Nanometer dimension of citrate-capped gold nanoparticles can be firmly bound with various functionalized polymer-modified glass plate and indium tin oxide (ITO) substrates. Herein we report 3-aminopropyltriethoxysilane, polyvinyl pyridine, polyethylene imines, etc. as binding agents to modify these substrates to stabilize the charged colloidal gold nanoparticles through electrostatic stabilization of gold nanoparticles. When gold nanoparticles pretreated substrate are exposed into the seeding growth solution, the preadsorbed gold nanoparticles grow further and then form nanoislands of gold on glass and ITO substrates. The formation of nanoislands on microscope glass slide and ITO was monitored with UV-visible spectroscopy, cyclic voltammetry, and atomic force microscopy methods. The gold nanoislands and gold nanoparticles pretreated substrates can be used as platform to study the self-assembling behavior of long chain alkanethiols such as C12SH, C16SH, and C18SH. The binding, coverage, and electron transfer characteristics of monolayer assembly on modified gold nanoisland and nanoparticles modified substrates are studied using electrochemical studies. The gold substrates can be prepared by this method, which is simple and reproducible and can be applied to various sensor and electrocatalytic applications. 相似文献
EIS (electrolyte-insulator-semiconductor) sensors based on the functionalization of uncoated gold nanoparticles supported on a Si/SiO2 structure are presented. Oxygen plasma etching at moderate power (<200 W) provides a convenient and efficient way to remove organic capping agents from the gold nanoparticles without significant damage. Higher power intensities destroy the linkage between the SiO2 and the gold nanoparticles, and some of the gold nanoparticles are removed from the surface. The flat-band potential shift, i.e. the pH dependence of the gold-coated EIS sensors is similar (33 mV/pH) to the uncoated EIS pH-sensor. Lead, penicillin and glucose sensors were prepared by immobilization of β-cyclodextrin, penicillinase and glucose oxidase by various immobilization techniques.
A simple, green, one‐pot synthesis of gold nanoparticles was achieved through the reaction of an aqueous mixture of potassium tetrachloroaurate(III) and the macrocycle cucurbit[7]uril in the presence of sodium hydroxide at room temperature without introducing any kind of traditional reducing agents and/or external energy. The as‐prepared gold nanoparticles showed catalytic activity for the reduction reaction of 4‐nitrophenol in the presence of NaBH4, which has been established by visual inspection and UV/Vis spectroscopy. This report is the first for the preparation of gold nanoparticles using cucurbit[7]uril in aqueous media through chemical reduction without employing conventional reducing agents and/or external energy. 相似文献
Condensation reaction of several ketones with pyrrole in the presence of ferric hydrogen sulfate as a green homogenous acidic catalyst furnished the corresponding pure dipyrromethanes in good yields. Gold nanoparticles were produced through reduction of HAuCl4 with substituted dipyrromethanes as new reducing agents at room temperature with the exclusion of any capping agent or surfactant. Gold nanoparticles were characterized by transmission electron microscopy, scanning electron microscopy, XRD and UV–visible absorption spectroscopic measurements. It is proposed that in situ formed oxidative products of dipyrromethane, such as polydipyrromethane could serve effectively as a capping agent to preferably adsorb the {111} facets of gold crystals during the reduction process, which leads to the formation of gold nanoparticles. 相似文献
An aqueous dispersion was prepared by attaching positively charged gold nanoparticles to the surface of poly-sodium-p-styrenesulfonate-modified Fe3O4 nanoparticles. The Fe3O4@positively charged gold nanoparticles offer high monodispersion, stability against aggregation, and high magnetization with uniform size. The Fe3O4@positively charged gold nanoparticles were efficient and recyclable catalysts due to the formation of a positively charged gold layer on the surface of Fe3O4 nanoparticles and were stable in aqueous solution for over forty-eight hours and hence may have a broad range of applications. 相似文献
Nanoscale magnetic material is becoming an important topic in nanoscience and magnetism. Especially, gold nanoparticles chemisorbed by alkanethiols have drawn much attention due to the size effect on their electronic structure. However, magnetic interaction of gold nanoparticles derivatized by magnetically active ligands has not been investigated in detail. In order to elucidate the magnetic interaction in gold nanoparticles chemisorbed by alkanethiol systems, small gold cluster, such as Au3 and Au13, and π-radical hybrid model systems were examined using the hybrid DFT method. 相似文献
Dendrimer‐protected gold nanoparticles have been facilely obtained by heating an aqueous solution containing third‐generation poly(propyleneimine) dendrimers and HAuCl4 without the additional step of introducing other reducing agents. Transmission electron microscopy (TEM) and UV‐vis data indicate the size, the nucleation, and growth kinetics of gold nanoparticles thus formed, which can be tuned by changing the initial molar ratio of dendrimer to gold.
