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61.
Magnetically separable CuO nanoparticles supported on graphene oxide (Fe3O4 NPs/GO-CuO NPs) is synthesized and characterized for the preparation of propargylamines in EtOH, at 90℃. Fe3O4 NPs/GO-CuO NPs is found to be an efficient catalyst for the A3-coupling of aldehydes, amines, and alkynes through C-H activation. Both aromatic and aliphatic aldehydes and alkynes are combined with secondary amines to provide a wide range of propargylamines in moderate to excellent yields. 相似文献
62.
In order to develop a sensor for the detection of toxic N2O molecules, the interaction of pristine and Aldoped BN nanosheets with an N2O molecule was investigated using density functional theory calculations. It was found that unlike the pristine sheet, the Al-doped sheet can effectively interact with the N2O molecule so that its electronic properties and conductivity are dramatically changed. Webelieve that replacing a B atom of the BN sheet with an Al atom may be a good strategy for improving the sensitivity of these nanosheets toward N2O, which cannot be trapped and detected by the pristine sheet. 相似文献
63.
Two‐dimensional (2D) layered nanomaterials, e.g. graphene and molybdenum disulfide (MoS2), have rapidly emerged in material sciences due to their unique physical, chemical and mechanical properties. In the meanwhile, there is a growing interest in constructing electrochemical sensors for a wide range of chemical and biological molecules by using these 2D nanomaterials. In this review, we summarize recent advances on using graphene and MoS2 for the development of electrochemical sensors for small molecules, proteins, nucleic acids and cells detection. We also provide our perspectives in this rapidly developing field. 相似文献
64.
High Sensitive Microsensor Based on Organic‐Inorganic Composite for Two‐Dimensional Mapping of H2O2 by SECM 下载免费PDF全文
Danielle Diniz Justino Isabel Lourenço Torres Rita de Cássia Silva Luz Flavio Santos Damos 《Electroanalysis》2015,27(5):1202-1209
The present work describes the development of a selective, sensitive and stable sensing microsensor for scanning electrochemical microscopy (SECM) to measure H2O2 during electrochemical reduction of oxygen. The microsensor is based on graphene and Poly(3,4‐ethylenedioxythiophene) composite as support to iron (III) hexacyanoferrate (II) (PEDOT/graphene/FeIII4[FeII(CN)6]3 microsensor). The electrochemical properties of the PEDOT/graphene/FeIII4[FeII(CN)6]3 microsensor were investigated by cyclic voltammetry (CV) and scanning electrochemical microscopy (SECM). The PEDOT/graphene/FeIII4[FeII(CN)6]3 microsensor showed an excellent electrocatalytic activity toward hydrogen peroxide (H2O2) reduction with a diminution of the overpotential of about 500 mV in comparison to the process at a bare gold microelectrode. The microsensor presented excellent performance for two dimensional mapping of H2O2 by SECM in 0.1 mol L?1 phosphate buffer solution (pH 7.0). Under optimized conditions, a linear response range from 1 up to 1000 µmol L?1 was obtained with a sensitivity of 0.08 nA L µmol?1 and limit of detection of 0.5 µmol L?1. 相似文献
65.
Electrochemical Detection of a Cancer Biomarker mir‐21 in Cell Lysates Using Graphene Modified Sensors 下载免费PDF全文
Tugba Kilic Arzum Erdem Yasemin Erac M. Ozgur Seydibeyoglu Salih Okur Mehmet Ozsoz 《Electroanalysis》2015,27(2):317-326
In the present study, the voltammetric and impidimetric detection of microRNA‐21, mir‐21 from cell lysates was investigated for the first time by using graphene modified disposable pencil graphite electrodes (GME). The surface characterization of GME was performed via electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). Upon passive adsorption of inosine substituted antimicroRNA‐21, antimir‐21 probe, InP, onto the surface of GME and then solid phase hybridization of InP with mir‐21, the target, the electrochemical detection was performed by using Differential Pulse Voltammetry (DPV) and EIS techniques. This developed biosensor, GME has presented a 2.77 times lower detection limit of 2.09 µg/mL (3.12 pmol) with respect to unmodified pencil graphite electrode (GE). Moreover it is capable of analyzing mir‐21 in the cell lysates of mir‐21 positive breast cancer cell line (MCF‐7) contrast to mir‐21 negative hepatoma cell line (HUH‐7). The proposed electrochemical yes‐no system does not require any purification and/or amplification step prior to fast detection of mir‐21 from real samples. 相似文献
66.
