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 H(2)O(2) to the mixture of silver nanoparticles (AgNPs) and Hg(2+) induced color changes of the solution within several seconds even at 2.0 nM Hg(2+). Other metallic ions could not induce color change even at 10 μM. Of importance, this probe was not only successfully applied to detect Hg(2+), but also it could be used to sense H(2)O(2) at a concentration as low as 50 nM (by naked-eye). The outstanding sensitivity and selectivity property for Hg(2+) and H(2)O(2) resulted from the AgNPs mediated reduction of Hg(2+) to elementary Hg in the presence of H(2)O(2), causing the aggregation and colorimetric response of AgNPs. This sensitive and selective colorimetric 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.