Label-free impedimetric immunosensor for sensitive detection of ochratoxin A

Area of Science:

• Electrochemistry
• Biosensors
• Immunochemistry

Background:

• Ochratoxin A (OTA) is a harmful mycotoxin frequently found in food products.
• Sensitive and reliable detection methods for OTA are essential for food safety and regulatory compliance.
• Existing detection methods can be complex or require labeling, necessitating simpler alternatives.

Purpose of the Study:

• To develop a novel, label-free electrochemical impedimetric immunosensor for sensitive ochratoxin A detection.
• To establish a robust two-step modification protocol for gold electrodes for immunosensor fabrication.
• To validate the performance of the developed immunosensor for OTA quantification.

Main Methods:

• Fabrication of a gold electrode modified with a 4-carboxyphenyl monolayer via electrochemical reduction of 4-carboxyphenyl diazonium salt (4-CPDS).
• Immobilization of ochratoxin A antibody onto the modified electrode using carbodiimide chemistry.
• Detection of OTA using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) to monitor impedance changes.

Main Results:

• The immunosensor demonstrated sensitive detection of ochratoxin A (OTA) in a label-free manner.
• A linear relationship was observed between the increase in electron-transfer resistance (DeltaR(et)) and OTA concentration (1-20 ng/mL).
• The immunosensor achieved a low detection limit of 0.5 ng/mL for OTA.

Conclusions:

• The developed electrochemical impedimetric immunosensor provides a sensitive and label-free platform for ochratoxin A detection.
• The fabrication method utilizing 4-CPDS and carbodiimide chemistry is effective for creating a stable immunosensor surface.
• This approach holds promise for rapid and reliable monitoring of ochratoxin A in various matrices, contributing to food safety.