Fluorometric determination of okadaic acid using a truncated aptamer

Area of Science:

• Marine Biology
• Analytical Chemistry
• Biotechnology

Background:

• Okadaic acid (OKA) is a marine toxin from dinoflagellates responsible for diarrhetic shellfish poisoning (DSP).
• Accurate detection of OKA is crucial for public health and food safety.
• Existing detection methods may require complex procedures or lack sensitivity.

Purpose of the Study:

• To develop a novel, sensitive, and selective competitive displacement assay for the detection of okadaic acid (OKA).
• To utilize aptamer technology for a rapid and efficient fluorescent detection of OKA.

Main Methods:

• Development of an OKA-binding aptamer assay utilizing a competitive displacement mechanism.
• Truncation of the aptamer into two sequences, one labeled with 6-carboxyfluorescein (FAM) and the other with a quencher.
• Measurement of fluorescence changes upon OKA binding to the aptamer, leading to spatial separation of the label and quencher.

Main Results:

• A truncated aptamer demonstrated significantly enhanced binding affinity for OKA (Kd = 2.77 nM) compared to the full-length aptamer (Kd = 526 nM).
• The assay successfully detected OKA fluorometrically in the presence of other diarrhetic toxins and in complex shellfish extracts, demonstrating high selectivity.
• The assay achieved a low detection limit of 39 pg·mL⁻¹ for OKA.

Conclusions:

• The developed competitive displacement aptamer assay provides a sensitive and selective method for OKA detection.
• This assay offers a promising tool for monitoring shellfish contamination and ensuring food safety.
• The aptamer-based fluorescence assay is a viable alternative to traditional methods for toxin detection.