Homo-DNA functionalized carbon nanotube chemical sensors

Arrays of chemical sensors based on homo-oligomer single-stranded DNA (ssDNA) adsorbed to single-walled carbon nanotube field effect transistors (SWNT-FETs) were employed to detect several gaseous analytes. Exposure of these devices to analytes results in a characteristic current shift in the SWNT-FET. The magnitude of this current shift for a particular analyte varies with the base sequence of adsorbed ssDNA and follows the trend d(G)21-SWNT>d(A)21-SWNT>d(C)21-SWNT>d(T)21-SWNT. Molecular dynamics simulations suggest that a comparable trend of d(G)21>d(A)21>d(T)21->d(C)21 exists for ssDNA-SWNT binding affinities. This indicates that the nature of ssDNA-SWNT binding plays a vital role in the performance of the sensor. Stronger binding implies a greater amount of ssDNA adsorbed to SWNT surface. This would result in a more hydrophilic environment around the hydrophobic SWNT core and thus facilitate the adsorption of polar analytes.