Integration of β-cyclodextrin into graphene quantum dot nano-structure and its application towards detection of Vitamin C at physiological pH: A new electrochemical approach

For the first time, beta-Cyclodextrin (beta-CD) attachment to graphene quantum dot (GQD) structure was performed using simultaneous electrodeposition of GQD and beta-CD on the surface of glassy carbon electrode (GCE). Cyclic voltammetry at potential range -1.0 to 1.0 V from mixture of GQD and beta-CD produced a well-defined beta-CD-GQD deposited on the surface of glassy carbon electrode. beta-CD-GQD modified GCE was used as a new electrocatalytical nanocomposite towards electrooxidation of Vitamin C (as sample analyte). The synergistic effects and the catalytic activity of the beta-CD-GQD modified GCE were investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV) chronoamperometry (CA) and square wave voltammetry (SWV). The process of oxidation involved and its kinetics were established by using cyclic voltammetry, chronoamperometry techniques. It has been found that in the course of an anodic potential sweep the electro-oxidation of Vitamin C is catalyzed by synergetic effect of beta-CD and GQD through a mediated electron transfer mechanism. Therefore, beta-CD-GQDs promote the rate of oxidation by increasing the peak current. The cyclic voltammetric results indicate that beta-CD-GQDs-GCE can remarkably enhance electroactivity towards the oxidation of Vitamin C in buffer solution. We have illustrated that the as-obtained beta-CD-GQDs-GCE exhibited a much higher electrocatalytical behavior than GQDs for the electrooxidation and detection of Vitamin C which was about two fold higher than for GQDs. The electrochemical behavior was further exploited as detection scheme for the Vitamin C electrooxidation by square wave voltammetry. (C) 2016 Elsevier B.V. All rights reserved.