The [bmim][BF4] ionic liquid effect on gold nanoparticles formation in silica sol–gel materials is studied in order to produce gel-derived glasses with optical properties. The characteristic red color from gold nanoparticles is observed for transparent glass monoliths obtained sintering, between 365 and 425 °C, a silica sol–gel precursor containing HAuCl4·3H2O and [bmim][BF4], under normal atmospheric conditions. The effect of sintering the ionogel at different temperatures (Tsint) or times (tsint) on the optical properties, shape, size, and distribution of gold nanoparticles is discussed. Presence of the gold particles is observed using transmission electron microscopy images followed by energy dispersive X-ray spectroscopy analysis. The thermal decomposition of [bmim][BF4] in the ionogel is investigate using calorimetric and spectroscopic techniques, and by analysis of volatile compounds released by the sol–gel material during sintering. With these results a mechanism for the formation of the gold nanoparticles is proposed, where a first ionic liquid degradation step provides the reductive environment that enables the gold nanoparticles production at the range of temperatures between 350 and 425 °C. Upon sintering the synthesized materials the ionic liquid acts as a sacrificial additive and the ionic liquid thermal decomposition products enables the formation of gold nanoparticles in the sol–gel matrix. 相似文献
We discuss the fluorescence and Raman spectra of the amino acid tryptophan (Trp) in the presence of gold nanoparticles in
solution and on the surface of highly dispersed silica (aerosil) containing gold nanoparticles (Au-SiO2). The fluorescence of Trp is efficiently quenched in the presence of gold nanoparticles both in solution and on the SiO2 surface. The fluorescence and excitation spectra contain bands for molecular Trp and a charge transfer complex between Trp
and the nanoparticles. In the Raman spectra of Trp with gold nanoparticles, considerably enhanced intense vibrations appear
for the carboxyl and amino groups and also for the benzene and pyrrole rings. The effect of gold nanoparticles on the Raman
spectra of Trp in a heterogeneous system is considerably weakened due to strong light scattering by the dispersed silica. 相似文献
In the present work, we report the photochemical synthesis of gold nanoparticles in N,N′-dimethylformamide by addition of a photocatalyst like thiourea-modified polyoxometalate (γ-SiW12O40). The polyoxometalate behaves as an electron relay. Reduction of the polyoxometalate takes place under UV irradiation followed by a transfer of electrons to the gold ions, leading to the formation of gold nanoparticles. The formation of the gold particles was monitored with time by UV–Vis spectrophotometry. The polyoxometalate also acts as a stabilizing agent and helps in controlling the size of the nanoparticles. The shape and size distribution was obtained from transmission electron microscopy studies. Spherical and monodisperse gold nanoparticles of ~10 nm size were obtained. 相似文献
Flow field-flow fractionation (FlFFF) was used for size characterization of gold nanoparticles. The measured particle sizes
obtained from FlFFF for the commercial 10 nm gold nanoparticle standard and the gold nanoparticles synthesized in the laboratory
were in good agreement with those measured by transmission electron microscopy (TEM). Further, the capability of α-tocopherol
to induce enlargement of gold nanoparticles by catalysis of the reduction of AuCl4− by citrate was observed by monitoring the changes in particle size of gold nanoparticles using FlFFF. The effects of α-tocopherol
and incubation time on enlargement of the gold nanoparticles were examined. Higher concentrations of α-tocopherol resulted
in larger nanoparticles. At fixed α-tocopherol concentration, larger nanoparticles were formed at longer incubation times. 相似文献
