Label-free impedimetric aptasensor for ochratoxin-A detection using iridium oxide nanoparticles

Area of Science:

• Electrochemistry
• Nanomaterials Science
• Biosensor Technology

Background:

• Ochratoxin A (OTA) is a prevalent mycotoxin posing significant health risks.
• Accurate and sensitive detection of OTA is crucial for food safety.
• Existing detection methods often require complex procedures or expensive equipment.

Purpose of the Study:

• To develop a novel, highly sensitive, and label-free aptasensor for ochratoxin A (OTA) detection.
• To utilize a screen-printed carbon electrode (SPCE) modified with polythionine (PTH) and iridium oxide nanoparticles (IrO2 NPs).
• To achieve a low limit of detection for OTA in complex matrices.

Main Methods:

• Fabrication of a screen-printed carbon electrode (SPCE) modified with electropolymerized polythionine (PTH) and iridium oxide nanoparticles (IrO2 NPs).
• Immobilization of an OTA-specific aptamer via electrostatic interaction.
• Label-free detection of OTA using Electrochemical Impedance Spectroscopy (EIS) with a [Fe(CN)6](-3/-4) redox probe.

Main Results:

• The aptasensor demonstrated sensitive and label-free detection of OTA in the range of 0.01–100 nM.
• Achieved a low limit of detection of 14 pM (5.65 ng/kg) for OTA.
• The developed aptasensor showed high reproducibility, good performance in white wine samples, and excellent specificity.

Conclusions:

• The novel aptasensor based on SPCE/PTH/IrO2 NPs/aptamer is effective for sensitive ochratoxin A detection.
• This label-free impedimetric approach offers a promising tool for food safety analysis.
• The system's performance in real samples highlights its practical applicability.