Hongwei Ge

A novel electrochemical sensor based on Au@PANI composites film modified glassy carbon electrode binding molecular imprinting technique for the determination of melamine

A novel molecularly imprinted electrochemical sensor for the rapid detection of melamine was reported in this paper. Glassy carbon electrode (GCE) was modified by Au and polyaniline composites (Au@PANI) deposited on the surface of GCE and were used to increase the electrode sensitivity and to amplify the sensor signal. Melamine template molecule was further assembled onto Au@PANI by the formation of hydrogen bonds, can implement the selective detection of melamine. This simple but efficient electrochemistry analysis platform presents a low detection limit of 1.39×10-6µmolL-1 for detection of melamine, which is remarkably lower than the currently used methods and the previous reports. So, this method may open a new way for the determination of melamine which enables low cost, effective and sensitive determination. This shows the sensor can be potentially utilized for the detection of melamine in food, which allows the sensitive and selective determination of melamine from milk and feed.

Visible light-driven photocatalytic degradation performance for methylene blue with different multi-morphological features of ZnS

In this study, four different sphere structures of zinc sulfide (ZnS) materials, dandelion-ZnS, raspberry-ZnS, ball-ZnS and flower-ZnS, were synthesized via a hydro-thermal method. Afterwards, the photocatalytic performances of the produced ZnS powders were investigated using methylene blue (MB) visible light induced photodegradation. X-ray diffraction (XRD), scanning electronic microscopy (SEM), Brunauer–Emmett–Teller (BET), Fourier transform infrared spectroscopy (FT-IR) and UV-visible diffuse reflectance spectroscopy (UV-vis-DRS) were used for characterization of the as-prepared ZnS powders. The specific surface areas of dandelion-ZnS, raspberry-ZnS, ball-ZnS and flower-ZnS were found to be 112, 119, 5.89 and 37.4 m2 g−1, respectively. The MB photodegradation by ZnS fitted well with a pseudo-first-order model. The high specific surface areas, unique morphology, porous structures and high hydrophilicity contribute to the photocatalytic abilities of ZnS. However, it shows that ZnS with simple structures has better reusability.

Kinetics and thermodynamics studies on the BMP-2 adsorption onto hydroxyapatite surface with different multi-morphological features.

The effect of the surface topography on protein adsorption process is of great significance for designing hydroxyapatite (HA) ceramic material surfaces. In this work, three different topographies of HA materials HA-sheet, HA-rod, and HA-whisker were synthesized and testified by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Brunauer-Emmett-Teller (BET) and a field emission scanning electron microscopy (FE-SEM). We have systematically investigated the adsorption kinetics and thermodynamics of bone morphogenetic proteins (BMP-2) on the three different topography surfaces of HA, respectively. The results showed that the maximum adsorption capacities of HA-sheet, HA-rod and HA-whisker were (219.96 ± 10.18), (247.13 ± 12.35), and (354.67 ± 17.73) μg · g(-1), respectively. Kinetic parameters, rate constants, equilibrium adsorption capacities and related correlation coefficients, for each kinetic model were calculated as well as discussed. It demonstrated that the adsorption of BMP-2 onto HA could be described by the pseudo second-order equation. Adsorption of BMP-2 onto HA followed the Langmuir isotherm. It confirmed that compared with other samples HA-whisker had more adsorption sites for its high specific surface area which could provide more opportunities for protein molecules. The adsorption processes were endothermic (ΔH > 0), spontaneous (ΔG < 0) and entropy increasing (ΔS > 0). A possible adsorption mechanism has been proposed. In addition, the BMP-2 could be adsorbed to the surface which existed slight conformational changes by FT-IR.

An “on-off-on” fluorescent probe for ascorbic acid based on Cu-ZnCdS quantum dots and α-MnO2 nanorods

This work established a fluorescence approach for detecting ascorbic acid (AA) based on Cu-ZnCdS quantum dots (Cu-ZnCdS QDs) and α-MnO2 nanorods. Cu-ZnCdS QDs and α-MnO2 nanorods were characterized by high-resolution transmission electron microscopy (HRTEM), fluorescence spectroscopy, inductively coupled plasma optical emission spectroscopy (ICP-OES) and X-ray diffraction (XRD). In the presence of α-MnO2 nanorods, the fluorescence of Cu-ZnCdS QDs was greatly quenched through the inner filter effect (IFE). Subsequently, AA can trigger the decomposition of the α-MnO2 nanorods which can reduce α-MnO2 to Mn2+ and recover the fluorescence. Under optimal conditions, a linear relation was obtained over the range 5.02−401.77 μM with a 31.62 μM detection limit. Through applying the fluorescent sensing system for detecting AA, a satisfactory result is obtained with recoveries ranging from 89.23% to 110.99%.

Enhanced amperometric sensing using a NiCo2O4/nitrogen-doped reduced graphene oxide/ionic liquid ternary composite for enzyme-free detection of glucose

In our work, a NiCo2O4/nitrogen-doped reduced graphene oxide/ionic liquid (NiCo2O4/N-rGO/IL) nanocomposite was prepared using hydrothermal treatment and calcination followed by a facile reaction with stirring. The composite material was characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), FTIR spectra and thermogravimetric analysis (TGA). The biosensing properties of NiCo2O4/N-rGO/IL, NiCo2O4/N-rGO and NiCo2O4 towards glucose were studied based on a glassy carbon electrode. The NiCo2O4/N-rGO/IL nanocomposite exhibits excellent electrocatalytic activity towards glucose, with a sensitivity of 3.76 mA mM−1 cm−2 and a good linear response from 0.001 mM to 4.555 mM at a potential of +0.5 V. The limit of detection can reach 0.18 μM. It also shows significant electrochemical sensitivity, reproducibility and long-term stability. The good electrocatalytic activity is attributed to the synergistic effect of the metal oxides, graphene oxide and the IL. The N-doping of rGO accelerates the electron transfer of the IL further and enhances its electrochemical properties. In addition, the sensor is effectively applied to the determination of glucose in a human blood serum sample.