Daban Lu

Fabrication of β-cyclodextrin-coated poly (diallyldimethylammonium chloride)-functionalized graphene composite film modified glassy carbon-rotating disk electrode and its application for simultaneous electrochemical determination colorants of sunset yellow and tartrazine

We proposed a green and facile approach for the synthesis of β-cyclodextrin-coated poly(diallyldimethylammonium chloride)-functionalized graphene composite film (β-CD-PDDA-Gr) by using L-ascorbic acid (L-AA) as the reducing agent at room temperature. The β-CD-PDDA-Gr composite film modified glassy carbon-rotating disk electrode (GC-RDE) was then developed for the sensitive simultaneous determination of two synthetic food colorants: sunset yellow (SY) and tartrazine (TT). By cyclic voltammetry (CV), the peak currents of SY and TT increased obviously on the developed electrochemical sensor. The kinetic parameters, such as diffusion coefficient D and standard heterogeneous rate constant kb, were estimated by linear sweep voltammetry (LSV). Under the optimal conditions, the differential pulse voltammetry (DPV) signals of SY and TT on the β-CD-PDDA-Gr modified GC-RDE were significantly enhanced. The enhanced anodic peak currents represented the excellent analytical performance of simultaneous detection of SY and TT in the range of 5.0×10(-8) to 2.0×10(-5) mol L(-1), with a low limit of detection (LOD) of 1.25×10(-8) mol L(-1) for SY and 1.43×10(-8) mol L(-1) for TT (SN(-1)=3). This proposed method displayed outstanding selectivity, good stability and acceptable repeatability and reproducibility, and also has been used to simultaneously determine SY and TT in some commercial soft drinks with satisfactory results. The obtained results were compared to HPLC of analysis for those two colorants and no significant differences were found. By the treatment of the experimental data, the electrochemical reaction mechanisms of SY and TT both involved a one-electron-one-proton-transfer process.

Sensitive detection of acetaminophen based on Fe3O4 nanoparticles-coated poly(diallyldimethylammonium chloride)-functionalized graphene nanocomposite film

An electrochemical sensor based on Fe(3)O(4) nanoparticles (NPs)-coated poly(diallyldimethylammonium chloride) (PDDA)-functionalized graphene (Fe(3)O(4)-PDDA-G) nanocomposite was fabricated for sensitive detection of acetaminophen. The nanocomposite was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The electrochemical behaviors of acetaminophen on Fe(3)O(4)-PDDA-G composite film modified glassy carbon electrode (GCE) were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The experimental results indicated that the incorporation of Fe(3)O(4) NPs with PDDA-G greatly enhanced the electrochemical response of acetaminophen. This fabricated sensor displayed excellent analytical performance for acetaminophen detection over a range from 0.1 to 100 μ mol L(-1) with a detection limit of 3.7×10(-8) mol L(-1) (S/N=3). The redox peaks of acetaminophen, dopamine (DA) and ascorbic acid (AA) can be well separated on the Fe(3)O(4)-PDDA-G/GCE. Moreover, the proposed electrochemical sensor also exhibited good reproducibility and stability, and has been used to detect acetaminophen in tablets with satisfactory results.

Synthesis of PtAu bimetallic nanoparticles on graphene-carbon nanotube hybrid nanomaterials for nonenzymatic hydrogen peroxide sensor

PtAu bimetallic nanoparticles (NPs) were successfully synthesized on graphene sheets-multi walled carbon nanotubes (G-CNTs) hybrid nanomaterials via a simple one-step chemical co-reduction method in ethylene glycol (EG)-water system. The nanocomposites (PtAu/G-CNTs) were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Then a sensitive nonenzymatic hydrogen peroxide (H2O2) sensor was fabricated based on PtAu/G-CNTs nanocomposites modified glassy carbon electrode (GCE). The results of electrochemical experiments demonstrated that the sensor exhibited excellent electrocatalytic activity to the reduction of H2O2. The sensor displayed a fast amperometric response time of less than 4s with linear detection range from 2.0 to 8561 μM and a relatively low detection limit of 0.6 μM (S/N=3). In addition, the sensor also showed good selectivity for H2O2 detection, long-term stability and reproducibility.

Sensitive determination of thymol based on CeO2 nanoparticle–decorated graphene hybrid film

A novel thymol electrochemical sensor based on a CeO2 nanoparticle–decorated graphene hybrid was introduced. The hybrid was characterized by X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy. The electrochemical behavior of thymol on the CeO2/graphene modified glassy carbon electrode was investigated in pH 7.0 phosphate buffer solution by cyclic voltammetry and differential pulse voltammetry. Compared with the bare glassy carbon electrode, the proposed electrode showed improved analytical performance characteristics in catalytic oxidation of thymol. Under the selective conditions, the modified electrode showed a linear voltammetric response for the thymol within a concentration range of 1.0 × 10−7 to 1.8 × 10−5 mol L−1, and a value of 5.0 × 10−8 mol L−1 was calculated for the detection limit (S/N = 3). Furthermore, good selectivity with high sensitivity was obtained for the determination of thymol in real samples.

Sensitive determination of vanillin based on an arginine functionalized graphene film

An arginine (Arg) functionalized graphene (Arg-G) nanocomposite was produced successfully and the procedure was environment-friendly. An electrochemical sensor based on the Arg-G nanocomposite was developed for the determination of vanillin. The Arg-G modified glassy carbon electrode (GCE) showed excellent sensitivity properties by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Under the optimized conditions, the oxidation peak current was proportional to vanillin concentration in the range of 2.0 × 10−6 to 7.0 × 10−5 mol L−1 with the correlation coefficient of 0.9986 and the detection limit of 1.0 × 10−6 mol L−1 (S/N = 3). Moreover, the sensor could be used for the detection of vanillin in real food samples with satisfactory results.

Fabrication of a CuS/graphene nanocomposite modified electrode and its application for electrochemical determination of esculetin

In this paper, a CuS/graphene nanocomposite modified glassy carbon electrode (GCE) was successfully constructed and used for determination of esculetin. The electrochemical behavior of esculetin was studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The results indicated that the synergistic effect between CuS nanoparticles (NPs) and graphene enhanced the electrochemical response of esculetin. Under optimal conditions, the DPV peak current increased linearly with the esculetin concentration in the range from 1.0 × 10−7 to 1.0 × 10−4 mol L−1, and the detection limit (S/N = 3) was 5.8 × 10−8 mol L−1. Furthermore, a good selectivity with high sensitivity was obtained for the determination of esculetin in real samples.