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Gao F.,Zhangzhou Normal University | Zhang X.,Zhangzhou Normal University | Cai X.,Zhangzhou Normal University | Zheng M.,Zhangzhou Normal University | And 2 more authors.
Materials Science and Engineering C | Year: 2013

A stable and uniform organic-inorganic nanocomposite that consists of graphene (GR) and pyrenebutyric acid (PBA) was obtained by ultrasonication, which was characterized by scanning electron microscopy (SEM) and UV-vis absorption spectra. The dispersion was dropped onto a gold electrode surface to obtain GR-PBA modified electrode (GR-PBA/Au). Electrochemical behaviors of the modified electrode were characterized by cyclic voltammetry and electrochemical impedance spectroscopy using [Fe(CN)6]3 -/4 - as the electroactive probe. A novel DNA biosensor was constructed based on the covalent coupling of amino modified oligonucleotides with the carboxylic group on PBA. By using methylene blue (MB) as a redox-active hybridization indicator, the biosensor was applied to electrochemically detect the complementary sequence, and the results suggested that the peak currents of MB showed a good linear relationship with the logarithm values of target DNA concentrations in the range from 1.0 × 10- 15 to 5.0 × 10- 12 M with a detection limit of 3.8 × 10- 16 M. The selectivity experiment also showed that the biosensor can well distinguish the target DNA from the non-complementary sequences. © 2013 Elsevier B.V. Source


Wang Q.,Zhangzhou Normal University | Ding Y.,Zhangzhou Normal University | Gao F.,Zhangzhou Normal University | Jiang S.,Zhangzhou Product Quality Supervision and Inspection Institute | And 2 more authors.
Analytica Chimica Acta | Year: 2013

A novel DNA biosensor was fabricated through a facile sulfamide coupling reaction. First, the versatile sulfonic dye molecule of 1-amino-2-naphthol-4-sulfonate (AN-SO3 -) was electrodeposited on the surface of a glassy carbon electrode (GCE) to form a steady and ordered AN-SO3 - layer. Then the amino-terminated capture probe was covalently grafted to the surface of SO3 --AN deposited GCE through the sulfamide coupling reaction between the amino groups in the probe DNA and the sulfonic groups in the AN-SO3 -. The step-by-step modification process was characterized by electrochemistry and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. Using Ru(NH3)6 3+ as probe, the probe density and the hybridization efficiency of the biosensor were determined to be 3.18×1013strandscm-2 and 86.5%, respectively. The hybridization performance of the biosensor was examined by differential pulse voltammetry using Co(phen)3 3+/2+ (phen=1,10-phenanthroline) as the indicator. The selectivity experiments showed that the biosensor presented distinguishable response after hybridization with the three-base mismatched, non-complementary and complementary sequences. Under the optimal conditions, the oxidation peak currents of Co(phen)3 3+/2+ increased linearly with the logarithm values of the concentration of the complementary sequences in the range from 1.0×10-13M to 1.0×10-8M with a regression coefficient of 0.9961. The detection limit was estimated to be 7.2×10-14M based on 3σ. © 2013 Elsevier B.V. Source


Wang L.-H.,Zhangzhou Normal University | Gao F.,Zhangzhou Normal University | Jiang S.-L.,Zhangzhou Product Quality Supervision and Inspection Institute | Ding Y.-T.,Zhangzhou Normal University | And 3 more authors.
Gaodeng Xuexiao Huaxue Xuebao/Chemical Journal of Chinese Universities | Year: 2013

Ahomogeneous CdS-PVA (polyvinyl alcohol) nanocomposite dispersion was obtained by mixing hollow CdS nanospheres in PVA solution under ultrasonic condition. Then the dispersion was dropped on a glassy carbon electrode for dryness to obtain the CdS-PVA modified electrode. Further, a novel DNA biosensor for Escherichia coli was fabricated by covalent immobilization of Escherichia coli gene related oligonucleotides on the modified electrode using terephthalic acid as the arm linker. The analytical performance of the biosensor was investigated by electrochemical impedance method, and the results revealed that the constructed biosensor had a wide dynamic range from 1.0×10-12 mol/L to 1.0×10-7 mol/L and a low detection limit of 1.3×10-13 mol/L. The selectivity experiments showed that the DNA biosensor could accurately discriminate the complementary sequence from the single-base mismatched, three-base mismatched and noncomplementay sequences. When the biosensor was applied for the detection of the real sample of Escherichia coli, a satisfying result was obtained. Source


Zheng M.,Zhangzhou Normal University | Gao F.,Zhangzhou Normal University | Wang Q.,Zhangzhou Normal University | Cai X.,Zhangzhou Normal University | And 2 more authors.
Materials Science and Engineering C | Year: 2013

The electrochemical behaviors of acetaminophen (ACOP) on a graphene-chitosan (GR-CS) nanocomposite modified glassy carbon electrode (GCE) were investigated by cyclic voltammetry (CV), chronocoulometry (CC) and differential pulse voltammetry (DPV). Electrochemical characterization showed that the GR-CS nanocomposite had excellent electrocatalytic activity and surface area effect. As compared with bare GCE, the redox signal of ACOP on GR-CS/GCE was greatly enhanced. The values of electron transfer rate constant (k s), diffusion coefficient (D) and the surface adsorption amount (Γâ) of ACOP on GR-CS/GCE were determined to be 0.25 s- 1, 3.61 × 10- 5 cm2 s- 1 and 1.09 × 10- 9 mol cm- 2, respectively. Additionally, a 2e-/2H+ electrochemical reaction mechanism of ACOP was deduced based on the acidity experiment. Under the optimized conditions, the ACOP could be quantified in the range from 1.0 × 10 - 6 to 1.0 × 10- 4 M with a low detection limit of 3.0 × 10- 7 M based on 3S/N. The interference and recovery experiments further showed that the proposed method is acceptable for the determination of ACOP in real pharmaceutical preparations. © 2012 Elsevier B.V. All Rights Reserved. Source

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