In vitro corrosion behavior and in vivo biodegradation of biomedical β-Ca3(PO4)2/Mg-Zn composites

In this study 5, 10 and 15% β-Ca3(PO4)2/Mg-Zn composites were prepared through powder metallurgy methods, and their corrosion behavior and mechanical properties were studied in simulated body fluid (SBF) at 37 °C. The 10% β-Ca3(PO4)2/Mg-Zn composite was selected for cytocompatibility assessment and in vivo biodegradation testing. The results identified the α-Mg, MgZn and β-Ca3(PO4)2 phases in these sintered composites. The density and elastic modulus of the β-Ca3(PO4)2/Mg-6% Zn composite match those of natural bone, and the strength is approximately double that of natural bone. The 10% β-Ca3(PO4)2/Mg-6% Zn composites exhibit good corrosion resistance, as determined by a 30 day immersion test and electrochemical measurements in SBF at 37 °C. The 10% β-Ca3(PO4)2/Mg-6% Zn composite is safe for cellular applications, with a cytotoxicity grade of ∼0-1 against L929 cells in in vitro testing. The β-Ca3(PO4)2/Mg-6% Zn composite also exhibits good biocompatibility with the tissue and the important visceral organs the heart, kidney and liver of experimental rabbits. The composite has a suitable degradation rate and improves the concrescence of a pre-broken bone. The corrosion products, such as Mg(OH)2 and Ca5(PO4)6(OH)2, can improve the biocompatibility of the β-Ca3(PO4)2/Mg-Zn composite.