共查询到20条相似文献,搜索用时 15 毫秒
1.
Saikova S. V. Trofimova T. V. Pavlikov A. Yu. Karpov D. V. Chistyakov D. I. Mikhlin Yu. L. 《Russian Chemical Bulletin》2020,69(7):1284-1289
Methods for the synthesis of hybrid nanoparticles, consisting in the simultaneous modification of the magnetic core and reduction of gold on the surface using various reagents, were proposed and developed. Depending on synthesis conditions, various hybrid nanoparticles were obtained, namely, hybrid nanoparticles decorated with gold nuclei and hybrid nanoparticles of the core—shell type. The obtained products can be used as promising materials for catalytic and biomedical applications.
相似文献2.
A simple and green method for the controllable synthesis of core–shell Fe3O4 polydopamine nanoparticles (Fe3O4@PDA NPs) with tunable shell thickness and their application as a recyclable nanocatalyst support is presented. Magnetite Fe3O4 NPs formed in a one-pot process by the hydrothermal approach with a diameter of ∼240 nm were coated with a polydopamine shell layer with a tunable thickness of 15–45 nm. The facile deposition of Au NPs atop Fe3O4@PDA NPs was achieved by utilizing PDA as both the reducing agent and the coupling agent. The satellite nanocatalysts exhibited high catalytic performance for the reduction of p-nitrophenol. Furthermore, the recovery and reuse of the catalyst was demonstrated 8 times without detectible loss in activity. The synergistic combination of unique features of PDA and magnetic nanoparticles establishes these core–shell NPs as a versatile platform for potential applications. 相似文献
3.
Ferouani Ghaniya Ameur Nawal Bachir Redouane 《Research on Chemical Intermediates》2020,46(2):1373-1387
Research on Chemical Intermediates - Bimetallic gold–iron catalysts supported on ZrO2 and TiO2 were prepared by under potential deposition. The characterization of the catalysts was performed... 相似文献
4.
Patrycja Bober Jaroslav Stejskal Miroslava Trchov�� Jan Proke? 《Journal of Solid State Electrochemistry》2011,15(11-12):2361-2368
The oxidation of aniline with silver nitrate in 1?mol?L?1 acetic acid at 20?°C yielded a composite of two conducting components, polyaniline and silver; the acceleration with 1?mol% of p-phenylenediamine is needed for efficient synthesis. The yield and molecular weight increased when aniline was copolymerized with 10?mol% p-phenylenediamine. Such product displayed metallic conductivity below 180?K and semiconductor type above this temperature. As the result, the conductivity was the same at 100 and 300?K. The oxidation of p-phenylenediamine alone with silver nitrate also produced a conducting composite having the conductivity of 1,750?S cm?1 despite the assumed nonconductivity of poly(p-phenylenediamine). The present study demonstrates that all oxidations proceeded also in frozen reaction mixtures at ?24?°C, i.e., in the solid state. In most cases, molecular weights of polymer component increased, the conductivity of composites with silver improved, to 2,990?S?cm?1 for poly(p-phenylenediamine)?Csilver, and remained high after deprotonation with 1?mol?L?1 ammonium hydroxide. 相似文献
5.
In this study, well-dispersed gold nanoparticles were prepared by using intra-molecular reduction of sodium gold sulfite, without using additional reductants and chloride free. The technical parameters including transformation temperature, pH, and concentration were optimized by the single-factor method as 90 C, pH 1, and 0.01 mmol/L [Na3Au(SO3)2], respectively. The resultant colloidal transmission electron microscopy images (TEM) and UV-vis absorption spectrophotometer spectra were acquired to check their properties, and the results show this kind of colloidal gold is controlled to 6 nm in sizes and has good stability in solution. 相似文献
6.
