A comparison study of graphene-cyclodextrin conjugates for enhanced electrochemical performance of tyramine compounds

The present work describes the comparison of the abilities of graphene-cyclodextrin conjugates to enhance the electrochemical performance of four tyramine-related compounds. First, cyclodextrin (CD)-modified graphene conjugates were synthesized via the amine-epoxy reaction between graphene oxide (GO) and 6-deoxy-6-ethylenediamino-β-CD, followed by l-ascorbic acid reduction. The resulting conjugates were characterized using UV-vis spectroscopy, Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Subsequently, for the comparative study, glass carbon electrode electrochemical sensors modified with these conjugates were prepared to detect four structurally similar analytes (tyramine, l-tyrosine, dopamine and levodopa). The sensor sensitivities of the modified electrodes were markedly higher than that of the bare electrode. Based on the results of the comparative study, several crucial factors for improving the performance of the electrodes were proposed, including the binding affinity and the binding orientation of CD toward analytes. The conclusions drawn in this study could provide theoretical foundation for the design and optimization of versatile electrochemical platforms with excellent properties.