No abstract

Graphene-based materials have been widely used as electrode materials of supercapacitors. However, the intrinsic properties related to the capacitance of graphene-based materials essentially need to be clarified. In this work, we have prepared reduced graphene oxide (RGO) through a simple chemical reduction strategy by using hydrazine hydrate as the reducing reagent. The different reduction levels of graphene sheets were successfully realized by controlling the chemical reduction time, and the surface state and density of the functional group were precisely adjusted. We investigated the electrochemical performance of the as-prepared RGO electrode materials. A time dependence of the specific capacitance for the as-prepared RGO electrode was observed. Graphene oxide reduced by hydrazine hydrate at 95 °C for 60 min exhibited the highest weight specific capacitance. The RGO samples were systematically characterized with Fourier transform infrared (FTIR) spectra, X-ray photoelectron spectroscopy (XPS), and Raman measurements. We conclude that the oxygen-containing groups, electrical conductivity, density of defects, and carbon electronic state play substantial roles in deciding the specific capacitance of reduced graphene oxide.

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Genotyping of human hepatitis B virus (HBV) can be used to direct clinically effective therapeutic drug-selection. Herein we report that a quick genotyping method for human HBV was established by a specially designed giant magnetoresistive (GMR) biochip combined with magnetic nanoclusters (MNCs), PCR and line probe assay. Magnetic nanoclusters of around 180 nm in diameter were prepared and modified with streptavidin, and resultant streptavidin-modified magnetic nanoclusters were used for capturing biotin-labeled hybrid products on the detection interface of the sensor. The gene fragments of HBV's B and C gene types were obtained by PCR based on a template of B- and C-type plasmids. After gene fragments were hybridized with captured probes, streptavidin-modified magnetic nanoclusters could bind with biotin-conjugated gene fragments, and the resultant hydride products could be quickly detected and distinguished by the GMR sensor, with a detection sensitivity of 200 IU mL(-1) target HBV DNA molecules. The novel method has great potential application in clinical HBV genotyping diagnosis, and can be easily extended to other biomedical applications based on molecular recognition.