Preparation And Application Of Novel Nanocomposite For Electrochemical Analysis

Electrochemical analysis has exhibited great potential in the field of analyticalchemistry, owing to its high sensitivity, fast response, low detection limit and cheapequipment. Recently, some novel nanomaterials, including metal nanoparticles,carbon nanomaterial, and micro-nano conducting polymers, have been applied in thefield of electrochemical analysis. In this thesis, several new kinds of nanocompositewere developed. The electrochemical properties of the nanocomposites wereevaluated. Furthemore, the nanocomposite modified electrodes were applied to thedetermination of some pollutants and biomolecules. This work probably opens a newroute to the development of new nanocomposite, and improves the sensitivity,detection limit of the fabricated sensors.1. The nanopore array derived from L-cysteine oxide/gold hybrids (NA-COGH)was applied to the simultaneous determination of hydroquinone (HQ) and catechol(CT). NA-COGH was prepared by a sequential electrodeposition of L-cysteine oxideand gold into the voids of polystyrene spheres template, followed by removing thetemplate using tetrahydrofuran. A fast charge transfer rate was obtained by optimizingthe electrodeposition conditions. More interestingly, the as-prepared NA-COGH presents high electrocatalytic activity for the oxidation of HQ and CT. The sensingplatform based on NA-COGH was applied to the simultaneous determination of HQand CT.3. A novel composite film derived from cysteic acid andpoly(diallydimethylammonium chloride)-functionalized graphene (PDDA-GN) wasused as an enhanced electrode material for ultrasensitive determination ofmetronidazole. The cysteic acid/PDDA-GN composite film was prepared by theelectrochemical grafting of cysteic acid onto the PDDA-GN coated glassy carbonelectrode (GCE). The cyclic voltammetry investigations reveal that the peak currentof metronidazole reduction obtained with the cysteic acid/PDDA-GN/GCE was moreremarkably enhanced compared with those obtained with the bare GCE, the cysteicacid/GCE and the PDDA-GN/GCE. The heterogeneous electron transfer rate constantand the diffusion coefficient of metronidazole were further evaluated by rotating diskelectrode experiments. Moreover, we applied the present method to the determinationof metronidazole in urine and lake water with satisfactory results.3. b-cyclodextrin functionalized graphene/Ag nanocomposite (b-CD/GN/Ag) wasprepared via a microwave-assisted one-step reduction of the mixture of grapheneoxide and AgNO3. b-cyclodextrin was used both as the reductant and stabilizer. Theas-prepared b-CD/GN/Ag nanocomposite exhibits higher electrocatalytic activity inthe reduction of4-nitrophenol compared with b-CD/GN, b-CD/Ag, and bare electrode.The sensing platform based on b-CD/GN/Ag shows a wide linear response and a lowdetection limit for the determination of4-nitrophenol. Furthermore, the sensingplatform has been applied to the determination of4-nitrophenol in lake water, humanurine and serum with good selectivity and high sensitivity.4. Graphene-poly(styrene sulfonate)-Pt nanocomposite (GN-PSS-Pt) was used asan enhanced material for sensitive determination of dopamine by electrochemicalmethod. GN-PSS-Pt was prepared via a facile one-pot reduction of graphene oxideand H2PtCl6under microwave irradiation. The product was well characterized bytransmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy, respectively. The GN-PSS-Pt modified electrode exhibits excellentelectrocatalytic activity towards the redox reaction of dopamine. The calibration curvewas obtained over a linear range of2.0×10-7~4.0×10-3mol/L, with a detection limitof4.0×10-8mol/L (S/N=3). Moreover, the modified electrode has been applied to thedetermination of dopamine in human urine and serum samples with good selectivityand high sensitivity.