Pharmacological study of radioactive-gold colloid transport by blood and by serous exudate

International Nuclear Information System (INIS)

Rousselet, J.

1966-06-01

After giving the essential physico-chemical properties of the colloids, the author considers the biological role of these substances and, in connection with their transport by the blood, their capture by elements of the reticula-endothelial system. A summary is given of present knowledge concerning the role of serous proteins in the transport of substances, particularly that of radio-active colloidal gold. The blood fractions which can take part in colloidal gold transport are the red blood corpuscles, the leukocytes and histiocytic elements as well as the plasma. The radioactive distribution in these various fractions is obtained by autoradiography of blood sediments. After showing the importance of the role of the plasma in radioactive particle transport, the author, describes the attempts made to detect a possible of colloidal gold 198 on the various serous proteins using various methods of separation. The ''in vitro'' and ''in vivo'' bonds between colloidal gold-198 particles and either the serous proteins or healthy specimens or the effusion liquids of pathological origin in man, or due to an experimental inflammation with carregenin in the rat, have been studied. The bonding appears to be effective because of the protective macromolecular layer formed by the gelatine. The different positions of the colloidal grains on the electrophoregram can only be explained by their different physico-chemical characteristics. Gold in the ionic form, on the other hand, is combined only with the albumen is the amount metal present does not exceed a certain value. (author) [fr

SERS-barcoded colloidal gold NP assemblies as imaging agents for use in biodiagnostics

Science.gov (United States)

Dey, Priyanka; Olds, William; Blakey, Idriss; Thurecht, Kristofer J.; Izake, Emad L.; Fredericks, Peter M.

2014-03-01

There is a growing need for new biodiagnostics that combine high throughput with enhanced spatial resolution and sensitivity. Gold nanoparticle (NP) assemblies with sub-10 nm particle spacing have the benefits of improving detection sensitivity via Surface enhanced Raman scattering (SERS) and being of potential use in biomedicine due to their colloidal stability. A promising and versatile approach to form solution-stable NP assemblies involves the use of multi-branched molecular linkers which allows tailoring of the assembly size, hot-spot density and interparticle distance. We have shown that linkers with multiple anchoring end-groups can be successfully employed as a linker to assemble gold NPs into dimers, linear NP chains and clustered NP assemblies. These NP assemblies with diameters of 30-120 nm are stable in solution and perform better as SERS substrates compared with single gold NPs, due to an increased hot-spot density. Thus, tailored gold NP assemblies are potential candidates for use as biomedical imaging agents. We observed that the hot-spot density and in-turn the SERS enhancement is a function of the linker polymer concentration and polymer architecture. New deep Raman techniques like Spatially Offset Raman Spectroscopy (SORS) have emerged that allow detection from beneath diffusely scattering opaque materials, including biological media such as animal tissue. We have been able to demonstrate that the gold NP assemblies could be detected from within both proteinaceous and high lipid containing animal tissue by employing a SORS technique with a backscattered geometry.

Subcellular localization of alkaline phosphatase in Bacillus licheniformis 749/C by immunoelectron microscopy with colloidal gold

International Nuclear Information System (INIS)

Tinglu, G.; Ghosh, A.; Ghosh, B.K.

1984-01-01

Subcellular distribution of the alkaline phosphatase of Bacillus licheniformis 749/C was determined by an immunoelectron microscopy method. Anti-alkaline phosphatase antibody labeled with 15- to 18-nm colloidal gold particles (gold-immunoglobulin G [IgG] complex) were used for the study. Both the plasma membrane and cytoplasmic material were labeled with the gold-IgG particles. These particles formed clusters in association with the plasma membrane; in contrast, in the cytoplasm the particles were largely dispersed, and only a few clusters were found. The gold-IgG binding was quantitatively estimated by stereological analysis of labeled, frozen thin sections. This estimation of a variety of control samples showed that the labeling was specific for the alkaline phosphatase. Cluster formation of the gold -IgG particles in association with the plasma membrane suggests that existence of specific alkaline phosphatase binding sites (receptors) in the plasma membrane of B. licheniformis 749/C. 27 references, 6 figures, 1 table

A GoldSim Model for Colloid Facilitated Nuclide Transport

International Nuclear Information System (INIS)

Lee, Youn Myoung; Jeong, Jong Tae

2010-01-01

Recently several total system performance assessment (TSPA) programs, called 'template' programs, ready for the safety assessment of radioactive waste repository systems which are conceptually modeled have been developed by utilizing GoldSim and AMBER at KAERI. It is generally believed that chelating agents (chelators) that could be disposed of together with radioactive wastes in the repository and natural colloids available in the geological media affect on nuclides by enhancing their transport in the geological media. A simple GoldSim module to evaluate such quantitative effects, by which colloid and chelator-facilitated nuclide release cases could be modeled and evaluated is introduced. Effects of the chelators alone are illustrated with the case associated with well pumping scenario in a hypothetical repository system

Optical properties of spherical and oblate spheroidal gold shell colloids

NARCIS (Netherlands)

Penninkhof, J.J.; Moroz, A.; van Blaaderen, A.; Polman, A.

2008-01-01

The surface plasmon modes of spherical and oblate spheroidal core−shell colloids composed of a 312 nm diameter silica core and a 20 nm thick Au shell are investigated. Large arrays of uniaxially aligned core−shell colloids with size aspect ratios ranging from 1.0 to 1.7 are fabricated using a novel

Rapid adhesion and proliferation of keratinocytes on the gold colloid/chitosan film scaffold

International Nuclear Information System (INIS)

Zhang Yi; He Hong; Gao Wenjuan; Lu Shuangyun; Liu Yang; Gu Haiying

2009-01-01

The gold colloid/chitosan film scaffold, which could enhance the attached ratio and accelerate proliferation of newborn mice keratinocytes, was fabricated by nanotechnology and self-assembly technology. This nanometer scaffold was characterized by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The keratinocytes were cultured and observed on three different extracellular matrices (ECM): gold colloid/chitosan film scaffold, chitosan film and cell culture plastic (control groups). 6 h, 12 h, 24 h after inoculation, the cell attached ratios were calculated respectively. In comparison to control groups, this scaffold could significantly (P < 0.01) increase the attached ratio of keratinocytes and promote their growth. Meanwhile, there were not any fusiform fibroblasts growing on this scaffold. The rapidly proliferating keratinocytes were indentified and characterized by immunohistochemistry and transmissive electron microscope (TEM), which showed the cells maintain their biological activity well. The results indicated that gold colloid/chitosan film scaffold was nontoxic to keratinocytes, and was a good candidate for wound dressing in skin tissue engineering.

Synthesis of a colloid solution of silica-coated gold nanoparticles for X-ray imaging applications

Science.gov (United States)

Kobayashi, Yoshio; Nagasu, Ryoko; Shibuya, Kyosuke; Nakagawa, Tomohiko; Kubota, Yohsuke; Gonda, Kohsuke; Ohuchi, Noriaki

2014-08-01

This work proposes a method for fabricating silica-coated gold (Au) nanoparticles, surface modified with poly(ethylene glycol) (PEG) (Au/SiO2/PEG), with a particle size of 54.8 nm. X-ray imaging of a mouse is performed with the colloid solution. A colloid solution of 17.9 nm Au nanoparticles was prepared by reducing Au ions (III) with sodium citrate in water at 80 °C. The method used for silica-coating the Au nanoparticles was composed of surface-modification of the Au nanoparticles with (3-aminopropyl)-trimethoxysilane (APMS) and a sol-gel process. The sol-gel process was performed in the presence of the surface-modified Au nanoparticles using tetraethylorthosilicate, APMS, water, and sodium hydroxide, in which the formation of silica shells and the introduction of amino groups to the silica-coated particles took place simultaneously (Au/SiO2-NH2). Surface modification of the Au/SiO2-NH2 particles with PEG, or PEGylation of the particle surface, was performed by adding PEG with a functional group that reacted with an amino group in the Au/SiO2-NH2 particle colloid solution. A computed tomography (CT) value of the aqueous colloid solution of Au/SiO2/PEG particles with an actual Au concentration of 0.112 M was as high as 922 ± 12 Hounsfield units, which was higher than that of a commercial X-ray contrast agent with the same iodine concentration. Injecting the aqueous colloid solution of Au/SiO2/PEG particles into a mouse increased the light contrast of tissues. A CT value of the heart rose immediately after the injection, and this rise was confirmed for up to 6 h.

Determination of hepatic blood flow through radioactive colloidal gold in congestive heart foilure

International Nuclear Information System (INIS)

Papaleo Netto, M.; Carvalho, N.; Carvalho Filho, E.T.; Forti, N.A.; Giannini, S.D.; Diament, J.; Decourt, L.V.; Chiaverini, R.

1974-01-01

Hepatic blood flow as derermined by radioactive colloidal gold and its correlation with total blood valume are studied in 13 patients with predominantly right-side congestive heart failure. During the phase of cardiac compensation, the following events occur: 1) significant decrease of the half-life of the clearance of radioactive colloidal gold and of the total blood volume; 2) increase of the clearance constant of the radioactive substance and of hepatic blood flow; 3) significantion correlation between the clearance constant and the total blood volume [pt

Colloidal gold probe based rapid immunochromatographic strip assay for cortisol

International Nuclear Information System (INIS)

Nara, Seema; Tripathi, Vinay; Singh, Harpal; Shrivastav, Tulsidas G.

2010-01-01

A rapid and semi-quantitative immunochromatographic strip (ICS) test for cortisol analysis in serum was developed. The test strip was based on a competitive assay format. Colloidal gold nanoparticles were synthesized and coupled with cortisol-3-carboxymethyloxime-adipic acid dihydrazide-bovine serum albumin (F-3-CMO-ADH-BSA) antigen to directly compete with cortisol in human serum samples. F-3-CMO-ADH-BSA-gold label and uncoupled colloidal gold nanoparticles were appropriately characterized using UV-vis spectroscopy, transmission electron microscopy and atomic force microscopy. Anticortisol antibody raised against F-3-CMO-BSA immunogen in New Zealand white rabbits was coated on the NC membrane as test line. Anti-BSA antibody was used as control line. The lower detection limit of the ICS test was 30 ng mL -1 with visual detection and was completed in 10 min. About 30 human serum samples were also analyzed by the developed strip test and their range of cortisol concentration was established. The developed ICS test is rapid, economic and user friendly.

Colloidal gold probe based rapid immunochromatographic strip assay for cortisol

Energy Technology Data Exchange (ETDEWEB)

Nara, Seema, E-mail: seemanara@mnnit.ac.in [Department of Applied Mechanics (Biotechnology), Motilal Nehru National Institute of Technology, Allahabad 211004 (India); Department of Reproductive Biomedicine, National Institute of Health and Family Welfare, Munirka, New Delhi 110067 (India); Center for BioMedical Engineering, Indian Institute of Technology, New Delhi 110016 (India); Tripathi, Vinay [Department of Reproductive Biomedicine, National Institute of Health and Family Welfare, Munirka, New Delhi 110067 (India); Center for BioMedical Engineering, Indian Institute of Technology, New Delhi 110016 (India); Singh, Harpal [Center for BioMedical Engineering, Indian Institute of Technology, New Delhi 110016 (India); Shrivastav, Tulsidas G. [Department of Reproductive Biomedicine, National Institute of Health and Family Welfare, Munirka, New Delhi 110067 (India)

2010-12-03

A rapid and semi-quantitative immunochromatographic strip (ICS) test for cortisol analysis in serum was developed. The test strip was based on a competitive assay format. Colloidal gold nanoparticles were synthesized and coupled with cortisol-3-carboxymethyloxime-adipic acid dihydrazide-bovine serum albumin (F-3-CMO-ADH-BSA) antigen to directly compete with cortisol in human serum samples. F-3-CMO-ADH-BSA-gold label and uncoupled colloidal gold nanoparticles were appropriately characterized using UV-vis spectroscopy, transmission electron microscopy and atomic force microscopy. Anticortisol antibody raised against F-3-CMO-BSA immunogen in New Zealand white rabbits was coated on the NC membrane as test line. Anti-BSA antibody was used as control line. The lower detection limit of the ICS test was 30 ng mL{sup -1} with visual detection and was completed in 10 min. About 30 human serum samples were also analyzed by the developed strip test and their range of cortisol concentration was established. The developed ICS test is rapid, economic and user friendly.

Synthesis and optical properties of Au decorated colloidal tungsten oxide nanoparticles

International Nuclear Information System (INIS)

Tahmasebi, Nemat; Mahdavi, Seyed Mohammad

2015-01-01

Highlights: • Tungsten oxide nanoparticles were prepared by pulsed laser ablation (PLA). • A very fine metallic Au particles or coating are decorated on the surface of tungsten oxide nanoparticles. • UV–Vis spectroscopy shows an absorption peak at ∼530 nm which is due to SPR effect of gold. • After exposing to hydrogen gas, Au/WO_3 colloidal nanoparticles show excellent gasochromic coloring. - Abstract: In this study, colloidal tungsten oxide nanoparticles were fabricated by pulsed laser ablation of tungsten target using the first harmonic of a Nd:YAG laser (1064 nm) in deionized water. After ablation, a 0.33 g/lit HAuCl_4 aqueous solution was added into as-prepared colloidal nanoparticles. In this process, Au"3"+ ions were reduced to decorate gold metallic state (Au"0) onto colloidal tungsten oxide nanoparticles surface. The morphology and chemical composition of the synthesized nanoparticles were studied by AFM, XRD, TEM and XPS techniques. UV–Vis analysis reveals a distinct absorption peak at ∼530 nm. This peak can be attributed to the surface plasmon resonance (SPR) of Au and confirms formation of gold state. Moreover, X-ray photoelectron spectroscopy reveals that Au ions’ reduction happens after adding HAuCl_4 solution into as-prepared colloidal tungsten oxide nanoparticles. Transmission electron microscope shows that an Au shell has been decorated onto colloidal WO_3 nanoparticles. Noble metal decorated tungsten oxide nanostructure could be an excellent candidate for photocatalysis, gas sensing and gasochromic applications. Finally, the gasochromic behavior of the synthesized samples was investigated by H_2 and O_2 gases bubbling into the produced colloidal Au/WO_3 nanoparticles. Synthesized colloidal nanoparticles show excellent coloration contrast (∼80%) through NIR spectra.

Sub-10 nm colloidal lithography for circuit-integrated spin-photo-electronic devices

Directory of Open Access Journals (Sweden)

Adrian Iovan

2012-12-01

Full Text Available Patterning of materials at sub-10 nm dimensions is at the forefront of nanotechnology and employs techniques of various complexity, efficiency, areal scale, and cost. Colloid-based patterning is known to be capable of producing individual sub-10 nm objects. However, ordered, large-area nano-arrays, fully integrated into photonic or electronic devices have remained a challenging task. In this work, we extend the practice of colloidal lithography to producing large-area sub-10 nm point-contact arrays and demonstrate their circuit integration into spin-photo-electronic devices. The reported nanofabrication method should have broad application areas in nanotechnology as it allows ballistic-injection devices, even for metallic materials with relatively short characteristic relaxation lengths.

Inverse gold photonic crystals and conjugated polymer coated opals for functional materials

Energy Technology Data Exchange (ETDEWEB)

Landon, P.B.; Gutierrez, Jose; Ferraris, John P.; Martinez, I.L.; Giridharagopal, Rajiv; Wu, Y.-C.; Lee, Sergey; Parikh, Kunjal; Gillespie, Jessica; Ussery, Geoffrey; Karimi, Behzad; Baughman, Ray; Zakhidov, Anvar; Glosser, R

2003-10-01

Inverse gold photonic crystals templated from synthetic opals with a face centered cubic (FCC) crystal lattice were constructed by heat converting gold chloride to metallic gold. Tetrahedral formations constructed of alternating large and small octahedrons oriented in the zinc sulfide structure were created by controlling the infiltration of gold chloride. Silica spheres were coated with polyanilinesulfonic acid, polypyrrole, poly[2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) and 5 nm colloidal gold. Ordinary yeast cells were coated with polyanilinesulfonic acid, polypyrrole and 5 nm colloidal gold. Spheres coated with MEH-PPV were dispersed in H{sub 2}O and coated with polyelectrolytes which recharged and sterically stabilized the colloidal surfaces. The recharged spheres self-assembled by sedimentation with a FCC crystalline lattice possessing 500 {mu}m wide and 1 mm long crystallites. Silica spheres with diameters as large as 1500 {mu}m were self-assembled along the [1 0 0] direction of the FCC crystal lattice. Opals infiltrated with gold and opals constructed from polymer coated spheres were co-infiltrated with polypropylene yielding inverse polypropylene composite photonic crystals.

Reversible peptide oligomerization over nanoscale gold surfaces

Directory of Open Access Journals (Sweden)

Kazushige Yokoyama

2015-11-01

Full Text Available A selective oligomeric formation of amyloid beta 1-40 (Ab1-40 monomers over a nanogold colloidal surface was investigated. An unfolded Ab1-40 monomer is considered to construct a dimer or trimer based oligomeric form with its hydrophobic segment placing outward under an acidic condition. Under a basic condition, a conformation of Ab is expected to take a folded monomeric form with its hydrophilic segment folded inward, avoiding the networking with residual colloidal particles. The most probable oligomeric form constructed over a 20 nm gold colloidal surface within a 25 ℃ to 65 ℃ temperature range is a dimer based unit and that over 30 or 40 nm gold colloidal surface below 15 ℃ is concluded to be a trimer based unit. However, selective oligomerization was not successfully reproduced under the rest of the conditions. A dipole-induced dipole interaction must cause a flexible structural change between folded and unfolded forms.

Development of Colloidal Gold-Based Immunochromatographic Assay for Rapid Detection of Goose Parvovirus

Directory of Open Access Journals (Sweden)

Xianglong Yu

2018-05-01

Full Text Available Goose parvovirus (GPV remains as a worldwide problem in goose industry. For this reason, it is necessary to develop a new diagnostic approach that is easier and faster than conventional tests. A rapid immunochromatographic assay based on antibody colloidal gold nanoparticles specific to GPV was developed for the detection of GPV in goose allantoic fluid and supernatant of tissue homogenate. The monoclonal antibodies (Mab was produced by immunizing the BALB/c mice with purified GPV suspension, and the polyclonal antibody (pAb was produced by immunizing the rabbits with recombinant VP3 protein. The colloidal gold was prepared by the reduction of gold salt with sodium citrate coupled with Mab against GPV. The optimal concentrations of the coating antibody and capture antibody were determined to be 1.6 mg/ml and 9 μg/ml. With visual observation, the lower limit was found to be around 1.2 μg/ml. Common diseases of goose were tested to evaluate the specificity of the immune colloidal gold (ICG strip, and no cross-reaction was observed. The clinical detection was examined by carrying out the ICG strip test with 92 samples and comparing the results of these tests with those obtained via agar diffusion test and polymerase chain reaction (PCR test. Therefore, the ICG strip test was a sufficiently sensitive and accurate detection method for a rapid screening of GPV.

Prophylaxis of meningosis leukemia via intrathecal radioactive colloid gold injection

Energy Technology Data Exchange (ETDEWEB)

Angelov, A; Uzunov, I; Marshavelova, J [Meditsinski Fakultet, Plovdiv (Bulgaria)

1979-01-01

Prophylaxis against meningosis leukemia (ML) via intrathecal radioactive colloid gold injection was carried out for a period of three years (January 1974 - September 1976) in 21 children with acute lymphoblast leukemia (ALL). The analysis of those patients after one relatively long period of observation (28 months after the last case) reveals that ML developed as a primary isolated manifestation of a recurrence in three children, i.e. in 14.2 per cent versus 68 per cent in the control group without prophylaxis. In another child ML development is in parallel with bone marrow recurrence. The reduction of ML incidence is accompanied with a prolongation of the first remission (in 24 per cent over 2 years and 6 months) and a lengthening of survival for 50 per cent of the patients (62 per cent of the treated patients are alive two years and 4 months during the period of observation). The advantages of the prophylaxis with radioactive colloid gold is emphasized in comparison with the other prophylactic programmes.

Deposition of gold nanoparticles from colloid on TiO2 surface

Science.gov (United States)

Rehacek, Vlastimil; Hotovy, Ivan

2017-11-01

In this paper, experimental results are presented on the deposition of colloidal gold nanoparticles on the surfaces of TiO2 prepared on silicon/silicon dioxide. Important procedures, such as titanium dioxide surface hydrophilization as well as functionalization by an organosilane coupling agent (3-aminopropyl) trimethoxysilane and (3-mercaptopropyl) trimethoxysilane were investigated in order to obtain a metal oxide surface with the most convenient properties for immobilization of gold nanoparticles having a dense and uniform distribution. TiO2 nanotips prepared by reactive ion etching of oxide surface covered with self-mask gold nanoparticles are demonstrated.

Development of a colloidal gold immunochromatographic strip for rapid detection of Streptococcus agalactiae in tilapia.

Science.gov (United States)

Wen-de, Wu; Min, Li; Ming, Chen; Li-Ping, Li; Rui, Wang; Hai-Lan, Chen; Fu-Yan, Chen; Qiang, Mi; Wan-Wen, Liang; Han-Zhong, Chen

2017-05-15

A colloidal gold immunochromatographic strip was developed for rapid detection of Streptococcus agalactiae (S. agalactiae) infection in tilapia. The monoclonal antibodies (mAb) 4C12 and 3A9 were used to target S. agalactiae as colloidal gold-mAb conjugate and captured antibody, respectively. The colloidal gold immunochromatographic strip was assembled via routine procedures. Optimal pH and minimum antibody levels in the reaction system for gold colloidal-mAb 4C12 conjugation were pH 7.4 and 18μg/mL, respectively. Optimal concentrations of the captured antibody 3A9 and goat anti-mouse antibody were 0.6mg/mL and 2mg/mL, respectively. The sensitivity of the strip for detecting S. agalactiae was 1.5×10 5 colony forming units (CFU). No cross-reaction was observed with other commonly encountered bacteria, including Pseudomonas fluorescens, Aeromonas hydrophila, Vibrio anguillarum and Streptococcus iniae. The assay time for S. agalactiae was less than 15min. Tilapia samples artificially infected with S. agalactiae were tested using the newly developed strip. The results indicated that blood, brain, kidney, spleen, metanephros and intestine specimens of infected fish can be used for S. agalactiae detection. The validity of the strip was maintained for 6 months at 4°C. These findings suggested that the immunochromatographic strip was effective for spot and rapid detection of S. agalactiae infected tilapia. Copyright © 2016 Elsevier B.V. All rights reserved.

[Biosynthesis of gold nanoparticles by Azospirillum brasilense].

Science.gov (United States)

Kupriashina, M A; Vetchinkina, E P; Burov, A M; Ponomareva, E G; Nikitina, V E

2014-01-01

Plant-associated nitrogen-fixing soil bacteria Azospirillum brasilense were shown to reduce the gold of chloroauric acid to elemental gold, resulting in formation of gold nanoparicles. Extracellular phenoloxidizing enzymes (laccases and Mn peroxidases) were shown to participate in reduction of Au+3 (HAuCl4) to Au(0). Transmission electron microscopy revealed accumulation of colloidal gold nanoparticles of diverse shape in the culture liquid of A. brasilense strains Sp245 and Sp7. The size of the electron-dense nanospheres was 5 to 50 nm, and the size of nanoprisms varied from 5 to 300 nm. The tentative mechanism responsible for formation of gold nanoparticles is discussed.

A novel colloidal gold labeled antigen for the detection of Deoxynivalenol using an immunochromatographic assay method

Science.gov (United States)

Jin, Yu; Liu, Renrong; Zhu, Lixin; Chen, Zhenzhen

2017-11-01

In this paper, an immunochromatographic assay card was developed for the detection of DON in feed and cereals using a novel colloidal gold labeling method. For the colloidal gold immunochromatographic rapid detection (GICD) card, a monoclonal antibody DON-mAb and a goat anti-chicken IgY were drawn on NC membrane as the test line (T line) and the control line (C line) respectively. A gold labeled DON-CBSA conjugate and a gold labeled chicken IgY were sprayed onto the conjugate pad. The GICD card has cut-off levels of 50ng/mL for DON, which is invulnerable to matrix interference, and applicable to a wide range of samples. The GICD detecting results of feed and grain samples were compared with the results of ELISA testing, which showed good consistency.

