Tris(2,2′-bipyridyl)dichloro-ruthenium(II) modified carbon paste electrodes for electrocatalytic detection of DNA

Tris(2,2′-bipyridyl)dichloro-ruthenium(II) (TBRu) containing carbon paste electrodes (CPEs) exhibiting electrocatalytic response toward nucleic acids are described. The electrocatalytic action of the TBRu modifier results in a dramatic enhancement of guanine oxidation response of ssDNA. The influence of the paste composition, operating potential, DNA concentration, and other variables is described. The analytical advantages accrued from the electrocatalytic action of TBRu are demonstrated using flow injection amperometry (FIA) and square-wave voltammetry (SWV). Detection limits of 24 and 500 ppb are obtained using the FIA and SWV operations, respectively. The FIA response is highly linear (R2=0.999) and reproducible (R.S.D. of 1.65%, n=25). The attractive behavior of the carbon paste electrocatalytic detector holds promise for on-line monitoring of nucleic acids.