Selective nitrate detection by an enzymatic sensor based on an extended-gate type organic field-effect transistor

Area of Science:

• Electrochemistry
• Biosensors
• Organic electronics

Background:

• Nitrate detection is crucial for environmental and health monitoring.
• Existing methods often lack portability or are costly.
• Organic field-effect transistors (OFETs) offer potential for low-cost, flexible sensing platforms.

Purpose of the Study:

• To develop the first selective nitrate biosensor utilizing an extended-gate organic field-effect transistor (OFET).
• To investigate the sensing mechanism and performance of the OFET-based nitrate biosensor.
• To demonstrate the practical applicability of the biosensor for real-world sample analysis.

Main Methods:

• Fabrication of an extended-gate OFET functionalized with nitrate reductase and a bipyridinium derivative mediator.
• Utilizing an electron-relay mechanism on the extended-gate electrode for nitrate detection.
• Characterization of the OFET sensor's electrical properties and sensitivity.

Main Results:

• The developed OFET biosensor successfully detected nitrate with a detection limit of 45 ppb in water.
• The sensor demonstrated sensitivity comparable to conventional nitrate detection methods.
• Successful detection of nitrate in diluted human saliva, with results aligning with colorimetric measurements.

Conclusions:

• The extended-gate OFET biosensor provides a novel, selective, and sensitive platform for nitrate detection.
• The device's properties (printability, flexibility, disposability) enable low-cost, on-site monitoring in aqueous media.
• This technology opens new avenues for portable electronic devices for environmental and biomedical sensing.