Papers by Keyword: Gold Nanoparticles (GNP)

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Authors: Ke Ping Wang, Song Bai Lin, Na Na Wang, Ai Ru Ke
Abstract: A modified seed-mediated growth method was developed for in situ controllable preparation of gold nanoparticles (GNPs) within P(AMPS-co-HEMA) hydrogel networks. When the time of cycles absorbing procedure increased in mother solutions under given temperature during the processing stage, the number of GNPs was significantly increased and networks were utilized for in situ nanoparticles synthesis by reduction of glod ion absorbed. TEM images confirmed that GNPs were between 100 and 200 nm in size and distributed uniformly in gel. The network embedded GNPs also endows the composite gel with selective catalytic activity for selective catalysis in the reduction of nitro compound (2-NP, 3-NP and 4-NP). The kinetics of the reduction reaction were investigated under the same condition, the result showed the GNPs gel system was found to have an excellent catalytic activity and high conversion for 4-NP reduction among nitrophenol homologue, the nitrophenol hydrogenation rate got to 6.63 mol/g min for reducing of 4-NP compared to 3.69 mol/g min, the rate of 2-NP. It was almost zero for 3-NP implying no catalytic activity, even though they were isomeride.
Authors: Da Ming Ban, Ze Quan Liu, Yang Min
Abstract: This perspective reviews recent developments in the adsorption behavior and the adsorption kinetics of gold nanoparticles(AuNPs),with emphasis on papers initiating the developments and with an eye to their consequences. The aspect adsorption behavior of organic molecules on AuNPs have included the adsorption pattern of thionine, 1,4-PDI , 4-Methoxypyr-idine, 1,2,3-triazole and SH-PEG5K and the influence of adsorption. The aspect adsorption characteristics of biomolecules on AuNPs have included the adsorption kinetics of single-stranded DNA and proteins on the AuNPs. The last key aspect adsorption AuNPs on self-assembled monolayers have included the adsorption kinetics of AuNPs on different SAMs and semiconductor crystals.
Authors: Damra E. Mustafa, Hua Fan, Xuan Zhou, Hai Yang Tu, Ai Dong Zhang
Abstract: Non-adsorption of water dispersible gold nanoparticles (GNPs) is a major concern in its widely labeling applications. This paper presents the investigation of the adsorption properties of GNPs with superficially tethered ferrocene functions to different surfaces. The GNPs were coated with a mixed monolayer of PEG-thiol and progargyl PEG-thiol, and the later was linked with a ferrocene moiety (Fc) through the alkyne-azide click reaction. The adsorption behaviors of the Fc-GNP to glassy carbon, gold and platinum electrodes, in the absence and presence of a self-assembled monolayer (SAM) or protein layer, were studied by cyclic voltammetry (CV). It was found that the bare gold electrode possessed higher adsorption capacity. However, the adsorption was either reduced or completely prevented when the gold electrode was modified with monolayers of 2-mercaptoethanol (ME), dodecanethiolate (DT) and PEG-thiol. The electroactive and water dispersible GNPs with Fc labels allows us to use CV to explore the interaction between these GNP and bovine serum albumin (BSA). The BSA modified electrode resulted in better resistant to adsorption compared to other modifiers coated electrodes. Thus, the study of non-specific interaction by CV was found effective when compared to results obtained by surface plasmon resonance (SPR) and FTIR.
Authors: Bin Zheng, Mutsunori Uenuma, Yukiharu Uraoka, Ichiro Yamashita
Abstract: Novel assemblies of gold nanoparticles or gold nanoparticles with other inorganic nanoparticles have received considerable interest due to their fascinating properties desired for various detection applications. Here we present a bioconjugate containing ferritin and gold nanoparticles. In this bioconjugate, there is a central ferritin, and a several gold nanoparticles are located around by DNA base-pairing.
Authors: Geovana Dagostim Savi, Marcos Marques da Silva Paula, Jonathann Corrêa Possato, Tatiana Barichello, Denise Castagnaro, Vildes Maria Scussel
Abstract: Gold nanoparticles (GNP) were synthesized, characterized and their antifungal activities investigated against three pathogenic fungi of different genera and species (Fusarium verticillioides, Penicillium citrinum and Aspergillus flavus). The anti-fungi treatments efficiency of the GNP (concentrations: 0, 0.05, 0.1 and 0.2 mg L-1 in PDA media) were evaluated at 2, 4, 6 and 8 days after incubation by measuring the diameter of fungal colonies and investigating fungi structure alterations by scanning electron microscopy (SEM). It was observed that the GNP concentration increased, fungal colony growth diameter reduced. However, the highest GNP concentration applied in the experiment was not able to completely inhibit fungal growth. The SEM analysis of the fungi structure Au treated showed damaged hyphae and unusual bulges that were not observed in fungi that growth on medium without treatment (Control). Although up to the highest concentration of GNP media applied did not completely inhibited fungi growth, the hyphae modifications led growth reduction which could influence the toxins production by these fungi.
