Graphene Quantum Dots Functionalized by Chitosan and β-Cyclodextrin: An Advanced Nanocomposite for Sensing of Multi-Analytes at Physiological pH

Abstract

This article describes a new alternative approach to the fabrication of electrochemical sensors based on the graphene quantum dots (GQDs) functionalized with chitosan and β-cyclodextrin. The graphene quantum dots functionalized with chitosan and β-cyclodextrin are shown to exhibit electrochemical performance that rivals that of GQDs modified glassy carbon electrode and display excellent properties against severe electrochemically sensors. The graphene quantum dots functionalized with chitosan and β-cyclodextrin electrodes is further extended to the demonstration of novel electrochemical sensors through the transfer of the electrode fabricated by GQDs. For comparison of the recognition efficiency, other electrodes including bare glassy carbone electrode (GCE), and GQDs modified glassy carbone electrode (GQDs-GCE) were used for the control experiments. The resulting sensors demonstrate a wide range of usability, from the detection of various physiological analytes, including uric acid, ascorbic acid, dopamine to the identification of some amino acids. Comparison of recorded cyclic voltamograms in the presence of L-cysteine, dopamine, uric acid, L-Tyrosine, L-Phenylalanine, and ascorbic acid using GQD-CS-GCE, -CD-GQDs-GCE shows ΔEp was decreased as β-CD-GQDs-GCE > CS-GQD-GCE > GQDs-GCE. The larger lowering of the overvoltage observed in the presence of β-CD-GQDs-GCE clearly indicates the essential role of β-CD in the observed electrocatalytical behaviour. In general, the attachment of chitosan and β-cyclodextrin to structure of GQDs provides new opportunities within the personal healthcare, fitness, forensics, homeland security, and environmental monitoring domains.