An amperometric immunosensor for separation-free immunoassay of CA125 based on its covalent immobilization coupled with thionine on carbon nanofiber

A carbon nanomaterial, soluble carbon nanofiber, was used for the first time to construct an immunosensor for a rapid separation-free immunoassay. The acidic oxidation of the carbon nanofiber provided its solubility and wettability for convenient preparation of a porous carbon nanofiber membrane and...

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Bibliographic Details
Published in:Journal of immunological methods 2007-04, Vol.322 (1), p.12-19
Main Authors: Wu, Lina, Yan, Feng, Ju, Huangxian
Format: Article
Language:English
Subjects:
Biological and medical sciences
Biosensing Techniques - methods
Biosensors
Carbon - chemistry
Carbon nanofiber
Carcinoma antigen-125
Conductometry - methods
Electric Impedance
Electrochemical sensors
Fundamental and applied biological sciences. Psychology
Fundamental immunology
Humans
Immunoassay
Immunosensor
Molecular immunology
Nanostructures - chemistry
Nanotechnology - methods
Oxidation-Reduction
Phenothiazines - chemistry
Proteins - analysis
Techniques
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Summary:A carbon nanomaterial, soluble carbon nanofiber, was used for the first time to construct an immunosensor for a rapid separation-free immunoassay. The acidic oxidation of the carbon nanofiber provided its solubility and wettability for convenient preparation of a porous carbon nanofiber membrane and a larger number of active sites for covalent binding of carcinoma antigen-125 (CA125) and thionine as electron transfer mediator. This matrix was a suitable environment for the immobilized protein. The immobilized HRP-labeled immunoconjugate showed good enzymatic activity for the oxidation of thionine by hydrogen peroxide. With a competitive mechanism, the differential pulse voltammetric peak current of this system decreased linearly with increasing CA125 concentration (from 2 to 75 U/ml) in the incubation solution. The CA125 immunosensor showed good precision, high sensitivity, acceptable stability and reproducibility with a detection limit of 1.8 U/ml. The soluble carbon nanofiber is a novel method for preparation of immunosensors.
ISSN:0022-1759
1872-7905
DOI:10.1016/j.jim.2007.01.026