G-quadruplex DNAzyme-based microcystin-LR (toxin) determination by a novel immunosensor

Area of Science:

• Biochemistry
• Analytical Chemistry
• Environmental Science

Background:

• Microcystin-LR (MC-LR) is a potent cyanotoxin posing risks to aquatic ecosystems and human health.
• Traditional methods for MC-LR detection can be complex and time-consuming.
• There is a need for sensitive, selective, and rapid detection methods for MC-LR in water samples.

Purpose of the Study:

• To develop and validate a novel immunoassay for the detection of Microcystin-LR (MC-LR).
• To utilize G-quadruplex-hemin DNAzymes and gold nanoparticles (AuNPs) for enhanced sensitivity and selectivity.
• To provide an alternative screening method for MC-LR residues in water samples.

Main Methods:

• Application of G-quadruplex-hemin DNAzymes with high peroxidase activity.
• Utilizing gold nanoparticles (AuNPs) for signal amplification.
• Competitive immunoassay format involving MC-LR-ovalbumin (OVA) and MC-LR antibody.
• Colorimetric detection of MC-LR using G-quadruplex-labeled secondary antibodies.

Main Results:

• The developed immunoassay demonstrated high sensitivity and selectivity for MC-LR detection.
• A linear detection range of 0.1-10 ng/mL was achieved for MC-LR.
• A low limit of detection (LOD) of 0.05 ng/mL for MC-LR was established.
• The assay performance met the World Health Organization (WHO) standards for MC-LR in drinking water.

Conclusions:

• The G-quadruplex-hemin DNAzyme-based immunoassay is a viable and effective tool for MC-LR detection.
• This novel method offers a simple, sensitive, and selective alternative to traditional plate-based immunoassays.
• The assay's ability to meet WHO standards highlights its potential for routine MC-LR residue screening in water.