Ultrasensitive lateral flow immunoassay of phycotoxin microcystin-LR in seafood based on magnetic particles and peroxidase signal amplification

In this study, an immunochromatographic test system for the ultrasensitive and rapid detection of the highly toxic phycotoxin microcystin-leucine-arginine (MC-LR) has been developed. The lateral flow immunoassay (LFIA) is based on an indirect competitive format with the use of magnetic particles (MPs) as a colored label for secondary antibodies and a carrier for horseradish peroxidase (HRP) as a means of signal amplification. A simple method of simultaneous covalent binding of antibodies and HRP to the surface of MPs was applied. The developed test system allows for the detection of MC-LR with an instrumental detection limit of 2 pg/mL and cutoff of 50 pg/mL within 17 min. A high specificity of the LFIA has been demonstrated: the cross-reactivity with MC-LR structural analogs was negligible. A technique for sample preparation of various seafood samples was proposed. The applicability of the LFIA for the control of MC-LR contamination of shrimp, octopus, squid, and mussels has been confirmed. The assay recoveries ranged from 71% to 115%. The developed approach is of great potential as a universal tool that can be applied to a wide range of analytes.