Abstract: A gel-like paste was made by mixing 1:1 (w/w) carboxylic group-functionalized short single-walled carbon nanotubes (S-SWNTs) and a kind of room temperature ionic liquid (RTIL), 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6). The composite film was modified on the glassy carbon electrode (GCE) to prepare the S-SWNT&RTIL/GCE. The modified electrode showed an attractive electrocatalytic ability and could enhance the current response of electro-active molecules by employing potassium ferricyanide, ascorbic acid and methylene blue as probes. In the B-R buffer solution, ssDNA had a sensitive voltammetric response at the S-SWNT&RTIL/GCE and the oxidative peak potentials of guanine base and adenine base were 0.532 and 0.808 V, respectively. The mechanism of electrode reaction was studied and the results showed that the heterogeneous electron transfer rate constants (k’s) for the two bases were 1.84×10^-2 and 3.69×10^-2 s-1, respectively. Under the optimal conditions, the differential pulse voltammetric peak current of guanine base vs the concentration of ssDNA was linear in the range of 40 μg·L-1-5.0 mg·L-1 with a detection limit of 5 μg·L-1 (S/N=3, signal/noise).

Key words: Carbon nanotubes, Roomtemperature ionic liquid, Modified electrode, DNA, Voltammetry