Determination of microcystin-LR in water by a label-free aptamer based electrochemical impedance biosensor

In this study, an electrochemical impedance biosensor for cyanobacterial toxin microcystin-LR (MC-LR) detection has been developed. MC-LR aptamers were immobilized on the gold electrode through Au–S interaction, in the presence of target (MC-LR); the binding of MC-LR and aptamers probe led to a complex formation change on the electrode surface and resulted in the impedance decreasing. The decrease rate had a linear relationship with logarithm of the MC-LR concentration in the range of 1.0×10−7–5.0×10−11 mol/L, with a detection limit of 1.8×10−11 mol/L. The sensor has good selectivity and stability, it has been applied to detect MC-LR in three kinds of real water samples with satisfying results.