Pyrene-functionalized mesoporous silica as a fluorescent nanosensor for selective detection of Hg2+ in aqueous solution

Selective detection of Hg2+ is in high demand as Hg2+ can cause serious environmental problems and harmful diseases. In the present work, a pyrene- functionalized organic-inorganic hybrid nanosensor was synthesized by using mesoporous silica nanoparticles as scaffold and pyrene unit as signal output, which could realize selective turn-off detection of Hg2+ in aqueous solution. The successful synthesis of the pyrene-functionalized fluorescent nanoparticle was demonstrated by a series of characterization methods including TEM, BET-BJH, FT-IR, TGA, XPS and solid-state 13C NMR. Some measurements also indicated that there could be a grafting process on both the surface of mesoporous silica nanoparticles and the interior of mesopores. The fluorescence measurements showed that the fluorescent nanosensor exhibited selective turn-off responses to Hg2+ over a series of 15 other metal ions, and the selective detection was hardly interfered by the presence of these interfering metal ions even at 10 equiv. amount. Moreover, the nanosensor could semi-quantitatively detect Hg2+ over a concentration range from 1 to 20 μM with a detection limit of 0.62 μM. Time-resolved fluorescence measurements and 1H NMR titration indicated the binding of Hg2+ with the spacer contributed to the selective responses to Hg2+. The obtained pyrene-functionalized mesoporous silica nanoparticles illustrated high sensitivity, high selectivity and reliability in detecting Hg2+, contributing to the development of organic-inorganic hybrid materials for heavy metal ions.