title: Toxicity assessment and selective leaching characteristics of Cu-Al-Ni shape memory alloys in biomaterials applications.
abstract: BACKGROUND
  Cu-Al-Ni shape memory alloys (SMAs) possess two-way shape memory effects, superelasticity, and damping capacity. Nonetheless, Cu-Al-Ni SMAs remain promising candidates for use in biomedical applications, as they are more economical and machinable than other SMAs. Ensuring the biocompatibility of Cu-Al-Ni SMAs is crucial to their development for biomedical applications. Therefore, this study aimed to assess the toxicity of Cu-Al-Ni SMAs using a Probit dose-response model and augmented simplex design.
  
  
  METHODS
  In this study, the effects of Cu2+, Al3+ and Ni2+ metal ions on bacteria (Escherichia coli DH5α) using Probit dose-response analysis and augmented simplex design to assess the actual toxicity of the Cu-Al-Ni SMAs.
  
  
  RESULTS
  Extraction and repetition of Escherichia coli DH5α solutions with high Cu2+ ion concentrations and 30-hour incubation demonstrated that Escherichia coli DH5α was able to alter its growth mechanisms in response to toxins. Metal ions leached from Cu-Al-Ni SMAs appeared in a multitude of compositions with varying degrees of toxicity, and those appearing close to a saddle region identified in the contour plot of the augmented simplex model were identified as candidates for elevated toxicity levels. When the Cu-13.5Al-4Ni SMA plate was immersed in Ringer's solution, the selective leaching rate of Ni2+ ions far exceeded that of Cu2+ and Al3+. The number of Cu2+, Al3+ and Ni2+ ions leached from Cu-Al-Ni SMAs increased with immersion time; however, at higher ratios, toxicity interactions among the metal ions had the effect of gradually reducing overall toxicity levels with regard to Escherichia coli DH5α.
  
  
  CONCLUSIONS
  The quantities of Cu2+, Al3+ and Ni2+ ions leached from the Cu-13.5Al-4Ni SMA plate increased with immersion time, the toxicity interactions associated with these compositions reduced the actual toxicity to Escherichia coli DH5α.
authors.affiliation: Department of Chemical and Materials Engineering, National I-Lan University, I-Lan - Taiwan.
authors.forename: Shih-Hang
authors.initials: SH
authors.lastname: Chang
authors.affiliation: Department of Chemical and Materials Engineering, National I-Lan University, I-Lan - Taiwan.
authors.forename: Bor-Yann
authors.initials: BY
authors.lastname: Chen
authors.affiliation: Department of Chemical and Materials Engineering, National I-Lan University, I-Lan - Taiwan.
authors.forename: Jin-Xiang
authors.initials: JX
authors.lastname: Lin
mesh_terms: D000497:Alloys / Q000737:chemistry*; D000535:Aluminum / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D004926:Escherichia coli / Q000254:growth & development*; D009532:Nickel / Q000737:chemistry*
chemical_list: D000497:Alloys; D003300:Copper; D009532:Nickel; D000535:Aluminum