High-resolution separation of graphene oxide by capillary electrophoresis.
ABSTRACT Separation and purification of graphene oxide (GO) prepared from chemical oxidation of flake graphite and ultrasonication by capillary electrophoresis (CE) was demonstrated. CE showed the ability to provide high-resolution separations of GO fractionations with baseline separation. The GO fractionations after CE were collected for Raman spectroscopy, atomic force microscopy, and transmission electron microscopy characterizations. GO nanoparticles (unexfoliated GO) or stacked GO sheets migrated toward the anode, while the thin-layer GO sheets migrated toward the cathode. Therefore, CE has to be performed twice with a reversed electric field to achieve a full separation of GO. This separation method was suggested to be based on the surface charge of the GO sheets, and a separation model was proposed. This study might be valuable for fabrication of GO or graphene micro- or nanodevices with controlled thickness.
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ABSTRACT: A new method for the characterisation of purified detonation nanodiamond (DND) using capillary zone electrophoresis has been developed. The influence of BGE conditions on electrophoretic mobility, peak shape and particle aggregation was investigated, with resultant observations supported by zeta potential approximations and particle size measurements. Sodium tetraborate (pH 9.3), tris(hydroxymethyl)amminomethane (pH 9.3) and sodium phosphate (pH 7) were used in studying the BGE concentration effect on a commercial source of chemically stabilised DND. The BGE concentration had a strong effect on the stability of DND in suspension. The formation of aggregates of various sizes was observed as BGE concentration increased. The effect of pH on the electromigration of DND was examined using sodium phosphate (pH 8 and 10). The CZE method was subsequently applied to four different DND samples, which had undergone different routes of purification following detonation synthesis. Each sample produced a unique electrophoretic peak or profile in sodium tetraborate buffer (pH 9.3), such that the actual separation of DND samples from different sources could be achieved. This article is protected by copyright. All rights reserved.Electrophoresis 03/2014; · 3.26 Impact Factor
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ABSTRACT: A system for interfacing dark field microscopy (DFM) with capillary electrophoresis (CE) was demonstrated and applied to investigate the movement of single gold nanoparticles (AuNPs) visually and in real time for the first time. When using ∼60 nm cetyl trimethyl ammonium bromide (CTAB) and sodium dodecyl sulfate (SDS) capped AuNPs as target analytes, preliminary data indicated that differently charged AuNPs had different movement velocities (v). From the result of the effect of applied voltage and buffer pH value on the movement of single AuNPs, we could "image" that positively charged CTAB-capped AuNPs (red) moved faster than negatively charged SDS-capped AuNPs (green), and the former could catch up with and pass the latter. The results visually confirmed the separation rules and some fundamental theories of CE including the effect of buffer pH value on the electroosmotic flow (EOF) and the plug-like profile of EOF. This novel integration was successfully utilized to evaluate the size distribution and homogeneity of AuNPs, from which the results obtained were in accordance with transmission electron microscopy (TEM) results. The proposed system offers a new insight into CE analysis and has potential applications in many fields, such as the study of interaction between NPs and biomolecules in bioanalysis.The Analyst 05/2013; · 4.23 Impact Factor
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ABSTRACT: Graphene, a truly two-dimensional (2D) and fully π-conjugated honeycomb network, is exhibiting many unique physical and chemical properties that are interesting in a wide range of areas. Since its discovery in 2004, graphene has been extensively studies in many different fields including nano-electronics, composite materials, energy research, catalysis and so on. Based on the fascinating action of members in the carbon family, notably zero dimensional (0D) fullerenes and one dimensional (1D) carbon nanotubes (CNTs) in biomedical areas, increasing numbers of reports have explored the potential of graphene for different biomedical and biotechnical applications since 2008. This manuscript aims to provide a summary of current research progress of graphene-based carbon materials in biosensing, drug (gene) delivery and tissue engineering, and discusses the opportunities and challenges in this rapidly growing field.Current Medicinal Chemistry 11/2013; · 3.72 Impact Factor