Investigation of bioactivity and biodegradability of Mg-bioceramic implants: An in vitro study for biomedical applications

Abstract

In this study, Mg-based composites, by the addition of ZnO, Ca₂ZnSi₂O₇, Ca₂MgSi₂O₇, and CaSiO₃ as bioactive agents, were fabricated using friction stir processing. The microstructure and in vitro assessment of bioactivity, biodegradation rate, and corrosion behavior of the resultant composites were investigated in simulated body fluid (SBF). The results showed that during the immersion of composites in SBF for 28 d, due to the release of Ca²⁺ and PO₄ ³⁻ ions, hydroxyapatite (HA) crystals with cauliflower shaped morphology were deposited on the surface of composites, confirming good bioactivity of composites. In addition, due to the uniform distribution of bioceramic powders throughout Mg matrix, grain refinement of the Mg matrix, and uniform redistribution of secondary phase particles, the polarization resistance increased, and the biodegradation rate of composites significantly reduced compared to monolithic Mg matrix. The polarization corrosion resistance of Mg-ZnO increased from 0.216 to 2.499 KΩ/cm² compared to monolithic Mg alloy. Additionally, Mg-ZnO composite with the weight loss of 0.0217 g after 28 d immersion showed lower weight loss compared to other samples with increasing immersion time. Moreover, Mg-ZnO composite with the biodegradation rate of 37.71 mm/a exhibited lower biodegradation rate compared to other samples with increasing immersion time.

Keywords

Mg-bioceramic bone implants / friction stir processing / bioactivity / in vitro biodegradation / biocorrosion