Biosensing nitrite using the system nitrite redutase/Nafion/methyl viologen--a voltammetric study

Area of Science:

• Electrochemistry
• Biosensors
• Enzyme Catalysis

Background:

• Nitrite detection is crucial in environmental and biological monitoring.
• Developing sensitive and stable biosensors for nitrite is an ongoing challenge.

Purpose of the Study:

• To construct and characterize a nitrite biosensor using cytochrome c-type nitrite reductase (ccNiR) and methyl viologen.
• To investigate the influence of Nafion matrix and mediator concentration on biosensor performance.

Main Methods:

• Voltammetric characterization of the bioelectrode.
• Immobilization of ccNiR in a Nafion membrane with methyl viologen mediator.
• Optimization of enzyme/mediator ratio for enhanced sensitivity and linear range.

Main Results:

• The bioelectrode exhibited electrocatalytic activity towards nitrite, despite potential electrostatic repulsions.
• Optimized biosensor achieved a sensitivity of 445±8 mA M⁻¹cm⁻² within a linear range of 75–800 µM.
• Lowest detected nitrite concentration was 60 µM, with operational stability and interference effects evaluated.

Conclusions:

• The developed ccNiR/Nafion/methyl viologen biosensor is effective for nitrite detection.
• Membrane composition and mediator concentration significantly impact analytical parameters.
• Further studies are needed to fully elucidate charge transfer mechanisms and optimize stability.