Nitrate reductase electrode based on organic-inorganic hybrid material and carbon nanotube

An enzyme electrode based on organic-inorganic hybrid material and carbon nanotube for nitrate detection was fabricated. The organic-inorganic hybrid material was composed of silica sol and a grafting copolymer of poly(vinyl alcohol)with thiogycolic acid. Nitrate reductase and carbon nanotubes were immobilized in the hybrid material. The nitrate reduction reaction was driven by the enzyme and methyl viologen which was used as the electron-transfer mediator. The electrode was applied to detect nitrate with operating potential of -0.70 V (vs SCE). Carbon nanotube double enhanced the response current. The linearity range and detection limit were 0.01-0.5 mmol/L and 1.13 × 10-6 mol/L. Average response time of the enzyme electrode was 6.8 s.