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Issue 47, 2010
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Responsive nanogel-based dual fluorescent sensors for temperature and Hg2+ ions with enhanced detection sensitivity

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Abstract

We report on the fabrication of thermoresponsive poly(N-isopropylacrylamide) nanogel-based dual fluorescent sensors for temperature and Hg2+ ions, and the effects of thermo-induced nanogel collapse on the detection sensitivity of Hg2+ ions. Near-monodisperse thermoresponsive nanogels were prepared via emulsion polymerization of N-isopropylacrylamide (NIPAM) and a novel 1,8-naphthalimide-based polarity-sensitive and Hg2+-reactive fluorescent monomer (NPTUA, 3). At room temperature, PNIPAM nanogels labeled with a single type of naphthalimide-based dye (NPTUA) can act as ratiometric Hg2+ probes at the nanomolar level. Upon heating above the phase transition temperature, the fluorescence intensity of NPTUA-labeled nanogels in the absence of Hg2+ exhibit ∼3.4-fold increase due to that NPTUA moieties are now located in a more hydrophobic microenvironment. Moreover, it was observed that the detection sensitivity to Hg2+ can be further improved above the nanogel phase transition temperature. At a nanogel concentration of 0.05 g L−1 and in the same Hg2+ concentration range (0–3.0 equiv.), ∼10 fold and ∼57 fold increase in fluorescence emission intensity ratio changes can be achieved at 25 and 40 °C, respectively.

Graphical abstract: Responsive nanogel-based dual fluorescent sensors for temperature and Hg2+ ions with enhanced detection sensitivity

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Publication details

The article was received on 09 Jun 2010, accepted on 04 Aug 2010 and first published on 24 Sep 2010


Article type: Paper
DOI: 10.1039/C0JM01828G
J. Mater. Chem., 2010,20, 10716-10723

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    Responsive nanogel-based dual fluorescent sensors for temperature and Hg2+ ions with enhanced detection sensitivity

    C. Li and S. Liu, J. Mater. Chem., 2010, 20, 10716
    DOI: 10.1039/C0JM01828G

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