Carbon nanoparticle-enhanced immunoelectrochemical detection for protein tumor marker with cadmium sulfide biotracers.

Abstract

We have developed a sensitive electrochemical immunoassay system for the detection of a protein tumor marker, carcinoembryonic antigen (CEA), that is based on a carbon nanoparticle (CNP)/poly(ethylene imine) (PEI)-modified screen-printed graphite electrode (CNP-PEI/SPGE) covered with anti-CEA antibodies. The signal amplification strategy--using CdS nanocrystals as biotracers and CNPs to enhance electron transfer--improves the sensitivity and detection limit for CEA, suggesting that this system holds promise for development into a point-of-care or disposable home-care self-diagnostic tool. This biosensor is based on a sandwich complex immunoassay, which we assembled from sequential layers of the anti-CEA antibody (alphaCEA) on CNP-PEI/SPGE, the CEA sample, and the CdS nanocrystal quantum dots (QDs) sensitized with alphaCEA (alphaCEA-CdS QD). We used square wave anodic stripping voltammetry (SWASV) to amplify the signal current response obtained from the dissolved alphaCEA-CdS QDs. The calibration curve for CEA concentration was linear in the range of 0.032-10 ng/mL; the detection limit (estimated as the mean of the blank sample plus three times the standard deviation obtained on the blank sample) was 32 pg/mL (equivalent to 160 fg in a 5 microL sample). This method is suitably precise and sensitive to function as a means of determining urinary CEA, which is a better marker than serum CEA for the early detection of urothelial carcinoma.

• Authors: Ja-an Annie Ho, Yeh-Chun Lin, Li-Sheng Wang, Kuo-Chu Hwang, Pi-Tai Chou
• Journal: Analytical chemistry (Anal Chem) Vol. 81 Issue 4 Pg. 1340-6 (Feb 15 2009) ISSN: 1520-6882 [Electronic] United States
• PMID: 19159204 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Antibodies, Immobilized
• Biomarkers, Tumor
• Cadmium Compounds
• Carcinoembryonic Antigen
• Sulfides
• cadmium sulfide
• Carbon
• Graphite
• Polyethyleneimine

Topics

• Antibodies, Immobilized (chemistry, immunology)
• Biomarkers, Tumor (analysis, chemistry, immunology)
• Cadmium Compounds (chemistry)
• Calibration
• Carbon (chemistry)
• Carcinoembryonic Antigen (analysis, chemistry, immunology)
• Electrochemistry
• Electrodes
• Graphite (chemistry)
• Humans
• Immunoassay (methods)
• Nanoparticles (chemistry)
• Polyethyleneimine (chemistry)
• Quantum Dots
• Sulfides (chemistry)