We describe here that fine control of nanoparticle shape and size can be achieved by systematic varia-tion of experimental parameters in the seeded growth procedure in aqueous solution. Cubic and spherical gold nanoparticles are obtained respectively. In particularly, the Au cubes are highly mono-disperse in 33±2 nm diameter. The experimental methods involve the preparation of Au seed particles and the subsequent addition of an appropriate quantity of Au seed solution to the aqueous growth solutions containing desired quantities of CTAB and ascorbic acid (AA). Here, AA is a weak reducing agent and CTAB is not only a stable agent for nanoparticles but also an inductive agent for leading increase in the face of nanoparticle. Ultraviolet visible spectroscopy (UV-vis), X-ray diffraction (XRD), transmission electron microscopy (TEM) are used to characterize the nanoparticles. The results show that the different size gold nanoparticles displayed high size homogenous distribution and formed mono-membrane at the air/solid interface. 相似文献
7.
《Colloids and surfaces. B, Biointerfaces》2010,78(2):174-180
Biocompatible gold nanoparticles have received considerable attention in recent years because of their promising applications in bioimaging, biosensors, biolabels, and biomedicine. The generation of gold nanoparticles using extra-cellular α-amylase for the reduction of AuCl4 with the retention of enzymatic activity in the complex is being reported. The enhanced synthesis of particles has been brought about by optimizing the medium components for α-amylase. Response surface methodology and central composite rotary design (CCRD) were employed to optimize a fermentation medium for the production of α-amylase by Bacillus licheniformis at pH 8. The three variables involved in the study of α-amylase were fructose, peptone and soya meal. Only fructose had a significant effect on α-amylase production. The most optimum medium (medB) containing (%) fructose: 3, peptone: 1, soya meal: 2, resulted in a amylase activity of 201.381 U/ml which is same as that of the central level. The least optimum (medA) and most optimum (medB) media were compared for the synthesis of particles indicated by difference in color formation. Spectrophotometric analysis revealed that the particles exhibited a peak at 582 nm and the A582 for the Med B was 8-fold greater than that of the Med A. The TEM analysis revealed that the particle size ranged from 10 to 50 nm. 相似文献
8.
Yon Ju-Nam 《Journal of organometallic chemistry》2008,693(23):3504-3508
Two new ω-thioacetylalkylphosphonium salts that function as masked cationic alkanethiolate ligands for the stabilisation of gold nanoparticles have been prepared. Both (3-thioacetylpropyl)triphenylphosphonium bromide and (6-thioacetylhexyl)triphenylphosphonium bromide were shown to form water-soluble gold nanoparticles of ca. 5-10 nm in size that are stable for up to six months. The related (3-thioacetylpropyl)diphenylphosphine oxide was also prepared but did not act as a stabilising ligand in gold nanoparticle formation. 相似文献
9.
Man Chin Paau Chung Keung Lo Xiupei Yang Martin M.F. Choi 《Journal of chromatography. A》2009,1216(48):8557-8562
Capillary zone electrophoresis (CZE) has been employed to characterize nanometer-sized thiolated α-cyclodextrin-capped gold nanoparticles (α-CD-S-AuNPs). The addition of tetrabutylammonium (Bu4N+) ions to the run buffer greatly narrows the migration peak of α-CD-S-AuNP. The optimal run buffer was determined to be 10 mM Bu4N+ in 30 mM phosphate buffer at pH 12 and an applied voltage of 15 kV. The effect of various tetraalkylammonium ions on the peak width and electrophoretic mobility (μe) of α-CD-S-AuNP was studied in detail. Bu4N+ ions assist in inter-linking the α-CD-S-AuNPs and narrowing the migration peak in CZE. This observation can be explained by the fact that each Bu4N+ ion can simultaneously interact with several hydrophobic cavities of the surface-attached α-CDs on AuNPs. The TEM images show that α-CD-S-AuNPs with Bu4N+ are linked together but in the absence of Bu4N+, they are more dispersed. The migration mechanism in CZE is based on the formation of inclusion complexes between Bu4N+ and α-CD-S-AuNPs which induces changes in the charge-to-size ratio of α-CD-S-AuNPs and μe. An inverse linear relationship (r2 > 0.998) exists between the μe and size of α-CD-S-AuNPs in the core range 1.4–4.1 nm. The CZE analyses are rapid with migration time less than 4 min. A few nanoliters of each of the α-CD-S-AuNP samples were injected hydrodynamically at 0.5 psi for 5 s. Our work confirms that CZE is an efficient tool for characterizing the sizes of α-CD-S-AuNPs using Bu4N+ ions. 相似文献
10.
