Magnetic Particle-Based Enzyme Assays and Immunoassays for Microcystins: From Colorimetric to Electrochemical Detection

• Published in: Environmental science & technology Vol. 47; no. 1; pp. 471 - 478
• Main Authors: Reverté, Laia, Garibo, Diana, Flores, Cintia, Diogène, Jorge, Caixach, Josep, Campàs, Mònica
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 02.01.2013
• Subjects: Antibodies, Monoclonal - immunology; Applied sciences; Biotechnology; Colorimetry; Drinking water and swimming-pool water. Desalination; Electrocatalysis; Electrochemistry; Enzymes; Exact sciences and technology; Imino Acids - chemistry; Immunoassay; Immunoassay - methods; Magnetic Phenomena; Mass spectrometry; Microcystins - analysis; Microcystins - immunology; Molecules; Nickel - chemistry; Pollution; Protein Phosphatase 1 - chemistry; Recombinant Proteins - chemistry; Water treatment and pollution; Drinking water; Oligopeptides; Electrochemical method; Cyclic peptides; Toxicity; Immobilization; Microcystin; Liquid chromatography; Colorimetry; Enzyme immunoassay; Toxin; Magnetic particles; Microbial origin; Mass spectrometry MS/MS; Bloom; Cyanobacteria; Water quality; Bacteria; Water pollution; Measurement method; Hepatotoxicity; Organic compounds
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es304234n

In this work, magnetic particles (MPs) are used as supports for the immobilization of biorecognition molecules for the detection of microcystins (MCs). In one approach, a recombinant protein phosphatase 1 (PP1) has been conjugated to MPs via coordination chemistry, and MC-LR detection has been based on the inhibition of the enzyme activity. In the other approach, a monoclonal antibody (mAb) against MC-LR has been conjugated to protein G-coated MPs, and a direct competitive enzyme-linked immunoparticle assay (ELIPA) has been then performed. Conjugation of biomolecules to MPs has been first checked, and after optimization, MC detection has been performed. The colorimetric PPIA with PP1-MP and the best ELIPA strategy have provided limits of detection (LOD) of 7.4 and 3.9 μg/L of MC-LR, respectively. The electrochemical ELIPA has decreased the LOD to 0.4 μg/L, value below the guideline recommended by the World Health Organisation (WHO). The approaches have been applied to the analysis of a cyanobacterial culture and a natural bloom, and MC equivalent contents have been compared to those obtained by conventional assays and liquid chromatography-tandem mass spectrometry (LC-MS/MS). Results have demonstrated the viability of the use of MPs as biomolecule immobilization supports in biotechnological tools for MCs monitoring.