A simple method for preparing gold nanoparticles in aqueous solution has been developed by using glycosaminoglycan‐heparin as reducing and stabilizing agent and HAuCl4 as precursor. The obtained gold nanoparticles were characterized by UV‐vis spectroscopy, resonance light scattering spectroscopy (RLS), transmission electron microscopy (TEM) and electrophoresis technology. The influence of reactant concentration for the preparation of gold nanoparticles was investigated. The results indicated that the gold nanoparticles carried negative charges in the aqueous solution and the size and shape of the gold nanoparticles could be controlled by changing the concentration of the heparin. Moreover, the gold nanoparticles obtained with relatively high concentration of heparin were very stable and had relative narrow size distribution. 相似文献
In this report, we demonstrated a novel efficient post-modification route for preparation of smart hybrid gold nanoparticles with poly(4-vinylpyridine) (P4VP) based on RAFT and click chemistry. A new azide terminated ligand was first synthesized to modify gold nanoparticles by ligand exchange reaction, and then click reaction was used to graft alkyne terminated P4VP which was prepared by RAFT onto the surface of gold nanoparticles. The functionalized hybrid gold nanoparticles were characterized by TEM, FTIR, and XPS etc. The results indicated that the P4VP was successfully grafted onto the surface of gold nanoparticles by click reaction. The surface grafting density was calculated to be about 6 chains/nm2. In addition, the hybrid gold nanoparticles showed a pH responsive phenomenon as the pH value changed around 5. 相似文献
In this study, we present a simple and eco-friendly method for extracellular biosynthesis of gold nanoparticles by Streptomyces sp. ERI-3 cell-free supernatant. The research was also aimed to evaluate the effects of different reaction parameters including incubation temperature, reaction time, HAuCl4 concentration and pH on gold nanoparticles production. The UV?CVis spectroscopy was used to monitor the formation of gold nanoparticles. The synthesized gold nanoparticles were characterized with XRD, TEM, and SEM. The average particle size ranged from 10 to 30?nm with spherical shape at optimum conditions. 相似文献
This article describes a general method for the deposition of gold nanoparticles onto solid support based on the use of multilamellar vesicles (MLVs). Gold nanoparticles (nps) synthesized within lipid-based MLVs by UV- or γ-irradiation were deposited onto TiO2 powder support. The organic phase from MLVs was removed by calcination leading to high dispersion of naked Au nanoparticles. The resulting particles were investigated using spectrometry, electron microscopy and XPS. The gold nanoparticles were stable and well-separated on the titania surface. It was found that the metal nanoparticles produced by radiolysis have smaller average size and narrower size distribution than those synthesized by photochemical route. After calcinations, the particles tended to enlarge to reach c.a. 18 nm. The gold loading on the titania support could be controlled by changing the gold salt concentration and the MLV-to-TiO2 weight ratio; values of Au-to-Ti ratio up to 44 % could be obtained. 相似文献
Nanoscale magnetic material is the important topic in nanoscience and magnetism. Especially, gold nanoparticles chemisorbed by alkanethiols are one of the promising material for these purposes. However, magnetic interaction of magnetically active ligands grafted onto the surface of gold nanoparticles has not been investigated in detail. In order to elucidate the magnetic interaction in gold nanoparticles chemisorbed by alkanethiol systems, small slab gold cluster, such as Au10, and π-radical hybrid model systems were examined using the hybrid DFT method. 相似文献
The preparation and characterization of gold nanoparticles (~6 nm in diameter) modified with mono-6-thio-β-cyclodextrin (II) is described. The resulting monolayer-protected gold nanoparticles are water-soluble and more stable. The concentration of II plays a crucial role for the distribution of the modified nanoparticles. When the ratio of concentration of II to HAuCl4,[II]/[HAuCl4] ≥ 0.93, a stable gold nanoparticle with uniform distribution and diameter of 6.0 ± 0.9 nm will be obtained. The recognition of modified gold nanoparticles to organic guest molecule is researched. The modified gold nanoparticles can make the electrochemical reduction current of nitrobenzene decrease and can be self-assembled in three-dimensional to form spherical clusters with ligand of methylene green. 相似文献