Electrochemical impedance biosensor for detection of saxitoxin in aqueous solution.

Saxitoxin is a cyanotoxin which is very harmful to human health; the concentration limit in drinking water is only 3 µg/L. Therefore, a simple, fast, sensitive, low-cost, and specific method for its detection, quantification, and monitoring in water bodies is needed to avoid adverse effects on animal and human health. In this work, we developed an electrochemical impedimetric biosensor using a specific aptamer as recognition element for saxitoxin detection. This method allies the superior sensing characteristics of aptamers with the nondestructive, label-free, and easy working principles of the electrochemical impedance technique. The device presented sensitivity for detecting saxitoxin concentrations above 0.3 µg/L, with high selectivity in negative control experiments, demonstrating a promising alternative for water toxin detection.