Abstract:Mg/HA composite was fabricated using the stir-casting and extrusion processes and coated by electrospun PCL/HA fibers (2.5 and 5 wt.% HA) to enhance the corrosion resistance. The mechanical tests demonstrated an increment of 107% for the compressive yield strength of the composite (151 vs 73 MPa for pure magnesium). SEM, EDS, and XRD analysis illustrated that HA particles distribute in porous coatings. According to the polarization tests, all coated specimens show higher corrosion resistance compared to the uncoated ones. PCL coating reduces the corrosion current density of the sample by two orders of magnitude. The effectiveness of incorporating HA in the coatings was proved by polarization and in vitro corrosion tests. Employment of coatings and subsequent Ca-P layer formation prevents the penetration of simulated body fluid (SBF) and contact with the substrate, thus protecting the surface. PCL/2.5%HA coated sample has the lowest corrosion rate with an average value of 0.98 mm/a by a reduction of 81% compared to the uncoated composite in 14 d. Cell viability enhancement from 43% to 121% was achieved using PCL/2.5%HA coating according to 3 d 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) results. In conclusion, Mg/HA composites coated with PCL/2.5%HA fibers appear promising for bioabsorbable implant applications.

Key words: magnesium composite; composite coating; biodegradability; hydroxyapatite; polycaprolactone (PCL) fibers