A biosensor for nitrite analytical determination was developed using a cytochrome c nitrite reductase (ccNiR) from Desulfovibrio desulfuricans ATCC 27774 immobilized and electrically connected on a glassy carbon electrode by entrapment in an electrogenerated poly(pyrrole-viologen) matrix. The modified bioelectrode was studied by cyclic voltammetry and a catalytic current was observed in presence of nitrite. The linear range of the electrode response was 5.4-43.4 μM. The detection limit and the sensitivity were 5.4 μM and 1721 mA M-1 cm-2, respectively. The KM app value determined from the Lineweaver-Burk plot was 86 μM. The biosensor fully maintained its electroenzymatic activity towards nitrite after four days. No catalytic response was observed in the presence of nitrate ions while interference from sulfites was considered negligible. Finally, the biosensor composition was optimized in term of monomer-enzyme ratio.
- Enzyme wiring
- Nitrite reductase