A Membrane-Based ELISA Assay and Electrochemical Immunosensor for Microcystin-LR in Water Samples

• Published in: Environmental science & technology 2012-05, Vol.46 (10), p.5504-5510
• Main Authors: Lotierzo, M, Abuknesha, R, Davis, F, Tothill, I. E
• Format: Article
• Language: English
• Subjects: Analysis methods; Applied sciences; Benzothiazoles - chemistry; Biochemistry; Biological and medical sciences; Biosensing Techniques - methods; Biosensors; Biotechnology; Catalysis; Cross Reactions; Electrochemical Techniques - methods; Electrodes; Enzyme-Linked Immunosorbent Assay - methods; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Hydrogen peroxide; Immobilized Proteins - immunology; Immunoassay; Immunoglobulin G - immunology; Membranes, Artificial; Methods. Procedures. Technologies; Microcystins - analysis; Microcystins - chemistry; Natural water pollution; Peptides, Cyclic - analysis; Peptides, Cyclic - chemistry; Pollution; Sulfonic Acids - chemistry; Time Factors; Toxins; Various methods and equipments; Water; Water Pollutants, Chemical - analysis; Water treatment and pollution
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es2041042

We describe within this paper the development of an affinity sensor for the detection of the cyanobacterial toxin microcystin-LR. The first stage of the work included acquiring and testing of the antibodies to this target. Following the investigation, a heterogeneous direct competitive enzyme-linked immunosorbent assay (ELISA) format for microcystin-LR detection was developed, achieving a detection limit, LLD80 = 0.022 μg L–1. The system was then transferred to an affinity membrane sorbent-based ELISA. This was an amenable format for immunoassay incorporation into a disposable amperometric immunosensor device. This membrane-based ELISA achieved a detection limit, LLD80 = 0.06 μg L–1. A three-electrode immunosensor system was fabricated using thick-film screen-printing technology. Amperometric horseradish peroxidase transduction of hydrogen peroxide catalysis, at low reducing potentials, versus Ag/AgCl reference and carbon counter electrodes, was facilitated by hydroquinone-mediated electron transfer. A detection limit of 0.5 μg L–1 for microcystin-LR was achieved. Similar levels of detection could be obtained using direct electrochemical sensing of the dye produced using the membrane-based ELISA. These techniques proved to be simple, cost-effective, and suitable for the detection of microcystin-LR in buffer and spiked tap and river water samples.