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1.
J Nanosci Nanotechnol ; 11(5): 4034-8, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21780402

RESUMO

Electrochemical properties of a novel nanohybrid material, ferrocene-filled double-walled carbon nanotubes (Fc@DWNTs), have been successfully investigated for the first time by preparing different kinds of Fc@DWNTs modified glassy carbon electrodes. One pair of surface-confined redox waves corresponding to the couple of Fc/Fc+ is obtained, indicating Fc encapsulated in DWNTs retains electrochemical activity. Significantly differing from those of ferrocene-filled single-walled carbon nanotubes (Fc@SWNTs), Fc@DWNTs shows a specific electrochemical behavior, typically exhibiting thin-layer electrochemical characteristics at low scan rates, whereas diffusion-confined characteristics at high scan rates. The results indicate that the novel nanohybrid material possessing excellent electrochemical properties may have possible applications in constructing specific chemical and biological sensors.

2.
Biosens Bioelectron ; 26(5): 1853-9, 2011 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-20176468

RESUMO

We demonstrate the use of a novel electrochemical sensing platform based on aptamer conjugated Mo(6)S(9-x)I(x) nanowires (MoSI NWs) for the highly sensitive detection of the blood clotting enzyme thrombin. MoSI NWs nanowires were self-assembled on a gold electrode to which thrombin binding aptamers were covalently attached. The modification and immobilization steps of the electrodes were characterised by cyclic voltammetry along with high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy. The platform is based on the creation of a self-assembled MoSI MW layer via the sulfur-gold affinity followed by the creation of MoSI-thiolated aptamer conjugates via the sulfur-sulfur affinity. Using this system, sensitive quantitative detection of thrombin is realized by monitoring differences of differential pulse voltammetric responses of electrostatically trapped [Ru(NH(3))(6)](3+) cations to the aptamer before and after thrombin binding. The sensitivity limit for the detection of thrombin is 10 pM. This value is 10-fold better than all currently reported one step label free electrochemical strategies. Given the direct label free nature of the approach and the simplicity of the electronic detection, the aptamer conjugated MoSI NWs biosensor appears well suited for implementation in portable point of care microdevices directed at the rapid and sensitive detection of proteins and pathogens.


Assuntos
Aptâmeros de Nucleotídeos/química , Técnicas Biossensoriais/instrumentação , Condutometria/instrumentação , Eletrodos , Nanotubos/química , Trombina/análise , Desenho de Equipamento , Análise de Falha de Equipamento , Nanotubos/ultraestrutura
3.
Anal Chem ; 80(10): 3593-7, 2008 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-18407671

RESUMO

We demonstrate a novel and highly sensitive electrochemical detection of estrone based on an immunosensor platform, composed of bioassembled nanocircuits of Mo 6S 9- x I x nanowires (MoSI NWs) covalently connected to anti-estrone antibodies. The one-step, label-free, and quantitative detection of estrone is realized by employing the [Ru(NH 3) 6] (3+/2+) redox ions to sense anti-estrone antibody and estrone interactions. The MoSI NWs/anti-estrone antibody nanocircuit architectures provide an amplification and conductive pathway for the specific electrochemical sensing of estrone hapten. A detection limit of 1.4 pg x mL (-1) was achieved in contrast to previous electrochemical techniques in which the sensitivity was limited to the nanomolar range.


Assuntos
Eletroquímica/instrumentação , Estrona/análise , Haptenos/análise , Iodetos/química , Molibdênio/química , Nanofios , Enxofre/química , Cromatografia Líquida de Alta Pressão , Espectrofotometria Ultravioleta , Espectrometria de Massas em Tandem
4.
Langmuir ; 24(3): 991-8, 2008 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-18173292

