ31 Mg alloy than that of the uncoated alloy with coating efficiency of 98.89 %. The resulting materials possessed antibacterial activity against Gram-positive and Gram-negative bacteria. Cell viability, alkaline phosphatase, alizarin red, real-time PCR, and flow cytometry assays were performed to assess the response of MC3T3 cells to the materials over the course of 14 days in culture. Of the composite scaffolds examined, AZ31 surfaces coated with 4wt%PCL/ 3 wt% chitosan provided the best performance in adhesion, proliferation and osteogenic differentiation of cell, which was attributed to the presence of amine groups in the chitosan used in the PCL/chitosan blend. Thus, AZ31 modified by 3D printing of PCL/chitosan represents a promising strategy for regeneration and repair of bone defects.