"Signal off" aptasensor based on enzyme inhibition induced by conformational switch

Area of Science:

• Biosensors
• Electrochemistry
• Nucleic Acid Aptamers

Background:

• Nucleic acid aptamers offer an alternative to antibodies in biosensing.
• Aptamers undergo conformational changes upon target binding, enabling novel sensing strategies.
• Existing electrochemical "signal off" aptamer-based sensors often rely on target-induced displacement.

Purpose of the Study:

• To develop a novel electrochemical aptasensor strategy based on enzymatic inhibition.
• To demonstrate the detection of small molecules by monitoring aptamer conformational changes.
• To validate the sensor's performance using ochratoxin A (OTA) as a model analyte.

Main Methods:

• Development of an electrochemical aptasensor utilizing aptamer conformational changes for enzymatic inhibition.
• Surface plasmon resonance (SPR) assays to confirm aptamer conformational switching.
• Electrochemical detection of OTA in wine samples.

Main Results:

• The novel sensing strategy successfully detects OTA via target-induced aptamer conformational change leading to enzyme inhibition.
• SPR analysis confirmed aptamer conformational switching, not displacement.
• The aptasensor achieved sensitive OTA detection in wine, meeting European Commission limits.
• The sensor function was successfully regenerated using a potential pulse.

Conclusions:

• The developed enzymatic inhibition strategy is a feasible approach for small molecule detection using aptasensors.
• The aptasensor exhibits sensitivity, rapid detection, and regenerability, suitable for screening.
• This sensing strategy holds potential for diverse applications in food safety, environmental monitoring, and medical diagnostics.