RESUMO

Well-defined gold nanobelts as well as unique gold nanocombs made of nanobelts were readily synthesized by the reduction of HAuCl4 with ascorbic acid in aqueous mixed solutions of the cationic surfactant cetyltrimethylammonium bromide (CTAB) and the anionic surfactant sodium dodecylsulfonate (SDSn). Single-crystalline gold nanobelts grown along the <110> and <211> directions were prepared in mixed CTAB-SDSn solutions at 4 and 27 degrees C, respectively. Furthermore, single-crystalline gold nanocombs consisting of a <110>-oriented stem nanobelt and numerous <211>-oriented nanobelts grown perpendicularly on one side of the stem were fabricated by a two-step process with temperature changing from 4 to 27 degrees C. It was proposed that the mixed cationic-anionic surfactants exerted a subtle control on the growth of gold nanocrystals in solution due to the cooperative effect of mixed surfactants. This synthetic strategy may open a new route for the mild fabrication and hierarchical assembly of metal nanobelts in solution. The obtained gold nanobelts showed good electrocatalytic activity toward the oxidation of methanol in alkaline solution; in particular, the electrode modified with the nanobelts obtained at 27 degrees C exhibited an electrocatalytic activity considerably higher than normal polycrystalline gold electrode. Moreover, the gold nanobelts were used as the surface-enhanced Raman scattering (SERS) substrate for detecting the enhanced Raman spectra of p-aminothiophenol (PATP) molecules, and the gold nanobelts obtained at 4 degrees C exhibited an unusual larger enhancement of the b2 modes relative to the a1 modes for the adsorbed PATP molecules.

5.
Guang Pu Xue Yu Guang Pu Fen Xi ; 27(5): 999-1002, 2007 May.
Artigo em Chinês | MEDLINE | ID: mdl-17655123

RESUMO

The mechanism of the fluorescence quenching of pyridine by bisazafulleroid[60] derivative (eddy2) was discussed. When the C60 and eddy2 were added into pyridine respectively, the intensity of 426.27 nm emission peak of pyridine decreased obviously and shifted towards shorter wavelength, a typical quenching phenomenon. The fluorescence quenching of eddy2-pyridine is caused by the static quenching process resulting from the formation of charge-translated complex between molecules. The dissociation constant of eddy2 from pyridine is K(D) = 2.28 x 10(-6) (mol x L(-1)). The combination constant of eddy2 is Ks = 4.39 x 10(-5) (L x mol(-1)). The electrochemical properties of eddy2 were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) on a glassy carbon electrode in a mixed solvent of toluene and acetonitrile. The first three reduction waves for eddy2 shift to more positive than that for C60, indicating the electroreduction of eddy2 is easier than that of C60.

6.
Anal Chem ; 78(17): 6050-7, 2006 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-16944883

RESUMO

Electrochemical properties of a new nanomaterial ferrocene (Fc) peapod, Fc-filled single-walled carbon nanotubes (Fc@SWNTs), have been investigated in an aqueous solution in detail by preparing different kinds of Fc@SWNTs-modified glassy carbon electrodes (Fc@SWNTs/GCE and Fc@SWNTs-gel/GCE). One pair of surface-confined redox waves corresponding to the couple of Fc/Fc+ is obtained, which indicates that Fc encapsulated inside SWNTs retains electrochemical activity. The Fc@SWNTs-gel/GCE shows better electrochemical reversibility due to the existence of room temperature ionic liquid (RTIL). Furthermore, it shows excellent mediation of H2O2 based on Fc/Fc+ used as electron-transfer mediators for oxidation of H2O2 to O2 and reduction to H2O, suggesting specific properties of Fc@SWNTs due to a combination of Fc and SWNTs. The interaction between Fc and SWNTs is also characterized by UV-vis-NIR spectrometry and Raman spectrometry. A Fc@SWNTs-based sensor for H2O2 with a determination limit of 5 microM is fabricated, and it shows good stability and reproducibility. This work not only demonstrates that the Fc peapod is a new kind of functional nanomaterial but also appears promising in constructing novel chemical and biosensors and fuel cells.

7.
Bioelectrochemistry ; 65(1): 41-6, 2004 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-15522691

RESUMO

4-Amino-2-mercaptopyrimidine self-assembled monolayer (AMP SAMs/Au) was prepared on a gold electrode. The AMP SAMs/Au was characterized by using attenuated total reflection-fourier transform infrared (ATR-FTIR) and A.C. Impedance. The electrochemical behavior of brucine on AMP SAMs/Au was studied by cyclic voltammetry (CV) and square wave adsorptive stripping voltammetry (SWASV). The modified electrode showed an excellent electrocatalytic activity for the redox of brucine. The catalytic current increased linearly with the concentration of brucine in the range of 4.0 x 10(-7) to 2.0 x 10(-4) mol l(-1) by square wave voltammetry response. The detection limit was 6.0 x 10(-8) mol l(-1).


Assuntos
Ouro/química , Pirimidinas/química , Estricnina/análogos & derivados , Compostos de Sulfidrila/química , Eletroquímica , Eletrodos , Ferrocianetos/farmacologia , Estrutura Molecular , Oxirredução , Sensibilidade e Especificidade , Espectroscopia de Infravermelho com Transformada de Fourier , Estricnina/análise , Estricnina/química
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