A. P. Sadkov S. A. Golovanova N. V. Lariontseva L. A. Levchenko 《Russian Chemical Bulletin》2011,60(4):667-670
Protective properties of gold nanoparticles and gold—rutin complexes were studied. Aurophilic bacteria Micrococcus luteus and methanotrophic bacteria Methylococcus capsulatus were studied. Gold—rutin nanoparticles and complexes protect the respiratory activity of the bacteria against toxins. Pretreatment
of the cells with gold is more efficient than the treatment after the action of toxin. 相似文献
11.
Different amounts of Pt atoms were deposited onto the surface of Pd nanoparticles supported on carbon black by hydroquinone reduction method in anhydrous ethanol. Here, we surveyed electrochemical probing of surface compositions of Pd–Pt surface alloys. They were calculated from hydrogen desorption, carbon monoxide adlayer oxidation, and reduced carbon dioxide oxidation charges. The surface composition of Pt drastically increased up to Pt[0.3]/Pd/C (23.1 at.% of Pt) and then approached that of pure Pt with the moderate rate of increase. 相似文献
12.
13.
A self-assembly hybrid of gold nanoparticles on graphene modified electrodes for low-potential NADH detection has been achieved. We used the natural polymer chitosan (Chit) to assist the stabilization of graphene in aqueous solution, and immobilize the electronegative Au nanoparticles (NPs) through electrostatic attraction. The synergy of Au NPs with graphene for catalytic oxidation of NADH made the overpotential ca. 220 mV less positive than that on the bare electrode, and remarkably increased the oxidation current. The amperometric sensors based on such modified electrodes for detection of NADH exhibited a good linearity from 1.5 to 320 μM, and showed high sensitivity with a low detection limit of 1.2 μM (S/N = 3). It could also exclude common interfering electroactive compounds like ascorbic acid and possessed good reproducibility and operational stability. Such eminent performance of the Au-RGO/Chit film together with the ability of graphene to significantly enhance the electron transfer between enzymes and the electrode suggested its promise for constructing novel graphene based dehydrogenase biosensors. 相似文献
14.
Colorimetric detection of cadmium in water using L-cysteine Functionalized gold–silver nanoparticles
《Analytical letters》2012,45(18):2906-2919
AbstractA new simple colorimetric assay was developed for the selective and sensitive detection of cadmium (II) in water samples using L-cysteine functionalized gold–silver nanoparticles. The gold–silver nanoparticles were synthesized by reducing HAuCl4 and AgNO3 in aqueous medium and were further functionalized with L-cysteine. The formation of homogeneous gold–silver nanoparticles was characterized by transmission electron microscopy, energy-dispersive X-ray spectroscopy, particle size distribution, and ultraviolet–visible absorption methods. In the presence of cadmium (II), the aggregation of functionalized gold–silver nanoparticles caused by the interaction between cadmium (II) and L-cysteine resulted in a naked-eye visible color change of L-cysteine functionalized gold–silver nanoparticles from orange–yellow to green, which can be monitored by a simple ultraviolet–visible spectrophotometer. Under the optimal conditions, the absorbance ratio at 600–435?nm (A600/A435) was linear to the concentration of cadmium (II) from 0.4 to 38.6?μM, and the limit of detection of cadmium (II) was 44?nM. Interference measurements showed that the method exhibited good selectivity. The proposed method was successfully applied to the determination of cadmium (II) in environmental water samples. The results indicated that this simple, selective, and sensitive sensing system has good potential for practical applications. 相似文献
15.
