Preparation and characterization of conductive and photoluminescent DNA-templated polyindole nanowires

Polyindole (PIn) nanowires were formed on a λ-DNA template by chemical oxidation of indole using aqueous FeCl3. The resulting nanowires are smooth, regular, conductive and had diameters in the range of 5-30 nm. These features allow them to be aligned by molecular combing and studied by scanned conductance microscopy, conductive AFM, and two-terminal I-V measurements. Using this combination of measurements, we find that the conductivity of PIn/DNA nanowires is between 2.5 and 40 S cm-1 at room temperature, which is substantially greater than that in previous reports on the bulk polyindole conductivity (typically 10-2-10-1 S cm-1). The conductance at zero bias shows an Arrhenius-type of dependence on temperature over the range of 233 to 373 K, and the values observed upon heating and cooling are repeatable within 5%; this behavior is consistent with a hopping mechanism of conductivity. © 2010 American Chemical Society.