Nitrite electrochemical sensor for food analysis based on direct immobilization of hemoglobin on multi-walled carbon nanotube ionic liquid electrode

摘要

A novel nitrite biosensor was constructed by simultaneous immobilization of hemoglobin (Hb) and a room temperature ionic liquid, octylpyridinium chloride ([OcPy][Cl]), on multi-walled carbon ionic liquid electrode (MWILE). The direct electron transfer of Hb showed a pair of redox peaks with a formal potential of -0.187 V vs. Ag/AgCl in pH 5.0 acetate buffer solution. Nitrite (NO_2~-) catalysis on the modified electrode was investigated by cyclic voltammetry and amperometry. The biosensor exhibited a wide linear range for NO_2~- detection from 0.01 to 15 mM, with a detection limit (3σ) of 1.46 lM. MWILE provided an excellent matrix for protein immobilization and biosensor fabrication which could be used for the determination of NO_2~- with a low detection limit, fast response, long linearity, and excellent sensitivity.