Colloidal Gold--Collagen Protein Core--Shell Nanoconjugate: One-Step Biomimetic Synthesis, Layer-by-Layer Assembled Film, and Controlled Cell Growth.

Science.gov (United States)

Xing, Ruirui; Jiao, Tifeng; Yan, Linyin; Ma, Guanghui; Liu, Lei; Dai, Luru; Li, Junbai; Möhwald, Helmuth; Yan, Xuehai

2015-11-11

The biogenic synthesis of biomolecule-gold nanoconjugates is of key importance for a broad range of biomedical applications. In this work, a one-step, green, and condition-gentle strategy is presented to synthesize stable colloidal gold-collagen core-shell nanoconjugates in an aqueous solution at room temperature, without use of any reducing agents and stabilizing agents. It is discovered that electrostatic binding between gold ions and collagen proteins and concomitant in situ reduction by hydroxyproline residues are critically responsible for the formation of the core-shell nanoconjugates. The film formed by layer-by-layer assembly of such colloidal gold-collagen nanoconjugates can notably improve the mechanical properties and promote cell adhesion, growth, and differentiation. Thus, the colloidal gold-collagen nanoconjugates synthesized by such a straightforward and clean manner, analogous to a biomineralization pathway, provide new alternatives for developing biologically based hybrid biomaterials toward a range of therapeutic and diagnostic applications.

The green synthesis of gold nanoparticles using the ethanol extract pf black tea and its tannin free fraction

International Nuclear Information System (INIS)

Banoee, M.; Mokhtari, N.; Akhavan Sepahi, A.; Jafari Fesharaki, P.; Monsef-Esfahani, H. R.; Ehsanfar, Z.; Khoshayand, M. R.; Shahverdi, A. R.

2010-01-01

In this research the ethanol extract of black tea and its tannin free fraction used for green synthesis of gold nanoparticles. All the extracts were used separately for the synthesis of gold nanoparticles through the reduction of aqueous AuCl 4 - . Transmission electron microscopy and visible absorption spectroscopy confirmed the reduction of gold ions to gold nanoparticles. The ethanol extract of black tea and its tannin free ethanol extract produced gold nanoparticles in the size ranges of 2.5-27.5 nm and 1.25-17.5 nm with an average size of 10 nm and 3 nm, respectively. The prepared colloid gold nanoparticles, using the ethanol extract of black tea, did not show the appropriate stability during storage time (24 hours) at 4 d eg C . In contrast, gold colloids, which were synthesized by a tannin free fraction showed no particle aggregation during short and long storage times at the same conditions. To the best of our knowledge, this is the first report on the rapid synthesis of gold nanoparticles using ethanol extract of black tea and its tannin free fraction.

Optical Properties of Linoleic Acid Protected Gold Nanoparticles

Directory of Open Access Journals (Sweden)

Ratan Das

2011-01-01

Full Text Available Linoleic acid-protected gold nanoparticles have been synthesized through the chemical reduction of tetrachloroaurate ions by ethanol in presence of sodium linoleate. The structure of these nanoparticles is investigated using transmission electron microscopy, which shows that the Au nanoparticles are spherical in shape with a narrow size distribution which ranges from 8 to 15 nm. Colloidal dispersion of gold nanoparticles in cyclohexane exhibits absorption bands in the ultraviolet-visible range due to surface plasmon resonance, with absorption maximum at 530 nm. Fluorescence spectra of gold nanoparticles also show an emission peak at 610 nm when illuminated at 450 nm. UV-Vis spectroscopy reveals that these nanoparticles remain stable for 10 days.

Photochemical Synthesis and Properties of Colloidal Copper, Silver and Gold Adsorbed on Quartz

International Nuclear Information System (INIS)

Loginov, Anatoliy V.; Gorbunova, Valentina V.; Boitsova, Tatiana B.

2002-01-01

Original methods for the photochemical production of stable copper, silver and gold colloids in the form of films on quartz, and dispersion in liquids were devised. It is shown that photochemical synthesis of colloidal metals is a difficult multiphase process, and includes the formation of low-valence forms of Cu(I), Au(I) and nonmetal clusters, colloidal particles and their agglomerates. Cluster stabilization and further growth to colloidal particles are achieved by adsorption onto the solid surface (quartz) or by increasing the viscosity of photolyte. In the absence of these methods of stabilization, the processes of intermediate reoxidation to Cu(II) and Au(III) and agglomeration of Ag and Au colloids proceed in a photolyte. Adsorption and the rate of cluster growth on a quartz surface are speeded up by the action of monochromatic UV light. Experimental models of the mechanism of colloidal formation are suggested. The dependence of the growth rate and the properties of the colloids on conditions of the photochemical procedure (energy and light intensity, concentration of initial complex) has been established

One-Step Synthesis of PEGylated Gold Nanoparticles with Tunable Surface Charge

Directory of Open Access Journals (Sweden)

Rares Stiufiuc

2013-01-01

Full Text Available The present work reports a rapid, simple and efficient one-step synthesis and detailed characterisation of stable aqueous colloids of gold nanoparticles (AuNPs coated with unmodified poly(ethyleneglycol (PEG molecules of different molecular weights and surface charges. By mixing and heating aqueous solutions of PEG with variable molecular chain and gold(III chloride hydrate (HAuCl4 in the presence of NaOH, we have successfully produced uniform colloidal 5 nm PEG coated AuNPs of spherical shape with tunable surface charge and an average diameter of 30 nm within a few minutes. It has been found out that PEGylated AuNPs provide optical enhancement of the characteristic vibrational bands of PEG molecules attached to the gold surface when they are excited with both visible (532 nm and NIR (785 nm laser lines. The surface enhanced Raman scattering (SERS signal does not depend on the length of the PEG molecular chain enveloping the AuNPs, and the stability of the colloid is not affected by the addition of concentrated salt solution (0.1 M NaCl, thus suggesting their potential use for in vitro and in vivo applications. Moreover, by gradually changing the chain length of the biopolymer, we were able to control nanoparticles’ surface charge from −28 to −2 mV, without any modification of the Raman enhancement properties and of the colloidal stability.

A Portable Colloidal Gold Strip Sensor for Clenbuterol and Ractopamine Using Image Processing Technology

Directory of Open Access Journals (Sweden)

Yi Guo

2013-01-01

Full Text Available A portable colloidal golden strip sensor for detecting clenbuterol and ractopamine has been developed using image processing technology, as well as a novel strip reader has achieved innovatively with this imaging sensor. Colloidal gold strips for clenbuterol and ractopamine is used as first sensor with given biomedical immunication reaction. After three minutes the target sample dropped on, the color showing in the T line is relative to the content of objects as clenbuterol, this reader can finish many functions like automatic acquit ion of colored strip image, quantatively analysis of the color lines including the control line and test line, and data storage and transfer to computer. The system is integrated image collection, pattern recognition and real-time colloidal gold quantitative measurement. In experiment, clenbuterol and ractopamine standard substance with concentration from 0 ppb to 10 ppb is prepared and tested, the result reveals that standard solutions of clenbuterol and ractopamine have a good secondary fitting character with color degree (R2 is up to 0.99 and 0.98. Besides, through standard sample addition to the object negative substance, good recovery results are obtained up to 98 %. Above all, an optical sensor for colloidal strip measure is capable of determining the content of clenbuterol and ractopamine, it is likely to apply to quantatively identifying of similar reaction of colloidal golden strips.

Establishment of colloid gold immunity chromatography assay for cardiac troponin I (cTnI)

International Nuclear Information System (INIS)

Wang Dezhi; Chen Jiying; Qin Lili; Zhao Baojian; Zhang Chunming

2006-01-01

Objective: To establish the colloid gold Immunity chromatography assay for cardiac troponin I. Methods: To purify cTnI from human cardiac muscle and immunize rabbit with it. cTnI antibody of rabbit anti-human cardiac muscle has been prepared and colloid gold immunity chromatography assay was established by using immunity chromatography technology. Results: Anti-serum titles of cTnI were 1:100000, Ka=2.38 x 10 9 L/mol; Methodological index: Sensitivity: 5 ng/ml; Specificity: cTnI is no cross-reaction with cTnT, cTnC and CK-MB. conclusion: The assay is highly specific, quick and simple. It can be widely used for the early diagnosis of AMI and scientific research. (authors)

The electrical double layer on gold probed by electrokinetic and surface force measurements

NARCIS (Netherlands)

Giesbers, M.; Kleijn, J.M.; Cohen Stuart, M.A.

2002-01-01

Gold surfaces, obtained by vacuum deposition of 15-nm gold films on glass and silica wafers, were studied in aqueous solutions by streaming potential measurements and colloidal-probe AFM force measurements. In the force measurements both a bare and a gold-coated silica particle (6 m in diameter)

Heparin Assisted Photochemical Synthesis of Gold Nanoparticles and Their Performance as SERS Substrates

Science.gov (United States)

Rodríguez-Torres, Maria del Pilar; Díaz-Torres, Luis Armando; Romero-Servin, Sergio

2014-01-01

Reactive and pharmaceutical-grade heparins were used as biologically compatible reducing and stabilizing agents to photochemically synthesize colloidal gold nanoparticles. Aggregates and anisotropic shapes were obtained photochemically under UV black-light lamp irradiation (λ = 366 nm). Heparin-functionalized gold nanoparticles were characterized by Scanning Electron Microscopy and UV-Vis spectroscopy. The negatively charged colloids were used for the Surface Enhanced Raman Spectroscopy (SERS) analysis of differently charged analytes (dyes). Measurements of pH were taken to inspect how the acidity of the medium affects the colloid-analyte interaction. SERS spectra were taken by mixing the dyes and the colloidal solutions without further functionalization or addition of any aggregating agent. PMID:25342319

In situ growth of hollow gold-silver nanoshells within porous silica offers tunable plasmonic extinctions and enhanced colloidal stability.

Science.gov (United States)

Li, Chien-Hung; Jamison, Andrew C; Rittikulsittichai, Supparesk; Lee, Tai-Chou; Lee, T Randall

2014-11-26

Porous silica-coated hollow gold-silver nanoshells were successfully synthesized utilizing a procedure where the porous silica shell was produced prior to the transformation of the metallic core, providing enhanced control over the structure/composition of the bimetallic hollow core. By varying the reaction time and the precise amount of gold salt solution added to a porous silica-coated silver-core template solution, composite nanoparticles were tailored to reveal a readily tunable surface plasmon resonance that could be centered across the visible and near-IR spectral regions (∼445-800 nm). Characterization by X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, scanning electron microscopy, and transmission electron microscopy revealed that the synthetic methodology afforded particles having uniform composition, size, and shape. The optical properties were evaluated by absorption/extinction spectroscopy. The stability of colloidal solutions of our composite nanoparticles as a function of pH was also investigated, revealing that the nanoshells remain intact over a wide range of conditions (i.e., pH 2-10). The facile tunability, enhanced stability, and relatively small diameter of these composite particles (∼110 nm) makes them promising candidates for use in tumor ablation or as photothermal drug-delivery agents.

Colorimetric detection of Ehrlichia canis via nucleic acid hybridization in gold nano-colloids.

Science.gov (United States)

Muangchuen, Ajima; Chaumpluk, Piyasak; Suriyasomboon, Annop; Ekgasit, Sanong

2014-08-08

Canine monocytic ehrlichiosis (CME) is a major thick-bone disease of dog caused by Ehrlichia canis. Detection of this causal agent outside the laboratory using conventional methods is not effective enough. Thus an assay for E. canis detection based on the p30 outer membrane protein gene was developed. It was based on the p30 gene amplification using loop-mediated isothermal DNA amplification (LAMP). The primer set specific to six areas within the target gene were designed and tested for their sensitivity and specificity. Detection of DNA signals was based on modulation of gold nanoparticles' surface properties and performing DNA/DNA hybridization using an oligonucleotide probe. Presence of target DNA affected the gold colloid nanoparticles in terms of particle aggregation with a plasmonic color change of the gold colloids from ruby red to purple, visible by the naked eye. All the assay steps were completed within 90 min including DNA extraction without relying on standard laboratory facilities. This method was very specific to target bacteria. Its sensitivity with probe hybridization was sufficient to detect 50 copies of target DNA. This method should provide an alternative choice for point of care control and management of the disease.

Influence of the pH value of a colloidal gold solution on the absorption spectra of an LSPR-assisted sensor

International Nuclear Information System (INIS)

Zhu, Jin; Li, Wenbin; Zhu, Mao; Zhang, Wei; Niu, Wencheng; Liu, Guohua

2014-01-01

The localized surface plasmon resonances (LSPRs) of gold particles assembled on a crystal plate are a powerful tool for biological sensors. Here, we prepare gold colloids in different pH solutions. We monitor the effects of the particle radius and particle coverage on the absorption spectra of AT-cut (r-face dihedral angle of about 3°) crystal plates supporting gold nanoparticles. The surface morphologies were monitored on silicon dioxide substrates using ultraviolet and visible (UV-vis) spectroscopy, and atomic force microscopy (AFM). The results showed that the gold particle coverage decreases with increasing pH value of the gold colloid solution. This phenomenon demonstrates that self-assembled gold surfaces were formed via the electrostatic adsorption of gold particles on the positively charged, ionized amino groups on the crystal plates in the acidic solution. The spectrum of gold nanoparticles with different coverage degree on the crystal plates showed that the LSPR properties are highly dependent on pH

Preparation of gold nanoparticles for plasmonic applications

Energy Technology Data Exchange (ETDEWEB)

Benkovicova, Monika, E-mail: monika.benkovicova@savba.sk [Institute of Physics SAS, Dubravska cesta 9, 845 11 Bratislava (Slovakia); Polymer Institute SAS, Dubravska cesta 9, 845 41 Bratislava (Slovakia); Vegso, Karol; Siffalovic, Peter; Jergel, Matej; Luby, Stefan; Majkova, Eva [Institute of Physics SAS, Dubravska cesta 9, 845 11 Bratislava (Slovakia)

2013-09-30

We present a simple hot injection method for the preparation of colloidal solutions of hydrophobic spherical gold nanoparticles with the diameter around 20 nm and size dispersion below 20%. Various surfactants with different lengths of hydrocarbon chains, such as oleylamine, 1-octadecanethiol, poly (N-vinylpyrrolidone), and AgNO{sub 3} in 1,5-pentanediol, were used for sterical stabilization in the colloidal solution. The hydrodynamic nanoparticle size and size dispersion were determined by the dynamic light scattering (DLS) while the small-angle X-ray scattering (SAXS) from the colloidal solution provided information on the size of the metallic nanoparticle core (without surfactant). Plasmon enhanced resonant absorption peaks between 500 nm and 600 nm were detected by the UV–VIS spectrophotometry. The nanoparticle arrays on silicon prepared by solvent evaporation or Langmuir-Schaefer method were inspected by high-resolution scanning electron microscopy and grazing-incidence SAXS (GISAXS). The presence of side maxima in the GISAXS pattern gives evidence of the nanoparticle ordering by self-assembly while very close values of the interparticle distance derived from GISAXS and the nanoparticle size derived from DLS indicate a close-packed order. - Highlights: ► Preparation of gold nanoparticles by use a various of surfactants ► Preparation of monodisperse nanoparticles ► Characterization of nanoparticles on a solid substrate.

Single step synthesis and organization of gold colloids assisted by copolymer templates

Science.gov (United States)

Sarrazin, Aurélien; Gontier, Arthur; Plaud, Alexandre; Béal, Jérémie; Yockell-Lelièvre, Hélène; Bijeon, Jean-Louis; Plain, Jérôme; Adam, Pierre-Michel; Maurer, Thomas

2014-06-01

We report here an original single-step process for the synthesis and self-organization of gold colloids by simply incorporating gold salts into a solution prepared using polystyrene (PS)-polymethylmethacrylate copolymer and thiolated PS with propylene glycol methyl ether acetate as a solvent. The spin-coating and annealing of this solution then allows the formation of PS domains. Depending on the polymer concentration of the as-prepared solution, there can be either one or several gold nanoparticles (Au NPs) per PS domain. For high concentrations of Au NPs in PS domains, the coupling between plasmonic NPs leads to the observation of a second peak in the optical extinction spectrum. Such a collective effect could be relevant for the development of optical strain sensors in the near future.

Liver function evaluation in leptospirosis with colloidal gold 1 9 8 Au

Directory of Open Access Journals (Sweden)

Walber Miranda Silva

1977-12-01

Full Text Available Eight patients with leptospirosis were studied with colloidal gold 1 9 8 Au. The radiocolloidal hepatic distribution was altered, presenting a non-homogeneous tiver concentration in seven cases, and a minute to moderate splenic visualization in five. Two patients presented doubtful splenic image, and one seemed to be normal. Liver scanning with colloidal gold 1 9 8 Au is demonstra ted to be a good liver function test.Oito pacientes com Leptospirose foram investigados com ouro coloidal radioativo (1 9 8 Au. A distribuição intrahepática do radiocoloide era alterada, apresentando uma concentração hepática não-homogênea em 7 casos, e visualização esp/ênica de mínima a moderada em 5. Dois tinham dúvida quanto à imagem do baço, e um parecia normal. A cintigrafia hepática com ouro coloidai radioativo (1 9 8 Au é demonstrada ser um bom teste de função hepática.

Current state and prospects of the phytosynthesized colloidal gold nanoparticles and their applications in cancer theranostics.

Science.gov (United States)

Ovais, Muhammad; Raza, Abida; Naz, Shagufta; Islam, Nazar Ul; Khalil, Ali Talha; Ali, Shaukat; Khan, Muhammad Adeeb; Shinwari, Zabta Khan

2017-05-01

The design, development, and biomedical applications of phytochemical-based green synthesis of biocompatible colloidal gold nanoparticles (AuNPs) are becoming an emerging field due to several advantages (safer, eco-friendly, simple, fast, energy efficient, low-cost, and less toxic) over conventional chemical synthetic procedures. Biosynthesized colloidal gold nanoparticles are remarkably attractive in several biomedical applications including cancer theranostics due to small size, unusual physico-chemical properties, facile surface modification, high biocompatibility, and numerous other advantages. Of late, several researchers have investigated the biosynthesis and prospective applications (diagnostics, imaging, drug delivery, and cancer therapeutics) of AuNPs in health care and medicine. However, not a single review article is available in the literature that demonstrates the anti-cancer potential of biosynthesized colloidal AuNPs with detailed mechanistic study. In the present review article, we for the first time discuss the biointerface of colloidal AuNPs, plants, and cancer mainly (i) comprehensive mechanistic aspects of phytochemical-based synthesis of AuNPs; (ii) proposed anti-cancer mechanisms along with biomedical applications in diagnostics, imaging, and drug delivery; and (iii) key challenges for biogenic AuNPs as future cancer nanomedicine.

GOLD CLUSTER LABELS AND RELATED TECHNOLOGIES IN MOLECULAR MORPHOLOGY.

Energy Technology Data Exchange (ETDEWEB)

HAINFELD,J.F.; POWELL,R.D.

2004-02-04

Although intensely colored, even the largest colloidal gold particles are not, on their own, sufficiently colored for routine use as a light microscopy stain: only with very abundant antigens or with specialized illumination methods can bound gold be seen. Colloidal gold probes were developed primarily as markers for electron microscopy, for which their very high electron density and selectivity for narrow size distributions when prepared in different ways rendered them highly suited. The widespread use of gold labeling for light microscopy was made possible by the introduction of autometallographic enhancement methods. In these processes, the bound gold particles are exposed to a solution containing metal ions and a reducing agent; they catalyze the reduction of the ions, resulting in the deposition of additional metal selectively onto the particles. On the molecular level, the gold particles are enlarged up to 30-100 nm in diameter; on the macroscale level, this results in the formation of a dark stain in regions containing bound gold particles, greatly increasing visibility and contrast. The applications of colloidal gold have been described elsewhere in this chapter, we will focus on the use of covalently linked cluster complexes of gold and other metals. A gold cluster complex is a discrete molecular coordination compound comprising a central core, or ''cluster'' of electron-dense metal atoms, ligated by a shell of small organic molecules (ligands), which are linked to the metal atoms on the surface of the core. This structure gives clusters several important advantages as labels. The capping of the metal surface by ligands prevents non-specific binding to cell and tissue components, which can occur with colloidal gold. Cluster compounds are more stable and may be used under a wider range of conditions. Unlike colloidal gold, clusters do not require additional macromolecules such as bovine serum albumin or polyethylene glycol for

Single step synthesis and organization of gold colloids assisted by copolymer templates

International Nuclear Information System (INIS)

Sarrazin, Aurélien; Gontier, Arthur; Plaud, Alexandre; Béal, Jérémie; Yockell-Lelièvre, Hélène; Bijeon, Jean-Louis; Plain, Jérôme; Adam, Pierre-Michel; Maurer, Thomas

2014-01-01

We report here an original single-step process for the synthesis and self-organization of gold colloids by simply incorporating gold salts into a solution prepared using polystyrene (PS)-polymethylmethacrylate copolymer and thiolated PS with propylene glycol methyl ether acetate as a solvent. The spin-coating and annealing of this solution then allows the formation of PS domains. Depending on the polymer concentration of the as-prepared solution, there can be either one or several gold nanoparticles (Au NPs) per PS domain. For high concentrations of Au NPs in PS domains, the coupling between plasmonic NPs leads to the observation of a second peak in the optical extinction spectrum. Such a collective effect could be relevant for the development of optical strain sensors in the near future. (papers)

Femtosecond laser generated gold nanoparticles and their plasmonic properties

International Nuclear Information System (INIS)

Das, Rupali; Navas, M. P.; Soni, R. K.

2016-01-01

The pulsed laser ablation in liquid medium is now commonly used to generate stable colloidal nanoparticles (NPs) in absence of any chemical additives or stabilizer with diverse applications. In this paper, we report generation of gold NPs (Au NPs) by ultra-short laser pulses. Femtosecond (fs) laser radiation (λ = 800 nm) has been used to ablate a gold target in pure de-ionized water to produce gold colloids with smallsize distribution. The average size of the particles can be further controlled by subjecting to laser-induced post-irradiation providing a versatile physical method of size-selected gold nanoparticles. The optical extinction and morphological dimensions were investigated with UV-Vis spectroscopy and Transmission Electron Microscopy measurements, respectively. Finite difference time domain (FDTD) method is employed to calculate localized surface plasmon (LSPR) wavelength and the near-field generated by Au NPs and their hybrids.

Acute toxicity and pharmacokinetics of 13 nm-sized PEG-coated gold nanoparticles

International Nuclear Information System (INIS)

Cho, Wan-Seob; Cho, Minjung; Jeong, Jinyoung; Choi, Mina; Cho, Hea-Young; Han, Beom Seok; Kim, Sheen Hee; Kim, Hyoung Ook; Lim, Yong Taik; Chung, Bong Hyun; Jeong, Jayoung

2009-01-01

In general, gold nanoparticles are recognized as being as nontoxic. Still, there have been some reports on their toxicity, which has been shown to depend on the physical dimension, surface chemistry, and shape of the nanoparticles. In this study, we carry out an in vivo toxicity study using 13 nm-sized gold nanoparticles coated with PEG (MW 5000). In our findings the 13 nm sized PEG-coated gold nanoparticles were seen to induce acute inflammation and apoptosis in the liver. These nanoparticles were found to accumulate in the liver and spleen for up to 7 days after injection and to have long blood circulation times. In addition, transmission electron microscopy showed that numerous cytoplasmic vesicles and lysosomes of liver Kupffer cells and spleen macrophages contained the PEG-coated gold nanoparticles. These findings of toxicity and kinetics of PEG-coated gold nanoparticles may have important clinical implications regarding the safety issue as PEG-coated gold nanoparticles are widely used in biomedical applications

Nature vs. nurture: gold perpetuates "stemness".

