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.
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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)
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Chemical References |
- Antibodies, Immobilized
- Biomarkers, Tumor
- Cadmium Compounds
- Carcinoembryonic Antigen
- Sulfides
- cadmium sulfide
- Carbon
- Graphite
- Polyethyleneimine
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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)
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