Lina Zou

Graphene blended with SnO 2 and Pd-Pt nanocages for sensitive non-enzymatic electrochemical detection of H 2 O 2 released from living cells

This paper described a novel, facile and nonenzymatic electrochemical biosensor to detect hydrogen peroxide (H2O2). The sensor was fabricated based on Pd-Pt nanocages and SnO2/graphene nanosheets modified electrode (PdPt NCs@SGN/GCE). The electrochemical behavior of PdPt NCs@SGN/GCE exhibited excellent catalytic activity toward H2O2 with fast response, high selectivity, superior sensitivity, low detection limit of 0.3 μM and large linear range from 1 μM to 300 μM. Under these obvious advantages, the constructed biosensor provided to be reliable for determination of H2O2 secreted from human cervical cancer cells (Hela cells). Hence, the proposed biosensor is a promising candidate for detection of H2O2 in situ released from living cells in clinical diagnostics.

The novel voltammetric method for determination of hesperetin based on a sensitive electrochemical sensor.

A highly sensitive voltammetric sensor, based on reduced graphene oxide on SWCNTs modified glassy carbon electrode (GCE), was constructed and used for sensitive detection of hesperetin. The electrochemical behavior of hesperetin at this sensor was investigated systematically and a novel voltammetric method for determination of hesperetin was proposed. The redox characters of hesperetin was discussed in detail and a reasonable reaction mechanism was proposed also. As the analytical method, the response currents were linear relationship with the hesperetin concentrations in the range of 5.0 × 10(-8) to 3.0 × 10(-6) mol L-(1), with a detection limit of 2.0 × 10(-8) mol L(-1) (S/N=3). The method was also applied successfully to detect hesperetin in biological samples and Chinese herbal medicine Flos buddlejae with satisfactory results.

Greenly synthesized graphene with L-glutathione-modified electrode and its application towards determination of rutin

A simple, environmentally friendly and cost-effective approach for preparation of water-soluble functional graphene was proposed for constructing a voltammetric sensor platform. It was characterized by several techniques, including UV-vis spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy (TEM) and X-ray diffraction (XRD). This voltammetric sensor showed strong accumulation ability and excellent voltammetric response for rutin. The electrochemical behavior of rutin was investigated systematically in 0.1 mol L−1 phosphate buffer solution (PBS 3.0). Under optimum conditions by square wave voltammetry (SWV), a good linear relationship was obtained between peak currents and rutin concentrations in the wider range of 5 × 10−9 to 1 × 10−6 mol L−1 with a detection limit of 7 × 10−10 mol L−1. In addition, the proposed rutin sensor was successfully applied to test in real samples with good results.

Simple and rapid determination of trace iodide by cathodic stripping voltammetry.

This work establishes a highly sensitive and simple stripping voltammetric method for the direct determination of trace iodide. In the presence of abounding bromide and appropriate amount of cetylpyridine bromide (CPB), the iodine was accumulated on the glassy carbon electrode surface as ion association complex (CPBI2Br). After accumulation for a period of time, a linear sweep potential with negative scanning was applied and the I2 in CPBI2Br was reduced again into the solution. Under the optimization conditions, the stripping signals (peak current) were linear relationship with iodide concentration in range of 3.81×10(-3)µg/mL to 0.114 μg/mL and 0.127μg/mL to 2.54μg/mL, with a detection limit of 1.02ng/mL (S/N=3) for a accumulation time of 180s. Determination of trace iodine in pharmaceutical sample, kelp and table salt were performed with high accuracy and satisfactory recovery results.

Facile synthesized SnO2 decorated functionalized graphene modified electrode for sensitive determination of daidzein

A one-step and facile method using SnCl2·H2O as reducing agent to reduce graphene oxide (GO) was performed in the aid of poly(diallyldimethylammonium chloride) solution (PDDA). SnCl2·H2O is not only a reducing agent for graphene oxide (GO), but also a precursor of SnO2. SnO2-PDDA-GR composite was characterized by various surface, structural and electrochemical analysis techniques, such as transmission electron microscopy (TEM), UV spectrum (UV-vis), Infrared Spectrum (IR), X-ray diffraction (XRD), Cyclic voltammograms (CV) and electrochemical impedance (EIS). The SnO2-PDDA-GR composite was used to constructed electrochemical sensor (SnO2-PDDA-GR/GCE) for the determination of daidzein. Under the optimized experimental condition, it was found that the response of peak current is linear to the concentration of daidzein in the ranges of 2.0×10-8 -1.0×10-6molL-1, and the detection limit was estimated to be 6.7×10-9mol L-1 (S/N=3). Furthermore, this sensor was successfully applied for the determination of daidzein in traditional Chinese medicine (pueraria lobata) and Daidzein tablets.