A novel and effective electrochemical sensor for the determination of morphine (MO) in 0.04 mol L(-1) universal buffer solution (pH 7.4) is introduced using gold nanoparticles electrodeposited on a Nafion modified carbon paste electrode. The effect of various experimental parameters including pH, scan rate and accumulation time on the voltammetric response of MO was investigated. At the optimum conditions, the concentration of MO was determined using differential pulse voltammetry (DPV) in a linear range of 2.0 × 10(-7) to 2.6 × 10(-4) mol L(-1) with a correlation coefficient of 0.999, and a detection limit of 13.3 × 10(-10) mol L(-1), respectively. The effect of common interferences on the current response of morphine namely ascorbic acid (AA) and uric acid (UA) is studied. The modified electrode can be used for the determination of MO spiked into urine samples, and excellent recovery results were obtained. 相似文献
16.
This study demonstrates a facile but efficient approach to deposit metallic (gold) nanoparticles on β-FeOOH nanorods to obtain Au/β-FeOOH nanocomposites without the assistance of any polymers or surfactants at ambient conditions. In this method, a strong reducing agent (NaBH(4)) can be used to extensively produce Au nanoparticles, converting β-FeOOH into Fe(3)O(4) and depositing gold particles onto magnetic Fe(3)O(4) simultaneously. The microstructure, composition, and chemical properties of the obtained nanocomposites are characterized by various advanced techniques, including transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and UV-vis spectroscopy. Moreover, the Au/β-FeOOH nanocomposite can be used to detect trace melamine using UV spectrum in the ultraviolet wavelength range (190-260 nm), in which the nanocomposites show a higher sensitivity toward melamine due to the promotion of symmetry-forbidden bands (n→π(*)) of melamine molecules and also avoid the disturbance of commercial products containing solid colloids or food colorings that distort visual spectrum during the detection of chemical sensing. The deposition mechanisms and their sensing detection toward melamine are discussed. 相似文献
17.
We synthesized semiconducting polyaniline (PANI) nanoparticles through a solid-stabilized Pickering emulsion route using silica nanoparticles. Specific morphologies of the silica nanoparticle wrapped PANI particles were observed using both scanning electron microscope and transmission electron microscope, which showed the emulsifiability of silica nanoparticles in the emulsion system. Electrorheological (ER) behavior of this novel particle-based ER fluid dispersed in silicone oil was measured by a controlled shear stress rheometer and analyzed with a flow curve equation of Cho-Choi-Jhon model, which fitted well the flow curves measured in the exposed electric field. 相似文献
18.
Rodrigo Del Río Francisco Armijo Ricardo Schrebler Cesar Gutierrez Andrea Amaro Sonia R. Biaggio 《Journal of Solid State Electrochemistry》2011,15(4):697-702
In this work, the poly(styrene-vynil pyridine) block copolymer was used as a porous pattern to study the electrodeposition
of gold inside the pores, as a new method to obtain gold nanoparticles. The porous pattern left by the copolymer film onto
a conductive glass surface was characterized by atomic force microscopy (AFM), evidencing pores of 30 nm diameter. After the
electrodeposition, 30 nm diameter gold nanoparticles were obtained and they were characterized by cyclic voltammetry (CV)
and AFM, and then used to study the adsorption of glucose oxidase enzyme. The adsorption process of glucose oxidase on gold
nanowires was investigated by CV and electrochemical impedance spectroscopy. The morphological and capacitance results indicate
that the block copolymer–gold nanoparticle composite seems to be a good candidate to design biosensors and immunosensors. 相似文献
19.
Wimut Sermsri Purim Jarujamrus Juwadee Shiowatana Atitaya Siripinyanond 《Analytical and bioanalytical chemistry》2010,396(8):3079-3085
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
20.
An easy method of preparation of polymer/metal–nanoparticle composites is reported. KAu(CN)2 and pyrrole do not react (redox reaction) in solutions of moderate pH. The gold complex, due to its inertness, is stable in the presence of 10 μM CN? for weeks. Therefore the electrodeposition of controlled amounts of polypyrrole and Au nanoparticles on the graphite surface can be done in one solution by applying a sequence of 0.75 and ? 1.6 V potentials. Pulse deposition of both components leads to substantial improvement of the layer smoothness and homogenous distribution of Au nanocrystallites. 相似文献