A highly sensitive and selective molecularly imprinted electrochemical sensor modified with TiO2-reduced graphene oxide nanocomposite for determination of podophyllotoxin in real samples

To obtain an electrochemical sensor with high sensitivity and good selectivity for determination of podophyllotoxin (PPT), a kind of graphene composite (rGO@TiO 2 ) with multi-layer structure and excellent conductivity was prepared by hydrothermal treatment of reduced graphene oxide (rGO) and TiO 2 nanoparticles . The composite was characterized by transmission electron microscope (TEM), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), and a sensor using rGO@TiO 2 as a signal amplification element was fabricated by in-situ polymerization of PPT imprinted membrane (PPT-MIM) on the rGO@TiO 2 modified glassy carbon electrode (PPT-MIM/rGO@TiO 2 /GCE). The structure and electrochemical performance of PPT-MIM/rGO@TiO 2 /GCE as well as the mechanism with superior conductivity of rGO@TiO 2 exceeding the ones of the mixture of TiO 2 and rGO (TiO 2 -rGO) or the pure TiO 2 and rGO were explained with different technologies. Under the optimal conditions, the present sensor showed a linear response for the determination of PPT by differential pulse voltammetry (DPV) in the range of 1.0 × 10 −9  − 1.0 × 10 −7  mol L −1 (R 2  = 0.9980) and 1.0 × 10 −7  − 3.0 × 10 −4  mol L −1 (R 2  = 0.9991) with the limit of quantification is 1.0 × 10 −9  mol L −1 and the limit of detection of 3.0 × 10 −10  mol L −1 . The sensor not only possesses high sensitivity and good selectivity, but also exhibits excellent repeatability and stability. It has been used to detect PPT in real samples (including Podophyllum hexandrum , human urine and human whole blood) with satisfied recoveries of 92.0%–102.3%.