title: Microstructure, mechanical properties, in vitro degradation and cytotoxicity evaluations of Mg-1.5Y-1.2Zn-0.44Zr alloys for biodegradable metallic implants.
abstract: Mg-1.5Y-1.2Zn-0.44Zr alloys were newly developed as degradable metallic biomaterials. A comprehensive investigation of the microstructure, mechanical properties, in vitro degradation assessments and in vitro cytotoxicity evaluations of the as-cast state, as-heat treated state and as-extruded state alloys was done. The microstructure observations show that the Mg-1.5Y-1.2Zn-0.44Zr alloys are mainly composed of the matrix α-Mg phases and the Mg12ZnY secondary phases (LPS structure). The hot extrusion method significantly refined the grains and eliminated the defects of both as-cast and heat treated alloys and thereby contributed to the better mechanical properties and biodegradation resistance. The values of tensile strength and tensile yield strength of the alloy in the as-extruded condition are about 236 and 178 MPa respectively, with an excellent elongation of 28%. Meanwhile, the value of compressive strength is about 471 MPa and the value of bending strength is about 501 MPa. The superior bending strength further demonstrates the excellent ductility of the hot extruded alloys. The results of immersion tests and electrochemical measurements in the SBF indicate that a protective film precipitated on the alloy's surface with the extension of degradation. The protective film contains Mg(OH)2 and hydroxyapatite (HA) which can reinforce osteoblast activity and promote good biocompatibility. No significant cytotoxicity towards L-929 cells was detected and the immersion extracts of alloy samples could enhance the cell proliferation with time in the cytotoxicity evaluations, implying that the Mg-1.5Y-1.2Zn-0.44Zr alloys have the potential to be used for biomedical applications.
authors.affiliation: State Key Laboratory of Rare Earth Resources Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, PR China.
authors.forename: Jun
authors.initials: J
authors.lastname: Fan
authors.forename: Xin
authors.initials: X
authors.lastname: Qiu
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Niu
authors.forename: Zheng
authors.initials: Z
authors.lastname: Tian
authors.forename: Wei
authors.initials: W
authors.lastname: Sun
authors.forename: Xiaojuan
authors.initials: X
authors.lastname: Liu
authors.forename: Yangde
authors.initials: Y
authors.lastname: Li
authors.forename: Weirong
authors.initials: W
authors.lastname: Li
authors.forename: Jian
authors.initials: J
authors.lastname: Meng
mesh_terms: D020341:Absorbable Implants; D000497:Alloys / Q000737:chemistry* / Q000494:pharmacology*; D000818:Animals; D016923:Cell Death / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D055664:Electrochemical Techniques; D005347:Fibroblasts / Q000166:cytology* / Q000187:drug effects; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D008422:Materials Testing; D055595:Mechanical Phenomena / Q000187:drug effects*; D008670:Metals / Q000737:chemistry*; D051379:Mice; D008855:Microscopy, Electron, Scanning; D008970:Molecular Weight; D012996:Solutions; D013052:Spectrometry, X-Ray Emission; D014961:X-Ray Diffraction
chemical_list: D000497:Alloys; D008670:Metals; C583185:Mg-1.5Y-1.2Zn-0.44Zr alloy; D012996:Solutions