Third generation impedimetric sensor employing direct electron transfer type glucose dehydrogenase

Area of Science:

• Electrochemistry
• Biosensor Technology
• Enzyme Catalysis

Background:

• Faradaic electrochemical impedance spectroscopy (EIS) is a promising biosensing technique.
• Direct electron transfer (DET)-type redox enzymes have not been previously utilized with faradaic EIS sensors.
• Developing novel biosensors is crucial for advancing diagnostics and monitoring.

Purpose of the Study:

• To construct and characterize a 3rd-generation faradaic enzyme EIS sensor using DET-type flavin adenine dinucleotide (FAD) dependent glucose dehydrogenase (GDH).
• To investigate the sensor's properties for potential application as an immunosensor platform.
• To establish a glucose sensing method based on impedance changes.

Main Methods:

• Fabrication of gold disk electrodes (GDEs) with DET-type FADGDH immobilized via self-assembled monolayer (SAM).
• Electrochemical impedance spectroscopy measurements to analyze charge transfer resistance (Rct) changes.
• Nyquist and Bode plot simulations for sensor characterization and glucose sensing optimization.

Main Results:

• The fabricated sensor demonstrated glucose concentration-dependent impedance changes, correlated with Rct variations.
• Sensor performance was influenced by DC bias potential and SAM length.
• High sensitivity for low glucose concentrations (0.02–0.2 mM) was achieved by monitoring imaginary impedance at 5 mHz.

Conclusions:

• The 3rd-generation faradaic enzyme EIS sensor shows high sensitivity and a wide linear range for glucose detection.
• This sensor provides a viable alternative platform for future impedimetric immunosensing systems.
• The developed sensor successfully operates without the need for redox probes.