Design of Fe<sub>3</sub>O<sub>4</sub>@SiO<sub>2</sub>@Carbon Quantum Dot Based Nanostructure for Fluorescence Sensing,
Magnetic Separation, and Live Cell Imaging of Fluoride Ion
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Abstract
A robust
reusable fluoride sensor comprised of a receptor in charge of the
chemical recognition and a fluorophore responsible for signal recognition
has been designed. Highly fluorescent carbon quantum dot (CD) and
magnetically separable nickel ethylenediaminetetraacetic
acid (EDTA) complex bound-silica coated magnetite nanoparticle (Fe<sub>3</sub>O<sub>4</sub>@SiO<sub>2</sub>–EDTA–Ni) have
been used as fluorophore and fluoride ion receptor, respectively.
The assay is based on the exchange reaction between the CD and F<sup>–</sup>, which persuades the binding of fluoride to magnetic
receptor. This method is highly sensitive, fast, and selective for
fluoride ion in aqueous solution. The linear response range of fluoride
(<i>R</i><sup>2</sup> = 0.992) was found to be 1–20
μM with a minimum detection limit of 0.06 μM. Excellent
magnetic property and superparamagnetic nature of the receptor are
advantageous for the removal and well quantification of fluoride ion.
The practical utility of the method is well tested with tap water.
Because of high sensitivity, reusability, effectivity, and biocompatibility,
it exhibits great promise as a fluorescent probe for intracellular
detection of fluoride