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.

Fe3O4/Au magnetic nanoparticle amplification strategies for ultrasensitive electrochemical immunoassay of alfa-fetoprotein

“…19 The f irst method involves the use of metal and semiconductor nanoparticles directly as electroactive labels to amplify the electrochemical detection of proteins. 20,21 The second method uses nanoparticles as carriers for loading a large amount of electroactive species to amplify the detection signal. 22,23 The third method is the most extensively employed, and uses enzyme-functionalized nanoparticles as labels.…”

The Advances of Carbon Nanotubes in Cancer Diagnostics and Therapeutics

“…Moreover, the new system of CNTs can save time compared with the conventional ELISA commercial test kits while achieving the similar selectivity [64]. More importantly, this approach can provide handheld equipment with less expense compared with currently methods, such as immunoassays, test-strips, and kits [65]. In summary, the CNTs-based detection may be a selective way for cancer diagnosis and treatment in clinical analysis in the near future.…”

Disposable Biosensors for Clinical Diagnosis

“…Several disposable electrochemical immunosensors using different electroactive materials such as conducting polymers, 43 graphite, 44 carbon nanotubes, 45 or metals 46 47 Delivered by Publishing 50 and Viswanathan et al 51 for the detection of the carcinoembryonic antigen, a tumor marker. In the former, the authors have proposed a sensitive electrochemical immunosensor based on a carbon nanoparticle-modified screen-printed graphite electrode covered with specific antibodies, using CdS nanocrystals as biotracers as a strategy for signal amplification.…”