A membrane-based ELISA assay and electrochemical immunosensor for microcystin-LR in water samples

Area of Science:

• Environmental Science
• Analytical Chemistry
• Biosensor Technology

Background:

• Cyanobacterial toxins, such as microcystin-LR, pose significant risks to aquatic ecosystems and human health.
• Accurate and rapid detection methods are crucial for monitoring water quality and mitigating health risks associated with microcystin-LR exposure.
• Existing detection methods can be complex, time-consuming, or require specialized laboratory equipment.

Purpose of the Study:

• To develop and validate a novel affinity sensor for the sensitive and cost-effective detection of microcystin-LR.
• To integrate immunoassay principles with electrochemical sensing for a disposable and user-friendly detection device.
• To assess the sensor's performance in various water matrices, including buffer, tap water, and river water.

Main Methods:

• Development and testing of antibodies specific to microcystin-LR.
• Establishment of a heterogeneous direct competitive enzyme-linked immunosorbent assay (ELISA) format.
• Adaptation of the ELISA to an affinity membrane sorbent for integration into a disposable amperometric immunosensor device.
• Fabrication of a three-electrode immunosensor using thick-film screen-printing technology.
• Electrochemical detection via amperometric horseradish peroxidase transduction and hydroquinone-mediated electron transfer.
• Direct electrochemical sensing of the dye produced in the membrane-based ELISA.

Main Results:

• The competitive ELISA achieved a detection limit of 0.022 μg L⁻¹ for microcystin-LR.
• The membrane-based ELISA demonstrated a detection limit of 0.06 μg L⁻¹.
• The developed immunosensor achieved a detection limit of 0.5 μg L⁻¹ for microcystin-LR.
• Similar detection levels were obtained using direct electrochemical sensing of the ELISA dye.
• The sensor system proved effective for detecting microcystin-LR in buffer and spiked tap and river water samples.

Conclusions:

• The developed affinity sensor, based on ELISA and electrochemical detection, provides a simple, cost-effective, and suitable method for microcystin-LR detection.
• The disposable amperometric immunosensor device offers a promising platform for on-site and rapid water quality monitoring.
• The study highlights the potential of integrated immunoassay and electrochemical sensing for environmental toxin analysis.