Facile synthesis of polyaniline/carbon dot nanocomposites and their application as a fluorescent probe to detect mercuryElectronic supplementary information (ESI) available. See DOI: 10.1039/c5ra03832d

In this work, for the first time, novel polyaniline/carbon dot (PANI/Cdot) nanocomposites have been synthesized using a simple method. Meanwhile, the bright fluorescence of Cdots is effectively quenched by PANI through fluorescence resonance energy transfer. With the addition of Hg 2+ , the strong binding affinity between Hg 2+ and the amino groups of PANI makes the Cdots break away and release from the PANI, resulting in the restoration of Cdot fluorescence, which can be used as a fluorescent probe for Hg 2+ detection. This fluorescence "off-on" signal is sensitive to the concentration of Hg 2+ , and there is a good linear relationship between the fluorescence intensity of Cdots and Hg 2+ concentrations in the range of 0.05 to 1.0 μM. The detection limit for Hg 2+ at a given concentration is 0.8 nM. Moreover, it turns out that the nanoprobes represent a rather high selectivity for Hg 2+ detection. We believe that PANI/Cdot composites will emerge as a new class of fluorescence materials that could be very likely to be suitable for practical applications. Novel polyaniline/carbon dot nanocomposites have been synthesized using a simple method, and a PANI/Cdot "off-on" fluorescent probe has been constructed for the simple, ultrasensitive and selective detection of Hg 2+ in aqueous media.