Electrochemical Immunosensor for Cholera Toxin Using Liposomes and Poly(3,4-ethylenedioxythiophene)-Coated Carbon Nanotubes

A sensitive method for the detection of cholera toxin (CT) using an electrochemical immunosensor with liposomic magnification followed by adsorptive square-wave stripping voltammetry is described. Potassium ferrocyanide-encapsulated and ganglioside (GM1)-functionalized liposomes act as highly specif...

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Bibliographic Details
Published in:Analytical chemistry (Washington) 2006-02, Vol.78 (4), p.1115-1121
Main Authors: Viswanathan, Subramanian, Wu, Li-chen, Huang, Ming-Ray, Ho, Ja-an Annie
Format: Article
Language:English
Subjects:
Analytical chemistry
Antibodies - immunology
Biosensing Techniques
Biosensors
Bridged Bicyclo Compounds, Heterocyclic - chemistry
Carbon
Chemistry
Cholera
Cholera Toxin - analysis
Electrochemical methods
Electrochemistry - instrumentation
Exact sciences and technology
General, instrumentation
Liposomes
Microscopy, Electron, Scanning
Nanotubes
Nanotubes, Carbon
Polymers - chemistry
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Description
Summary:A sensitive method for the detection of cholera toxin (CT) using an electrochemical immunosensor with liposomic magnification followed by adsorptive square-wave stripping voltammetry is described. Potassium ferrocyanide-encapsulated and ganglioside (GM1)-functionalized liposomes act as highly specific recognition labels for the amplified detection of cholera toxin. The sensing interface consists of monoclonal antibody against the B subunit of CT that is linked to poly(3,4-ethylenedioxythiophene) coated on Nafion-supported multiwalled carbon nanotube caste film on a glassy carbon electrode. The CT is detected by a “sandwich-type” assay on the electronic transducers, where the toxin is first bound to the anti-CT antibody and then to the GM1-functionalized liposome. The potassium ferrocyanide molecules are released from the bounded liposomes on the electrode by lyses with methanolic solution of Triton X-100. The released electroactive marker is measured by adsorptive square-wave stripping voltammetry. The sandwich assay provides the amplification route for the detection of the CT present in ultratrace levels. The calibration curve for CT had a linear range of 10-14−10-7g mL-1. The detection limit of this immunosensor was 10-16 g of cholera toxin (equivalent to 100 μL of 10-15 g mL-1).
ISSN:0003-2700
1520-6882
DOI:10.1021/ac051435d