Ultrasensitive and dual functional colorimetric sensors for mercury (II) ions and hydrogen peroxide based on catalytic reduction property of silver nanoparticles

The method provides an innovative dual functional sensors for mercury (II) ions and hydrogen peroxide. The addition of H2O2 to the mixture of silver nanoparticles (AgNPs) and Hg2+ induced color changes of the solution within several seconds even at 2.0 nM Hg2+. Other metallic ions could not induce color change even at 10 mu M. Of importance, this probe was not only successfully applied to detect Hg2+, but also it could be used to sense H2O2 at a concentration as low as 50 nM (by naked-eye). The outstanding sensitivity and selectivity property for Hg2+ and H2O2 resulted from the AgNPs mediated reduction of Hg2+ to elementary Hg in the presence of H2O2, causing the aggregation and colorimetric response of AgNPs. This sensitive and selective calorimetric assay opens up a fresh insight of development facile and fast detection methods for metal ions and biomolecules using the special catalytic reactivity of AgNPs. (C) 2011 Elsevier B.V. All rights reserved.