Processing of bioresorbable closed-cell Mg foam for bone implant applications

Abstract

ABSTRACT Magnesium is the most promising element as a bioresorbable material in bone repairing applications. Closed-cell Mg-2Zn-2Ca foam was fabricated through melt processing route by using economical biocompatible pure dolomite+MgCO3 as dual-blowing agent with favorable advantages of uniform pore structure, improved mechanical properties and good biocompatibility. In addition, residuals of blowing agent act as biocompatible particles during degradation. Mg-2Zn-2Ca foam was characterized for its physical, mechanical, in vitro degradation properties and microstructure characterization. Mg-2Zn-2Ca foams having relative density 0.41–0.45, average uniform pore size in the range of 0.25–0.75 mm revealed plastic compression strength up-to 50.1 MPa, plateau strength up to 43.2 MPa with 56.3% densification strain and 30 MJ/m3 of energy absorption per unit volume were obtained. Moreover, Mg foam exhibited adequate compressive behavior during in vitro degradation up to 4 weeks in simulated body fluid. Despite higher amount of hydrogen release in initial stage, Mg foam observed stable degradation mechanism after 2 weeks due to formation and deposition of degradation products on cellular surfaces. Based on the processing method and results obtained, Mg-2Zn-2Ca closed-cell foam satisfied the requirement of physical, mechanical and in vitro degradation properties compared to natural bone properties and recommended as cost effective, biocompatible and bone substitution mechanical implant material.