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

摘要

A novel amperometric biosensor for nitrite was developed by immobilization of hemoglobin(Hb)and a room temperature ionic liquid,1-ethyl-3-methyl imidazo-lium 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 X 10~(-6)to 3.2X 10~(-4)M with a detection limit of 8.1Xl0~(-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.