Science.gov (United States)

Paul, Willi; Sharma, Chandra P; Deb, Kaushik Dilip

2011-01-01

Adult tissues contain quiescent reservoirs of multipotent somatic stem cells and pluripotent embryonic-like stem cells (ELSCs). Credited with regenerative properties gold is used across both -contemporary and -ancient medicines. Here, we show that gold exerted these effects by enhancing the pool of pluripotent ELSC while improving their stemness. We used hESCs as an in-vitro model to understand if gold could enhance self-renewal and pluripotency. Swarna-bhasma (SB), an ancient Indian gold microparticulate (41.1 nm), preparation, reduced spontaneous-differentiation, improved self-renewal, pluripotency and proliferation of hESCs. Colloidal gold-nanoparticles (GNP) (15.59 nm) were tested to confirm that the observations were attributable to nanoparticulate-gold. SB and GNP exposure: maintained -stemness, -karyotypic stability, enhanced pluripotency till day-12, increased average colony-sizes, and reduced the number of autonomously-derived differentiated FGFR1 positive fibroblast-niche-cells/colony. Particulate-gold induced upregulation of FGFR1 and IGF2 expression, and decrease in IGF1 secretion indicates IGF1/2 mediated support for enhanced pluripotency and self-renewal in hESCs.

Colloid Transport and Retention

DEFF Research Database (Denmark)

Yuan, Hao; Shapiro, Alexander

2012-01-01

related to historical prospective, synthesis, characterization, theoretical modeling and application of unique class of colloidal materials starting from colloidal gold to coated silica colloid and platinum, titania colloids. This book is unique in its design, content, providing depth of science about...

On the Enhanced Antibacterial Activity of Antibiotics Mixed with Gold Nanoparticles

Directory of Open Access Journals (Sweden)

Shantrokha AN

2009-01-01

Full Text Available Abstract The bacterial action of gentamicin and that of a mixture of gentamicin and 15-nm colloidal-gold particles onEscherichia coliK12 was examined by the agar-well-diffusion method, enumeration of colony-forming units, and turbidimetry. Addition of gentamicin to colloidal gold changed the gold color and extinction spectrum. Within the experimental errors, there were no significant differences in antibacterial activity between pure gentamicin and its mixture with gold nanoparticles (NPs. Atomic absorption spectroscopy showed that upon application of the gentamicin-particle mixture, there were no gold NPs in the zone of bacterial-growth suppression in agar. Yet, free NPs diffused into the agar. These facts are in conflict with the earlier findings indicating an enhancement of the bacterial activity of similar gentamicin–gold nanoparticle mixtures. The possible causes for these discrepancies are discussed, and the suggestion is made that a necessary condition for enhancement of antibacterial activity is the preparation of stable conjugates of NPs coated with the antibiotic molecules.

Hydrothermal synthesis of histidine-functionalized single-crystalline gold nanoparticles and their pH-dependent UV absorption characteristic.

Science.gov (United States)

Liu, Zhiguo; Zu, Yuangang; Fu, Yujie; Meng, Ronghua; Guo, Songling; Xing, Zhimin; Tan, Shengnan

2010-03-01

L-Histidine capped single-crystalline gold nanoparticles have been synthesized by a hydrothermal process under a basic condition at temperature between 65 and 150 degrees C. The produced gold nanoparticles were spherical with average diameter of 11.5+/-2.9nm. The synthesized gold colloidal solution was very stable and can be stored at room temperature for more than 6 months. The color of the colloidal solution can change from wine red to mauve, purple and blue during the acidifying process. This color changing phenomenon is attributed to the aggregation of gold nanoparticles resulted from hydrogen bond formation between the histidines adsorbed on the gold nanoparticles surfaces. This hydrothermal synthetic method is expected to be used for synthesizing some other amino acid functionalized gold nanomaterials.

The infrared transmission through gold films on ordered two-dimensional non-close-packed colloidal crystals

International Nuclear Information System (INIS)

Ju Jing; Zhou Yuqin; Dong Gangqiang

2014-01-01

We studied the infrared transmission properties of gold films on ordered two-dimensional non-close-packed polystyrene (PS) colloidal crystal. The gold films consist of gold half-shells on the PS spheres and gold film with 2D arrays of holes on the glass substrate. An extraordinary optical transmission phenomenon could be found in such a structure. Simulations with the finite-difference time-domain method were also employed to get the transmission spectra and electric field distribution. The transmission response of the samples can be adjusted by controlling the thickness of the gold films. Angle-resolved measurements were performed using polarized light to obtain more information about the surface plasmon polariton resonances of the gold films. As the angle changes, the transmission spectra change a lot. The transmission spectra of p-polarized light have quite different properties compared to those of s-polarized light. (semiconductor physics)

Preparation of gold ethanol colloid by the arc discharge method

International Nuclear Information System (INIS)

Tseng, K.-H.; Huang, J.-C.; Liao, C.-Y.; Tien, D.-C.; Tsung, T.-T.

2009-01-01

A new method using the arc discharge method (ADM) to synthesize gold nanoparticles in an anhydrous ethanol was studied. Fabricated gold nanoparticles were characterized by different techniques. Unlike conventional methods for metal nanoparticles synthesis, the ADM method does not require application of chemical surfactants and stabilizers. The microstructure of ADM-produced gold nanoparticles was examined by transmission electron microscope (TEM) and scanning electron microscope (SEM). The particle size was found in the range of 2-40 nm. The chemical composition of gold nanoparticles has been confirmed by the energy dispersive X-ray analysis (EDX). The crystal structure of the nanoscale gold particles was studied using the X-ray diffraction (XRD) method. Images of the gold nanoparticles, Zeta potential, size distribution, and ultraviolet-visible (UV-vis) absorbance were investigated. This innovative approach for gold nanoparticles preparation has been successfully established. The experimental results showed that the ADM technique is easy, cheap and clean method which can be used to manufacture gold nanoparticles suspended in ethanol solution without any surfactant

Synthesis of 2.5 nm colloidal iridium nanoparticles with strong surface enhanced Raman scattering activity

International Nuclear Information System (INIS)

Cui, Malin; Zhao, Yuan; Wang, Chan; Song, Qijun

2016-01-01

Colloidal iridium nanoparticles (IrNPs) were synthesized through an environmentally friendly approach by using trisodium citrate as the capping molecule in an aqueous medium. The resulting colloidal IrNPs have a typical diameter of 2.5 nm and display absorption bands at 250, 400 and 600 nm. They possess uniform morphology, good dispersibility, excellent stability in water, and exhibit strong surface enhanced Raman scattering (SERS) activity with an enhancement factor (EF) of 3.5 × 10 5 at the 1512 cm -1 peak when using Rhodamine 6G as the probe molecule. The excellent SERS performance of the IrNPs was exemplarily applied to the determination of the industrial colorant Sudan Red I. The peak intensity of the Raman band at 1236 cm -1 is linearly related to the concentration of Sudan Red I which can be determined by SERS in the 2 nM to 8 μM concentration range with a limit of detection as low as 0.6 nM. In our perception, this strong SERS activity of the IrNPs has a large potential in the SERS-based quantitation of various chemical substances. (author)

Ultralow-Power Electronic Trapping of Nanoparticles with Sub-10 nm Gold Nanogap Electrodes.

Science.gov (United States)

Barik, Avijit; Chen, Xiaoshu; Oh, Sang-Hyun

2016-10-12

We demonstrate nanogap electrodes for rapid, parallel, and ultralow-power trapping of nanoparticles. Our device pushes the limit of dielectrophoresis by shrinking the separation between gold electrodes to sub-10 nm, thereby creating strong trapping forces at biases as low as the 100 mV ranges. Using high-throughput atomic layer lithography, we manufacture sub-10 nm gaps between 0.8 mm long gold electrodes and pattern them into individually addressable parallel electronic traps. Unlike pointlike junctions made by electron-beam lithography or larger micron-gap electrodes that are used for conventional dielectrophoresis, our sub-10 nm gold nanogap electrodes provide strong trapping forces over a mm-scale trapping zone. Importantly, our technology solves the key challenges associated with traditional dielectrophoresis experiments, such as high voltages that cause heat generation, bubble formation, and unwanted electrochemical reactions. The strongly enhanced fields around the nanogap induce particle-transport speed exceeding 10 μm/s and enable the trapping of 30 nm polystyrene nanoparticles using an ultralow bias of 200 mV. We also demonstrate rapid electronic trapping of quantum dots and nanodiamond particles on arrays of parallel traps. Our sub-10 nm gold nanogap electrodes can be combined with plasmonic sensors or nanophotonic circuitry, and their low-power electronic operation can potentially enable high-density integration on a chip as well as portable biosensing.

Anisotropic deformation of metallo-dielectric core-shell colloids under MeV ion irradiation

International Nuclear Information System (INIS)

Penninkhof, J.J.; Dillen, T. van; Roorda, S.; Graf, C.; Blaaderen, A. van; Vredenberg, A.M.; Polman, A.

2006-01-01

We have studied the deformation of metallo-dielectric core-shell colloids under 4 MeV Xe, 6 and 16 MeV Au, 30 MeV Si and 30 MeV Cu ion irradiation. Colloids of silica surrounded by a gold shell, with a typical diameter of 400 nm, show anisotropic plastic deformation under MeV ion irradiation, with the metal flowing conform the anisotropically deforming silica core. The 20 nm thick metal shell imposes a mechanical constraint on the deforming silica core, reducing the net deformation strain rate compared to that of pure silica. In colloids consisting of a Au core and a silica shell, the silica expands perpendicular to the ion beam, while the metal core shows a large elongation along the ion beam direction, provided the silica shell is thick enough (>40 nm). A minimum electronic energy loss of 3.3 keV/nm is required for shape transformation of the metal core. Silver cores embedded in a silica shell show no elongation, but rather disintegrate. Also in planar SiO 2 films, Au and Ag colloids show entirely different behavior under MeV irradiation. We conclude that the deformation model of core-shell colloids must include ion-induced particle disintegration in combination with thermodynamical effects, possibly in combination with mechanical effects driven by stresses around the ion tracks

Anisotropic deformation of metallo-dielectric core shell colloids under MeV ion irradiation

Science.gov (United States)

Penninkhof, J. J.; van Dillen, T.; Roorda, S.; Graf, C.; van Blaaderen, A.; Vredenberg, A. M.; Polman, A.

2006-01-01

We have studied the deformation of metallo-dielectric core-shell colloids under 4 MeV Xe, 6 and 16 MeV Au, 30 MeV Si and 30 MeV Cu ion irradiation. Colloids of silica surrounded by a gold shell, with a typical diameter of 400 nm, show anisotropic plastic deformation under MeV ion irradiation, with the metal flowing conform the anisotropically deforming silica core. The 20 nm thick metal shell imposes a mechanical constraint on the deforming silica core, reducing the net deformation strain rate compared to that of pure silica. In colloids consisting of a Au core and a silica shell, the silica expands perpendicular to the ion beam, while the metal core shows a large elongation along the ion beam direction, provided the silica shell is thick enough (>40 nm). A minimum electronic energy loss of 3.3 keV/nm is required for shape transformation of the metal core. Silver cores embedded in a silica shell show no elongation, but rather disintegrate. Also in planar SiO2 films, Au and Ag colloids show entirely different behavior under MeV irradiation. We conclude that the deformation model of core-shell colloids must include ion-induced particle disintegration in combination with thermodynamical effects, possibly in combination with mechanical effects driven by stresses around the ion tracks.

Pharmacological study of radioactive-gold colloid transport by blood and by serous exudate; Contribution a l'etude pharmacologique du transport des colloides d'or radioactif par le sang et les exsudats sereux

Energy Technology Data Exchange (ETDEWEB)

Rousselet, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1966-06-01

After giving the essential physico-chemical properties of the colloids, the author considers the biological role of these substances and, in connection with their transport by the blood, their capture by elements of the reticula-endothelial system. A summary is given of present knowledge concerning the role of serous proteins in the transport of substances, particularly that of radio-active colloidal gold. The blood fractions which can take part in colloidal gold transport are the red blood corpuscles, the leukocytes and histiocytic elements as well as the plasma. The radioactive distribution in these various fractions is obtained by autoradiography of blood sediments. After showing the importance of the role of the plasma in radioactive particle transport, the author, describes the attempts made to detect a possible of colloidal gold 198 on the various serous proteins using various methods of separation. The ''in vitro'' and ''in vivo'' bonds between colloidal gold-198 particles and either the serous proteins or healthy specimens or the effusion liquids of pathological origin in man, or due to an experimental inflammation with carregenin in the rat, have been studied. The bonding appears to be effective because of the protective macromolecular layer formed by the gelatine. The different positions of the colloidal grains on the electrophoregram can only be explained by their different physico-chemical characteristics. Gold in the ionic form, on the other hand, is combined only with the albumen is the amount metal present does not exceed a certain value. (author) [French] Apres avoir enonce les proprietes physicochimiques essentielles des colloides nous etudions le devenir biologique de ces substances et, en relation avec leur transport par le sang, leur captation par les elements du Systeme Reticulo-Endothelial. Nous resumons les connaissances acquises jusqu'alors sur le role des proteines seriques dans le transport des substances et particulierement dans le

Colorimetric detection of manganese(II) ions using gold/dopa nanoparticles.

Science.gov (United States)

Narayanan, Kannan Badri; Park, Hyun Ho

2014-10-15

We report here a one-pot, greener, eco-friendly strategy for the synthesis of gold nanoparticles using L-dopa. The as-prepared dopa-functionalized gold nanoparticles (AuNPs/dopa) can detect low concentrations of manganese(II) metal ions in aqueous solution. The binding forces between dopa and Mn(2+) ions cause dopa-functionalized gold nanoparticles to come closer together, decreasing the interparticle distance and aggregating it with a change in color of colloidal solution from red to purplish-blue. Dynamic light scattering (DLS) analysis showed a decreased surface charge on the surface of gold nanoparticles when exposed to Mn(2+) ions, which caused cross-linking aggregation. Transmission electron microscopic (TEM) images also revealed the aggregation of gold nanoparticles with the addition of Mn(2+) ions. The extinction ratio of absorbance at 700-550nm (A700/A550) was linear against the concentration of [Mn(2+)] ions. Thus, the optical absorption spectra of gold colloidal solution before and after the addition of Mn(2+) ions reveal the concentration of Mn(2+) ions in solution. Copyright © 2014 Elsevier B.V. All rights reserved.

Cytotoxicity evaluation of gold nanoparticles on microalga Dunaliella salina in microplate test system

Science.gov (United States)

Chumakov, Daniil; Prilepskii, Artur; Dykman, Lev; Khlebtsov, Boris; Khlebtsov, Nikolai; Bogatyrev, Vladimir

2018-04-01

Gold nanoparticles are intensively studied in biomedicine. Assessment of their biocompatibility is highly important. Currently there is lack of evidence, concerning nanotoxicity of ultrasmall gold nanoparticles < 5 nm. Existing data are rather contradictory. The aim of that study was to evaluate the toxicity of 2 nm colloidal gold, using microalga Dunaliella salina. Cellular barriers of that microalga are very similar to animal cells so it might be considered as a valuable model for nanotoxicity testing. Chlorophyll content as a test-function was used. Spectrophotometric method for chlorophyll determination in vivo in suspensions of D.salina cultures was applied. Calculated EC50 48h value of ionic gold was 25.8 +/- 0.3 mg Au/L. EC50 value of phosphine-stabilized gold nanoclusters was 32.2 +/-1.1 mg Au/L. It was not possible to calculate EC50 for 15 nm citrate gold nanoparticles, as they were non-toxic at all concentrations tested. These results are confirmed by fluorescent -microscopic monitoring of the same probes. It was shown that 10-fold growth of phosphine-stabilized gold nanoparticles (from 2.3 +/- 0.9 nm to 21.1 +/- 7.5 nm) led to 7-fold decrease of their toxicity.

pH Triggered Recovery and Reuse of Thiolated Poly(acrylic acid) Functionalized Gold Nanoparticles with Applications in Colloidal Catalysis.

Science.gov (United States)

Ansar, Siyam M; Fellows, Benjamin; Mispireta, Patrick; Mefford, O Thompson; Kitchens, Christopher L

2017-08-08

Thiolated poly(acrylic acid) (PAA-SH) functionalized gold nanoparticles were explored as a colloidal catalyst with potential application as a recoverable catalyst where the PAA provides pH-responsive dispersibility and phase transfer capability between aqueous and organic media. This system demonstrates complete nanoparticle recovery and redispersion over multiple reaction cycles without changes in nanoparticle morphology or reduction in conversion. The catalytic activity (rate constant) was reduced in subsequent reactions when recovery by aggregation was employed, despite unobservable changes in morphology or dispersibility. When colloidal catalyst recovery employed a pH induced phase transfer between two immiscible solvents, the catalytic activity of the recovered nanoparticles was unchanged over four cycles, maintaining the original rate constant and 100% conversion. The ability to recover and reuse colloidal catalysts by aggregation/redispersion and phase transfer methods that occur at low and high pH, respectively, could be used for different gold nanoparticle catalyzed reactions that occur at different pH conditions.

A new method to determine the skin thickness of asymmetric UF-membranes using colloidal gold particles

NARCIS (Netherlands)

Cuperus, Folkert Petrus; Bargeman, Derk; Smolders, C.A.

1990-01-01

In this paper a new method is presented for the determination of the skin thickness of asymmetric ultrafiltration membranes. The method is based on the use of well-defined, uniformly sized colloidal gold particles, permeated from the sublayer side of the membrane, combined with electron microscopic

Two-dimensional nanopatterning by PDMS relief structures of polymeric colloidal crystals

Science.gov (United States)

Nam, Hye Jin; Kim, Ju-Hee; Jung, Duk-Young; Park, Jong Bae; Lee, Hae Seong

2008-06-01

A new constructive method of fabricating a nanoparticle self-assembly on the patterned surface of a poly(dimethylsiloxane) (PDMS) relief nanostructure was demonstrated. Patterned PDMS templates with close-packed microwells were fabricated by molding against a self-assembled monolayer of polystyrene spheres. Alkanethiol-functionalized gold nanoparticles with an average particle size of 2.5 nm were selectively deposited onto a hydrophobic self-assembled monolayer printed on the substrate by the micro-contact printing (μCP) of the prepared PDMS microwell, in which the patterned gold nanoparticles consisted of close-packed hexagons with an average diameter of 370 nm. In addition, two-dimensional colloidal crystals derived from PMMA microspheres with a diameter of 380 nm and a negative surface charge were successfully formed on the hemispherical microwells by electrostatic force using positively charged PAH-coated PDMS as a template to produce multidimensional nanostructures.

Preparation of gold nanoparticles by γ-ray irradiation method using polyvinyl pyrrolidone (PVP) as stabilizer

International Nuclear Information System (INIS)

Nguyen Tan Man; Le Hai; Le Huu Tu; Tran Thu Hong; Tran Thi Tam; Pham Thi Le Ha; Pham Thi Sam

2011-01-01

Gold nanoparticles were prepared from (Au 3+ ) aqueous solution by the method of γ-ray irradiation using polyvinylpyrrolidone (PVP) as stabilizer. The saturated conversion dose (Au 3+ --> Au o ) determined by UV-Vis spectroscopy was found to be about 5 kGy. The UV-Vis spectrum showed that an absorption peak at λ max =524 nm due to surface plasmon resonance. The image of transmission electron microscopy (TEM) showed that the gold nanoparticles are mostly spherical in shape and have an average diameter of ≅20 nm. The prepared colloidal gold nanoparticles solution is good stability for 6 months of storage. (author)

Location on chitin in the cyst wall of Entamoeba invadens with colloidal gold tracers.

Science.gov (United States)

Arroyo-Begovich, A; Cárabez-Trejo, A

1982-04-01

Chitin was located in the cyst wall of Entamoeba invadens with colloidal gold-linked wheat germ agglutinin. Cysts stained differentially from trophozoites when encysting cultures were treated with the gold tracer; cysts acquired a wine-red coloration while, in general trophozoites remained unstained. Observation of cells with the electron microscope revealed that the tracer particles were bound specifically to the walls of the surface of the cyst when cells were exposed in suspension, and to the cyst wall cross-section, when cells were exposed to the tracer in thin section, indicating that chitin fibers were distributed on the surface as well as throughout the matrix of the cyst wall.

Bio-synthesis of gold nanoparticles by human epithelial cells, in vivo

International Nuclear Information System (INIS)

Larios-Rodriguez, E; Rangel-Ayon, C; Herrera-Urbina, R; Castillo, S J; Zavala, G

2011-01-01

Healthy epithelial cells, in vivo, have the ability to synthesize gold nanoparticles when aqueous tetrachloroauric acid is made to react with human skin. Neither a reducing agent nor a protecting chemical is needed for this bio-synthesis method. The first indication of gold nanoparticle formation is the staining of the skin, which turns deep purple. Stereoscopic optical micrographs of human skin tissue in contact with aqueous tetrachloroauric acid clearly show the staining of the epithelial cells. The UV-Vis spectrum of these epithelial cells shows an absorption band with a maximum at 553 nm. This absorption peak is within the wavelength region where the surface plasmon resonance (SPR) band of aqueous colloidal gold exhibits a maximum. Transmission electron micrographs show that gold nanoparticles synthesized by epithelial cells have sizes between 1 and 100 nm. The electron diffraction pattern of these nanoparticles reveals a crystalline structure whose interplanar distances correspond to fcc metallic gold. Transmission electron micrographs of ultra-thin (70 nm thick) slices of epithelial cells clearly and undoubtedly demonstrate that gold nanoparticles are inside the cell. According to high resolution transmission electron micrographs of intracellular single gold nanoparticles, they have the shape of a polyhedron.

Bio-synthesis of gold nanoparticles by human epithelial cells, in vivo

Energy Technology Data Exchange (ETDEWEB)

Larios-Rodriguez, E; Rangel-Ayon, C; Herrera-Urbina, R [Departamento de Ingenieria Quimica y Metalurgia, Universidad de Sonora, Rosales y Luis Encinas S/N, Hermosillo, Sonora, C.P. 83000 (Mexico); Castillo, S J [Departamento de Investigacion en Fisica, Universidad de Sonora, Rosales y Luis Encinas S/N, Hermosillo, Sonora, C.P. 83000 (Mexico); Zavala, G, E-mail: elarios@polimeros.uson.mx [Instituto de Biotecnologia, Universidad Nacional Autonoma de Mexico, Cuernavaca, Morelos (Mexico)

2011-09-02

Healthy epithelial cells, in vivo, have the ability to synthesize gold nanoparticles when aqueous tetrachloroauric acid is made to react with human skin. Neither a reducing agent nor a protecting chemical is needed for this bio-synthesis method. The first indication of gold nanoparticle formation is the staining of the skin, which turns deep purple. Stereoscopic optical micrographs of human skin tissue in contact with aqueous tetrachloroauric acid clearly show the staining of the epithelial cells. The UV-Vis spectrum of these epithelial cells shows an absorption band with a maximum at 553 nm. This absorption peak is within the wavelength region where the surface plasmon resonance (SPR) band of aqueous colloidal gold exhibits a maximum. Transmission electron micrographs show that gold nanoparticles synthesized by epithelial cells have sizes between 1 and 100 nm. The electron diffraction pattern of these nanoparticles reveals a crystalline structure whose interplanar distances correspond to fcc metallic gold. Transmission electron micrographs of ultra-thin (70 nm thick) slices of epithelial cells clearly and undoubtedly demonstrate that gold nanoparticles are inside the cell. According to high resolution transmission electron micrographs of intracellular single gold nanoparticles, they have the shape of a polyhedron.

The in vitro formation of placer gold by bacteria

Science.gov (United States)

Southam, Gordon; Beveridge, Terrance J.

