جستجوی مقالات مرتبط با کلیدواژه « Gold nanoparticles » در نشریات گروه « مواد و متالورژی »

Recently, plasmonic nanoparticles with unique optical properties have been used in nanomedicine ranging from optical biosensing to bioimaging to drug delivery. Meanwhile, gold nanoparticles with very small and uniform size are desirable for these applications due to their low toxicity. In this project, reduction of gold by sodium borohydride (NaBH4) led to preparation of metal nanoparticles anchored gelatin matrix successfully. Due to its high biocompatibility, gelatin is very suitable as a stabilizing agent and despite other organic capping agents, it reduces the toxicity of these Au nanoparticles (Au Nps). These nanomaterials have been studied using Fourier transformed infrared (FT-IR), Optical Absorption, Photoluminescence (PL) spectroscopy techniques, using transmission electron microscope (TEM) and X ray diffraction (XRD). And influence of different concentrations of reducing agent have been investigated in preparation and optical properties of Au Nanoparticles with Gelatin as a capping agent. These nanomaterials are very promising for making devices with high luminosity in nano dimensions. In addition, since non -toxic and solvent materials are used in synthesis, the integration of these particles into a variety of systems, especially those related to biological and biomedical applications, can be practical and useful.

Polyethylene terephthalate is used in various industries, but due to the lack of functional groups on the surface, it is limited in use and needs surface modification to improve the application. In this study, the surface of PET fibers was first functionalized with carboxylic acid groups. Then, in an alkaline medium, gold nanoparticles were synthesized sonochemically on their surface, and the effect of parameters affecting the size and density of nanoparticles was investigated and optimized (temperature, power of ultrasonic device, and pH). The ability of PET-AuNPs nanocomposites to remove industrial dyes from the environment was used, and the removal and measurement of methyl orange dye from aqueous media were used. The effect of initial dye concentration, time, and pH was investigated and optimized. In quantitative electrochemical dye measurements, the modified AuNPs-PET / CNT / Au electrode had a linear response in the range of 20 to 60 μM. The detection limit of this electrode was 55 μM, and the effect of potential scanning speed on peak flow and the effect of solution pH were investigated. Adsorption equation studies have shown that adsorption follows the obedience isotherm.

In this paper, the preparation of nanoparticles core-shell of gold-silica was carried out by coating of citrated gold particles using the Stöber method and products were investigated by XRD, uv-visible and TEM. In this method, first the nanoparticles were synthesized and then the silica shell was obtained. The results showed that gold nanoparticles have been successfully synthesized and results of transmission electron microscopy showed a particle size of about 20 nm. Preparation of coated gold particles with silica is successfully performed and the results showed a thickness of the shell in order of about 35 nm. The results of the uv-visible spectroscopy of gold nanoparticles and core-shell structure indicate a strong peak at 520 nm, characteristic plasmon peak of the gold particles. However, this peak is more intense for the core-shell structure, which is due to the scattering effect of silica shell having a resonant impact on the peak intensity.

The effect of applying different types of carbon substances including: Norit® activated carbon samples with different physical shapes (i.e., powder, granola and granola, which has powdered), Vulcan carbon (V), CMK-3 mesoporous carbon (C3), CMK-8 mesoporous carbon (C8) and also NCCR-41 mesoporous carbon (C41) as nanocatalysts support on the catalytic activity of small gold nanoparticles (Au101) was studied. These gold nanocatalysts were activated by hot toluene (W) and then heated by constant air flow (S) or under vacuum (V) at 100 °C for 3 h. The highest catalytic activity was exhibited by Au101/C8 (W+S) nanocatalysts at the rate of 96% with approximately 3.3 nm particle size. However, Au101/C41 (wash with hot toluene and then heated under vacuum at 100 °C for 3 h) showed the highest selectivity of methyl benzoate as the major product (S%: 88) during a 3 h reaction time with an approximate 2.6 nm gold particle size. It appears that, the type of carbon support can be considered as an important player in the oxidation of benzyl alcohol in the presence of gold nanocatalysts in addition to the type of activation procures

In this paper, multi-wall carbon nanotubes (MWCNTs), gold nanoparticles (GNp) and glucose oxidase (GOD) was developed for the specific detection of glucose. MWCNTs were chemically modified with the H2SO4–HNO3 preatreated to introduce carboxyl groups which were used to interact with the amino groups of poly allylamine (PAA) and cysteamine via 1-ethyl-3-(3 dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide cross-linking reaction, respectively. A cleaned Pt electrode was immersed in PAA, MWCNTs, cysteamine and GNp, respectively, followed by the adsorption of GOD, assembling the one layer of films on the surface of Pt electrode (GOD/GNp/MWCNTs/Pt electrode) and was used as working electrodes (anode) along with a platinum auxiliary electrode and the reference electrode Ag/AgCl (cathode). Working electrode was containing the phosphate-buffered saline (PBS) with pH= 4, 6 and 8 enzyme. To evaluate the performance of the constructed biosensor, it was put into a dish containing 0.05, 0.5 and 1 mmol/l (mM) glucose concentrations which were dissolved in doubly distilled water. Glucose concentration and pH design has been tested and analyzed by QUALTEK-4 software measure. According to the performed experiments and software analysis, with increasing concentration, the flow rate of current production is increased and pH deviance from neutral range reduces the flow. Optimal conditions was obtained in concentrations 1 mmol/l and pH=6, respectively. After confirmation tests in optimum conditions, the rate of production was obtained, 21.67 mA, which with respect to the expected error rate of application, it was calculated to be 8.1%. This error rate demonstrates that the accuracy of tests is with high sensitivity and accuracy.

Comparison of the effects of two substrates and additives on pulse current electrodeposition of Au nanoparticles showed that using indium-tin oxide instead of Cu and cysteine instead of potassium iodide can improve morphology, current efficiency, photocatalytic effect and increase the number of nanocrystals. The examinations using the field-emission scanning-electron-microscope (FE-SEM) showed that Au nanoclusters appear on the Cu surface when pulse frequency increases from 50 to 142.8 Hz and potassium iodide additive is added, whereas both the coating thickness and the current efficiency increased with the frequency of the pulse current. As current density decreased, the deposition thickness and the cathodic current efficiency decreased from 10 to 2.5 mA/cm2.