Development of an amperometric sulfite biosensor based on SO(x)/PBNPs/PPY modified ITO electrode

Area of Science:

• Electrochemistry
• Biosensor Technology
• Enzyme Immobilization

Background:

• Sulfite is a crucial additive in winemaking, but its levels must be monitored.
• Accurate and rapid sulfite detection methods are needed for quality control.

Purpose of the Study:

• To develop and characterize an amperometric sulfite biosensor.
• To immobilize sulfite oxidase (SO(x)) onto a Prussian blue nanoparticles/polypyrrole composite (PBNPs/PPY) electrode.
• To evaluate the biosensor's performance for sulfite determination in wine samples.

Main Methods:

• Enzyme immobilization of SO(x) onto PBNPs/PPY electrodeposited on an indium tin oxide (ITO) electrode.
• Fabrication of an amperometric biosensor using the modified electrode.
• Characterization using FTIR, CV, SEM, and EIS.
• Optimization of operational parameters (potential, buffer, temperature).

Main Results:

• The biosensor demonstrated an optimal response within 2 seconds.
• A linear detection range of 0.5-1000 μM with a low detection limit of 0.12 μM was achieved.
• High correlation (r=0.99) with a standard method and good recovery (97%) in real wine samples were observed.
• The enzyme electrode showed excellent stability, usable 200 times over 3 months.

Conclusions:

• The developed sulfite biosensor is highly sensitive, selective, and stable.
• It provides a reliable method for determining sulfite levels in wine.
• The PBNPs/PPY composite material is effective for enzyme immobilization and biosensor fabrication.