Magnesium/nano-hydroxyapatite porous biodegradable composite for biomedical applications

The main purpose of this study was to fabricate a magnesium/nano-hydroxyapatite porous composite with appropriate mechanical properties and degradation rate for biomedical applications. Magnesium scaffolds including different weight of nano-hydroxyapatite (0, 2, 4 and 8%) were fabricated using the powder metallurgy method. To study the phase and microstructure, the samples were characterized by x-ray diffraction (XRD) and scanning electron microscopy (SEM). Measurement of the mechanical properties was performed using a compression test, and the porosimetry test was performed by following the Archimedes method. Biodegradation properties of the specimens were evaluated by soaking in the phosphate-buffered saline (PBS). Based on the results, composites with 2 and 4 wt% of nano-hydroxyapatite (nHA) had the optimum characteristics; the yield strength of these composites was about twice and the plateau stress was about three to four times more than that of the pure magnesium. Also, the elastic modulus of these composites (0.25 GPa) was in cancellous bone range. The degradation rate of the composites with 2 and 4 wt% of nano-hydroxyapatite, as compared with pure magnesium, was decreased about 35 to 40 percent. Mg/nHA composite including 2-4 wt% of hydroxyapatite could be, therefore, considered as an appropriate alternative material for degradable load bearing implantation.