Hybridization kinetics and thermodynamics of DNA adsorbed to individually dispersed single-walled carbon nanotubes

Hybridization of DNA adsorbed to single-walled carbon nanotubes in solution has much slower kinetics than free solution DNA, and can be detected through a blue shift in the near-infrared nanotube fluorescence. Adsorption of the receptor DNA strand to the nanotube surface is consistent with models of polyelectrolyte adsorption on charged surfaces, introducing and activation energy both entropic (46.8 calmol(-1) K-1) and activation energy (20.4 kcalmol(-1)) barriers to the hybridization, which are greater than free solution values (31.9 calmol(-1)K(-1) and 12.9 kcalmol(-1)) at 25 degrees C The increased hybridization barriers on the nanotube result in exceedingly slow kinetics for hybridization with t(1/2) == 3.4 h, compared to the free solution value of t(1/2) = 4 min. These results have significant implications for nanotube and nanowire biosensors.