Journal
MICROCHIMICA ACTA
Volume 182, Issue 11-12, Pages 2045-2053Publisher
SPRINGER WIEN
DOI: 10.1007/s00604-015-1540-6
Keywords
Aptamer; Sandwich; Cytochrome c; SEM; Gold-nanoparticles electrochemical impedance spectroscopy
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Funding
- Research Executive Agency (REA) of the European Union [PITN-GA-2010-264772]
- Ministry of Science and Innovation (MCINN, Madrid, Spain) [CTQ2013-41577-P]
- Catalonia program ICREA Academia
- Ministry of Science and Innovation (MICINN, Madrid, Spain)
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We report on a sensitive aptamer-antibody interaction-based assay for cytochrome c (Cyt c) using electrochemical impedance. 4-Amino benzoic acid is used for the oriented immobilization of aminated aptamers onto multi-walled carbon nanotubes on the surface of a screen-printed electrode via electrochemical grafting. Impedance was measured in a solution containing the redox system ferro/ferricyanide. The change in interfacial charge transfer resistance (R-ct) experienced by the redox marker was recorded to confirm the formation of a complex between aptamer and the target (Cyt c). A biotinylated antibody against cytochrome c was then used in a sandwich type of assay. The addition of streptavidin conjugated to gold nanoparticles and signal enhancement by treatment with silver led to a further increase in Rct. Under optimized conditions, a detection limit as low as 12 pM was obtained. Cross-reactivity against other serum proteins including fibrinogen, BSA and immunoglobulin G demonstrated improved selectivity.
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