Electrochemical sensor for ultrasensitive determination of isoquercitrin and baicalin based on DM-β-cyclodextrin functionalized graphene nanosheets

In this study, 2,6-dimethyl-β-cyclodextrin (DM-β-CD) functionalized graphene nanosheets (DM-β-CD-GNs) were successfully synthesized by a simple wet-chemical strategy. The as obtained DM-β-CD-GNs were characterized by UV-vis spectroscopy, Fourier transform Infrared (FT-IR) spectroscopy, atomic force microscopy (AFM) and transmission electron microscopy (TEM). The new nanocomposite possesses the unique properties of graphene (large surface area and high conductivity) and DM-β-CD (high supramolecular recognition and enrichment capability). Based on the above properties, a highly sensitive electrochemical sensor was developed to detect two flavonoid drugs (isoquercitrin and baicalin). At the DM-β-CD-GNs modified glassy carbon electrode (DM-β-CD-GNs/GCE), the peak currents of the two drugs increased dramatically compared with that on the bare GCE and GNs/GCE which due to the synergetic effects of GNs and DM-β-CD molecules. The linear response ranges for isoquercitrin and baicalin are 10 nM-3.0 μM and 0.04 μM -3.0 μM, with the detection limits of 4 nM and 10 nM, respectively. The method might open up a new possibility for the widespread use of electrochemical sensors for monitoring of ultra-trace flavonoid drugs owing to its advantages of simple preparation, low cost, high sensitivity, good stability and reproducibility.