Discriminating between Different Heavy Metal Ions with Fullerene-Derived Nanoparticles.

A novel type of graphene-like nanoparticle, synthesized by oxidation and unfolding of C buckminsterfullerene fullerene, showed multiple and reproducible sensitivity to Cu, Pb, Cd, and As(III) through different degrees of fluorescence quenching or, in the case of Cd, through a remarkable fluorescence enhancement. Most importantly, only for Cu and Pb, 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 Cu, Pb, Cd, 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.