Nanomolar Determination of Methyldopa in the Presence of Large Amounts of Hydrochlorothiazide Using a Carbon Paste Electrode Modified with Graphene Oxide Nanosheets and 3‐(4′‐Amino‐3′‐hydroxy‐biphenyl‐4‐yl)‐acrylic Acid 下载免费PDF全文
A novel electrochemical sensor for sensitive detection of methyldopa at physiological pH was developed by the bulk modification of carbon paste electrode (CPE) with graphene oxide nanosheets and 3‐(4′‐amino‐3′‐hydroxy‐biphenyl‐4‐yl)‐acrylic acid (3,′AA). Applying square wave voltammetry (SWV), in phosphate buffer solution (PBS) of pH 7.0, the oxidation current increased linearly with two concentration intervals of methyldopa, one is 1.0×10?8–1.0×10?6 M and the other is 1.0×10?6–4.5×10?5 M. The detection limit (3σ) obtained by SWV was 9.0 nM. The modified electrode was successfully applied for simultaneous determination of methyldopa and hydrochlorothiazide. Finally, the proposed method was applied to the determination of methyldopa and hydrochlorothiazide in some real samples. 相似文献
67.
Dually Electroactive Disulfide‐Confined Aryldiazonium Salt Used as a Linker Molecule for Preparing Immunosensor Platforms 下载免费PDF全文
Md. Mohibul Islam Khan Mithrabinda K. Poduval Tae‐Hyun Kim Kyuwon Kim 《Electroanalysis》2015,27(8):1952-1959
A new electroactive disulfide‐confined aryl diazonium (DSAD) salt was synthesized and used as a linker for biomolecules immobilization to prepare two kinds of immunoassay platforms. DSAD was electrodeposited on ITO electrode surfaces by cyclic voltammetry. Disulfide group of DSAD attached on the surfaces were electrochemically oxidized into thiosulfinate or thiosulfonate groups. For the first work, a detection of rabbit antigen was performed on ITO microelectrodes array by spatially‐selective approach. In the second work, DSAD was deposited on electrochemically reduced graphene oxide‐modified ITO surfaces, which were used as a platform for electrochemical sandwich immunoassay for detecting mouse antigen. 相似文献
68.
Halogen-functionalized graphenes are utilized as electronic devices and energy materials. In the present paper, the effects of halogen-termination of graphene edge on the structures and electronic states of graphene flakes have been investigated by means of density functional theory (DFT) method. It was found that the ionization potential (Ip) and electron affinity of graphene (EA) are blue-shifted by the halogen termination, while the excitation energy is red-shifted. The drastic change showed a possibility as electronic devices such as field-effect transistors. The change of electronic states caused by the halogen termination of graphene edge was discussed on the basis of the theoretical results. 相似文献
69.
《Current Applied Physics》2015,15(5):563-568
We demonstrate the surface treatment of graphene using an atmospheric pressure plasma jet (APPJ) system. The graphene was synthesized by a thermal chemical vapor deposition with methane gas. A Mo foil and a SiO2 wafer covered by Ni films were employed to synthesize monolayer and mixed-layered graphene, respectively. The home-built APPJ system was ignited using nitrogen gas to functionalize the graphene surface, and we studied the effect of different treatment times and interdistance between the plasma jet and the graphene surface. After the APPJ treatment, the hydrophobic character of graphene surface changed to hydrophilic. We found that the change is due to the formation of functionalities such as hydroxyl and carboxyl groups. Furthermore, it is worth noting that the nitrogen plasma treatment induced charge doping on graphene, and the pyridinic nitrogen component in the X-ray photoelectron spectroscopy spectrum was significantly enhanced. We conclude that the atmospheric pressure plasma treatment enables controlling the graphene properties without introducing surface defects. 相似文献
70.
In the present study, the anisotropic resistivity of the monolayer graphene has been obtained in semiclassical regime beyond the Dirac point approximation. In particular, detailed investigations were made on the dependence of conductivity on the Fermi energy. At low energies, in the vicinity of the Dirac points, band energy of the monolayer graphene is isotropic at the Fermi level. Meanwhile, at the intermediate Fermi energies anisotropic effects such as trigonal warping is expected to be the origin of the anisotropic resistivity. However, besides the band anisotropy there also exists an other source of anisotropic resistivity which was introduced by scattering matrix. At high energies it was shown that the band anisotropy is less effective than the anisotropy generated by the scattering matrix. It was also shown that there exist two distinct regimes of anisotropic resistivity corresponding the trigonal warping and connected Fermi curve at intermediate and high energies respectively. 相似文献