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 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(-7)g mL(-1). The detection limit of this immunosensor was 10(-16) g of cholera toxin (equivalent to 100 microL of 10(-15) g mL(-1)).
BioAnalytical Chemistry Laboratory, Department of Chemistry, National Tsing Hua University, Hsinchu, 300 Taiwan.
Subramanian
S
Viswanathan
Li-Chen
LC
Wu
Ming-Ray
MR
Huang
Ja-An Annie
JA
Ho
D000906:Antibodies / Q000276:immunology*; D015374:Biosensing Techniques; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000737:chemistry*; D002772:Cholera Toxin / Q000032:analysis*; D004563:Electrochemistry / Q000295:instrumentation*; D008081:Liposomes; D008855:Microscopy, Electron, Scanning; D037742:Nanotubes, Carbon; D011108:Polymers / Q000737:chemistry*
D000906:Antibodies; D019086:Bridged Bicyclo Compounds, Heterocyclic; D008081:Liposomes; D037742:Nanotubes, Carbon; D011108:Polymers; C121383:poly(3,4-ethylene dioxythiophene); D002772:Cholera Toxin