Accurate detection of cancer biomarker proteins in serum is critically important for early cancer diagnosis, leading to greatly improved patient prognoses, treatment success, and cancer prevention. High accuracy of cancer detection requires simultaneous measurement of collections of biomarkers for each type of cancer. Our long term goal is to develop sensitive electrochemical immunoarrays based on single-wall carbon nanotube forests to measure cancer biomarkers proteins fro point-of-care and research applications.
We have developed prototype sensors featuring vertical single-wall carbon nanotubes (SWNT forests) on pyrolytic graphite surfaces and amperometric enzyme-linked immunoassays. Enhancement was found with performance with aged nanotubes, with several experiments suggesting less side wall defects and denser nanotube forests.
Protein immunosensors were made by attaching antibodies to the carboxylated ends of nanotube forests, which combine high surface areas for attachment of capture antibodies with efficient electrical transduction. Utilizing casein/Tween-20 to minimize non-specific binding and electron mediation of the immunosensors by water soluble mediator hydroquinone, Prostate Specific Antigen (PSA), a biomarker for prostate cancer, was detected at 0.1 nM and below, providing better performance than alternative methods. Effect of sample size, blocking/washing buffer component, reaction/washing time, antibody and mediator concentration on residue NSB, detection limit and sensitivity were systematically evaluated. The practical outcome of this research will integrate optimized fabrication/detection into microarrays for groups of cancer biomarkers suitable diagnostics and cancer research.
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