Development of an impedimetric aptasensor for Shiga-like toxin 1 using a DNA aptamer and an interdigitated...

Area of Science:

• Biosensor technology
• Food safety diagnostics
• Molecular recognition

Background:

• Shiga toxin-producing Escherichia coli (STEC) causes life-threatening diarrheal disease.
• Rapid, sensitive, and portable diagnostics are crucial for food safety and disease management.
• Current methods may lack the speed and portability for effective on-field monitoring.

Purpose of the Study:

• To develop an impedimetric aptasensor for detecting Shiga-like toxin-1 (SLT-1) from STEC.
• To evaluate the sensor's analytical performance, stability, and applicability in real-world samples.
• To provide a low-cost, point-of-care diagnostic tool for STEC infections.

Main Methods:

• Systematic Evolution of Ligands by Exponential Enrichment (SELEX) to identify a specific ssDNA aptamer (sT3).
• Fabrication of an interdigitated chain-type microelectrode sensor.
• Impedimetric detection of toxin binding to the aptamer-modified electrode.
• Isothermal titration calorimetry (ITC) for binding affinity determination.

Main Results:

• The aptasensor achieved a low detection limit of 2.88 pM and a wide linear dynamic range (10-450 pM).
• High sensitivity (107.02 Ω pM⁻¹) and excellent stability (retaining 97.6% response after 25 days) were observed.
• The sensor demonstrated high reproducibility (3.9% SD) and selectivity, successfully detecting toxin in spiked milk samples.

Conclusions:

• The developed impedimetric aptasensor offers a highly sensitive, stable, and reproducible method for STEC toxin detection.
• Its practical applicability in food samples highlights its potential for point-of-care diagnostics.
• This technology can significantly enhance food safety monitoring and clinical management of STEC infections.