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Huang H.,Shaanxi Academy of Environmental Science | Bai W.,Shaanxi Academy of Environmental Science | Bai W.,Shaanxi University of Science and Technology | Dong C.,Nanjing Agricultural University | And 2 more authors.
Biosensors and Bioelectronics | Year: 2015

An ultrasensitive electrochemical DNA biosensor for human papillomavirus (HPV) detection was developed by electrochemical impedance spectroscopy and differential pulse voltammetry. A capture probe was immobilized on a glassy carbon electrode modified with graphene/Au nanorod/polythionine (G/Au NR/PT). Two auxiliary probes were designed and used to long-range self-assemble DNA nanostructure. The target DNA can connect DNA structure to the capture probe on the electrode surface. [Ru(phen)3]2+ was selected as a redox indicator for amplifying electrochemical signal significantly. Enhanced sensitivity was obtained through combining the excellent electric conductivity of G/Au NR/PT architecture and the long-range self-assembly DNA nanostructure with the multi-signal amplification. The DNA biosensor displayed excellent performance for HPV DNA detection over the range from 1.0×10-13 to 1.0×10-10mol/L with a detection limit of 4.03×10-14mol/L. Furthermore, the proposed method can also be used for the detection of HPV DNA in human serum samples and provides a potential application of DNA detection in clinic research. © 2015 Elsevier B.V. Source

Bai W.,Shaanxi Academy of Environmental Science | Bai W.,Shaanxi University of Science and Technology | Huang H.,Shaanxi Academy of Environmental Science | Li Y.,Northwest University, China | And 5 more authors.
Electrochimica Acta | Year: 2014

Well-dispersed graphene/gold nanorod (G/GNR) composites were synthesized by directly reducing a mixture of graphene and gold growth solution with sodium borohydride. The synthesized G/GNR composites were characterized by ultraviolet-visible spectroscopy and Fourier transform infrared spectroscopy, and the composites were observed by transmission electronic microscopy, which revealed that the GNRs were self-assembled onto the surface of graphene sheets. Glassy carbon electrodes were modified with G/GNR composites to construct a ractopamine electrochemical sensor. A sensitive, rapid, and simple electrochemical method was developed for the detection of ractopamine based on the strong enhancement effect of G/GNRs. The peak currents varied linearly with the concentration of ractopamine over the range of 1 × 10-9 to 2.7 × 10-6 mol L-1, and the detection limit was 5.1 × 10-10 mol L-1 (S/N = 3). This method was applied to detect the content of ractopamine in swine urine samples, and the recovery was in the range of 99.2 to 107.3%. © 2013 Elsevier Ltd. Source

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