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

Abstract

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.

• Authors: Lina Wu, Feng Yan, Huangxian Ju
• Journal: Journal of immunological methods (J Immunol Methods) Vol. 322 Issue 1-2 Pg. 12-9 (Apr 30 2007) ISSN: 0022-1759 [Print] Netherlands
• PMID: 17350032 (Publication Type: Evaluation Study, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Intracellular Signaling Peptides and Proteins
• NBR1 protein, human
• Phenothiazines
• Proteins
• Carbon
• thionine

Topics

• Biosensing Techniques (methods)
• Carbon (chemistry)
• Conductometry (methods)
• Electric Impedance
• Humans
• Immunoassay
• Intracellular Signaling Peptides and Proteins
• Nanostructures (chemistry)
• Nanotechnology (methods)
• Oxidation-Reduction
• Phenothiazines (chemistry)
• Proteins (analysis)