1994-10-01

A laboratory simulation was developed to provide mechanistic information about placer (nugget) gold development in the natural environment. To initiate the simulation, ionic gold was immobilized to a high capacity by Bacillus subtilis 168 (116.2 μg/mg dry weight bacteria) as fine-grained intracellular colloids (5-50 nm). During the low-temperature diagenesis experiment (60°C), the release of organics due to bacterial autolysis coincided with the in vitro formation of hexagonal-octahedral gold crystals (20 μm). This octahedral gold was observed to aggregate, forming fine-grained placer gold (50 μm). In addition to achieving a fundamental understanding into secondary gold deposition, a significant economic benefit could be realized by employing this environmentally safe procedure to concentrate widely dispersed gold in placer deposits to facilitate mining by conventional methodologies.

Extracellular biosynthesis of gold and silver nanoparticles using Krishna tulsi ( Ocimum sanctum) leaf

Science.gov (United States)

Philip, Daizy; Unni, C.

2011-05-01

Aqueous extract of Ocimum sanctum leaf is used as reducing agent for the environmentally friendly synthesis of gold and silver nanoparticles. The nanoparticles were characterized using UV-vis, transmission electron microscopy (TEM), X-ray diffraction (XRD) and FTIR analysis. These methods allow the synthesis of hexagonal gold nanoparticles having size ∼30 nm showing two surface plasmon resonance (SPR) bands by changing the relative concentration of HAuCl 4 and the extract. Broadening of SPR is observed at larger quantities of the extract possibly due to biosorption of gold ions. Silver nanoparticles with size in the range 10-20 nm having symmetric SPR band centered around 409 nm are obtained for the colloid synthesized at room temperature at a pH of 8. Crystallinity of the nanoparticles is confirmed from the XRD pattern. Biomolecules responsible for capping are different in gold and silver nanoparticles as evidenced by the FTIR spectra.

Study on gamma radiation-induced synthesis of gold nanoparticles stabilized by hyaluronan

International Nuclear Information System (INIS)

Dang Van Phu; Bui Duy Du

2013-01-01

Gold nanoparticles (AuNPs) with diameter from 4 to 10 nm were synthesized by γ-irradiation in hyaluronan (HA) solution without usage of any OH radical scavenger. The size distribution of AuNPs were determined by TEM images. The λ max (517-525 nm) of colloidal AuNPs solutions as prepared was measured by UV-Vis spectroscopy. The influence factor on the size of AuNPs particularly the concentration of Au 3+ , HA and dose rate were investigated. The colloidal solution of AuNPs/HA as synthesized was stable more than 6 months stored under ambient condition. AuNPs with the size less than 10 nm narrow size distribution stabilized by HA which is biocompatible polysaccharide can potentially be applied in biomedicine and cosmetic. (author)

Periodically arranged colloidal gold nanoparticles for enhanced light harvesting in organic solar cells

DEFF Research Database (Denmark)

Mirsafaei, Mina; Fernandes Cauduro, André Luis; Kunstmann-Olsen, Casper

2016-01-01

Although organic solar cells show intriguing features such as low-cost, mechanical flexibility and light weight, their efficiency is still low compared to their inorganic counterparts. One way of improving their efficiency is by the use of light-trapping mechanisms from nano- or microstructures......, which makes it possible to improve the light absorption and charge extraction in the device’s active layer. Here, periodically arranged colloidal gold nanoparticles are demonstrated experimentally and theoretically to improve light absorption and thus enhance the efficiency of organic solar cells....... Surface-ordered gold nanoparticle arrangements are integrated at the bottom electrode of organic solar cells. The resulting optical interference and absorption effects are numerically investigated in bulk hetero-junction solar cells based on the Finite-Difference Time-Domain (FDTD) and Transfer Matrix...

Fabrication of Periodic Gold Nanocup Arrays Using Colloidal Lithography

Energy Technology Data Exchange (ETDEWEB)

DeVetter, Brent M.; Bernacki, Bruce E.; Bennett, Wendy D.; Schemer-Kohrn, Alan; Alvine, Kyle J.

2017-01-01

Within recent years, the field of plasmonics has exploded as researchers have demonstrated exciting applications related to chemical and optical sensing in combination with new nanofabrication techniques. A plasmon is a quantum of charge density oscillation that lends nanoscale metals such as gold and silver unique optical properties. In particular, gold and silver nanoparticles exhibit localized surface plasmon resonances—collective charge density oscillations on the surface of the nanoparticle—in the visible spectrum. Here, we focus on the fabrication of periodic arrays of anisotropic plasmonic nanostructures. These half-shell (or nanocup) structures can exhibit additional unique light-bending and polarization dependent optical properties that simple isotropic nanostructures cannot. Researchers are interested in the fabrication of periodic arrays of nanocups for a wide variety of applications such as low-cost optical devices, surface-enhanced Raman scattering, and tamper indication. We present a scalable technique based on colloidal lithography in which it is possible to easily fabricate large periodic arrays of nanocups using spin-coating and self-assembled commercially available polymeric nanospheres. Electron microscopy and optical spectroscopy from the visible to near-IR was performed to confirm successful nanocup fabrication. We conclude with a demonstration of the transfer of nanocups to a flexible, conformal adhesive film.

Pharmacological study of radioactive-gold colloid transport by blood and by serous exudate; Contribution a l'etude pharmacologique du transport des colloides d'or radioactif par le sang et les exsudats sereux

Energy Technology Data Exchange (ETDEWEB)

Rousselet, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1966-06-01

After giving the essential physico-chemical properties of the colloids, the author considers the biological role of these substances and, in connection with their transport by the blood, their capture by elements of the reticula-endothelial system. A summary is given of present knowledge concerning the role of serous proteins in the transport of substances, particularly that of radio-active colloidal gold. The blood fractions which can take part in colloidal gold transport are the red blood corpuscles, the leukocytes and histiocytic elements as well as the plasma. The radioactive distribution in these various fractions is obtained by autoradiography of blood sediments. After showing the importance of the role of the plasma in radioactive particle transport, the author, describes the attempts made to detect a possible of colloidal gold 198 on the various serous proteins using various methods of separation. The ''in vitro'' and ''in vivo'' bonds between colloidal gold-198 particles and either the serous proteins or healthy specimens or the effusion liquids of pathological origin in man, or due to an experimental inflammation with carregenin in the rat, have been studied. The bonding appears to be effective because of the protective macromolecular layer formed by the gelatine. The different positions of the colloidal grains on the electrophoregram can only be explained by their different physico-chemical characteristics. Gold in the ionic form, on the other hand, is combined only with the albumen is the amount metal present does not exceed a certain value. (author) [French] Apres avoir enonce les proprietes physicochimiques essentielles des colloides nous etudions le devenir biologique de ces substances et, en relation avec leur transport par le sang, leur captation par les elements du Systeme Reticulo-Endothelial. Nous resumons les connaissances acquises jusqu'alors sur le role des proteines seriques dans le transport des

Photopyroelectric Techniques for thermo-optical characterization of gold nano-particles

International Nuclear Information System (INIS)

Chávez-Sandoval, B E; Balderas-López, J A; Padilla-Bernal, G; Moreno-Rivera, M A; Franco-Hernández, M O; Martínez-Jiménez, A; García-Franco, F

2015-01-01

Since the first methodology, proposed by Turkevich, to produce gold nanoparticles (AuNPs), improvements have been made as to allow better controllability in their size and shape. These two parameters play important role for application of gold nanoparticles since they determine their optical and thermal properties. Two photopyroelectric techniques for the measurement of the thermal diffusivity and the optical absorption coefficient for nano-particles are introduced. These thermo-physical properties were measured for the colloidal systems at different nano-particle's sizes and, for optical properties, at three different wavelengths (405 nm, 488 nm and 532 nm). No significant difference, on thermal properties, was found in the range of nano-particles' sizes studied in this work; in opposition optical properties shown more sensitive to this parameter

Mercury adsorption to gold nanoparticle and thin film surfaces

Science.gov (United States)

Morris, Todd Ashley

Mercury adsorption to gold nanoparticle and thin film surfaces was monitored by spectroscopic techniques. Adsorption of elemental mercury to colloidal gold nanoparticles causes a color change from wine-red to orange that was quantified by UV-Vis absorption spectroscopy. The wavelength of the surface plasmon mode of 5, 12, and 31 nm gold particles blue-shifts 17, 14, and 7.5 nm, respectively, after a saturation exposure of mercury vapor. Colorimetric detection of inorganic mercury was demonstrated by employing 2.5 nm gold nanoparticles. The addition of low microgram quantities of Hg 2+ to these nanoparticles induces a color change from yellow to peach or blue. It is postulated that Hg2+ is reduced to elemental mercury by SCN- before and/or during adsorption to the nanoparticle surface. It has been demonstrated that surface plasmon resonance spectroscopy (SPRS) is sensitive to mercury adsorption to gold and silver surfaces. By monitoring the maximum change in reflectivity as a function of amount of mercury adsorbed to the surface, 50 nm Ag films were shown to be 2--3 times more sensitive than 50 nm Au films and bimetallic 15 nm Au/35 nm Ag films. In addition, a surface coverage of ˜40 ng Hg/cm2 on the gold surface results in a 0.03° decrease in the SPR angle of minimum reflectivity. SPRS was employed to follow Hg exposure to self-assembled monolayers (SAMs) on Au. The data indicate that the hydrophilic or hydrophobic character of the SAM has a significant effect on the efficiency of Hg penetration. Water adsorbed to carboxylic acid end group of the hydrophilic SAMs is believed to slow the penetration of Hg compared to methyl terminated SAMs. Finally, two protocols were followed to remove mercury from gold films: immersion in concentrated nitric acid and thermal annealing up to 200°C. The latter protocol is preferred because it removes all of the adsorbed mercury from the gold surface and does not affect the morphology of the gold surface.

Improvement of kinetics, yield, and colloidal stability of biogenic gold nanoparticles using living cells of Euglena gracilis microalga

Energy Technology Data Exchange (ETDEWEB)

Dahoumane, Si Amar, E-mail: sa.dahoumane@gmail.com [Paris-Diderot University, Sorbonne Paris Cité, Interfaces, Traitements, Organisation et Dynamique des Systèmes (ITODYS), UMR 7086, CNRS (France); Yéprémian, Claude; Djédiat, Chakib; Couté, Alain [Muséum National d’Histoire Naturelle, Département RDDM, UMR 7245, Unité MCAM (France); Fiévet, Fernand [Paris-Diderot University, Sorbonne Paris Cité, Interfaces, Traitements, Organisation et Dynamique des Systèmes (ITODYS), UMR 7086, CNRS (France); Coradin, Thibaud, E-mail: thibaud.coradin@upmc.fr [UPMC—Paris 06, CNRS, Chimie de la Matière Condensée de Paris, Collège de France (France); Brayner, Roberta, E-mail: roberta.brayner@univ-paris-diderot.fr [Paris-Diderot University, Sorbonne Paris Cité, Interfaces, Traitements, Organisation et Dynamique des Systèmes (ITODYS), UMR 7086, CNRS (France)

2016-03-15

Recent years have witnessed a boom in the biosynthesis of a large variety of nanomaterials using different biological resources among which algae-based entities have been gaining much more attention within the community of material scientists worldwide. In our previously published findings, we explored some factors that governed the biofabrication of gold nanoparticles using living cultures of microalgae, such as the utilized microalgal genera, the phylum they belong to, and the impact of tetrachloroauric acid concentrations on the ability of these strains to perform the biosynthesis of gold nanoparticles once in contact with these cations. As a follow-up, we present in this paper an improvement of the features of bioproduced gold colloids using living cells of Euglena gracilis microalga when this species is grown under either mixotrophic or autotrophic conditions, i.e., exposed to light and grown in an organic carbon-enriched culture medium versus under autotrophic conditions. As an outcome to this alteration, the growth rate of this photosynthetic microorganism is multiplied 7–8 times when grown under mixotrophic conditions compared to autotrophic ones. Therefore, the yield, the kinetics, and the colloidal stability of the biosynthesized gold nanoparticles are dramatically enhanced. Moreover, the shape and the size of the as-produced nano-objects via this biological method are affected. In addition to round-shaped gold nanoparticles, particular shapes, such as triangles and hexagons, appear. These findings add up to the amassed knowledge toward the design of photobioreactors for the scalable and sustainable production of interesting nanomaterials.

Improvement of kinetics, yield, and colloidal stability of biogenic gold nanoparticles using living cells of Euglena gracilis microalga

Science.gov (United States)

Dahoumane, Si Amar; Yéprémian, Claude; Djédiat, Chakib; Couté, Alain; Fiévet, Fernand; Coradin, Thibaud; Brayner, Roberta

2016-03-01

Recent years have witnessed a boom in the biosynthesis of a large variety of nanomaterials using different biological resources among which algae-based entities have been gaining much more attention within the community of material scientists worldwide. In our previously published findings, we explored some factors that governed the biofabrication of gold nanoparticles using living cultures of microalgae, such as the utilized microalgal genera, the phylum they belong to, and the impact of tetrachloroauric acid concentrations on the ability of these strains to perform the biosynthesis of gold nanoparticles once in contact with these cations. As a follow-up, we present in this paper an improvement of the features of bioproduced gold colloids using living cells of Euglena gracilis microalga when this species is grown under either mixotrophic or autotrophic conditions, i.e., exposed to light and grown in an organic carbon-enriched culture medium versus under autotrophic conditions. As an outcome to this alteration, the growth rate of this photosynthetic microorganism is multiplied 7-8 times when grown under mixotrophic conditions compared to autotrophic ones. Therefore, the yield, the kinetics, and the colloidal stability of the biosynthesized gold nanoparticles are dramatically enhanced. Moreover, the shape and the size of the as-produced nano-objects via this biological method are affected. In addition to round-shaped gold nanoparticles, particular shapes, such as triangles and hexagons, appear. These findings add up to the amassed knowledge toward the design of photobioreactors for the scalable and sustainable production of interesting nanomaterials.

Self-assembly of gold nanoparticles as colloidal crystals induced by polymerization of amphiphilic monomers

Czech Academy of Sciences Publication Activity Database

Zucchi, I. A.; Hoppe, C. E.; Galante, M. J.; Williams, R. J. J.; López-Quintela, M. A.; Matějka, Libor; Šlouf, Miroslav; Pleštil, Josef

2008-01-01

Roč. 41, č. 13 (2008), s. 4895-4903 ISSN 0024-9297 R&D Projects: GA AV ČR IAA400500701 Grant - others:National Agency for the Promotion of Science and Technology(AR) PICT03-14738; Ministry of Science and Technology(ES) MAT2005-07554-C02-01 Institutional research plan: CEZ:AV0Z40500505 Keywords : self -assembly * gold nanoparticles * hierarchical structure * colloidal crystals Subject RIV: CD - Macromolecular Chemistry Impact factor: 4.407, year: 2008

Wound healing applications of biogenic colloidal silver and gold nanoparticles: recent trends and future prospects.

Science.gov (United States)

Ovais, Muhammad; Ahmad, Irshad; Khalil, Ali Talha; Mukherjee, Sudip; Javed, Rabia; Ayaz, Muhammad; Raza, Abida; Shinwari, Zabta Khan

2018-05-01

Nanotechnology has emerged as a prominent scientific discipline in the technological revolution of this millennium. The scientific community has focused on the green synthesis of metal nanoparticles as compared to physical and chemical methods due to its eco-friendly nature and high efficacy. Medicinal plants have been proven as the paramount source of various phytochemicals that can be used for the biogenic synthesis of colloidal silver and gold nanoparticles as compared to other living organisms, e.g., microbes and fungi. According to various scientific reports, the biogenic nanoparticles have shown promising potential as wound healing agents. However, not a single broad review article was present that demonstrates the wound healing application of biogenic silver and gold nanoparticles. Foreseeing the overall literature published, we for the first time intended to discuss the current trends in wound healing via biogenic silver and gold nanoparticles. Furthermore, light has been shed on the mechanistic aspects of wound healing along with futuristic discussion on the faith of biogenic silver and gold nanoparticles as potential wound healing agents.

Effect of concentration of imperata cylindrica L leaf extraction synthesis process of gold nanoparticles

International Nuclear Information System (INIS)

Iwan Syahjoko Saputra; Yoki Yulizar; Sudirman

2018-01-01

Gold Nanoparticles (Gold NPs) successful was performed using HAuCl 4 precursor as Au 3+ ion source with 7 x 10 -4 M concentration. There search aims to knows effect of concentration variation of Imperata cylindrica L leaf extract on synthesis process of gold nanoparticles. There search used of green synthesis method. Colloid of nanoparticles which is formed in analyzed using UV - Vis Spectrophotometer, FT-IR Spectroscopy, PSA, PZC, XRD and TEM. The results of synthesis showed the best concentration of Imperata cilyndrica L leaf extract at 3.46 %, happen a shift of wave length at UV-Vis from 216 nm to 530 nm with 1.779 absorbance value. The PSA analysis showed a particle size of 51.87 nm and a PZC value of -19.2 mV. The result of FT - IR indicated a shift of wave number in the hydroxyl group from 3354 cm -1 to 3390 cm -1 and showed a interaction of hydroxyl group at imperata cylindrica L leaf extract with Au 3+ ion. TEM analysis shows the morphology of Gold NPs that spherical shape with a particle size of 20 nm. XRD calculation results show crystallite size of gold nano particles is 15.47 nm. (author)

Tuning plasmons layer-by-layer for quantitative colloidal sensing with surface-enhanced Raman spectroscopy.

Science.gov (United States)

Anderson, William J; Nowinska, Kamila; Hutter, Tanya; Mahajan, Sumeet; Fischlechner, Martin

2018-04-19

Surface-enhanced Raman spectroscopy (SERS) is well known for its high sensitivity that emerges due to the plasmonic enhancement of electric fields typically on gold and silver nanostructures. However, difficulties associated with the preparation of nanostructured substrates with uniform and reproducible features limit reliability and quantitation using SERS measurements. In this work we use layer-by-layer (LbL) self-assembly to incorporate multiple functional building blocks of collaborative assemblies of nanoparticles on colloidal spheres to fabricate SERS sensors. Gold nanoparticles (AuNPs) are packaged in discrete layers, effectively 'freezing nano-gaps', on spherical colloidal cores to achieve multifunctionality and reproducible sensing. Coupling between layers tunes the plasmon resonance for optimum SERS signal generation to achieve a 10 nM limit of detection. Significantly, using the layer-by-layer construction, SERS-active AuNP layers are spaced out and thus optically isolated. This uniquely allows the creation of an internal standard within each colloidal sensor to enable highly reproducible self-calibrated sensing. By using 4-mercaptobenzoic acid (4-MBA) as the internal standard adenine concentrations are quantified to an accuracy of 92.6-99.5%. Our versatile approach paves the way for rationally designed yet quantitative colloidal SERS sensors and their use in a variety of sensing applications.

Surface-Enhanced Raman Spectroscopy Study of 4-ATP on Gold Nanoparticles for Basal Cell Carcinoma Fingerprint Detection

Science.gov (United States)

Quynh, Luu Manh; Nam, Nguyen Hoang; Kong, K.; Nhung, Nguyen Thi; Notingher, I.; Henini, M.; Luong, Nguyen Hoang

2016-05-01

The surface-enhanced Raman signals of 4-aminothiophenol (4-ATP) attached to the surface of colloidal gold nanoparticles with size distribution of 2 to 5 nm were used as a labeling agent to detect basal cell carcinoma (BCC) of the skin. The enhanced Raman band at 1075 cm-1 corresponding to the C-S stretching vibration in 4-ATP was observed during attachment to the surface of the gold nanoparticles. The frequency and intensity of this band did not change when the colloids were conjugated with BerEP4 antibody, which specifically binds to BCC. We show the feasibility of imaging BCC by surface-enhanced Raman spectroscopy, scanning the 1075 cm-1 band to detect the distribution of 4-ATP-coated gold nanoparticles attached to skin tissue ex vivo.

Green synthesis of gold nanoparticles using Citrus fruits (Citrus limon, Citrus reticulata and Citrus sinensis) aqueous extract and its characterization

Science.gov (United States)

Sujitha, Mohanan V.; Kannan, Soundarapandian

2013-02-01

This study reports the biological synthesis of gold nanoparticles by the reduction of HAuCl4 by using citrus fruits (Citrus limon, Citrus reticulata and Citrus sinensis) juice extract as the reducing and stabilizing agent. A various shape and size of gold nanoparticles were formed when the ratio of the reactants were altered with respect to 1.0 mM chloroauric acid solution. The gold nanoparticles obtained were characterized by UV-visible spectra, transmission electron microscopy (TEM) and X-ray diffraction (XRD). TEM studies showed the particles to be of various shapes and sizes and particle size ranges from 15 to 80 nm. Selected-area electron diffraction (SAED) pattern confirmed fcc phase and crystallinity of the particles. The X-ray diffraction analysis revealed the distinctive facets (1 1 1, 2 0 0, 2 2 0 and 2 2 2 planes) of gold nanoparticles. Dynamic light scattering (DLS) studies revealed that the average size for colloid gp3 of C. limon, C. reticulata and C. sinensis are 32.2 nm, 43.4 nm and 56.7 nm respectively. The DLS graph showed that the particles size was larger and more polydispersed compared to the one observed by TEM due to the fact that the measured size also includes the bio-organic compounds enveloping the core of the Au NPs. Zeta potential value for gold nanoparticles obtained from colloid gp3 of C. limon, C. reticulata and C. sinensis are -45.9, -37.9 and -31.4 respectively indicating the stability of the synthesized nanoparticles. Herein we propose a novel, previously unexploited method for the biological syntheses of polymorphic gold nanoparticles with potent biological applications.

Ultra-high sensitive substrates for surface enhanced Raman scattering, made of 3 nm gold nanoparticles embedded on SiO2 nanospheres

Science.gov (United States)

Phatangare, A. B.; Dhole, S. D.; Dahiwale, S. S.; Bhoraskar, V. N.

2018-05-01

The surface properties of substrates made of 3 nm gold nanoparticles embedded on SiO2 nanospheres enabled fingerprint detection of thiabendazole (TBZ), crystal violet (CV) and 4-Aminothiophenol (4-ATP) at an ultralow concentration of ∼10-18 M by surface enhanced Raman spectroscopy (SERS). Gold nanoparticles of an average size of ∼3 nm were synthesized and simultaneously embedded on SiO2 nanospheres by the electron irradiation method. The substrates made from the 3 nm gold nanoparticles embedded on SiO2 nanospheres were successfully used for recording fingerprint SERS spectra of TBZ, CV and 4-ATP over a wide range of concentrations from 10-6 M to 10-18 M using 785 nm laser. The unique features of these substrates are roughness near the surface due to the inherent structural defects of 3 nm gold nanoparticles, nanogaps of ≤ 1 nm between the embedded nanoparticles and their high number. These produced an abundance of nanocavities which act as active centers of hot-spots and provided a high electric field at the reporter molecules and thus an enhancement factor required to record the SERS spectra at ultra low concentration of 10-18 M. The SERS spectra recorded by the substrates of 4 nm and 6 nm gold nanoparticles are discussed.

Gold Nanohole Array with Sub-1 nm Roughness by Annealing for Sensitivity Enhancement of Extraordinary Optical Transmission Biosensor

Science.gov (United States)

Zhang, Jian; Irannejad, Mehrdad; Yavuz, Mustafa; Cui, Bo

2015-05-01

Nanofabrication technology plays an important role in the performance of surface plasmonic devices such as extraordinary optical transmission (EOT) sensor. In this work, a double liftoff process was developed to fabricate a series of nanohole arrays of a hole diameter between 150 and 235 nm and a period of 500 nm in a 100-nm-thick gold film on a silica substrate. To improve the surface quality of the gold film, thermal annealing was conducted, by which an ultra-smooth gold film with root-mean-square (RMS) roughness of sub-1 nm was achieved, accompanied with a hole diameter shrinkage. The surface sensitivity of the nanohole arrays was measured using a monolayer of 16-mercaptohexadecanoic acid (16-MHA) molecule, and the surface sensitivity was increased by 2.5 to 3 times upon annealing the extraordinary optical transmission (EOT) sensor.