Authors: Panittamat Kumlangdudsana, Luxsana Dubas, Adisorn Tuantranont, Stephan Thierry Dubas
Abstract: A new method has been developed for the determination of carbaryl pesticides, , in water and fruit samples using gold nanoparticles electrode conductivity detection. The effects of pH on the binding between carbaryl and humic acid (HA) and number of layer coated electrode were investigated and optimized. HA modified the polyelectrolyte multilayer thin films (PEMs) coating electrode was used to detect carbaryl. The current was decreased 4.75% after dipping in HA for 10 minutes. The current was decreased around 7.28% from the initial value after HA binding with carbaryl. The results demonstrated that the newly developed method was an efficient procedure for the detection of carbamate pesticides in water.
Authors: Qing Zeng, Ai Hui Liang, Wen Qing Yin, Zhi Liang Jiang
Abstract: In 6 mol/L HCl medium, TeO42- is reduced by NaH2PO2 to Te that catalyze NaH2PO2 reducing HAuCl4 to form gold nanoparticles (AuNPs), which exhibited a strong resonance Rayleigh scattering (RRS) peak at 370 nm. With the TeO42- concentration increased, the catalytic reaction enhanced and formed more AuNPs that resulting in the RRS peak increased. Under the chosen conditions, the RRS intensity at 370 nm enhanced linearly with the concentration of TeO42- in the range of 12.5-287.5 nmol/L. This RRS method was sensitivity, selectivity, and simplicity.
Authors: Raja Aamir, Michael F. Walsh, Stuart P. Lansley, Robert M. Doesburg, Rafidah Zainon, N. J. A. De Ruiter, Philip H. Butler, Anthony P. H. Butler
Abstract: We have been characterizing various sensor layers bump-bonded to Medipix detector chips. We report here characterizationthe leakage current variations of a cadmium telluride (CdTe) assembled-Medipix2 assemblyat different temperatures.Medipix detectors are being used in small animal computed tomography (CT) scanner systems known as MARS-CT. The spectroscopic imaging of a mouse and human atheroma using this system has previously been reported [1-2]. In those reports, Medipix2 detectors were used with Si and GaAs sensor layers, respectively. Cadmium telluride (CdTe) is expected to be a useful sensor layer for clinical CT imaging detectors because of its good detection efficiency for x-rays in the energy range up to 120 keV. However, Aan understanding of the detection characteristics of these sensor layers is vital to high-quality imaging. This work presents the results of inhomogeneities within the CdTe sensor, temperature variations and wrinkle pattern instability.We present leakage current variations with temperature and sensitivity inhomogeneity across the detector. This is an extension of the tests previously reported in Aamir R et al [1][3].
Authors: Juan Zhang, Jiang Yu, Nai Yan Zhang, Pei Liu
Abstract: For different requirements of particle size of syhthesizing nanoparticles, five practical chemical methods have been introduced including two phase method, homogeneous phase method and seeding growth method and so on. And detailed explanation on the experimental operation methods has been given.
Authors: Chong Jin, Hui Min Zhao, Meng Liu, Jun Ping Tian, Xie Quan
Abstract: A simple, fast and reliable colorimetric method for melamine detection based on gold nanoparticles (AuNPs) and poly-thymine (poly-T) is reported. Poly-T strands attract AuNPs through static electricity and keep them stable against aggregation in the presence of NaCl. The affinity between melamine and poly-T, hydrogen bond, frees AuNP from the protection provided by poly-T and thus makes AuNPs aggregate in the presence of NaCl. The color change of AuNPs from wine red to blue can be observed immediately by the naked eye during the aggregation process, and can be accurately recorded with the help of a UV/vis spetrophotometer within 5 minutes. The limit of detection (LOD) of melamine in pure water is 0.146 μmol/L with a linear range from 0.2×10-7 mol/L to 10.0×10-7 mol/L. In fresh milk and milk powder, the LOD is respectively as low as 2.37 μmol/L and 5.36 μmol/L.
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