Optical biosensor based on nitrite reductase immobilised in controlled pore glass

Area of Science:

• Environmental Science
• Analytical Chemistry
• Biotechnology

Background:

• Nitrite contamination in water poses significant environmental and public health risks.
• Accurate and sensitive detection methods for nitrite are essential for water quality monitoring.

Purpose of the Study:

• To develop an optical biosensor for quantifying nitrite.
• To utilize cytochrome cd(1) nitrite reductase immobilized in controlled pore glass (CPG) beads for nitrite detection.

Main Methods:

• Immobilization of cytochrome cd(1) nitrite reductase onto CPG beads.
• Measurement of optical reflectance changes upon nitrite binding to the enzyme.
• Optimization of immobilization conditions, including pH and capacity.
• Stability assessment of the immobilized enzyme at 4°C.
• Evaluation of enzyme characteristics post-immobilization.

Main Results:

• Optimized immobilization showed high efficiency dependent on pH.
• Maximum CPG capacity for cd(1) immobilization estimated at 57±10 mg cd(1)/g CPG.
• Immobilized enzyme exhibited stable activity at 4°C for 15 days with only a 10% decrease.
• Immobilization did not significantly alter enzyme's red/ox spectra or specific activity.
• Biosensor demonstrated sensitive nitrite detection, with a detection limit of 0.93 µM at 460 nm.

Conclusions:

• The developed optical biosensor is effective for sensitive and stable nitrite quantification.
• The detection limit is below the European Community's maximum admissible concentration for nitrite.
• This biosensor offers a promising tool for monitoring nitrite levels in environmental water samples.