A versatile fluorimetric chemosensor for mercury (II) assay based on carbon nanodots

Human urine mercury level functions as a pre-warning signal for mercury explosure, either in acute or chronic events. Unlike common hydrargyrism due to organic mercury uptake overproof via aquatic products, the risk of inorganic mercury toxication would be much higher for residents living in mercury related industry areas due to direct or indirect mercury wastewater emission to vicinal water system. In this work, we reported a novel fluorimetric chemosensor, 2,6-pyridinedicarboxylic acid-derived carbon nanodots (PECDs), which exhibits excellent versatility in direct inorganic Hg2+ detection. The fabrication was proved facile, inexpensive and eco-friendly. The morphology, chemical and spectral properties of PECDs were thoroughly investigated by using HRTEM, XPS, ATR-FTIR, UV-vis and fluorescent spectrum. PECDs showed a broad range of linearity between fluorescence intensity and Hg2+ concentration. The limit of detection was calculated as low as 75 nM. The sensing mechanism was investigated and assumed as fluorescence quenching originated from the formation of PECDs-Hg2+ complex, which facilitates the non radiative relaxation of surface emission of PECDs. In Hg2+ assay for real samples, considerable recoveries (RSD < 6%) and good linearity (R-2 > 0.99) were obtained in all four kinds of samples, involving reservoir water, tap water, female and male human urines. Thus, we believe our method would make certain contribution to the development of applicable versatile sensing platform for Hg2+. (C) 2018 Elsevier B.V. All rights reserved.