Graphite nanosheet-based composites for mediator-free H2O2 biosensor

Area of Science:

• Materials Science
• Electrochemistry
• Biosensor Technology

Background:

• Hemoglobin (Hb) immobilization is crucial for developing efficient biosensors.
• Mediator-free biosensors offer advantages in simplicity and reduced interference.
• Graphite nanosheets (GNS) present a promising material for electrochemical applications due to their unique properties.

Purpose of the Study:

• To develop a mediator-free hydrogen peroxide (H2O2) biosensor using a graphite nanosheet (GNS)-Nafion composite for hemoglobin (Hb) immobilization.
• To characterize the electrochemical properties and performance of the Hb-GNS-Nafion composite film.
• To compare the biosensor's performance with existing carbon-based biosensor platforms.

Main Methods:

• Preparation of GNS-Nafion composites for Hb immobilization.
• Characterization using Scanning Electron Microscopy (SEM), UV-vis spectroscopy, and Fourier Transform Infrared Spectroscopy (FTIR).
• Electrochemical measurements to assess direct electrochemistry, electron-transfer rate, and electrocatalytic activity towards H2O2 reduction.

Main Results:

• The Hb-GNS-Nafion composite film exhibited good biocompatibility, preserving the native structure of immobilized Hb.
• Direct electrochemistry with a fast electron-transfer rate (6.63 s(-1)) and high electrocatalytic activity was observed.
• The biosensor achieved high sensitivity (412.7 mA M(-1) cm(-2)), a low detection limit (2.0 x 10(-7) M), and a low apparent Michaelis-Menten constant (37 microM).
• Performance was comparable or superior to carbon nanofiber (CNF)- and carbon nanotube (CNT)-based biosensors.

Conclusions:

• GNS-Nafion composites provide an excellent platform for developing sensitive and efficient mediator-free biosensors.
• The GNS-based composite offers a cost-effective alternative for Hb immobilization.
• This technology holds potential for applications in mediator-free biosensors, bioelectronics, and biofuel cells.