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Silver is widely used in medical materials, photography, electronics and other industries as a precious metal. The large-scale industrial production of silver-containing products and liquid waste emissions aggravate the environmental pollution. Silver ion is one of the most toxic metal ions, causing pollution to the environment and damage to public health. Therefore, the efficient and sensitive detection of Ag + in the water environment is extremely important. Sulfur-doped carbon nitride nanosheets (SCN Ns) were prepared by melamine and thiourea via high-temperature calcination. The morphology, chemical composition and surface functional groups of the SCN Ns were characterized by SEM, TEM, XRD, XPS, and FT-IR. The fluorescence of SCN Ns was gradually quenched as the Ag + concentration increased. The detection limit for Ag + was as low as 0.28 nM. The quenching mechanism mainly is attributed to static quenching. In this paper, SCN Ns were used as the fluorescent probe for detecting Ag + . SCN Ns have successfully detected Ag + in different environmental aqueous samples and cells. Finally, SCN Ns were further applied to the visual quantitative detection of intracellular Ag + ., (© 2022 IOP Publishing Ltd.)

Green fluorescent silver (Ag)-doped graphite carbon nitride (Ag-g-C 3 N 4 ) nanosheets have been fabricated by an ultrasonic exfoliating method. The fluorescence of the Ag-g-C 3 N 4 nanosheets is quenched by curcumin. The fluorescence intensity decreases with the increase in the concentration of curcumin, indicating that the Ag-g-C 3 N 4 nanosheets can function as a non-toxic and facile fluorescence probe to detect curcumin. The fluorescence intensity of Ag-g-C 3 N 4 nanosheets shows a linear relationship to curcumin in the concentration range 0.01-2.00 μM with a low detection limit of 38 nM. The fluorescence quenching process between curcumin and Ag-g-C 3 N 4 nanosheets mainly is based on static quenching. The fluorescent probe has been successfully applied to analyse curcumin in human urine and serum samples with satisfactory results., (© 2018 John Wiley & Sons, Ltd.)