Direct electrochemistry of double strand DNA on ionic liquid modified screen-printed graphite electrode

An ionic liquid modified screen-printed graphite electrode (SPE) was used for direct electrochemistry of herring sperm double strand DNA (dsDNA) by voltammetry. Due to the high conductivity of ionic liquid n-octylpyridinum hexafluorophosphate (OPPF), this electrode exhibited excellent electrochemical activity for the oxidation of dsDNA. Two irreversible oxidation peaks were obtained at the developed electrode, which corresponded to the oxidation of guanine and adenine residues present in the dsDNA. The basic electrochemical behavior of dsDNA at the OPPF modified SPE was carefully investigated. Combined with the differential pulse voltammetry, this electrode exhibited a good linear range from 20 mu g mL(-1) to 120 mu g mL(-1) with a detection limit of 5 mu g mL(-1) for the direct determination of dsDNA. Furthermore, the OPPF modified electrode displayed high reproducibility and stability for the dsDNA determination. (C) 2011 Elsevier Ltd. All rights reserved.