Stability of contamination-free gold and silver nanoparticles produced by nanosecond laser ablation of solid targets in water

International Nuclear Information System (INIS)

Nikov, R.G.; Nikolov, A.S.; Nedyalkov, N.N.; Dimitrov, I.G.; Atanasov, P.A.; Alexandrov, M.T.

2012-01-01

Highlights: ► Au and Ag colloids were prepared by nanosecond laser ablation of solids in water. ► The alteration of the produced colloids during one month was investigated. ► Optical transmission spectra of the samples were measured from 350 to 800 nm. ► TEM measurements were made of as-prepared colloids and on the 30-th day. ► Zeta potential measurements were performed of as-prepared samples. - Abstract: Preparation of noble metal nanoparticle (NPs) colloids using pulsed laser ablation in water has an inherent advantage compared to the different chemical methods used, especially when biological applications of the colloids are considered. The fabrication method is simple and the NPs prepared in this way are contamination free. The method of laser ablation of a solid target in water is applied in the present work in order to obtain gold and silver NP colloids. The experiment was preformed by using the fundamental wavelength (1064 nm) of a Nd:YAG laser system. The target immersed in double distilled water was irradiated for 20 min by laser pulses with duration of 15 ns and repetition rate of 10 Hz. The sedimentation and aggregation of NPs in the colloids, stored at constant temperature, as a function of the time after preparation were investigated. The analyses are based on optical transmission spectroscopy in UV and vis regions. The change of the plasmon resonance wavelength as a function of time was studied. Zeta potential measurement was also utilized to measure the charge of the NPs in the colloids. The size distribution of the NPs and its change in time was determined by transmission electron microscopy (TEM). On the basis of the results obtained, the optimal conditions of post fabrication manipulation with gold and silver colloids are defined in view of producing stable NPs with a narrow size distribution.

Studies on hemodynamics in liver diseases by the use of colloidal gold198 uptakes by liver and spleen

International Nuclear Information System (INIS)

Matsunaga, Atsushi

1983-01-01

In this study, hepatic blood flow was observed using colloidal gold 198 uptakes by the liver and spleen in the pathogenic conditions in which the uptake was increased in the area of extra hepatic reticuloendothelial systems (especially in splenic RES). The change in the uptake ability of the liver and the contribution to it of intra and extra hepatic shunts were examined. In addition, study was made on the mechanism of how splenic visualization occurred in the colloidal gold 198 scintigram in liver diseases. Out of 84 subjects, 35, 11, 24, and 8 had hepatic cirrhosis and precirrhosis and chronic and acute hepatitis, respectively, and 6 were normal. The results obtained in this study were as follows: (1) The mean value of splenic clearance (splenic blood flow component) in hepatic cirrhosis was 88+-67.5 ml/min. This accounts for approximately 14.6+-11.9 % of the total RES clearance (Classic Effective Hepatic Blood Flow). (2) In hepatic cirrhosis, Classic Hepatic Blood Flow which had been measured up to date was considered to be overestimation by about 19.9+-20.4 % over the mean value of hepatic clearance (hepatic blood flow component) obtained in this study, (3) The hepatic clearance was better indicator of liver disease than the total RES clearance, (4) The ratio between hepatic clearance and cardiac output was considered to be a useful index in assessing the amount of intra and extra hepatic shunts, which had an inverse relationship to the ability of colloid uptake by the liver. (5) Splenic visualization in hepatic cirrhosis was shown to have resulted from the increase in splenic extraction of the colloid, followed by the increase in total splenic blood flow. (author)

Sub-10 ohm resistance gold films prepared by removal of ligands from thiol-stabilized 6 nm gold nanoparticles.

Science.gov (United States)

Sugden, Mark W; Richardson, Tim H; Leggett, Graham

2010-03-16

The optical and electrical properties of dodecanethiol-stabilized nanoparticles (6 nm diameter gold core) have been investigated over a range of film thicknesses and temperatures. The surface plasmon resonance absorbance is found to be dependent on temperature. Heating of the nanoparticle film causes desorption of the thiol from the surface of the gold nanoparticle, resulting in irreversible changes to the absorption spectra of the nanoparticle film. Atomic force microscopy images of the samples before and after heating for different film thicknesses reveal structural changes and increased domain connectivity for thicker films leading to sub-10 ohm resistances measured for the 15-layer film.

Vibrational properties of gold nanoparticles obtained by green synthesis

Science.gov (United States)

Alvarez, Ramón A. B.; Cortez-Valadez, M.; Bueno, L. Oscar Neira; Britto Hurtado, R.; Rocha-Rocha, O.; Delgado-Beleño, Y.; Martinez-Nuñez, C. E.; Serrano-Corrales, Luis Ivan; Arizpe-Chávez, H.; Flores-Acosta, M.

2016-10-01

This study reports the synthesis and characterization of gold nanoparticles through an ecological method to obtain nanostructures from the extract of the plant Opuntia ficus-indica. Colloidal nanoparticles show sizes that vary between 10-20 nm, and present various geometric morphologies. The samples were characterized through optical absorption, Raman Spectroscopy and Transmission Electron Microscopy (TEM). Additionally, low energy metallic clusters of Aun (n=2-20 atoms) were modeled by computational quantum chemistry. The theoretical results were obtained with Density Functional Theory (DFT). The predicted results of Au clusters show a tendency and are correlated with the experimental results concerning the optical absorption bands and Raman spectroscopy in gold nanoparticles.

Interaction of gold nanoparticles with nanosecond laser pulses: Nanoparticle heating

International Nuclear Information System (INIS)

Nedyalkov, N.N.; Imamova, S.E.; Atanasov, P.A.; Toshkova, R.A.; Gardeva, E.G.; Yossifova, L.S.; Alexandrov, M.T.; Obara, M.

2011-01-01

Theoretical and experimental results on the heating process of gold nanoparticles irradiated by nanosecond laser pulses are presented. The efficiency of particle heating is demonstrated by in-vitro photothermal therapy of human tumor cells. Gold nanoparticles with diameters of 40 and 100 nm are added as colloid in the cell culture and the samples are irradiated by nanosecond pulses at wavelength of 532 nm delivered by Nd:YAG laser system. The results indicate clear cytotoxic effect of application of nanoparticle as more efficient is the case of using particles with diameter of 100 nm. The theoretical analysis of the heating process of nanoparticle interacting with laser radiation is based on the Mie scattering theory, which is used for calculation of the particle absorption coefficient, and two-dimensional heat diffusion model, which describes the particle and the surrounding medium temperature evolution. Using this model the dependence of the achieved maximal temperature in the particles on the applied laser fluence and time evolution of the particle temperature is obtained.

Interaction of gold nanoparticles with nanosecond laser pulses: Nanoparticle heating

Science.gov (United States)

Nedyalkov, N. N.; Imamova, S. E.; Atanasov, P. A.; Toshkova, R. A.; Gardeva, E. G.; Yossifova, L. S.; Alexandrov, M. T.; Obara, M.

2011-04-01

Theoretical and experimental results on the heating process of gold nanoparticles irradiated by nanosecond laser pulses are presented. The efficiency of particle heating is demonstrated by in-vitro photothermal therapy of human tumor cells. Gold nanoparticles with diameters of 40 and 100 nm are added as colloid in the cell culture and the samples are irradiated by nanosecond pulses at wavelength of 532 nm delivered by Nd:YAG laser system. The results indicate clear cytotoxic effect of application of nanoparticle as more efficient is the case of using particles with diameter of 100 nm. The theoretical analysis of the heating process of nanoparticle interacting with laser radiation is based on the Mie scattering theory, which is used for calculation of the particle absorption coefficient, and two-dimensional heat diffusion model, which describes the particle and the surrounding medium temperature evolution. Using this model the dependence of the achieved maximal temperature in the particles on the applied laser fluence and time evolution of the particle temperature is obtained.

Multidentate-Protected Colloidal Gold Nanocrystals: pH Control of Cooperative Precipitation and Surface Layer Shedding

Science.gov (United States)

Kairdolf, Brad A.; Nie, Shuming

2011-01-01

Colloidal gold nanocrystals with broad size tunability and unusual pH-sensitive properties have been synthesized by using multidentate polymer ligands. Containing both carboxylic functional groups and sterically hindered aliphatic chains, the multidentate ligands are able to both reduce gold precursors and to stabilize gold nanoclusters during nucleation and growth. The “as-synthesized” nanocrystals are protected by an inner coordinating layer and an outer polymer layer, and are soluble in water and polar solvents. When the solution pH is lowered by just 0.6 units (from pH 4.85 to 4.25), the particles undergo a dramatic cooperative transition from being soluble to insoluble, allowing rapid isolation, purification, and redispersion of the multidentate-protected nanocrystals. A surprise finding is that when a portion of the surface carboxylate groups is neutralized by protonation, the particles irreversibly shed their outer polymer layer and become soluble in nonpolar organic solvents. Further, the multidentate polymer coatings are permeable to small organic molecules, in contrast to tightly packed self-assembled monolayers of alkanethiols on gold. These insights are important towards the design of “smart” imaging and therapeutic nanoparticles that are activated by small pH changes in the tumor interstitial space or endocytic organelles. PMID:21510704

Extensive Characterization of Oxide-Coated Colloidal Gold Nanoparticles Synthesized by Laser Ablation in Liquid

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Romuald Intartaglia

2016-09-01

Full Text Available Colloidal gold nanoparticles are a widespread nanomaterial with many potential applications, but their aggregation in suspension is a critical issue which is usually prevented by organic surfactants. This solution has some drawbacks, such as material contamination and modifications of its functional properties. The gold nanoparticles presented in this work have been synthesized by ultra-fast laser ablation in liquid, which addresses the above issues by overcoating the metal nanoparticles with an oxide layer. The main focus of the work is in the characterization of the oxidized gold nanoparticles, which were made first in solution by means of dynamic light scattering and optical spectroscopy, and then in dried form by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and finally by surface potential measurements with atomic force microscopy. The light scattering assessed the nanoscale size of the formed particles and provided insight in their stability. The nanoparticles’ size was confirmed by direct imaging in transmission electron microscopy, and their crystalline nature was disclosed by X-ray diffraction. The X-ray photoelectron spectroscopy showed measurements compatible with the presence of surface oxide, which was confirmed by the surface potential measurements, which are the novel point of the present work. In conclusion, the method of laser ablation in liquid for the synthesis of gold nanoparticles has been presented, and the advantage of this physical approach, consisting of coating the nanoparticles in situ with gold oxide which provides the required morphological and chemical stability without organic surfactants, has been confirmed by using scanning Kelvin probe microscopy for the first time.

Colloidal gold-labeled insulin complex. Characterization and binding to adipocytes.

Science.gov (United States)

Moll, U M; Thun, C; Pfeiffer, E F

1986-01-01

Biologically active insulin gold complex was used as an ultrastructural marker to study insulin binding sites, uptake, and internalization in isolated rat adipocytes. The preparation conditions for monodispersed particles, ca. 16 nm in diameter and loaded with approximately 100 insulin molecules, are reported. The complex is stable for at least six weeks. Single particles or small clusters were scattered across the cell membrane. The distribution of unbound receptors seemed to be independent of the extensive system of pre-existing surface connected vesicles in adipocytes. The uptake of particles took place predominantly via non-coated pinocytotic invaginations; clathrin-coated pits did not seem to be important for this process. Lysosome-like structures contained aggregates of 10-15 particles. These data suggest that insulin gold complex is a useful marker for the specific labeling of insulin binding sites.

Synthesis of gold nanorods with a longitudinal surface plasmon resonance peak of around 1250 nm

Science.gov (United States)

Nguyen, Thi Nhat Hang; Le Trinh Nguyen, Thi; Thanh Tuyen Luong, Thi; Thang Nguyen, Canh Minh; Nguyen, Thi Phuong Phong

2016-03-01

We prepared gold nanorods and joined them to chemicals such as tetrachloauric (III) acid trihydrate, silver nitrate, hydroquinone, hexadecyltrimethylammonium bromide, sodium hydroxide and sodium borohydride using the seed-mediated method. The combination of hydroquinone, with or without salicylic acid, influences the size of the gold nanorods, and this is demonstrated by the results of TEM images, UV-vis spectra and the value of the longitudinal surface plasmon resonance peak with respect to the UV-vis spectra. By changing the Ag+ ion and hydroquinone concentration and the combination of hydroquinone and salicylic acid, the size of the gold nanorods can be controlled and this is manifested by longitudinal surface plasmon resonance peaks forming between 875 and 1278 nm. In particular, sample E2 achieved a longitudinal surface plasmon peak at 1273 nm and an aspect ratio of more than 10 by modifying the hydroquinone to 2.5 mM and salicylic acid to 0.5 mM concentration in the growth solution.

The kinetics of phagocytosis of 198Au colloids ''in vitro''

International Nuclear Information System (INIS)

Astorri, N.L.; Bergoc, R.M.; Bianchin, A.M.; Caro, R.A.; Ihlo, J.E.; Rivera, E.S.

1982-01-01

The kinetics of the phagocytosis of 198-Au colloids by macrophages ''in vitro'' was studied by incubating during 5 hours phagocytic cells from the liver and the spleen of Wistar rats with colloidal radiogold particles, in the presence of an adequate culture medium (TC-199 with 10 per cent of Bovine Fetal Serum). In each experiment, the number of colloidal gold particles offered to each phatocytic cell, (Au) 0 and the mean rate of phagocytosis v, were calculated. The latter value was determined by measuring the radioactivity incorporated into the phagocytic cells during the incubation; it was expressed as the number of phagocytized colloidal gold particles per cell per minute. The values of log v = f [log (Au) 0 ] were plotted. The Lineweaver-Burk analysis of the results demonstrates that the kinetics of the phagocytosis of colloidal radiogold particles ''in vitro'' follows a model similar to Michaelis-Menten equations for enzyme reactions. The values of the substratum constant Ks and maximun velocity Vm were obtained by the regression analysis of the 1/v vs. 1/(Au) 0 graph. Vm was equal to 9.44 x 10 and 1.63 x 10 phagocytized colloidal gold particles per cell per minute for liver and spleen macrophages, respectively. Ks was equal to 6.01 x 10 9 and 8.02 x 10 8 colloidal gold particles per cell for liver and spleen macrophages, respectively. The significance of these differences is discussed and attributed mainly to a change of the specific engulfment rate constant. (author) [es

Orange pectin mediated growth and stability of aqueous gold and silver nanocolloids

International Nuclear Information System (INIS)

Nigoghossian, Karina; Santos, Molíria V. dos; Barud, Hernane S.; Silva, Robson R. da; Rocha, Lucas A.; Caiut, José M.A.; Assunção, Rosana M.N. de; Spanhel, Lubomir; Poulain, Marcel; Messaddeq, Younes; Ribeiro, Sidney J.L.

2015-01-01

Graphical abstract: - Highlights: • Pectin from orange was used as stabilizer of Ag, Au and Ag–Au nanoparticles. • Sodium citrate, oxalic acid or pectin were used as reducing agents. • Colloids spanning all visible region were obtained depending on Ag/Au-ratio and pH. • Pectin is a highly efficient stabilizer of nanocolloidal solutions for years. - Abstract: The role of orange based pectin in the nucleation and growth of silver and gold nanoparticles is addressed. Pectin is a complex polysaccharide found in fruits such as oranges, lemons, passion fruits or apples. It displays smooth and hairy chain regions containing hydroxyl-, ester-, carboxylate- and eventually amine groups that can act as surface ligands interacting under various pH conditions more or less efficiently with growing nanometals. Here, a high methoxy pectin (>50% esterified) was used as a stabilizer/reducing agent in the preparation of gold, silver and silver–gold nanoparticles. Commercial pectin (CP) and pectin extracted from orange bagasse (OP) were used. Optionally, trisodium citrate or oxalic acid we used to reduce AgNO 3 and HAuCl 4 in aqueous environment. Characterization methods included UV–vis absorption spectroscopy, transmission electron microscopy, electron diffraction and energy-dispersive X-ray spectroscopy. The results show that under different pH conditions, pectin and reducing agents allow producing various nanostructures shapes (triangles, spheres, rods, octahedrons and decahedrons) often with high polydispersity and sizes ranging between 5 nm and 30 nm. In addition, depending on Ag/Au-ratio and pH, the surface plasmon bands can be continuously shifted between 410 nm and 600 nm. Finally, pectin seems to be a highly efficient stabilizer of the colloidal systems that show a remarkable stability and unchanged optical spectral response even after five years

Orange pectin mediated growth and stability of aqueous gold and silver nanocolloids

Energy Technology Data Exchange (ETDEWEB)

Nigoghossian, Karina; Santos, Molíria V. dos; Barud, Hernane S.; Silva, Robson R. da [Institute of Chemistry, São Paulo State University – UNESP, 14801-970 Araraquara, SP (Brazil); Rocha, Lucas A. [Departamento de Quimica, Universidade de Franca, Franca, SP (Brazil); Caiut, José M.A. [Departamento de Química, FFCLRP, USP, Ribeirão Preto, SP (Brazil); Assunção, Rosana M.N. de [Faculdade de Ciências Integradas do Pontal, Universidade Federal de Uberlândia, 38302-000 Ituiutaba, MG (Brazil); Spanhel, Lubomir [CEITEC-Central European Institute of Technology, Masaryk University Brno (Czech Republic); Institute of Chemical Sciences, University of Rennes 1, Campus Beaulieu, 35 042 Rennes (France); Poulain, Marcel [Institute of Chemical Sciences, University of Rennes 1, Campus Beaulieu, 35 042 Rennes (France); Messaddeq, Younes [Institute of Chemistry, São Paulo State University – UNESP, 14801-970 Araraquara, SP (Brazil); Ribeiro, Sidney J.L., E-mail: sidney@iq.unesp.br [Institute of Chemistry, São Paulo State University – UNESP, 14801-970 Araraquara, SP (Brazil)

2015-06-30

Graphical abstract: - Highlights: • Pectin from orange was used as stabilizer of Ag, Au and Ag–Au nanoparticles. • Sodium citrate, oxalic acid or pectin were used as reducing agents. • Colloids spanning all visible region were obtained depending on Ag/Au-ratio and pH. • Pectin is a highly efficient stabilizer of nanocolloidal solutions for years. - Abstract: The role of orange based pectin in the nucleation and growth of silver and gold nanoparticles is addressed. Pectin is a complex polysaccharide found in fruits such as oranges, lemons, passion fruits or apples. It displays smooth and hairy chain regions containing hydroxyl-, ester-, carboxylate- and eventually amine groups that can act as surface ligands interacting under various pH conditions more or less efficiently with growing nanometals. Here, a high methoxy pectin (>50% esterified) was used as a stabilizer/reducing agent in the preparation of gold, silver and silver–gold nanoparticles. Commercial pectin (CP) and pectin extracted from orange bagasse (OP) were used. Optionally, trisodium citrate or oxalic acid we used to reduce AgNO{sub 3} and HAuCl{sub 4} in aqueous environment. Characterization methods included UV–vis absorption spectroscopy, transmission electron microscopy, electron diffraction and energy-dispersive X-ray spectroscopy. The results show that under different pH conditions, pectin and reducing agents allow producing various nanostructures shapes (triangles, spheres, rods, octahedrons and decahedrons) often with high polydispersity and sizes ranging between 5 nm and 30 nm. In addition, depending on Ag/Au-ratio and pH, the surface plasmon bands can be continuously shifted between 410 nm and 600 nm. Finally, pectin seems to be a highly efficient stabilizer of the colloidal systems that show a remarkable stability and unchanged optical spectral response even after five years.

Dilated cardiomyopathy and left bundle branch block associated with ingestion of colloidal gold and silver is reversed by British antiLewisite and vitamin E: The potential toxicity of metals used as health supplements

Science.gov (United States)

Archer, Stephen Lawrence

2008-01-01

A case of left bundle branch block and a dilated, nonhypertrophic cardiomyopathy associated with ingestion of colloidal gold and silver as an ‘energy tonic’ is described. The cardiac disease was reversed within two months by a course of dimercaprol (Akorn Inc, USA) (British antiLewisite) and vitamin E. This is the first case of gold and silver cardiomyopathy in humans, and highlights the risks of these colloidal metal ‘health supplements’. PMID:18464946

Antitumour, antimicrobial and catalytic activity of gold nanoparticles synthesized by different pH propolis extracts

Science.gov (United States)

Gatea, Florentina; Teodor, Eugenia Dumitra; Seciu, Ana-Maria; Covaci, Ovidiu Ilie; Mănoiu, Sorin; Lazăr, Veronica; Radu, Gabriel Lucian

2015-07-01

The Romanian propolis was extracted in five different media, respectively, in water (pH 6.8), glycine buffer (pH 2.5), acetate buffer (pH 5), phosphate buffer (pH 7.4) and carbonate buffer (pH 9.2). The extracts presented different amounts of flavonoids and phenolic acids, increasing pH leading to higher concentrations of active compounds. Five variants of gold nanoparticles suspensions based on different pH Romanian propolis aqueous extracts were successfully synthesized. The obtained nanoparticles presented dimensions between 20 and 60 nm in dispersion form and around 18 nm in dried form, and different morphologies (spherical, hexagonal, triangular). Fourier transform infrared spectroscopy proved the attachment of organic compounds from propolis extracts to the colloidal gold suspensions and X-ray diffraction certified that the suspensions contain metallic gold. The obtained propolis gold nanoparticles do not exhibit any antibacterial or antifungal activity, but presented different catalytic activities and toxicity on tumour cells.

Antitumour, antimicrobial and catalytic activity of gold nanoparticles synthesized by different pH propolis extracts

Energy Technology Data Exchange (ETDEWEB)

Gatea, Florentina; Teodor, Eugenia Dumitra, E-mail: eu-teodor@yahoo.com [National Institute for Biological Sciences, Centre of Bioanalysis (Romania); Seciu, Ana-Maria [National Institute for Biological Sciences, Cellular and Molecular Biology Department (Romania); Covaci, Ovidiu Ilie [SARA Pharm Solutions (Romania); Mănoiu, Sorin [National Institute for Biological Sciences, Cellular and Molecular Biology Department (Romania); Lazăr, Veronica [University of Bucharest, Faculty of Biology (Romania); Radu, Gabriel Lucian [University “Politehnica” Bucharest, Faculty of Applied Chemistry and Materials Science (Romania)

2015-07-15

The Romanian propolis was extracted in five different media, respectively, in water (pH 6.8), glycine buffer (pH 2.5), acetate buffer (pH 5), phosphate buffer (pH 7.4) and carbonate buffer (pH 9.2). The extracts presented different amounts of flavonoids and phenolic acids, increasing pH leading to higher concentrations of active compounds. Five variants of gold nanoparticles suspensions based on different pH Romanian propolis aqueous extracts were successfully synthesized. The obtained nanoparticles presented dimensions between 20 and 60 nm in dispersion form and around 18 nm in dried form, and different morphologies (spherical, hexagonal, triangular). Fourier transform infrared spectroscopy proved the attachment of organic compounds from propolis extracts to the colloidal gold suspensions and X-ray diffraction certified that the suspensions contain metallic gold. The obtained propolis gold nanoparticles do not exhibit any antibacterial or antifungal activity, but presented different catalytic activities and toxicity on tumour cells.

Colloidal Plasmonic Titanium Nitride Nanoparticles: Properties and Applications

Directory of Open Access Journals (Sweden)

Guler Urcan

2015-01-01

Full Text Available Optical properties of colloidal plasmonic titanium nitride nanoparticles are examined with an eye on their photothermal and photocatalytic applications via transmission electron microscopy and optical transmittance measurements. Single crystal titanium nitride cubic nanoparticles with an average size of 50 nm, which was found to be the optimum size for cellular uptake with gold nanoparticles [1], exhibit plasmon resonance in the biological transparency window and demonstrate a high absorption efficiency. A self-passivating native oxide at the surface of the nanoparticles provides an additional degree of freedom for surface functionalization. The titanium oxide shell surrounding the plasmonic core can create new opportunities for photocatalytic applications.

