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ABSTRACT: A green, one-step method for synthesis of graphene-Au nanoparticles (graphene-AuNPs) was introduced in this article, using an environmentally benign hexamethylenetetramine (HMTA) as reducing and stabilizing agent. HMTA slowly was hydrolyzed to generate aldehyde ammonia to reduce graphene oxides (GO) and hydrogen tetrachloroaurate (Au precursor). The structure and composition of the graphene-AuNPs nanocomposites were studied by means of ultraviolet visible (UV) absorption spectra, X-ray photoelectron spectroscopy (XPS) and Transmission electron microscopy (TEM). The AuNPs are well-dispersed on graphene nanosheets in narrow size range. The nanocomposites have excellent electrocatalytical properties for catalytic reduction of O(2) and H(2)O(2).
Talanta 05/2012; 93:345-9. · 3.79 Impact Factor
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ABSTRACT: A simple, inexpensive, one-step synthesis of graphene/PAA-Au nanocomposites was achieved by using polyallylamine (PAA) as a reducing and stabilizing agent. The synthetic process was carried out only in aqueous solution, which is versatile and environmentally friendly. The resulting nanocomposites could be dispersed into water stably without any additional protection by polymeric or surfactant stabilizers. The products were further characterized by UV-visible absorption spectroscopy, transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FTIR) and photoelectron spectroscopy (XPS). The results indicate that graphene sheets played an important role as a support material to increase the active area of Au nanoparticles (AuNPs). And the resulting graphene/PAA-Au nanocomposites film exhibited good electrocatalytical activity towards reduction of both H(2)O(2) and O(2), which showed potential application in electrochemical sensors.
Talanta 01/2012; 89:391-5. · 3.79 Impact Factor
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ABSTRACT: An efficient DNA impedance biosensing platform is constructed, in which positively charged N,N-bis-(1-aminopropyl-3-propylimidazol salt)-3,4,9,10-perylene tetracarboxylic acid diimide (PDI) is anchored to graphene sheets. The π-π stacking and electronic interactions are elucidated by the distinct absorption features in UV-vis spectra and by quenching perylene fluorescence in contact with graphene. The rational design and tailoring of graphene surface invest it with desired properties (dispersive, structural, photoelectrical and conductive, etc.) and boost its application. Electrostatic interaction between PDI's positively charged imidazole rings and negatively charged phosphate backbones of single-stranded DNA (ssDNA) facilitates ssDNA immobilization. This manner is different from these mainly based on the attraction between the rings in DNA bases and the hexagonal cells of graphene, which is disturbed after hybridization and causes the leaving of formed double-stranded DNA from graphene surface. The electrostatic ssDNA grafting occupies phosphate backbones and particularly leaves the bases available for efficient hybridization. DNA immobilization and hybridization lead to PDI/graphene interfacial property changes, which are monitored by electrochemical impedance spectroscopy and adopted as the analytical signal. The conserved sequence of the pol gene of human immunodeficiency virus 1 is satisfactorily detected via this PDI/graphene platform and shows high reproducibility, selectivity.
Biomaterials 11/2011; 33(4):1097-106. · 7.40 Impact Factor
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ABSTRACT: Negative-charge change and conformation transition upon DNA immobilization and hybridization on functionalized graphene sheets were monitored by the EIS technique and adopted as the signal for label-free electrochemical DNA hybridization detection.
Chemical Communications 02/2011; 47(6):1743-5. · 6.17 Impact Factor
