β-Cyclodextrin functionalized carbon quantum dots as sensors for determination of water-soluble C60 fullerenes in water

Abstract

A selective photoluminescence method based on Carbon Quantum Dots (CQDs) functionalized with carboxymethyl-β-cyclodextrin for the direct determination of water-soluble C₆₀ fullerene has been developed. CQDs were synthesized using a top-down methodology from multiwall carbon nanotubes (MWCNTs) and further functionalized with N-Boc-ethylenediamine to confer monoprotected amine groups onto their surface. Once amine-functionalized CQDs were obtained after deprotection, an amidation reaction with carboxymethyl-β-cyclodextrin cavitands was achieved and the obtained fluorescent β-cyclodextrin functionalized Carbon Quantum Dots (cd-CQDs) were investigated for the inclusion complexation of water-soluble C₆₀. Quenching of their fluorescence was observed owing to the non-covalent self-assembly of cd-CQDs and C₆₀, making possible the quantification of C₆₀. A method to determine water-soluble C₆₀ is then proposed with detection and quantification limits of 0.525 and 1.751 μg mL⁻¹, respectively. The method was validated by determining soluble C₆₀ fullerene in spiked river water. One added value of the paper is the fact that it can be ascribed to the “Third Way in Analytical Nanoscience and Nanotechnology”.