A Novel Carbon Nanotube Network and Aptamer Based Biosensor

A carbon nanotube network field effect transistor (CNTN-FET) based biosensor for the detection of Tenascin C will be presented. The device consisted of CVD-grown CNTNs incorporated into FETs coupled with surface bound DNA aptamers. The aptamer conjugated FET provides highly selective and sensitive detection of protein concentrations. The sidewalls of the CNTs initially were functionalized with a short oligonucleotide which has the dual functions of blocking non-specific binding and serving as a tether for the addition of another DNA strand. Specific detection was accomplished through hybridization of an aptamer for Tenascin C to which the complementary strand of our blocking sequence was added to the 5' end. IV curves and conductance versus time were collected, demonstrating detection of each of the two DNA strands and the protein Tenascin C. The protein produced an undetectable signal in the absence of the aptamer, even at higher concentrations. Confirmation of adsorption of the oligonucleotide, hybridization of the aptamer, and binding of Tenascin C were each confirmed through fluorescence microscopy. The resulting device is an important step toward low cost, label-free biosensors.