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An sp2 and sp3 hybrid nanocrystalline carbon film electrode for anodic stripping voltammetry and its application for electrochemical immunoassay.

  • Kurita, Ryoji1
  • Nakamoto, Kohei
  • Sato, Yuko
  • Kamata, Tomoyuki
  • Ueda, Akio
  • Kato, Dai
  • Hirono, Shigeru
  • Niwa, Osamu
  • 1 National Institute of Advanced Industrial Science and Technology, Tsukuba Central, Higashi, Ibaraki, Japan. [email protected] , (Japan)
Published Article
Analytical sciences : the international journal of the Japan Society for Analytical Chemistry
Publication Date
Jan 01, 2012
PMID: 22232218


A hybridized nanocrystalline carbon film electrode consisting of sp(2) and sp(3) bonds was investigated to reveal the reduction properties of Cd(2+) and for application as a highly sensitive and reliable electrochemical immunoassay. Conductive nanocrystalline carbon film consisting of about 60% sp(2) and 40% sp(3) bonds was fabricated using electron cyclotron resonance (ECR) sputtering equipment, and then the Cd(2+) concentrations were measured with an ECR sputtered carbon (ECR nano-carbon) electrode by employing an anodic stripping voltammetry (ASV) technique. The preconcentrated Cd was analyzed with Kelvin probe force microscopy and energy dispersive X-ray spectroscopy while observing the morphology change with an atomic force microscope and a scanning electron microscope. The preconcentrated Cd on the ECR nano-carbon electrode was revealed to be a thin sheet structure, which was significantly different from the Cd on a conventional carbon material that grows with a coralloid structure. The background current during an ASV measurement maintains a low level equivalent to that found with boron-doped diamond because the surface of the ECR nano-carbon is robust and angstrom-level flat. The carbon-electrode performance for ASV was improved by controlling its structure at a nanometer scale without any metal doping or coating. Finally, the ECR nano-carbon was used for biomolecular determination by electrochemical immunoassay with a CdSe nanoparticle label. Electrochemical immunoassay results were successfully obtained with the ECR nano-carbon, and they correlated well with fluorescence results obtained for CdSe nanoparticles.

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