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Sensitive and high-fidelity electrochemical immunoassay using carbon nanotubes coated with enzymes and magnetic nanoparticles

Cited 33 time in Web of Science Cited 32 time in Scopus
Issue Date
2011-03
Citation
Biosensors and Bioelectronics, Vol.26 No.7, pp.3192-3199
Keywords
Enzyme coatingElectrochemical immunoassaySubstrate recyclingCarbon nanotubeTyrosinase
Abstract
We demonstrate a highly sensitive electrochemical immunosensor based on the combined use of substrate recycling and carbon nanotubes (CNTs) coated with tyrosinase (TYR) and magnetic nanoparticles (MNP). Both TYR and MNP were immobilized on the surface of CNTs by covalent attachment, followed by additional cross-linking via glutaraldehyde treatment to construct multi-layered cross-linked TYR-MNP aggregates (M-EC-CNT). Magnetically capturable, highly active and stable M-EC-CNT were further conjugated with primary antibody against a target analyte of hIgG, and used for a sandwich-type immunoassay with a secondary antibody conjugated with alkaline phosphatase (ALP). In the presence of a target analyte, a sensing assembly of M-EC-CNT and ALP-conjugated antibody was attracted onto a gold electrode using a magnet. On an electrode, ALP-catalyzed hydrolysis of phenyl phosphate generated phenol, and successive TYR-catalyzed oxidation of phenol produced electrochemically measurable o-quinone that was converted to catechol in a scheme of substrate recycling. Combination of highly active M-EC-CNT and substrate recycling for the detection of hIgG resulted in a sensitivity of 27.6 nA ng(-1) mL(-1) and a detection limit of 0.19 ng mL(-1) (1.2 pM), respectively, representing better performance than any other electrochemical immunosensors relying on the substrate recycling with the TYR-ALP combination. The present immunosensing system also displayed a long-term stability by showing a negligible loss of electrochemical detection signal even after reagents were stored in an aqueous buffer at 4 degrees C for more than 6 months. (C) 2010 Elsevier B.V. All rights reserved.
ISSN
0956-5663
URI
https://hdl.handle.net/10371/166233
DOI
https://doi.org/10.1016/j.bios.2010.12.025
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College of Engineering/Engineering Practice School (공과대학/대학원)Dept. of Chemical and Biological Engineering (화학생물공학부)Journal Papers (저널논문_화학생물공학부)
College of Engineering/Engineering Practice School (공과대학/대학원)Dept. of Chemical and Biological Engineering (화학생물공학부)Chemical Convergence for Energy and Environment (에너지환경 화학융합기술전공)Journal Papers (저널논문_에너지환경 화학융합기술전공)
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