The effect of MgO on the biodegradation, physical properties and biocompatibility of a Mg/HA/MgO nanocomposite manufactured by powder metallurgy method

Abstract

Recently, magnesium-hydroxyapatite composites have shown the potential to serve as biodegradable metal matrix composite implants that can repair load-bearing defects in osseous tissue. However, the mechanical properties and corrosion resistance of magnesium-hydroxyapatite composites have been restricted by the significant agglomeration of HA particulates. In this study, the bio-corrosion properties of a Mg/HA-based composite were improved by the addition of different amounts of hydroxyapatite (HA) and periclase (MgO) nanopowders to pure magnesium and fabrication of the Mg/HA/MgO nanocomposites using a blend-cold press-sinter powder metallurgy (PM) technique. X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, atomic force microscopy and field-emission scanning electron microscopy were used to characterize the compositions of the corrosion products and the surface morphologies of the corroded specimens. Based on the electrochemical test, the corrosion resistance of the nanocomposites is shown to increase from 0.25 kΩ cm2 to 1.23 kΩ cm2 with the addition of 10 wt% MgO; however, the ultimate compressive strength decreased from ∼237 to ∼198 MPa. During immersion test in SBF solution, the growth of the Mg(OH)2 nanorods on the Mg-12.5HA-10MgO and Mg-5HA-15MgO (wt%) nanocomposites increased the contact angle between the SBF solution and the substrate; as a result, the corrosion rate decreased compared to that of the Mg-27.5HA-10MgO and Mg-20HA-5MgO (wt%) nanocomposites. The corrosion products formed on the nanocomposites surface are shown to be primarily Mg(OH)2, HA, Ca3(PO4)2 and amorphous CaP compounds. The cell culture results indicated that the Mg/HA/MgO nanocomposites remained biocompatible with osteoblasts by increasing of MgO amount.