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【答案】应助回帖
★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★
感谢参与，应助指数 +1
yajing511: 金币+20, ★有帮助 2012-04-23 15:35:53
phu_grassman: 金币+5, Thanks for your exhaustive answer.o(≧v≦)o~~ 2012-04-26 09:17:41
phu_grassman: 金币+5, MN-EPI+1, good answer. Thanks for sharing your scientific experience. 2012-04-26 09:18:35
Colloids Surf B Biointerfaces. 2010 Nov 1;81(1):235-41. Epub 2010 Jul 13.
Functionalization of gold nanoparticles with amino acid, beta-amyloid peptides and fragment.
Majzik A, Fülöp L, Csapó E, Bogár F, Martinek T, Penke B, Bíró G, Dékány I.
Source
Supramolecular and Nanostructured Materials Research Group of the Hungarian Academy of Sciences, University of Szeged, 6720 Szeged Aradi vt 1, Hungary.
Abstract
Gold nanoparticles (Au NPs) were functionalized by cysteine (Cys), beta-amyloid peptides (Cys(0)Abeta(1-28), Cys(0)Abeta(1-40), Abeta(1-42)) and a pentapeptide fragment (Leu-Pro-Phe-Phe-Asp-OH (LPFFD-OH)). Optical absorption spectra of these systems were recorded and the plasmon resonance maximum values (lambda(max)) of the UV-vis spectra together with the transmission electron microscopy (TEM) images were also analysed. Both TEM images and the appearance of a new absorption band between approximately 720 and 750 nm in the visible spectra of the Au-cysteine and Au-LPFFD-OH systems most probably indicate that upon addition of these molecules to Au NPs-containing aqueous dispersions formation of aggregates is occurred. The wavelength shift between the two observed absorption bands in cysteine- and pentapeptide-modified Au NPs systems are Deltalambda=185 and 193 nm, respectively. These results suggest that the monodisperse spherical gold nanoparticles were arranged to chained structure due to the effect of these molecules. For confirmation of the binding of citrate and cysteine onto the plasmonic metal surface (1)H NMR measurements were also performed. (1)H NMR results may suggest that the citrate layer on the metal surface is replaced by cysteine leading to a formation of organic double layer structure. In the presence of beta-amyloid peptides the aggregation was not observed, especially in the Au-Cys(0)Abeta(1-40) and Au-Abeta(1-42) systems, however compared to the cysteine or LPFFD-OH-containing gold dispersion with Cys(0)Abeta(1-28) measurable less aggregation were occurred. The spectral parameters clearly suggest that Abeta(1-42) can attach or bind to the surface of gold nanoparticles via both the apolar and the N-donors containing side-chains of amino acids and no aggregation in the colloidal gold dispersion was observed.
Copyright (c) 2010 Elsevier B.V. All rights reserved.
Langmuir. 2010 Jun 15;26(12):9860-74.
Understanding the mechanism of amino acid-based Au nanoparticle chain formation.
Sethi M, Knecht MR.
Source
Department of Chemistry, University of Kentucky, 101 Chemistry-Physics Building, Lexington, Kentucky 40506-0055, USA.
Abstract
Understanding the surface orientation and interactions between biomolecules and nanoparticles is important in order to determine their effects on the final structure and activity. At present, limited analytical techniques are available to probe these interactions, especially for materials dispersed in solution. We recently demonstrated that arginine, a simple amino acid, is able to bind to the surface of Au nanoparticles in a segregated pattern, which produces an electronic dipole across the structure. As a result, the formation of linear chains of Au nanoparticles occurred that was dependent upon of the concentration of arginine. Here, we present new information concerning the mechanism of assembly and demonstrate unique reaction conditions that can be used to directly control the assembly rate, and thus the size of the final superstructure that is produced. The assembly process was modulated by the arginine/Au nanoparticle ratio, the temperature of the system, the dielectric of the solvent, and the solution ionic strength, all of which can be used in combination to control the process. These effects were monitored using UV-vis spectroscopy, transmission electron microscopy, and dynamic light scattering. From these results, it is suggested that the second step of the assembly process, which is the formation of nanoparticle chains mediated by Brownian motion, controls the overall assembly rate and thus the size and orientation of the final superstructure produced. Furthermore, the reaction kinetics of the system have been studied from which rate constants and activity energies have been extracted for electrostatic-based nanoparticle assembly. This analysis indicates that the assembly/organization step is likely broken into two substeps with the formation of nanoparticle dimers occurring in solution first, followed by the oligomerization of the dimers to form the linear and branched chains. The dimerization step follows traditional second-order kinetics and is relatively fast, while the oligomerization process is quite complex and is anticipated to be slower than the dimerization step. These results are important, as they lay the basis for the subsequent use of this technique for the possible fabrication of electronic device components or as sensitive assays to probe the surface structure of nanomaterials.
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