An aptamer based fluorometric microcystin-LR assay using DNA strand-based competitive displacement

Area of Science:

• Environmental Chemistry
• Biotechnology
• Analytical Chemistry

Background:

• Microcystin-LR (MC-LR) is a potent cyanotoxin posing risks to aquatic ecosystems and human health.
• Accurate and sensitive detection methods for MC-LR are crucial for environmental monitoring and water safety.

Purpose of the Study:

• To develop a sensitive and rapid fluorescence-based assay for MC-LR determination.
• To utilize a high-affinity truncated aptamer for enhanced detection capabilities.

Main Methods:

• Development of a competitive displacement assay employing molecular beacons and a truncated aptamer.
• Hybridization of fluorophore-quencher labeled complementary sequences with the aptamer.
• Monitoring fluorescence changes upon MC-LR binding and aptamer duplex dissociation.

Main Results:

• A truncated aptamer exhibited a 50-fold increase in affinity for MC-LR (0.93 nM) compared to the wild type (50 nM).
• The assay demonstrated sensitivity in the 0.5 to 200 nM MC-LR concentration range.
• Application to spiked tap water samples yielded high recovery rates (around 95% ± 5%).

Conclusions:

• The developed fluorescence assay provides a sensitive and efficient method for MC-LR detection.
• The truncated aptamer significantly enhances the affinity and sensitivity of the assay.
• This method shows practical applicability for monitoring MC-LR in environmental water samples.