title: In vitro investigation of NiTiW shape memory alloy as potential biomaterial with enhanced radiopacity.
abstract: In the present study, a novel kind of NiTiW shape memory alloy with chemical composition of Ni43.5Ti45.5W11 (at.%) has been successfully developed with excellent X-ray radiopacity by the introduction of pure W precipitates into the NiTi matrix phase. Its microstructure, X-ray radiopacity, mechanical properties, corrosion resistance in simulated body fluid, hemocompatibility and in vitro cytocompatibility were systematically investigated. The typical microstructural feature of NiTiW alloy at room temperature was tiny pure W particles randomly distributing in the NiTi matrix phase. The presence of W precipitates was found to result in enhanced radiopacity and microhardness of NiTiW alloy in comparison to that of NiTi binary alloy. NiTiW alloy exhibits excellent shape memory effect, and a maximum shape recovery ratio of about 30% was obtained with a total prestrain of 8% for the NiTiW alloy sample. In the electrochemical test, NiTiW alloy presented an excellent corrosion resistance in simulated body fluid, comparable to that of NiTi alloy. Hemocompatibility tests indicated that the NiTiW alloy has quite low hemolysis (lower than 0.5%) and the adherent platelet showed round shape without pseudopod. Besides, in vitro cell viability tests demonstrated that the cell viability is all above 90%, and the cells spread well on the NiTiW alloy, having polygon or spindle healthy morphology. The hemocompatibility tests, in vitro cell viability tests and morphology observation indicated that the NiTiW shape memory alloys have excellent biocompatibility. The excellent X-ray radiopacity makes the NiTiW alloys show obvious advantages in orthopedic, stomatological, neurological and cardiovascular domains where radiopacity is quite important factor in order to guarantee successful implantation.
authors.affiliation: State Key Laboratory for Turbulence and Complex System, and Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871, China.
authors.forename: Huafang
authors.initials: H
authors.lastname: Li
authors.affiliation: Physics Specialty in YuanPei College, Peking University, Beijing 100871, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Cong
authors.affiliation: State Key Laboratory for Turbulence and Complex System, and Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871, China. Electronic address: yfzheng@pku.edu.cn.
authors.forename: Yufeng
authors.initials: Y
authors.lastname: Zheng
authors.affiliation: State Key Laboratory of Heavy Oil Processing, and Department of Materials Science and Engineering, China University of Petroleum, Beijing 102249, China.
authors.forename: Lishan
authors.initials: L
authors.lastname: Cui
mesh_terms: D000497:Alloys / Q000737:chemistry*; D001672:Biocompatible Materials / Q000737:chemistry*; D008422:Materials Testing; D009532:Nickel / Q000737:chemistry; D014025:Titanium / Q000737:chemistry
chemical_list: D000497:Alloys; D001672:Biocompatible Materials; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium
keywords: Biomaterials; Corrosion behavior; Metals and alloys; Phase transformation; Radiopacity; Shape memory alloys (SMAs)