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

In this study 5, 10 and 15% beta-Ca-3(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 degrees C. The 10% beta-Ca-3(PO4)(2)/Mg-Zn composite was selected for cytocompatibility assessment and in vivo biodegradation testing. The results identified the alpha-Mg, MgZn and beta-Ca-3(PO4)(2) phases in these sintered composites. The density and elastic modulus of the beta-Ca-3(PO4)(2)/Mg-6% Zn composite match those of natural bone, and the strength is approximately double that of natural bone. The 10% beta-Ca-3(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 degrees C. The 10% beta-Ca-3(PO4)(2)/Mg-6% Zn composite is safe for cellular applications, with a cytotoxicity grade of similar to 0-1 against L929 cells in in vitro testing. The beta-Ca-3(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 Ca-5(PO4)(6)(OH)(2), can improve the biocompatibility of the beta-Ca-3(PO4)(2)/Mg-Zn composite. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.