Photofragmentation of colloidal solutions of gold nanoparticles under femtosecond laser pulses in IR and visible ranges

International Nuclear Information System (INIS)

Danilov, P A; Zayarnyi, D A; Ionin, A A; Kudryashov, S I; Makarov, S V; Rudenko, A A; Saraeva, I N; Yurovskikh, V I; Lednev, V N; Pershin, S M

2015-01-01

The specific features of photofragmentation of sols of gold nanoparticles under focused femtosecond laser pulses in IR (1030 nm) and visible (515 nm) ranges is experimentally investigated. A high photofragmentation efficiency of nanoparticles in the waist of a pulsed laser beam in the visible range (at moderate radiation scattering) is demonstrated; this efficiency is related to the excitation of plasmon resonance in nanoparticles on the blue shoulder of its spectrum, in contrast to the regime of very weak photofragmentation in an IR-laser field of comparable intensity. Possible mechanisms of femtosecond laser photofragmentation of gold nanoparticles are discussed. (extreme light fields and their applications)

Synthesis and characterization of core-shell Fe3O4-gold-chitosan nanostructure

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Salehizadeh Hossein

2012-01-01

Full Text Available Abstract Background Fe3O4-gold-chitosan core-shell nanostructure can be used in biotechnological and biomedical applications such as magnetic bioseparation, water and wastewater treatment, biodetection and bioimaging, drug delivery, and cancer treatment. Results Magnetite nanoparticles with an average size of 9.8 nm in diameter were synthesized using the chemical co-precipitation method. A gold-coated Fe3O4 monotonous core-shell nanostructure was produced with an average size of 15 nm in diameter by glucose reduction of Au3+ which is then stabilized with a chitosan cross linked by formaldehyde. The results of analyses with X-ray diffraction (XRD, Fourier Transformed Infrared Spectroscopy (FTIR, Transmission Electron Microscopy (TEM, and Atomic Force Microscopy (AFM indicated that the nanoparticles were regularly shaped, and agglomerate-free, with a narrow size distribution. Conclusions A rapid, mild method for synthesizing Fe3O4-gold nanoparticles using chitosan was investigated. A magnetic core-shell-chitosan nanocomposite, including both the supermagnetic properties of iron oxide and the optical characteristics of colloidal gold nanoparticles, was synthesized.

Rapid detection of fumonisin B1 using a colloidal gold immunoassay strip test in corn samples.

Science.gov (United States)

Ling, Sumei; Wang, Rongzhi; Gu, Xiaosong; Wen, Can; Chen, Lingling; Chen, Zhibin; Chen, Qing-Ai; Xiao, Shiwei; Yang, Yanling; Zhuang, Zhenhong; Wang, Shihua

2015-12-15

Fumonisin B1 (FB1) is the most common and highest toxic of fumonisins species, exists frequently in corn and corn-based foods, leading to several animal and human diseases. Furthermore, FB1 was reported that it was associated with the human esophageal cancer. In view of the harmful of FB1, it is urgent to develop a feasible and accuracy method for rapid detection of FB1. In this study, a competitive immunoassay for FB1 detection was developed based on colloidal gold-antibody conjugate. The FB1-keyhole limpet hemoeyanin (FB1-KLH) conjugate was embedded in the test line, and goat anti-mouse IgG antibody embedded in the control line. The color density of the test line correlated with the concentration of FB1 in the range from 2.5 to 10 ng/mL, and the visual limit detection of test for FB1 was 2.5 ng/mL. The results indicated that the test strip is specific for FB1, and no cross-reactivity to other toxins. The quantitative detection for FB1 was simple, only needing one step without complicated assay performance and expensive equipment, and the total time of visual evaluation was less than 5 min. Hence, the developed colloidal gold-antibody assay can be used as a feasible method for FB1 rapid and quantitative detection in corn samples. Copyright © 2015 Elsevier Ltd. All rights reserved.

Towards thiol functionalization of vanadium pentoxide nanotubes using gold nanoparticles

International Nuclear Information System (INIS)

Lavayen, V.; O'Dwyer, C.; Cardenas, G.; Gonzalez, G.; Sotomayor Torres, C.M.

2007-01-01

Template-directed synthesis is a promising route to realize vanadate-based 1-D nanostructures, an example of which is the formation of vanadium pentoxide nanotubes and associated nanostructures. In this work, we report the interchange of long-chained alkyl amines with alkyl thiols. This reaction was followed using gold nanoparticles prepared by the Chemical Liquid Deposition (CLD) method with an average diameter of ∼0.9nm and a stability of ∼85 days. V 2 O 5 nanotubes (VOx-NTs) with lengths of ∼2μm and internal hollow diameters of 20-100nm were synthesized and functionalized in a Au-acetone colloid with a nominal concentration of ∼4x10 -3 mol dm -3 . The interchange reaction with dodecylamine is found only to occur in polar solvents and incorporation of the gold nanoparticles is not observed in the presence of n-decane

Pseudo-template synthesis of gold nanoparticles based on polyhydrosilanes

International Nuclear Information System (INIS)

Sacarescu, Liviu; Simionescu, Mihaela; Sacarescu, Gabriela

2011-01-01

Highly stable colloidal gold nanoparticles are obtained in a pseudo-template system using a specific polyhydrosilane copolymeric structure. This process takes place in situ by microwaves activation of the polymer solution in a non-polar solvent followed by stirring with solid HAuCl 4 in natural light. The experimental procedure is very simple and the resulted colloidal gold solution is indefinitely stable. The specific surface plasmon resonance absorption band of the gold nanoparticles is strongly red shifted and is strictly related to their size. AFM correlated with DLS analysis showed flattened round shaped colloidal polymer-gold nanoparticles with large diameters. SEM-EDX combined analysis reveals that the polysilane-gold nanoparticles show a natural tendency to auto-assemble in close packed structures which form large areas over the polymer film surface.

Synthesis of camptothecin-loaded gold nanomaterials

International Nuclear Information System (INIS)

Xing Zhimin; Liu Zhiguo; Zu Yuangang; Fu Yujie; Zhao Chunjian; Zhao Xiuhua; Meng Ronghua; Tan Shengnan

2010-01-01

Camptothecin-loaded gold nanomaterials have been synthesized by the sodium borohydride reduction method under a strong basic condition. The obtained gold nanomaterials have been characterized by transmission electron microscopy (TEM), atomic force microscopy (AFM) and UV-vis absorption spectroscopy. The camptothecin-loaded gold colloidal solution was very stable and can be stored for more than two months at room temperature without obvious changes. The color of the colloidal solution can change from wine red to purple and blue during the acidifying process. It was revealed that the release of camptothecin and the aggregation of gold nanoparticles can be controlled by tuning the solution pH. The present study implied that the gold nanomaterials can be used as the potential carrier for CPT delivery.

Synthesis of camptothecin-loaded gold nanomaterials

Energy Technology Data Exchange (ETDEWEB)

Xing Zhimin [Key Laboratory of Forest Plant Ecology of Ministry of Education, Northeast Forestry University, Harbin 150040 (China); Engineering Research Center of Forest Bio-preparation, Ministry of Education, Northeast Forestry University, Harbin 150040 (China); Liu Zhiguo, E-mail: zguoliu@yahoo.com.cn [Key Laboratory of Forest Plant Ecology of Ministry of Education, Northeast Forestry University, Harbin 150040 (China); Engineering Research Center of Forest Bio-preparation, Ministry of Education, Northeast Forestry University, Harbin 150040 (China); Zu Yuangang, E-mail: nefunano@yahoo.com.cn [Key Laboratory of Forest Plant Ecology of Ministry of Education, Northeast Forestry University, Harbin 150040 (China); Engineering Research Center of Forest Bio-preparation, Ministry of Education, Northeast Forestry University, Harbin 150040 (China); Fu Yujie; Zhao Chunjian; Zhao Xiuhua; Meng Ronghua; Tan Shengnan [Key Laboratory of Forest Plant Ecology of Ministry of Education, Northeast Forestry University, Harbin 150040 (China); Engineering Research Center of Forest Bio-preparation, Ministry of Education, Northeast Forestry University, Harbin 150040 (China)

2010-04-01

Camptothecin-loaded gold nanomaterials have been synthesized by the sodium borohydride reduction method under a strong basic condition. The obtained gold nanomaterials have been characterized by transmission electron microscopy (TEM), atomic force microscopy (AFM) and UV-vis absorption spectroscopy. The camptothecin-loaded gold colloidal solution was very stable and can be stored for more than two months at room temperature without obvious changes. The color of the colloidal solution can change from wine red to purple and blue during the acidifying process. It was revealed that the release of camptothecin and the aggregation of gold nanoparticles can be controlled by tuning the solution pH. The present study implied that the gold nanomaterials can be used as the potential carrier for CPT delivery.

Feasibility Study on the Use of the Seeding Growth Technique in Producing a Highly Stable Gold Nanoparticle Colloidal System

Directory of Open Access Journals (Sweden)

Kim Han Tan

2015-01-01

Full Text Available Stable colloidal gold nanoparticles (Au NPs are synthesized successfully using a seeding growth technique. The size of the nanoparticles is determined using transmission electron microscopy (TEM, and it is observed that the size of the nanoparticles ranges from 7 to 30 nm. The TEM images and optical absorption spectra of the Au NPs reveal that the suspension is well dispersed and consistent with the particle size. The feasibility of the seeding growth technique is investigated using Turbiscan Classic MA 2000 screening stability tester. Based on the peak thickness kinetics and mean value kinetics, the backscattered light profiles indicate that the suspension is highly stable without particle sedimentation as well as negligible agglomeration. In addition, the Au NPs are proven to remain stable over a period of 2 months. Particle sedimentation eventually occurs due to the weight of nanoparticles. It is concluded that the seeding growth technique is feasible in synthesizing stable Au NPs. Controlling the stability, size and shape of Au NPs are technologically important because of the strong correlation between these parameters and the optical, electrical, and catalytic properties of the nanoparticles.

In situ spectroscopy of ligand exchange reactions at the surface of colloidal gold and silver nanoparticles

International Nuclear Information System (INIS)

Dinkel, Rebecca; Peukert, Wolfgang; Braunschweig, Björn

2017-01-01

Gold and silver nanoparticles with their tunable optical and electronic properties are of great interest for a wide range of applications. Often the ligands at the surface of the nanoparticles have to be exchanged in a second step after particle formation in order to obtain a desired surface functionalization. For many techniques, this process is not accessible in situ . In this review, we present second-harmonic scattering (SHS) as an inherently surface sensitive and label-free optical technique to probe the ligand exchange at the surface of colloidal gold and silver nanoparticles in situ and in real time. First, a brief introduction to SHS and basic features of the SHS of nanoparticles are given. After that, we demonstrate how the SHS intensity decrease can be correlated to the thiol coverage which allows for the determination of the Gibbs free energy of adsorption and the surface coverage. (topical review)

Gold nanoshell photomodification under a single-nanosecond laser pulse accompanied by color-shifting and bubble formation phenomena

International Nuclear Information System (INIS)

Akchurin, Garif; Khlebtsov, Boris; Akchurin, Georgy; Tuchin, Valery; Zharov, Vladimir; Khlebtsov, Nikolai

2008-01-01

Laser-nanoparticle interaction is crucial for biomedical applications of lasers and nanotechnology to the treatment of cancer or pathogenic microorganisms. We report on the first observation of laser-induced coloring of gold nanoshell solution after a one nanosecond pulse and an unprecedentedly low bubble formation (as the main mechanism of cancer cell killing) threshold at a laser fluence of about 4 mJ cm -2 , which is safe for normal tissue. Specifically, silica/gold nanoshell (140/15 nm) suspensions were irradiated with a single 4 ns (1064 nm) or 8 ns (900 nm) laser pulse at fluences ranging from 0.1 mJ cm -2 to 50 J cm -2 . Solution red coloring was observed by the naked eye confirmed by blue-shifting of the absorption spectrum maximum from the initial 900 nm for nanoshells to 530 nm for conventional colloidal gold nanospheres. TEM images revealed significant photomodification of nanoparticles including complete fragmentation of gold shells, changes in silica core structure, formation of small 20-30 nm isolated spherical gold nanoparticles, gold nanoshells with central holes, and large and small spherical gold particles attached to a silica core. The time-resolved monitoring of bubble formation phenomena with the photothermal (PT) thermolens technique demonstrated that after application of a single 8 ns pulse at fluences 5-10 mJ cm -2 and higher the next pulse did not produce any PT response, indicating a dramatic decrease in absorption because of gold shell modification. We also observed a dependence of the bubble expansion time on the laser energy with unusually very fast PT signal rising (∼3.5 ns scale at 0.2 J cm -2 ). Application of the observed phenomena to medical applications is discussed, including a simple visual color test for laser-nanoparticle interaction

Seed Mediated Growth of Gold Nanoparticles Based on Liquid Arc Discharge

International Nuclear Information System (INIS)

Ashkarran, Ali Akbar

2013-01-01

We report studies on the growth of gold nanoparticles by a seed-mediated approach in solution. The synthetic method is adapted from one we published earlier (Ashkarran et al. Appl. Phys. A 2009, 96, 423). The synthesized gold nanoparticles were characterized by X-ray diffraction (XRD), dynamic light scattering (DLS), UV-Vis spectroscopy, optical imaging and atomic force microscopy (AFM). Optical absorption spectroscopy of the prepared samples at 15 A arc current in HAuCl 4 solution shows a surface plasmon resonance around 520 nm. It is found that sodium citrate acts as a stabilizer and surface capping agent of the colloidal nanoparticles. The intensity of the plasmonic peak of the prepared gold nanoparticles for 1 minute arc duration gradually increases due to seed mediation for up to 6 hours. The formation time of gold nanoparticles at higher seed concentrations is less than that at lower seed concentrations. (plasma technology)

Phoenix dactylifera L. leaf extract phytosynthesized gold nanoparticles; controlled synthesis and catalytic activity

Science.gov (United States)

Zayed, Mervat F.; Eisa, Wael H.

2014-03-01

A green synthesis route was reported to explore the reducing and capping potential of Phoenix dactylifera extract for the synthesis of gold nanoparticles. The processes of nucleation and growth of gold nanoparticles were followed by monitoring the absorption spectra during the reaction. The size and morphology of these nanoparticles was typically imaged using transmission electron microscopy (TEM). The particle size ranged between 32 and 45 nm and are spherical in shape. Fourier transform infrared (FTIR) analysis suggests that the synthesized gold nanoparticles might be stabilized through the interactions of hydroxyl and carbonyl groups in the carbohydrates, flavonoids, tannins and phenolic acids present in P. dactylifera. The as-synthesized Au colloids exhibited good catalytic activity for the degradation of 4-nitrophenol.

A simple gel electrophoresis method for separating polyhedral gold nanoparticles

Science.gov (United States)

Kim, Suhee; Lee, Hye Jin

2015-07-01

In this paper, a simple approach to separate differently shaped and sized polyhedral gold nanoparticles (NPs) within colloidal solutions via gel electrophoresis is described. Gel running parameters for separating efficiently gold NPs including gel composition, added surfactant types and applied voltage were investigated. The plasmonic properties and physical structure of the separated NPs extracted from the gel matrix were then investigated using transmission electron microscopy (TEM) and UV-vis spectrophotometry respectively. Data analysis revealed that gel electrophoresis conditions of a 1.5 % agarose gel with 0.1 % sodium dodecyl sulfate (SDS) surfactant under an applied voltage of 100 V resulted in the selective isolation of ~ 50 nm polyhedral shaped gold nanoparticles. Further efforts are underway to apply the method to purify biomolecule-conjugated polyhedral Au NPs that can be readily used for NP-enhanced biosensing platforms.

Optoacoustic response of gold nanorods in soft phantoms using high-power diode laser assemblies at 870 and 905 nm.

Science.gov (United States)

Leggio, L; Gawali, S; Gallego, D; Rodríguez, S; Sánchez, M; Carpintero, G; Lamela, H

2017-03-01

In the present paper we show the optoacoustic (OA) response of two solutions of gold nanorods dispersed in distilled water (0.8 mg/ml) and hosted in tissue-like phantoms by using small arrays of HPDLs at 870 and 905 nm as excitation sources. The HPDLs are coupled to a 7-to-1 optical fiber bundle with output diameter of 675 μm. Each solution of gold nanorods exhibits an absorption peak close to the operating wavelength, i.e. ~860 nm and ~900 nm, respectively, to optimize the generation of OA signals. The phantoms are made of agar, intralipid and hemoglobin to simulate a soft biological tissue with reduced properties of scattering. Three 3-mm diameter tubes done in the phantoms at different depths (0.9 cm, 1.8 cm, and 2.7 cm) have been filled with gold nanorods. In this way, OA signals with appreciable SNR are generated at different depths in the phantoms. The high OA response exhibited by gold nanorods suggests their application in OA spectroscopy as exogenous contrast agents to detect and monitor emerging diseases like metastasis and arteriosclerotic plaques.

Lithographically patterned electrodeposition of gold, silver, and nickel nanoring arrays with widely tunable near-infrared plasmonic resonances.

Science.gov (United States)

Halpern, Aaron R; Corn, Robert M

2013-02-26

A novel low-cost nanoring array fabrication method that combines the process of lithographically patterned nanoscale electrodeposition (LPNE) with colloidal lithography is described. Nanoring array fabrication was accomplished in three steps: (i) a thin (70 nm) sacrificial nickel or silver film was first vapor-deposited onto a plasma-etched packed colloidal monolayer; (ii) the polymer colloids were removed from the surface, a thin film of positive photoresist was applied, and a backside exposure of the photoresist was used to create a nanohole electrode array; (iii) this array of nanoscale cylindrical electrodes was then used for the electrodeposition of gold, silver, or nickel nanorings. Removal of the photoresist and sacrificial metal film yielded a nanoring array in which all of the nanoring dimensions were set independently: the inter-ring spacing was fixed by the colloidal radius, the radius of the nanorings was controlled by the plasma etching process, and the width of the nanorings was controlled by the electrodeposition process. A combination of scanning electron microscopy (SEM) measurements and Fourier transform near-infrared (FT-NIR) absorption spectroscopy were used to characterize the nanoring arrays. Nanoring arrays with radii from 200 to 400 nm exhibited a single strong NIR plasmonic resonance with an absorption maximum wavelength that varied linearly from 1.25 to 3.33 μm as predicted by a simple standing wave model linear antenna theory. This simple yet versatile nanoring array fabrication method was also used to electrodeposit concentric double gold nanoring arrays that exhibited multiple NIR plasmonic resonances.

Demonstration of vessels in CNS and other organs by AMG silver enhancement of colloidal gold particles dispersed in gelatine.

Science.gov (United States)

Danscher, G; Andreasen, A

1997-12-01

We present a new autometallographic technique for demonstrating vessels and other small cavities at light microscopy (LM) and electron microscopy (EM) levels. It is possible to obtain detailed knowledge of the 3-D appearance of the vascular system by exchanging blood with a 40 degrees C, 8% gelatine solution containing colloidal gold particles (gold gelatine solution, GGS) and ensuing silver enhancement of the gold particles by autometallography (AMG). The GGS-AMG technique demonstrates the vascular system as a dark web that can be studied in cryostat, vibratome, methacrylate, paraffin and Epon sections at all magnifications. The infused GGS becomes increasingly viscous and finally becomes rigid when the temperature falls below 20 degrees C. An additional advantage of this technique is the fact that none of the tested counterstains or immunotechniques interfere with this AMG approach. The GGS-AMG technique is demonstrated on rat brains but can be applied to any organ. We believe that the present technique is valuable for both experimental studies and routine pathology.

Reverse Transfection Using Gold Nanoparticles

Science.gov (United States)

Yamada, Shigeru; Fujita, Satoshi; Uchimura, Eiichiro; Miyake, Masato; Miyake, Jun

Reverse transfection from a solid surface has the potential to deliver genes into various types of cell and tissue more effectively than conventional methods of transfection. We present a method for reverse transfection using a gold colloid (GC) as a nanoscaffold by generating nanoclusters of the DNA/reagentcomplex on a glass surface, which could then be used for the regulation of the particle size of the complex and delivery of DNA into nuclei. With this method, we have found that the conjugation of gold nanoparticles (20 nm in particle size) to the pEGFP-N1/Jet-PEI complex resulted in an increase in the intensity of fluorescence of enhanced green fluorescent protein (EGFP) (based on the efficiency of transfection) from human mesenchymal stem cells (hMSCs), as compared with the control without GC. In this manner, we constructed a method for reverse transfection using GC to deliver genes into the cells effectively.

Orange pectin mediated growth and stability of aqueous gold and silver nanocolloids

Science.gov (United States)

Nigoghossian, Karina; dos Santos, Molíria V.; Barud, Hernane S.; da Silva, Robson R.; Rocha, Lucas A.; Caiut, José M. A.; de Assunção, Rosana M. N.; Spanhel, Lubomir; Poulain, Marcel; Messaddeq, Younes; Ribeiro, Sidney J. L.

2015-06-01

The role of orange based pectin in the nucleation and growth of silver and gold nanoparticles is addressed. Pectin is a complex polysaccharide found in fruits such as oranges, lemons, passion fruits or apples. It displays smooth and hairy chain regions containing hydroxyl-, ester-, carboxylate- and eventually amine groups that can act as surface ligands interacting under various pH conditions more or less efficiently with growing nanometals. Here, a high methoxy pectin (>50% esterified) was used as a stabilizer/reducing agent in the preparation of gold, silver and silver-gold nanoparticles. Commercial pectin (CP) and pectin extracted from orange bagasse (OP) were used. Optionally, trisodium citrate or oxalic acid we used to reduce AgNO3 and HAuCl4 in aqueous environment. Characterization methods included UV-vis absorption spectroscopy, transmission electron microscopy, electron diffraction and energy-dispersive X-ray spectroscopy. The results show that under different pH conditions, pectin and reducing agents allow producing various nanostructures shapes (triangles, spheres, rods, octahedrons and decahedrons) often with high polydispersity and sizes ranging between 5 nm and 30 nm. In addition, depending on Ag/Au-ratio and pH, the surface plasmon bands can be continuously shifted between 410 nm and 600 nm. Finally, pectin seems to be a highly efficient stabilizer of the colloidal systems that show a remarkable stability and unchanged optical spectral response even after five years.

Gold Nanoparticle Conjugation Enhances the Antiacanthamoebic Effects of Chlorhexidine

Science.gov (United States)

Aqeel, Yousuf; Siddiqui, Ruqaiyyah; Anwar, Ayaz; Shah, Muhammad Raza

2015-01-01

Acanthamoeba keratitis is a serious infection with blinding consequences and often associated with contact lens wear. Early diagnosis, followed by aggressive topical application of drugs, is a prerequisite in successful treatment, but even then prognosis remains poor. Several drugs have shown promise, including chlorhexidine gluconate; however, host cell toxicity at physiologically relevant concentrations remains a challenge. Nanoparticles, subcolloidal structures ranging in size from 10 to 100 nm, are effective drug carriers for enhancing drug potency. The overall aim of the present study was to determine whether conjugation with gold nanoparticles enhances the antiacanthamoebic potential of chlorhexidine. Gold-conjugated chlorhexidine nanoparticles were synthesized. Briefly, gold solution was mixed with chlorhexidine and reduced by adding sodium borohydride, resulting in an intense deep red color, indicative of colloidal gold-conjugated chlorhexidine nanoparticles. The synthesis was confirmed using UV-visible spectrophotometry that shows a plasmon resonance peak of 500 to 550 nm, indicative of gold nanoparticles. Further characterization using matrix-assisted laser desorption ionization-mass spectrometry showed a gold-conjugated chlorhexidine complex at m/z 699 ranging in size from 20 to 100 nm, as determined using atomic force microscopy. To determine the amoebicidal and amoebistatic effects, amoebae were incubated with gold-conjugated chlorhexidine nanoparticles. For controls, amoebae also were incubated with gold and silver nanoparticles alone, chlorhexidine alone, neomycin-conjugated nanoparticles, and neomycin alone. The findings showed that gold-conjugated chlorhexidine nanoparticles exhibited significant amoebicidal and amoebistatic effects at 5 μM. Amoebicidal effects were observed by parasite viability testing using a Trypan blue exclusion assay and flow-cytometric analysis using propidium iodide, while amoebistatic effects were observed using growth

Silver enhancement of nanogold and undecagold

Energy Technology Data Exchange (ETDEWEB)

Hainfield, J.F.; Furuya, F.R.