Electrochemical behavior of amaranth and its sensitive determination based on Pd-doped polyelectrolyte functionalized graphene modified electrode

In this work, poly(sodium p-styrenesulfonate) (PSS)-functionalized graphene supported palladium nanoparticles (Pd) composites were fabricated with simple ultrasonic bath method. The morphology and structure of PSS-GR-Pd composites were characterized using UV-vis absorption spectra, X-ray diffraction and Transmission Electron Microscopy. By combining the merits of the PSS-GR and Pd NPs, a new electrochemical sensor was erected to detect amaranth based on the PSS-GR-Pd nanocomposites. The electrochemical behavior of amaranth was investigated systematically in 0.1molL-1 phosphate buffer solution (PBS 2.0). At the optimum parameter, Ipa was found to be linearly dependent on the concentrations of amaranth (1×10-7-9×10-6molL-1). The detection limit was 7nM (S/N=3) and sensitivity was 5.85μAμM-1. Finally, this system was utilized for determining amaranth in soft drink using the standard addition method.

Highly sensitive determination of gallic acid based on a Pt nanoparticle decorated polyelectrolyte-functionalized graphene modified electrode

A sensitive voltammetric sensor for gallic acid was fabricated by using a poly(diallyldimethylammonium chloride) (PDDA)-functionalized graphene supported platinum nanoparticle nanocomposite (PDDA–GR–Pt) modified glassy carbon electrode. The nanocomposite was characterized using UV-vis spectra, transmission electron microscopy (TEM) and X-ray diffraction (XRD). This voltammetric sensor exhibited an excellent electrochemical response for gallic acid. The electrode process of gallic acid was investigated in detail and some dynamics parameters were calculated. Under optimum conditions by square wave voltammetry (SWV), a good linear relationship was obtained between peak currents and gallic acid concentrations in the wider range of 3 × 10−8 to 1 × 10−6 mol L−1 with a lower detection limit of 7 × 10−9 mol L−1 (S/N = 3). In addition, the proposed voltammetric method was successfully applied to test gallic acid in real samples with good results.

Green synthesized Co nanoparticles doped amino-graphene modified electrode and its application towards determination of baicalin

The present paper reported an one-pot synthesis of Co nanoparticles doped amino-graphene nanocomposites (Co-amino-Gr), involving in situ generation of Co nanoparticles (NPs). The simultaneous reduction of graphene oxide (GO) and Co2+ to produce Co-amino-Gr had been achieved under mild reaction conditions using an environmentally benign reducing agent, glycine. By combining the merits of amino-Gr and the Co NPs, a highly sensitive electrochemical sensor was erected to detect baicalin based on the Co-amino-Gr nanocomposites. Under optimum conditions, the response peak currents were linear related with baicalin concentrations in the range of 1.0×10-8-8.0×10-7molL-1 with a lower detection limit of 5.0×10-9molL-1 (S/N=3). Additionally, the proposed method was used to detect baicalin in the medicinal capsules with satisfactory results.

Highly sensitive determination of esculetin on TiO2-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 4×10-9molL-1 (S/N=3) and a wide linear detection range from 1×10-8 to 3.5×10-6molL-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.

Electrochemical behavior of isofraxidin at an electrodeposition reduced graphene oxide electrode and its analytical application

An electrochemical sensor, based on an electrodeposition reduced graphene oxide modified glassy carbon electrode (ERGO/GCE), was established and used for investigating the electrochemical behaviors of isofraxidin for the first time. The complicated redox characteristics of isofraxidin were studied in detail, some dynamics parameters of the electrode process were calculated comprehensively and a possible reaction mechanism was proposed. A sensitive voltammetric method for the determination of isofraxidin was proposed with the detection linear range from 8.0 × 10−8 to 4.0 × 10−6 mol L−1 and a detection limit of 3.0 × 10−8 mol L−1 (S/N = 3). Additionally, the proposed method was successfully applied to detect isofraxidin in urine samples and Chinese herbal medicine Herba Sarcandrae with satisfactory results.