A Comparative Study of a Multi-Method Electrochemical Biosensor for Rapid Detection of Microcystins in Treated Wastewater

Cyanotoxins, particularly Microcystins (MCs), pose significant environmental and public health risks due to their increasing prevalence in surface water. Electrochemical biosensors (ECBs) for MCs detection offers promising solution due to their simplicity, miniaturization potential, high sensitivity, and broad analytical range. This study presents a multi-method electrochemical biosensor integrating immuno-impedimetric and substrate-mediated amperometric detection on similar biochips for rapid and accurate quantification of MCs. The immuno-impedimetric sensor, based on electrochemical impedance spectroscopy, enables label-free, real-time detection with a dynamic range spanning five orders of magnitude (3 × 10 −3 to 30 μg L −1 ) and a limit of detection of 3 × 10 −3 μg L −1 , making it suited for ultra-low concentration monitoring in environmental water samples. Complementing this, the substrate-mediated amperometric immunosensor achieves a LOD of 6.6 × 10 −2 μg L −1 . Detection times are under 10 min for the impedimetric sensor and 20 min for the amperometric sensor. Benchmarked against conventional ELISA in treated wastewater, both ECB methods demonstrated comparable sensitivity and enhanced reliability, meeting regulatory standards such as the WHO guideline of 1 μg L −1 for MC-LR in water. This dual-detection ECB offers significant advancement over traditional methods, providing sensitive, rapid, and versatile MCs monitoring in complex water matrices for proactive water quality management.