Highly sensitive determination of esculetin on TiO 2 -NPs-coated poly(diallyldimethylammonium chloride)-functionalized graphene modified electrode.

The nanocomposites of titanium dioxide nanoparticles decorated poly(diallyldimethylammonium chloride)-functionalized graphene (TiO2 -PDDA-Gr) were successfully synthesized via a facile and green strategy. The prepared nanocomposites were characterized by X-ray diffraction (XRD), UV-visible spectrophotometry (UV-vis), Fourier Transform infrared spectroscopy (FT-IR) and transmission electron microscopy (TEM). By combining the merits of the PDDA-Gr and TiO2 NPs, a highly sensitive electrochemical sensor was erected to detect esculetin based on the TiO2 -PDDA-Gr nanocomposites. Under the optimized conditions, a lower detection limit of 4×10-9 molL-1 (S/N=3) and a wide linear detection range from 1×10-8 to 3.5×10-6 molL-1 were achieved by differential pulse voltammetry (DPV). Additionally, the proposed electroanalytical methodology was applied in Chinese herb Viola yedoensis Makino and Cortex Fraxini with satisfactory results, showing that fabricated sensor has potential to be applied.