1995-07-01

A recent advance in immunogold technology has been the use of molecular gold instead of colloidal gold. A number of advantages are realized by this approach, such as stable covalent, site-specific attachment, small probe size and absence of aggregates for improved penetration. Silver enhancement has led to improved and unique results for electron and light microscopy, as well as their use with blots and gels. Most previous work with immunogold silver staining has been done with colloidal gold particles. More recently, large gold compounds (``clusters``) having a definite number of gold atoms and defined organic shell, have been used, frequently with improved results. These gold dusters, large compared to simple compounds, are, however, at the small end of the colloidal gold scale in size; undecagold is 0.8 nm and Nanogold is 1.4 nm. They may be used in practically all applications where colloidal gold is used (Light and electron microscopy, dot blots, etc.) and in some unique applications, where at least the larger colloidal golds don`t work, such as running gold labeled proteins on gels (which are later detected by silver enhancement). The main differences between gold clusters and colloidal golds are the small size of the dusters and their covalent attachment to antibodies or other molecules.

Colloidal gold-McAb probe-based rapid immunoassay strip for simultaneous detection of fumonisins in maize.

Science.gov (United States)

Yao, Jingjing; Sun, Yaning; Li, Qingmei; Wang, Fangyu; Teng, Man; Yang, Yanyan; Deng, Ruiguang; Hu, Xiaofei

2017-05-01

Fumonisins are a kind of toxic and carcinogenic mycotoxin. A rapid immunochromatographic test strip has been developed for simultaneous detection of fumonisin B 1 , B 2 and B 3 (FB 1 , FB 2 and FB 3 ) in maize based on colloidal gold-labelled monoclonal antibody (McAb) against FB 1 probe. The anti-FB 1 McAb (2E11-H3) was produced through immunisation and cell fusion, and identified as high affinity, specificity and sensitivity. The cross-reaction ratios with fumonisin B 2 and B 3 were accordingly 385% and 72.4%, while none with other analogues. The colloid gold-labelled anti-FB 1 McAb probe was successfully prepared and used for establishing the immunochromatographic strip. The test strip showed high sensitivity and specificity, the IC 50 for FB 1 was 58.08 ng mL -1 , LOD was 11.24 ng mL -1 , calculated from standard curve. Moreover, the test strip exhibited high cross-reactivity with FB 2 and FB 3 , and could be applied to the simultaneous detection of FBs (FB 1 :FB 2 :FB 3 = 12:4:1) in maize sample with high accuracy and precision. The average recoveries of FBs in maize ranged from 90.42% to 95.29%, and CVs were 1.25-3.77%. The results of the test strip for FBs samples showed good correlation with high-performance liquid chromatography analysis. The immunochromatographic test strip could be employed in the rapid simultaneous detection of FB 1 , FB 2 and FB 3 in maize samples on-site. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Synoviorthesis with sup 198 Au colloid gold in haemophilia patients. A preliminary report

Energy Technology Data Exchange (ETDEWEB)

Ortonowski, G.; Ziemski, J.M.; Kucharski, W.; Woy-Wojciechowski, J. (Institute of Haematology, Warsaw (Poland). Dept. of Surgery Institute of Clinical Medicine, Warsaw (Poland). Dept. of Nuclear Medicine)

1990-01-01

In 1988-1989 fifteen patients with severe haemophilia A and recurrent bleedings into the knee joint, aged from 19 to 44 years were treated by an intraarticular injection of {sup 198}Au colloid gold. So far 10 of them were assessed after 6 months follow-up. In 6 cases cessation and in 2 cases reduction in number and volume of bleeding were observed. Only in 2 patients the frequency of haemarthroses remained unchanged. No significant difference in tracer uptake was observed between pretreatment {sup 99m}Tc-pertrechnate gamma scans of the knee joints and controls completed 6 months after the radiogold injections. It is worthy to stress the lower costs of the {sup 198}Au synoviorthesis as compared with surgical synovectomy of the knee joint. The radioisotope method is also much less traumatic to the patient than the surgical one. (orig.).

Adsorption kinetics of alkanethiol-capped gold nanoparticles at the hexane–water interface

International Nuclear Information System (INIS)

Ferdous, Sultana; Ioannidis, Marios A.; Henneke, Dale

2011-01-01

The pendant drop technique was used to characterize the adsorption behavior of n-dodecane-1-thiol and n-hexane-1-thiol-capped gold nanoparticles at the hexane–water interface. The adsorption process was studied by analyzing the dynamic interfacial tension versus nanoparticle concentration, both at early times and at later stages (i.e., immediately after the interface between the fluids is made and once equilibrium has been established). A series of gold colloids were made using nanoparticles ranging in size from 1.60 to 2.85 nm dissolved in hexane for the interfacial tension analysis. Following free diffusion of nanoparticles from the bulk hexane phase, adsorption leads to ordering and rearrangement of the nanoparticles at the interface and formation of a dense monolayer. With increasing interfacial coverage, the diffusion-controlled adsorption for the nanoparticles at the interface was found to change to an interaction-controlled assembly and the presence of an adsorption barrier was experimentally verified. At the same bulk concentration, different sizes of n-dodecane-1-thiol nanoparticles showed different absorption behavior at the interface, in agreement with the findings of Kutuzov et al. (Phys Chem Chem Phys 9:6351–6358, 2007). The experiments additionally demonstrated the important role played by the capping agent. At the same concentration, gold nanoparticles stabilized by n-hexane-1-thiol exhibited greater surface activity than gold nanoparticles of the same size stabilized by n-dodecane-1-thiol. These findings contribute to the design of useful supra-colloidal structures by the self-assembly of alkane-thiol-capped gold nanoparticles at liquid–liquid interfaces.

Characterization of natural groundwater colloids at Palmottu

International Nuclear Information System (INIS)

Vuorinen, U.; Kumpulainen, H.

1993-01-01

Characterization of groundwater colloids (size range from 2 nm to 500 nm) in the Palmottu natural analogue (for radioactive waste disposal in Finland) area was continued by sampling another drill hole, 346, at three depths. Results evaluated so far indicate the presence of both organic and inorganic colloids. In terms of chemical composition and morphology, the inorganic colloids differ from those found in previous studies. According to SEM/EDS and STEM/EDS they mostly contain Ca and are spherical in shape. At this stage further characterization and evaluation of results is provisional and does not allow very accurate conclusions to be drawn

Biological Atomic Force Microscopy for Imaging Gold-Labeled Liposomes on Human Coronary Artery Endothelial Cells

Directory of Open Access Journals (Sweden)

Ana-María Zaske

2013-01-01

Full Text Available Although atomic force microscopy (AFM has been used extensively to characterize cell membrane structure and cellular processes such as endocytosis and exocytosis, the corrugated surface of the cell membrane hinders the visualization of extracellular entities, such as liposomes, that may interact with the cell. To overcome this barrier, we used 90 nm nanogold particles to label FITC liposomes and monitor their endocytosis on human coronary artery endothelial cells (HCAECs in vitro. We were able to study the internalization process of gold-coupled liposomes on endothelial cells, by using AFM. We found that the gold-liposomes attached to the HCAEC cell membrane during the first 15–30 min of incubation, liposome cell internalization occurred from 30 to 60 min, and most of the gold-labeled liposomes had invaginated after 2 hr of incubation. Liposomal uptake took place most commonly at the periphery of the nuclear zone. Dynasore monohydrate, an inhibitor of endocytosis, obstructed the internalization of the gold-liposomes. This study showed the versatility of the AFM technique, combined with fluorescent microscopy, for investigating liposome uptake by endothelial cells. The 90 nm colloidal gold nanoparticles proved to be a noninvasive contrast agent that efficiently improves AFM imaging during the investigation of biological nanoprocesses.

Nonlinear-Optical and Fluorescent Properties of Ag Aqueous Colloid Prepared by Silver Nitrate Reduction

Directory of Open Access Journals (Sweden)

Xiaoqiang Zhang

2010-01-01

Full Text Available The nonlinear-optical properties of metal Ag colloidal solutions, which were prepared by the reduction of silver nitrate, were investigated using Z-scan method. Under picosecond 532 nm excitation, the Ag colloidal solution exhibited negative nonlinear refractive index (n2=−5.17×10−4 cm2/W and reverse saturable absorption coefficient (β=4.32 cm/GW. The data fitting result of optical limiting (OL response of metal Ag colloidal solution indicated that the nonlinear absorption was attributed to two-photon absorption effect at 532 nm. Moreover, the fluorescence emission spectra of Ag colloidal solution were recorded under excitations at both 280 nm and 350 nm. Two fluorescence peaks, 336 nm and 543 nm for 280 nm excitation, while 544 nm and 694 nm for 350 nm excitation, were observed.

Quantum and dielectric confinements of sub-10 nm gold in dichroic phosphate glass nanocomposites

International Nuclear Information System (INIS)

Singh, Shiv Prakash; Nath, Mithun; Karmakar, Basudeb

2014-01-01

Blue shifts of the surface plasmon resonance band of sub-10 nm gold in dichroic phosphate glass nanocomposites are observed with increase in both size of gold nanoparticles and refractive index of the medium, which are contrary to the common trends. These phenomena have been enlightened with the electrodynamics theories (Mie and Drude models) and happened due to quantum and dielectric confinements. Nanocomposites have been synthesized by in-situ thermochemical reduction technique in reducing phosphate glass matrices. The plasmon bands are characterized by the UV–vis spectrophotometer, and shape and size of the nanogold by the transmission electron microscopy. All the nanocomposites are dichroic in nature. - Highlights: • We fabricated Au 0 embedded nanocomposites in P 2 O 5 –SnO–ZnO glass matrix. • Au 0 synthesized by a single step in-situ thermochemical reduction technique. • We have reported the blue shifts of the SPR band of sub-10 nm Au 0 NPs. • The optical property has been explained on the basis of electrodynamics theories

Size control in the synthesis of 1-6 nm gold nanoparticles via solvent-controlled nucleation.

Science.gov (United States)

Song, Jieun; Kim, Dukhan; Lee, Dongil

2011-11-15

We report a facile synthetic route for size-controlled preparation of gold nanoparticles. Nearly monodisperse gold nanoparticles with core diameters of 1-6 nm were obtained by reducing AuP(Phenyl)(3)Cl with tert-butylamine borane in the presence of dodecanethiol in the solvent mixture of benzene and CHCl(3). Mechanism studies have shown that the size control is achieved by the solvent-controlled nucleation in which the nuclei concentration increases with increasing the fraction of CHCl(3), leading to smaller particles. It was also found that, following the solvent-controlled nucleation, particle growth occurs via ligand replacement of PPh(3) on the nuclei by Au(I)thiolate generated by the digestive etching of small particles. This synthetic strategy was successfully demonstrated with other alkanethiols of different chain length with which size-controlled, monodisperse gold nanoparticles were prepared in remarkable yield without requiring any postsynthesis treatments.

Identification of Paracoccidioides brasiliensis by gold nanoprobes

Science.gov (United States)

Martins, Jaciara F. S.; Castilho, Maiara L.; Cardoso, Maria A. G.; Carreiro, Andrea P.; Martin, Airton A.; Raniero, Leandro

2012-01-01

Paracoccidioides brasiliensis (P. brasiliensis) is a thermal dimorphic fungus and causal agent of paracoccidioidomycosis. Epidemiological data shows that it is mainly concentrated in Central and South America countries, with most registered cases in Colombia, Brazil, and Venezuela. The histopathological similarity with others fungal infection makes the diagnosis of P. brasiliensis more complicated. Therefore, the aim of this work was to find a positive and negative test for P. brasiliensis using gold nanoprobes as a new tool for P. brasiliensis detection. Gold nanoparticles were synthesized by reduction of gold chloride with sodium citrate. The results of this procedure is a wine-red solution with a maximum absorption in the range of ~520-530nm. A specific P. brasiliensis sequence of oligonucleotide was bonded to the nanoparticles, which maintained the wine-red color. The color changes from red to blue for negative diagnostic and is unchanged for a positive test. The H-bond interaction of DNA with the complementary DNA keeps strands together and forms double helical structure, maintaining the colloid stability. However, for non-complimentary DNA sequence the nanoprobes merge into a cluster, changing the light absorption.

Tuning the structural and optical properties of gold/silver nanoalloys prepared by laser ablation in liquids for ultra-sensitive spectroscopy and optical trapping

Directory of Open Access Journals (Sweden)

F. Neri

2011-09-01

Full Text Available The plasmon resonance of metallic Au/Ag alloys in the colloidal state was tuned from 400 nm to 500 nm using a laser irradiated technique, performed directly in the liquid state. Interesting optical nonlinearities, trapping effects and spectroscopic enhancements were detected as function of gold concentration in the nanoalloys. In particular a reduction of the limiting threshold was observed by increasing the gold amount. The SERS activity of the Au/Ag alloys was tested in liquid and in solid state in presence of linear carbon chains as probe molecules. The dependence of the increased Raman signals on the nanoparticle Au/Ag atomic ratio is presented and discussed. Finally preliminary studies and prospects for optical and Raman tweezers experiments are discussed.

Validity of Dynamic Light Scattering Method to Analyze a Range of Gold and Copper Nanoparticle Sizes Attained by Solids Laser Ablation in Liquid

Directory of Open Access Journals (Sweden)

Yu. V. Golubenko

2014-01-01

Full Text Available Nanoparticles of metals possess a whole series of features, concerned with it’s sizes, this leads to appearing or unusual electromagnetic and optical properties, which are untypical for particulates.An extended method of receiving nanoparticles by means of laser radiation is pulse laser ablation of hard targets in liquid medium.Varying the parameters of laser radiation, such as wavelength of laser radiation, energy density, etc., we can operate the size and shape of the resultant particles.The greatest trend of application in medicine have the nanoparticles of iron, copper, silver, silicon, magnesium, gold and zinc.The subject matter in this work is nanoparticles of copper and gold, received by means of laser ablation of hard targets in liquid medium.The aim of exploration, represented in the article, is the estimation of application of the dynamic light scattering method for determination of the range of nanoparticles sizes in the colloidal solution.For studying of the laser ablation process was chosen the second harmonic of Nd:YAG laser with the wavelength of 532 nm. Special attention was spared for the description of the experiment technique of receiving of nanoparticles.As the liquid medium ethanol and distillation water were used.For exploration of the received colloidal system have been used the next methods: DLS, transmission electron microscopy (TEM and scanning electron microscopy (SEM.The results of measuring by DLS method showed that colloidal solution of the copper in the ethanol is the steady system. Copper nanoparticle’s size reaches 200 nm and is staying in the same size for some time.Received system from the gold’s nanoparticles is polydisperse, unsteady and has a big range of the nanoparticle’s sizes. This fact was confirmed by means of photos, got from the TEM FEI Tecnai G2F20 + GIF and SEM Helios NanoLab 660. The range of the gold nanoparticle’s sizes is from 5 to 60 nm. So, it has been proved that the DLS method is

Infrared Harvesting Colloidal Quantum Dot Solar Cell Based on Multi-scale Disordered Electrodes

KAUST Repository

Tian, Yi

2015-06-23

Colloidal quantum dot photovoltaics (CQDPV) offer a big potential to be a renewable energy source due to low cost and tunable band-gap. Currently, the certified power conversion efficiency of CQDPV has reached 9.2%. Compared to the 31% theoretical efficiency limit of single junction solar cells, device performances have still have a large potential to be improved. For photovoltaic devices, a classical way to enhance absorption is to increase the thickness of the active layers. Although this approach can improve absorption, it reduces the charge carriers extraction efficiency. Photo-generated carriers, in fact, are prone to recombine within the defects inside CQD active layers. In an effort to solve this problem, we proposed to increase light absorption from a given thickness of colloidal quantum dot layers with the assistance of disorder. Our approach is to develop new types of electrodes with multi-scale disordered features, which localize energy into the active layer through plasmonic effects. We fabricated nanostructured gold substrates by electrochemical methods, which allow to control surface disorder as a function of deposition conditions. We demonstrated that the light absorption from 600 nm to 800 nm is impressively enhanced, when the disorder of the nanostructured surface increases. Compared to the planar case, the most disorder case increased 65% light absorption at the wavelength of λ = 700nm in the 100 nm PbS film. The average absorption enhancement across visible and infrared region in 100 nm PbS film is 49.94%. By developing a photovoltaic module, we measured a dramatic 34% improvement in the short-circuit current density of the device. The power conversion efficiency of the tested device in top-illumination configuration showed 25% enhancement.

Study on gamma radiation-induced synthesis of gold nanoparticles stabilized by hyaluronan

International Nuclear Information System (INIS)

Dang Van Phu; Nguyen Ngoc Duy; Nguyen Tue Anh; Nguyen Quoc Hien

2011-01-01

Gold nanoparticles (AuNPs) with diameter from 4 to 10 nm were synthesized in hyaluronan (HA) solution without usage of any reductant and *OH radical scavenger by gamma irradiation reduction. The size and size distribution of AuNPs were determined by TEM images. The λ max (517 - 525 nm) of colloidal AuNPs solutions as prepared were measured by UV-Vis spectroscopy. The influence factors on the size of AuNPs particularly the concentration of Au 3+ , HA and dose rate were investigated. The stability of AuNPs/HA as synthesized was more than 6 months in storage under atmospheric condition. AuNPs with the size less than 10 nm and narrow size distribution stabilized by HA which is biocompatible natural polysaccharide so that AuNPs/HA can potentially be applied in biomedicine and cosmetic. (author)

2, 4, 6-Trithiol-1, 3, 5-Triazine-Modified Gold Nanoparticles and Its Potential as Formalin Detector

Science.gov (United States)

Yulizar, Y.; Ariyanta, H. A.; Rakhmania, L.; Hafizah, M. A. E.

2018-04-01

Stabilized gold nanoparticles (AuNP) have been successfully prepared by a modification of ligand 2, 4, 6-trithiol-1, 3, 5-triazine (TT). TT has three thiol groups and nitrogen atoms on the aromatic ring that can interact and stabilize AuNP. TT modified AuNP (AuNP/TT) was characterized using UV-Vis spectrophotometer, particle size analyzer (PSA) and transmission electron microscopy (TEM). The characterization showed that AuNP/TT stable at a maximum wavelength (λmaks) of 537 nm with the particle diameter of 9.41 nm. The increased acidity (pH) causes the protonated thiol groups of TT marked with a visual change of colloidal AuNP/TT from purple to blue, causing AuNP and TT bonds weakened. In this study, the AuNP/TT was reacted with formalin. This interaction shows that AuNP/TT has a potential as an efficient detector of formalin, marked by changes in the diameter of the particle, colloidal color, and maximum wavelength shift.

Reaction parameters for controlled sonosynthesis of gold nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Gonzalez M, A. L. [Universidad Autonoma del Estado de Mexico, Facultad de Quimica, Paseo Colon esq. Paseo Tollocan s/n, 50120 Toluca, Estado de Mexico (Mexico); Cabrera L, L. I. [UNAM-UAEM, Centro Conjunto de Investigacion en Quimica Sustentable, Km 14.5 Carretera Toluca-Atlacomulco, 50200 San Cayetano-Toluca, Estado de Mexico (Mexico)

2015-07-01

The synthesis of gold nanoparticles by sonochemical technique has been previously performed with excellent results. The synthesis has been carried out in the presence of citric acid, a strong reducing agent, which allows the nucleation and growth of gold nanoparticles, at the same time that controls particle size. In this work we report the use of sodium tartrate as a mild reducing agent that allows a better understanding of the effect of the reaction parameters during gold nanoparticle synthesis. A conventional sonication bath (37 k Hz) was used for the sonochemical synthesis. This work focuses on the reaction temperature effect and the effect of sodium tartrate concentration. It was confirmed that particle size, and particle morphology is dependent of these two reaction parameters. Equally, colloidal stabilization was related to reaction temperature and sodium tartrate concentration. It was also determined that Ostwald ripening takes place during sonochemical reaction under our conditions, allowing to understand the mechanism that takes place during synthesis. Gold nanoparticles with main particle size of 17 nm were achieved by this method. Characterization techniques used: Fourier transform infrared spectra (Ftir), X-ray diffraction and Atomic Force Microscope was used in order to determine particle size of the synthetic product of reaction M10c by tapping mode. (Author)

Reaction parameters for controlled sonosynthesis of gold nanoparticles

International Nuclear Information System (INIS)

Gonzalez M, A. L.; Cabrera L, L. I.

2015-01-01

The synthesis of gold nanoparticles by sonochemical technique has been previously performed with excellent results. The synthesis has been carried out in the presence of citric acid, a strong reducing agent, which allows the nucleation and growth of gold nanoparticles, at the same time that controls particle size. In this work we report the use of sodium tartrate as a mild reducing agent that allows a better understanding of the effect of the reaction parameters during gold nanoparticle synthesis. A conventional sonication bath (37 k Hz) was used for the sonochemical synthesis. This work focuses on the reaction temperature effect and the effect of sodium tartrate concentration. It was confirmed that particle size, and particle morphology is dependent of these two reaction parameters. Equally, colloidal stabilization was related to reaction temperature and sodium tartrate concentration. It was also determined that Ostwald ripening takes place during sonochemical reaction under our conditions, allowing to understand the mechanism that takes place during synthesis. Gold nanoparticles with main particle size of 17 nm were achieved by this method. Characterization techniques used: Fourier transform infrared spectra (Ftir), X-ray diffraction and Atomic Force Microscope was used in order to determine particle size of the synthetic product of reaction M10c by tapping mode. (Author)

A new green chemistry method based on plant extracts to synthesize gold nanoparticles

Science.gov (United States)

Montes Castillo, Milka Odemariz

solved. In this work, secondary metabolites were extracted from alfalfa biomass in liquid phase by hot water, isopropanol, and methanol, and used to reduce tetrachloroaurate ion (AuCl4-) for the synthesis of gold nanoparticles. Biosyntheses of gold nanoparticles were performed by mixing 0.75, 1.5 and 3.0 mM Au3+ solutions with each one of the extracts at a ratio of 3:1 respectively, and shaken at room temperature for 1h. Resulting gold colloids were characterized by UV-Vis spectrophotometry and electron microscopy techniques, showing size and morphology dependency on the reaction conditions. Isopropanol alfalfa extracts reacted with Au 3+ produced gold nanoparticles with a size range of 15-60 nm. The most abundant were from 40-50 nm, and the morphologies found were polygons, decahedra and icosahedra. Methanol alfalfa extracts produced monodisperse 50 nm decahedral and icosahedral gold nanoparticles. Lastly, water alfalfa extracts reacted with Au3+ produced triangular, truncated triangular and hexagonal nanoplates with diameters ranging from 500 nm to 4 mum and thicknesses of ˜15-40 nm. The production of gold nanoplates by alfalfa extracts has never been reported before. In order to extract the formed gold nanoparticles from the biomass, physical and chemical extractions were used. For the chemical extraction, NaCl, dilute H2SO4, Triton X and DI water were tested. In these cases, the best results were obtained with DI water, followed by NaCl. The extracted nanoparticles had an absorption band at about 539 nm. For the physical extractions, alfalfa biomass containing gold nanoparticles were exposed to 400°C, 500°C, 550°C and 600°C to recover the gold nanoparticles. X-ray diffractograms taken after pyrolysis of the biomass showed that the recovered nanoparticles kept their crystal structure.

Colloidal assemblies modified by ion irradiation

NARCIS (Netherlands)

Snoeks, E.; Blaaderen, A. van; Dillen, T. van; Kats, C.M. van; Velikov, K.P.; Brongersma, M.L.; Polman, A.

