Microcystin-LR label-free immunosensor based on exfoliated graphite nanoplatelets and silver nanoparticles.

This paper describes a simple, rapid and accurate label-free immunosensor for the determination of MC-LR in water samples. The anti-MC-LR was immobilized in a hybrid nanocomposite, comprised of exfoliated graphite nanoplatelets dispersed in a suspension of silver nanoparticles (AgNP-Nafion-xGnP), by adsorption. The nanomaterial obtained was then employed to prepare an immunosensor using a glassy carbon electrode (GCE) in one-step. Under optimized conditions, using square-wave voltammetry (SWV) and an incubation time of 10min, the immunosensor showed a linear relationship between the oxidation current and MC-LR concentration in the range of 0.5-5000ngmL with a detection limit of 0.017ngmL. The immunosensor demonstrated good precision, with coefficients of variation of 4.5% (inter-day; n = 7) and 3.1% (intra-day; n = 5), and acceptable selectivity (low interference in the presence of potential interferents), indicating that it is suitable for analytical applications. The immunosensor was successfully applied in the determination of MC-LR in a water sample and this platform offers advantages when compared to other electrochemical sensors reported in the literature, especially with regard to the time of incubation.