Label-free immunosensing of microcystin-LR using a gold electrode modified with gold nanoparticles

AbstractThe hepatotoxic microcystins, especially microcystin–LR (MC–LR), are causing serious problems to public health and fisheries. We describe here a label-free amperometric immunosensor for rapid determination of MC–LR in water sample. The sensor was prepared by immobilizing antibody on a gold electrode coated with L-cysteine-modified gold nanoparticles. The stepwise self-assembly of the immunosensor was monitored and characterized by means of electrochemical impedance spectroscopy and differential pulse voltammetry. A 0.60 mmol L−1 solution of hydroquinone was used as the electron mediator. The immunosensor was incubated with MC–LR at 25 °C for 20 min, upon which the differential pulse voltammetric current changed linearly over the concentration range from 0.05 to 15.00 μg L−1, with a detection limit of 20 ng L−1. The developed biosensor was used to determine MC–LR in spiked crude algae samples. The recovery was in the range from 95.6 to 105%. This method is simple, economical and efficient, this making it potentially suitable for field analysis of MC-LR in crude algae and water samples. FigureThe present investigation combines SAM monolayer with gold nanoparticles monolayer to prepare a stable film to immobilize the antibody, and takes hydroquinone as electron mediator, establishes a miniature, economic, compatible and label-free amperometric immunosensor for the quick detection of MC-LR.