Sensitivity to Heavy-Metal Ions of Unfolded Fullerene Quantum Dots

Abstract

A novel type of graphene-like quantum dots, synthesized by oxidation and cage-opening of C60 buckminsterfullerene, has been studied as a fluorescent and absorptive probe for heavy-metal ions.The lattice structure of such unfolded fullerene quantum dots (UFQDs) is distinct from that of graphene since it includes both carbon hexagons and pentagons. The basic optical properties, however, are similar to those of regular graphene oxide quantum dots. On the other hand, UFQDs behave quite differently in the presence of heavy-metal ions, in that multiple sensitivity to Cu 2+ , Pb 2+ and As(III) was observed through comparable quenching of the fluorescent emission and different variations of the transmittance spectrum. By dynamic light scattering measurements we confirmed, for the first time in metal sensing, that this response is due to multiple complexation and subsequent aggregation of UFQDs. Nonetheless, the explanation of the distinct behaviour of transmittance in the presence of As(III) and the formation of precipitate with Pb 2+ require further studies. These differences, however, also make it possible to discriminate between the three metal ions in view of the implementation of a selective multiple sensor.

X‐ray and UV photoelectron spectroscopy of Ag nanoclusters

“…Another optical property, which is even more sensible to a change of the surrounding medium is the PL emission. As it was mentioned before, metal NCs exhibit this optical feature, which can be used to detect easily and rapidly the presence of pollutants 3,35,37 . In general, the peak position and intensity can change due to the presence of heavy metal ions.…”

“…Recently, many sensors based on different nanosized materials have been developed, achieving a high sensitivity and selectivity for heavy metal ions 29–39 . Metal NP systems, for example, exhibit a pronounced LSPR effect, and this optical property can be monitored also in the presence of various types of contaminants, such as heavy metal ions 19,23 .…”

“…Recently, many sensors based on different nanosized materials have been developed, achieving a high sensitivity and selectivity for heavy metal ions. [29][30][31][32][33][34][35][36][37][38][39] Metal NP systems, for example, exhibit a pronounced LSPR effect, and this optical property can be monitored also in the presence of various types of contaminants, such as heavy metal ions. 19,23 In general, three parameters can change due to the contamination: energy peak position (maximum of the LSPR band), FWHM, and the band intensity.…”

“…As it was mentioned before, metal NCs exhibit this optical feature, which can be used to detect easily and rapidly the presence of pollutants. 3,35,37 In general, the peak position and intensity can change due to the presence of heavy metal ions. Exploiting the PL emission of Ag NCs, we have developed a sensor able to detect the lead ions in potable water near the legal limit, 23 established by the World Health Organization.…”

Designing an Optimal Ion Adsorber at the Nanoscale: The Unusual Nucleation of AgNP/Co2+–Ni2+ Binary Mixtures

“…[1][2][3][4] To tackle this issue nanotechnologies are starting to play a key role in designing and developing tunable systems able to selectively sense the presence of such pollutants. [5][6][7][8][9][10][11][12][13][14][15][16][17][18] Silver nanoparticles (AgNPs) coated with thiols have been proven to be a very effective tool for detection and removal of heavy metals in aqueous solutions. [19][20][21] Their ability to selectively interact and induce nucleation of the latter, has been recently shown 22,23 in the case in which colloidal AgNPs, functionalised with 3-mercapto-1-propanesulfonic acid sodium salt , are dispersed in aqueous solutions containing either Co 2+ or Ni 2+ ions.…”