Journal
BIOSENSORS & BIOELECTRONICS
Volume 26, Issue 8, Pages 3660-3665Publisher
ELSEVIER ADVANCED TECHNOLOGY
DOI: 10.1016/j.bios.2011.02.026
Keywords
Immunosensor; Electrochemical impedance spectroscopy; Aryl diazonium salts; Functionalized gold nanoparticles
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Funding
- Australia Research Council [LP0775216]
- Australian Research Council [LP0775216] Funding Source: Australian Research Council
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Electrodes modified with passivating organic layers have been shown to, here and previously, to exhibit good Faradaic electrochemistry upon attachment of gold nanoparticles (AuNP). Due to their low background capacitances these constructs have good potential in electrochemical sensing. Herein is reported the application of these electrode constructs for impedance based immunosensing. The immunosensor was constructed by modifying a gold electrode with 4-thiophenol (4-TP) passivating layers by diazonium salt chemistry. Subsequently, the attachment of AuNP and then a biotin derivative as a model epitope to detect anti-biotin IgG were carried out. The interfacial properties of the modified electrodes were evaluated in the presence of Fe(CN)(6)(4-/3-) redox couple as a probe by cyclic voltammetry and electrochemical impedance spectroscopy. The impedance change, due to the specific immuno-interaction at the immunosensor surface was utilized to detect anti-biotin IgG. The increase in charge-transfer resistance (R-ct) was linearly proportional to the concentration of anti-biotin IgG in the range of 5-500 ng mL(-1), with a detection limit of 5 ng mL(-1). (C) 2011 Elsevier B.V. All rights reserved.
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