CQD@γ-Fe2O3 multifunctional nanoprobe for selective fluorescence sensing, detoxification and removal of Hg(II)

Abstract In this paper we have developed a simple integrated nanoprobe that combines fluorescent carbon quantum dots (CQD) and superparamagnetic magnetic iron oxide(SPION) equipped with –SH, -COOH functionalization for sensing and removal of mercury from aqueous medium. The probe has diminished fluorescence due to photoelectron transfer between CQD fluorophore and magnetic nanoparticle. A remarkable enhancement in fluorescence emission intensity is achieved in presence of Hg2+ which inhibits the PET mechanism. The limit of detection of this fluorescence turn on sensing is 0.376 nM which is the lowest among all reported protocol for Hg sensing. Due to presence of abundant functional groups such as –SH, -COOH in the magnetic component the probe shows excellent mercury removal efficiency of 70%. The utility of the probe has also been explored to monitor Hg in bacteria as well as in living fish sample.