, Volume 164, Issue 1-2, pp 167-171
Date: 15 May 2008

A reagentless nitrite biosensor based on direct electron transfer of hemoglobin on a room temperature ionic liquid/carbon nanotube-modified electrode

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A novel amperometric biosensor for nitrite was developed by immobilization of hemoglobin (Hb) and a room temperature ionic liquid, 1-ethyl-3-methyl imidazolium tetrafluoroborate (EMIT), on a multi-walled carbon nanotubes (MWNTs) modified electrode. Compared with Hb/MWNTs modified electrode, the Hb/RTILs/MWNTs modified electrode showed better electrochemical response, indicating that EMIT can promote direct electron transfer of Hb. A pair of well-defined, quasi-reversible redox peaks of Hb with a formal potential of −0.315 V was observed. The immobilized Hb exhibited remarkable electrocatalytic activity for the reduction of nitrite. The linear response range was from 4.0 × 10−6 to 3.2 × 10−4 M with a detection limit of 8.1 × 10−7 M at a signal-to-noise ratio of 3. The resulting biosensor has been successfully applied to the determination of nitrite in water samples.