Abstract
A novel type of graphene-like nanoparticle, synthesized by oxidation and unfolding of C60 buckminsterfullerene fullerene, showed multiple and reproducible sensitivity to Cu2+, Pb2+, Cd2+, and As(III) through different degrees of fluorescence quenching or, in the case of Cd2+, through a remarkable fluorescence enhancement. Most importantly, only for Cu2+ and Pb2+, the fluorescence intensity variations came with distinct modifications of the optical absorption spectrum. Time-resolved fluorescence study confirmed that the common origin of these diverse behaviors lies in complexation of the metal ions by fullerene-derived carbon layers, even though further studies are required for a complete explanation of the involved processes. Nonetheless, the different response of fluorescence and optical absorbance towards distinct cationic species makes it possible to discriminate between the presence of Cu2+, Pb2+, Cd2+, and As(III), through two simple optical measurements. To this end, the use of a three-dimensional calibration plot is discussed. This property makes fullerene-derived nanoparticles a promising material in view of the implementation of a selective, colorimetric/fluorescent detection system.
Highlights
Research on nanostructured materials has recently produced noteworthy results in several fields, including biology, medicine, energy, and sensors [1,2,3,4,5,6]
The stable blue/green fluorescent emission reported by several groups in graphene oxide quantum dots (GOQDs) [12,13,14,15,16], regardless of the different synthesis methods, exhibited a fluorescence-quenching effect in the presence of certain heavy metal ions (Hg2+, Fe3+, Cu2+, Pb2+ ), generally attributed to the metal ion chelating with the different functional groups [17,18,19,20,21,22,23,24]
This property makes GOQDs promising for applications in optical sensors for the detection of heavy metals, which have long been known as highly toxic for Sensors 2018, 18, 1496; doi:10.3390/s18051496
Summary
Research on nanostructured materials has recently produced noteworthy results in several fields, including biology, medicine, energy, and sensors [1,2,3,4,5,6]. In order to detect and measure heavy metal concentrations, potentially portable, fast, easy-to-use, and cheap optical methods are desirable, since the traditional techniques for standard laboratory analysis generally need expensive and heavy instrumentation which require highly skilled staff and time consuming procedures [28] To this end, compared to other fluorometric materials, GOQDs seem to offer some distinct advantages that could offset a generally lower sensitivity [17]. The intrinsic presence of oxygen-containing functional groups gives
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