Nanosurface Energy Transfer Based Highly Selective and Ultrasensitive “Turn on” Fluorescence Mercury Sensor

Mercury is highly toxic to human health in all of its oxidation states. Thus, developing a low cost, efficient metal ion sensor for the detection of mercury ions at concentration levels down to parts-per-billion (ppb) remains a challenge. In the present work, we have developed a silver nanoparticles (Ag-NPs) impregnated poly(vinyle alcohol) capped 4-nitrophenylanthranilate (PVA-NPA) complex for mercury detection. The fluorescence intensity of the synthesized PVA-NPA is found to be quenched by the impregnated Ag-NPs through dynamic quenching. Moreover, energy transfer (ET) between the acceptor (Ag-NPs) and the donor (PVA-NPA) is observed to follow the nanosurface energy transfer (NSET) mechanism. We have utilized the amalgamation of Ag-NPs with Hg to develop a low cost prototype, which is highly efficient NSET based ultrasensitive “turn on” fluorescence mercury sensor. This sensor has high selectivity for Hg ions over a wide range of other competing heavy metal ions, generally present in water of natural sources. The sensor response is found to be linear over the Hg ions concentration regime from 0 to 1 ppb with a lower detection limit of 100 ppt (0.5 nM). The proposed method demonstrated successfully for monitoring trace Hg ions in real world samples.