2001-01-01

Spherical SiO2 and ZnS colloidal particles show a dramatic anisotropic plastic deformation under 4 MeV Xe ion irradiation, that changes their shape into oblate into oblate ellipsional, with an aspect ratio that can be precisely controlled by the ion fluence. The 290 nm and 1.1 um diameter colloids

Fabrication and characterisation of gold nano-particle modified polymer monoliths for flow-through catalytic reactions and their application in the reduction of hexacyanoferrate

International Nuclear Information System (INIS)

Floris, Patrick; Twamley, Brendan; Nesterenko, Pavel N.; Paull, Brett; Connolly, Damian

2014-01-01

Polymer monoliths in capillary (100 μm i.d.) and polypropylene pipette tip formats (vol: 20 μL) were modified with gold nano-particles (AuNP) and subsequently used for flow-through catalytic reactions. Specifically, methacrylate monoliths were modified with amine-reactive monomers using a two-step photografting method and then reacted with ethylenediamine to provide amine attachment sites for the subsequent immobilisation of 4 nm, 7 nm or 16 nm AuNP. This was achieved by flushing colloidal suspensions of gold nano-particles through each aminated polymer monolith which resulted in a multi-point covalent attachment of gold via the lone pair of electrons on the nitrogen of the free amine groups. Field emission scanning electron microscopy and scanning capacitively coupled conductivity detection was used to characterise the surface coverage of AuNP on the monoliths. The catalytic activity of AuNP immobilised on the polymer monoliths in both formats was then demonstrated using the reduction of Fe(III) to Fe(II) by sodium borohydride as a model reaction by monitoring the reduction in absorbance of the hexacyanoferrate (III) complex at 420 nm. Catalytic activity was significantly enhanced on monoliths modified with smaller AuNP with almost complete reduction (95 %) observed when using monoliths agglomerated with 7 nm AuNPs. (author)

Determination of gold in natural waters by neutron activation-#betta#-spectrometry after preconcentration on activated charcoal

International Nuclear Information System (INIS)

Hamilton, T.W.; Ellis, J.; Florence, T.M.

1983-01-01

A method for the determination of gold at very low levels in waters is presented. The method involves batchwise pre-concentration of gold from 1 l of water at pH 3-4 onto 0.1 g of activated charcoal by shaking for 5 min and subsequent treatment of the activated charcoal by instrumental neutron activation-#betta#-spectrometry. Activated charcoal quantitatively adsorbs ionic and colloidal gold from solutions prepared with distilled water and also from natural surface waters spiked and equilibrated with these two forms of gold. Three ion-exchange resins were evaluated for pre-concentration purposes; ionic gold removal was quantitative but colloidal gold removal was incomplete. Electrodeposition at a carbon fibre electrode gave similar results. The charcoal pre-concentration technique was tested on solutions containing 198 Au tracer and a total gold concentration of 1 μg l - 1 . The limit of detection of total gold (ionic and colloidal) for the carbon adsorption/neutron activation-#betta#-spectrometry procedure is 0.3 ng l - 1 . The method was used to determine gold in surface waters from auriferous regions. (Auth.)

Preparation of poly(N-vinylpyrrolidone-stabilized ZnO colloid nanoparticles

Directory of Open Access Journals (Sweden)

Tatyana Gutul

2014-04-01

Full Text Available We propose a method for the synthesis of a colloidal ZnO solution with poly(N-vinylpyrrolidone (PVP as stabilizer. Stable colloidal solutions with good luminescence properties are obtained by using PVP as stabilizer in the synthesis of ZnO nanoparticles by a sol–gel method assisted by ultrasound. Nanoparticles with sizes of 30–40 nm in a PVP matrix are produced as a solid product. The colloidal ZnO/PVP/methanol solution, apart from the most intense PL band at 356 nm coming from the PVP, exhibits a strong PL band at 376 nm (3.30 eV which corresponds to the emission of the free exciton recombination in ZnO nanoparticles.

Surface-enhanced Raman scattering of the adsorption of pesticide endosulfan on gold nanoparticles.

Science.gov (United States)

Hernández-Castillo, M I; Zaca-Morán, O; Zaca-Morán, P; Orduña-Diaz, A; Delgado-Macuil, R; Rojas-López, M

2015-01-01

The absorption of pesticide endosulfan on the surface of gold nanoparticles results from the formation of micrometric structures (1-10 μm) with irregular shape because of the aggregation of individual particles. Such aggregation of gold nanoparticles after absorption of pesticide shows a surface-enhanced Raman scattering (SERS) spectrum, whose intensity depends on the concentration of endosulfan. In addition, the discoloration of the colloidal solution and a diminishing of the intensity of the surface plasmon resonance absorption from individual particles were observed by UV-visible spectroscopy. At the same time, a second band between 638 and 700 nm confirms the formation of aggregates of gold nanoparticles as the concentration of endosulfan increases. Finally, we used the SERS intensity of the S-O stretching vibration at 1239 cm(-1) from the SO3 group as a measure of concentration of pesticide endosulfan. This method could be used to estimate the level of pollution in water by endosulfan in a simple and practical form.

Plasmonic Switches and Sensors Based on PANI-Coated Gold Nanostructures

Science.gov (United States)

Jiang, Nina

Gold nanostructures have been received intense and growing attention due to their unique properties associated with localized surface plasmon resonance (LSPR). The frequency and strength of the LSPR are highly dependent on the dielectric properties of the surrounding environment around gold nanostructures. Such dependence offers the essential basis for the achievement of plasmonic switching and sensing. While the plasmonic response of gold nanostructures is tuned by changing their dielectric environment, the external stimuli inducing the changes in the dielectric environment will be read out through the plasmonic response of gold nanostructures. As a consequence, plasmonic sensors and switches can be engineered by integrating active media that can respond to external stimuli with gold nanostructures. In this thesis research, I have achieved the coating of polyaniline (PANI) ' a conductive polymer, on gold nanostructures, and exploited the application of the core/shell nanostructures in plasmonic switching and sensing. Large modulation of the longitudinal plasmon resonance of single gold nanorods is achieved by coating PANI shell onto gold nanorods to produce colloidal plasmonic switches. The dielectric properties of PANI shell can be tuned by changing the proton-doping levels, which allows for the modulation of the plasmonic response of gold nanorods. The coated nanorods are sparsely housed in a simple microfluidic chamber. HCl and NaOH solutions are alternately pumped through the chamber for the realization of proton doping and dedoping. The plasmonic switching behavior is examined by monitoring the single-particle scattering spectra under the proton-doped and dedoped state of PANI. The coated nanorods exhibit a remarkable switching performance, with the modulation depth and scattering peak shift reaching 10 dB and 100 nm, respectively. Electrodynamic simulations are employed to confirm the plasmon switching behavior. I have further investigated the modulation of

Sampling and analysis of groundwater colloids. A literature review

International Nuclear Information System (INIS)

Takala, M.; Manninen, P.

2006-03-01

The purpose of this literature study was to give basic information of colloids: their formation, colloid material, sampling and characterisation of groundwater colloids. Colloids are commonly refereed to as particles in the size range of 1 nm to 1000 nm. They are defined as a suspension of solid material in a liquid that does not appear to separate even after a long period of time. Colloids can be formed from a variety of inorganic or organic material. Inorganic colloids in natural groundwaters are formed by physical fragmentation of the host rock or by precipitation. The water chemistry strongly controls the stability of colloids. The amount of colloid particles in a solution tends to decrease with the increasing ionic strength of the solution. Increases in pH and organic material tend to increase the stability of colloids. The mobility of colloids in a porous medium is controlled mainly by groundwater movement, sedimentation, diffusion and interception. Factors controlling sampling artefacts are oxygen diffusion: leads to e.g. calcite precipitation, pumping rates and filtering techniques. Efforts to minimise artefact formation should be taken if the scope of the sampling programme is to study the colloid particles. The colloid phase size distribution can be determined by light scattering systems, laser induced break down or by single particle analysis using SEM micrographs. Elemental compositions can be analysed with EDS spectrometry from single colloid particles. Bulk compositions of the colloid phase can be analysed with e.g. ICP-MS analyser. The results of this study can be used as guidelines for groundwater colloid samplings. Recommendations for future work are listed in the conclusions of this report. (orig.)

Immunocytochemical localisation of phloem lectin from Cucurbita maxima using peroxidase and colloidal-gold labels.

Science.gov (United States)

Smith, L M; Sabnis, D D; Johnson, R P

1987-04-01

Antibodies were raised against lectin purified from the sieve-tube exudate of Cucurbita maxima. Immunocytochemistry, using peroxidase-labelled antibodies and Protein A-colloidal gold, was employed to determine the location of the lectin within the tissues and cells of C. maxima and other cucurbit species. The anti-lectin antibodies bound to P-protein aggregates in sieve elements and companion cells, predominantly in the extrafascicular phloem of C. maxima. This may reflect the low rate of translocation in these cells. Under the electron microscope, the lectin was shown to be a component of P-protein filaments and was also found in association with the sieve-tube reticulum which lines the plasmalemma. The anti-lectin antibodies reacted with sieve-tube proteins from other species of the genus Cucurbita but showed only limited reaction with other genera. We suggest that the lectin serves to anchor P-protein filaments and associated proteins to the parietal layer of sieve elements.

Visible luminescence in polyaniline/(gold nanoparticle) composites

Energy Technology Data Exchange (ETDEWEB)

Santos, Renata F. S. [Universidade Federal de Pernambuco, Pos-Graduacao em Ciencia de Materiais (Brazil); Andrade, Cesar A. S. [Universidade Federal de Pernambuco, Departamento de Bioquimica (Brazil); Santos, Clecio G. dos [Instituto de Educacao, Ciencia e Tecnologia de Pernambuco (Brazil); Melo, Celso P. de, E-mail: celso@df.ufpe.br [Universidade Federal de Pernambuco, Pos-Graduacao em Ciencia de Materiais (Brazil)

2013-01-15

We describe the use of solution chemistry methods to prepare polyaniline/(gold nanoparticles)-PANI/AuNPs-composites as colloidal particles that exhibit an intense green fluorescence after excitation in the ultraviolet region. Measurements of the relative fluorescence quantum yield indicate that the intensity of the observed luminescence of these nanocomposites is a few orders of magnitude higher than the corresponding fluorescence of either the isolated polymer or the pure AuNPs. Hence, cooperative effects between the conducting polymer chains and the metallic particles must dominate the emission behavior of these materials. Transmission electron microscopy reveals the existence of metal nanoparticle aggregates with sizes in the 2-3 nm range dispersed in the polymer matrix. By implementing an experimental planning, we have been able to change the preparation parameters so as to vary in a controlled manner the intensity and the profile of the luminescence spectrum as well as the size and aggregation characteristics of the colloidal particles. We also show that when the pH of the medium is varied, the dielectric properties (such as the degree of conductivity) of the PANI/AuNPs colloidal solutions and the intensity of their luminescence change in a consistent manner. Due to the polycation nature of the doped PANI chains, we suggest that these composites may find interesting applications as fluorescent markers of biologic molecules.

Nanosecond-pulsed Q-switched Nd:YAG laser at 1064 nm with a gold nanotriangle saturable absorber

Science.gov (United States)

Chen, Xiaohan; Li, Ping; Dun, Yangyang; Song, Teng; Ma, Baomin

2018-06-01

Gold nanotriangles (GNTs) were successfully employed as a saturable absorber (SA) to achieve passively Q-switched lasers for the first time. The performance of the Q-switched Nd:YAG laser at 1064 nm has been systematically investigated. The corresponding shortest pulsewidth, the threshold pump power and the maximum Q-switched average output power were 275.5 ns, 1.37 W, and 171 mW, respectively. To our knowledge, this is the shortest pulsewidth and the lowest threshold in a passively Q-switched laser at approximately 1.1 µm based on a gold nanoparticle SA (GNPs-SA). Our experimental results proved that the GNTs-SA can be used as a promising saturable absorber for nanosecond-pulsed lasers.

Preparation and use of recombinant protein G-gold complexes as markers in double labelling immunocytochemistry

DEFF Research Database (Denmark)

Balslev, Y; Hansen, Gert Helge

1989-01-01

Recombinant protein G (RPG) was conjugated to colloidal gold particles and used for immunocytochemistry. In this report, the preparation of RPG-gold conjugates (RPGG) and the application of these conjugates in spot blot tests and in double immunolabelling are described. The immunolabelling...... was performed on ultracryosections of pig small intestine using antibodies directed against aminopeptidase N and sucrase-isomaltase. The labelling efficiency of RPGG was compared to that of protein A-gold conjugates (PAG) in different compartments of the enterocyte. Quantification showed that the labelling...... intensity was dependent on the size of the marker as well as on the kind of protein used for complex formation. The distributions for RPGG and PAG were respectively: for the 12 nm particles, 10.3 and 6.2 particles/micron of length of microvillar membrane, 3.5 and 1.0 particles/micron2 of Golgi profile and 5...

Colloidal Gold Nanoclusters Spiked Silica Fillers in Mixed Matrix Coatings: Simultaneous Detection and Inhibition of Healthcare-Associated Infections.

Science.gov (United States)

Alsaiari, Shahad K; Hammami, Mohammed A; Croissant, Jonas G; Omar, Haneen W; Neelakanda, Pradeep; Yapici, Tahir; Peinemann, Klaus-Viktor; Khashab, Niveen M

2017-03-01

Healthcare-associated infections (HAIs) are the infections that patients get while receiving medical treatment in a medical facility with bacterial HAIs being the most common. Silver and gold nanoparticles (NPs) have been successfully employed as antibacterial motifs; however, NPs leaching in addition to poor dispersion and overall reproducibility are major hurdles to further product development. In this study, the authors design and fabricate a smart antibacterial mixed-matrix membrane coating comprising colloidal lysozyme-templated gold nanoclusters as nanofillers in poly(ethylene oxide)/poly(butylene terephthalate) amphiphilic polymer matrix. Mesoporous silica nanoparticles-lysozyme functionalized gold nanoclusters disperse homogenously within the polymer matrix with no phase separation and zero NPs leaching. This mixed-matrix coating can successfully sense and inhibit bacterial contamination via a controlled release mechanism that is only triggered by bacteria. The system is coated on a common radiographic dental imaging device (photostimulable phosphor plate) that is prone to oral bacteria contamination. Variation and eventually disappearance of the red fluorescence surface under UV light signals bacterial infection. Kanamycin, an antimicrobial agent, is controllably released to instantly inhibit bacterial growth. Interestingly, the quality of the images obtained with these coated surfaces is the same as uncoated surfaces and thus the safe application of such smart coatings can be expanded to include other medical devices without compromising their utility. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Colloidal Gold Nanoclusters Spiked Silica Fillers in Mixed Matrix Coatings: Simultaneous Detection and Inhibition of Healthcare-Associated Infections

KAUST Repository

Alsaiari, Shahad K.

2017-01-25

Healthcare-associated infections (HAIs) are the infections that patients get while receiving medical treatment in a medical facility with bacterial HAIs being the most common. Silver and gold nanoparticles (NPs) have been successfully employed as antibacterial motifs; however, NPs leaching in addition to poor dispersion and overall reproducibility are major hurdles to further product development. In this study, the authors design and fabricate a smart antibacterial mixed-matrix membrane coating comprising colloidal lysozyme-templated gold nanoclusters as nanofillers in poly(ethylene oxide)/poly(butylene terephthalate) amphiphilic polymer matrix. Mesoporous silica nanoparticles-lysozyme functionalized gold nanoclusters disperse homogenously within the polymer matrix with no phase separation and zero NPs leaching. This mixed-matrix coating can successfully sense and inhibit bacterial contamination via a controlled release mechanism that is only triggered by bacteria. The system is coated on a common radiographic dental imaging device (photostimulable phosphor plate) that is prone to oral bacteria contamination. Variation and eventually disappearance of the red fluorescence surface under UV light signals bacterial infection. Kanamycin, an antimicrobial agent, is controllably released to instantly inhibit bacterial growth. Interestingly, the quality of the images obtained with these coated surfaces is the same as uncoated surfaces and thus the safe application of such smart coatings can be expanded to include other medical devices without compromising their utility.

Colloidal Gold Nanoclusters Spiked Silica Fillers in Mixed Matrix Coatings: Simultaneous Detection and Inhibition of Healthcare-Associated Infections

KAUST Repository

Alsaiari, Shahad K.; Hammami, Mohamed Amen; Croissant, Jonas G.; Omar, Haneen; Neelakanda, Pradeep; Yapici, Tahir; Peinemann, Klaus-Viktor; Khashab, Niveen M.

2017-01-01

Healthcare-associated infections (HAIs) are the infections that patients get while receiving medical treatment in a medical facility with bacterial HAIs being the most common. Silver and gold nanoparticles (NPs) have been successfully employed as antibacterial motifs; however, NPs leaching in addition to poor dispersion and overall reproducibility are major hurdles to further product development. In this study, the authors design and fabricate a smart antibacterial mixed-matrix membrane coating comprising colloidal lysozyme-templated gold nanoclusters as nanofillers in poly(ethylene oxide)/poly(butylene terephthalate) amphiphilic polymer matrix. Mesoporous silica nanoparticles-lysozyme functionalized gold nanoclusters disperse homogenously within the polymer matrix with no phase separation and zero NPs leaching. This mixed-matrix coating can successfully sense and inhibit bacterial contamination via a controlled release mechanism that is only triggered by bacteria. The system is coated on a common radiographic dental imaging device (photostimulable phosphor plate) that is prone to oral bacteria contamination. Variation and eventually disappearance of the red fluorescence surface under UV light signals bacterial infection. Kanamycin, an antimicrobial agent, is controllably released to instantly inhibit bacterial growth. Interestingly, the quality of the images obtained with these coated surfaces is the same as uncoated surfaces and thus the safe application of such smart coatings can be expanded to include other medical devices without compromising their utility.

Pore water colloid properties in argillaceous sedimentary rocks

Energy Technology Data Exchange (ETDEWEB)

Degueldre, Claude, E-mail: c.degueldre@lancaster.ac.uk [Engineering Department, University of Lancaster, LA1 4YW Lancaster (United Kingdom); ChiAM & Institute of Environment, University of Geneva, 1211 Genève 4, Swizerland (Switzerland); Earlier, NES, Paul Scherrer Institute, 5232 Villigen (Switzerland); Cloet, Veerle [NAGRA, Hardstrasse 73, 5430 Wettingen (Switzerland)

2016-11-01

colloid concentration is expected to be very low (< 1 ppb, for 10–100 nm) which restricts their relevance for radionuclide transport. - Graphical abstract: Processes describing the colloid live to build up a colloid population. - Highlights: • This study predicts pore water colloid properties from argillaceous sedimentary rocks. • The study combines field, laboratory and model results. • The high mineralization of the pore water limits the clayeous colloid concentration. • The study predicts colloid concentrations below the ppb level for sizes from 10 to 100 nm.

Synthesis of curcumin-functionalized gold nanoparticles and cytotoxicity studies in human prostate cancer cell line

Science.gov (United States)

Nambiar, Shruti; Osei, Ernest; Fleck, Andre; Darko, Johnson; Mutsaers, Anthony J.; Wettig, Shawn

2018-03-01

Gold nanoparticles synthesized using plant extracts with medicinal properties have gained traction in recent years, especially for their use in various biomedical applications. Colloidal stability of these nanoparticles in different environments is critical to retain the expected therapeutic/diagnostic efficacy and toxicological outcome. Any change in the colloidal stability leads to dramatic changes in the physico-chemical properties of the nanoparticles such as size and surface charge, which in turn may alter the biological activity of the particles. Such changes are imminent in physiologically-relevant environment wherein interactions with different biomolecules, such as serum proteins, may modify the overall properties of the nanoparticles. In this regard, we synthesized 15 nm sized gold nanoparticles using curcumin, a plant extract from turmeric root, to evaluate cytotoxicity, uptake, and localization in human prostate cancer cells using cell-culture medium supplemented with or without fetal bovine serum (FBS). The results indicate a dramatic difference in the cytotoxicity and uptake between cells treated with curcumin-functionalized gold nanoparticles (cur-AuNPs) in cell-culture medium with and without serum. The addition of FBS to the medium not only increased the stability of the nanoparticles but also enhanced the biocompatibility (i.e. minimal cytotoxicity for a wide range of cur-AuNP concentrations). We conclude that the presence of serum proteins significantly impact the therapeutic potential of cur-AuNPs.

Manipulation of extinction spectra of P3HT/PMMA medium arrays on silicon substrate containing self-assembled gold nanoparticles

International Nuclear Information System (INIS)

Wu, Ming-Chung; Chen, Shih-Wen; Li, Jia-Han; Chou, Yi; Lin, Jhih-Fong; Chen, Yang-Fang; Su, Wei-Fang

2012-01-01

In this study, we report a simple novel approach to modulate the extinction spectra of P3HT/PMMA by manipulating the medium arrays on a substrate that is coated with self-assembled gold nanoparticles. The 20 nm gold nanoparticles were synthesized and then self-assembled on the APTMS/silicon substrate surface by immersing the substrate into the gold colloid suspension. A high-resolution P3HT/PMMA photoluminescent electron beam resist was used to fabricate various square hole arrays on the substrate containing gold nanoparticles. The P3HT/PMMA medium composition causes the blue shifts in the extinction peaks of up to 40.6 nm by decreasing the period from 500 nm to 200 nm for P3HT/PMMA square hole arrays with a diameter of 100 nm. The magnitude of blue shift is directly proportional to the product of the changes of medium refractive index and the array structure factor. These peak shifts and intensity of extinction spectra for various P3HT/PMMA medium arrays are well described by the finite-difference time-domain (FDTD) simulation results. Since this simple cost-effective technique can tune the extinction spectrum of medium and adding the gold nanoparticles can give more functionalities for sensing applications, such as surface-enhanced Raman scattering (SERS), that provides good opportunities for the design and fabrication of new optoelectronic devices and sensors. Highlights: ► We can tune the extinction spectra of P3HT/PMMA by manipulating the medium arrays. ► These optical behaviors of P3HT/PMMA medium arrays are well described by FDTD simulation results. ► Adding the Au nanoparticles can give more functionalities for sensing applications.

Manipulation of extinction spectra of P3HT/PMMA medium arrays on silicon substrate containing self-assembled gold nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Wu, Ming-Chung [Department of Chemical and Materials Engineering, Chang Gung University, Taoyuan 333-02, Taiwan (China); Chen, Shih-Wen; Li, Jia-Han [Department of Engineering Science and Ocean Engineering, National Taiwan University, Taipei 106-17, Taiwan (China); Chou, Yi; Lin, Jhih-Fong [Department of Materials Science and Engineering, National Taiwan University, Taipei 106-17, Taiwan (China); Chen, Yang-Fang [Department of Physics, National Taiwan University, Taipei 106-17, Taiwan (China); Su, Wei-Fang, E-mail: suwf@ntu.edu.tw [Department of Materials Science and Engineering, National Taiwan University, Taipei 106-17, Taiwan (China)

2012-11-15

In this study, we report a simple novel approach to modulate the extinction spectra of P3HT/PMMA by manipulating the medium arrays on a substrate that is coated with self-assembled gold nanoparticles. The 20 nm gold nanoparticles were synthesized and then self-assembled on the APTMS/silicon substrate surface by immersing the substrate into the gold colloid suspension. A high-resolution P3HT/PMMA photoluminescent electron beam resist was used to fabricate various square hole arrays on the substrate containing gold nanoparticles. The P3HT/PMMA medium composition causes the blue shifts in the extinction peaks of up to 40.6 nm by decreasing the period from 500 nm to 200 nm for P3HT/PMMA square hole arrays with a diameter of 100 nm. The magnitude of blue shift is directly proportional to the product of the changes of medium refractive index and the array structure factor. These peak shifts and intensity of extinction spectra for various P3HT/PMMA medium arrays are well described by the finite-difference time-domain (FDTD) simulation results. Since this simple cost-effective technique can tune the extinction spectrum of medium and adding the gold nanoparticles can give more functionalities for sensing applications, such as surface-enhanced Raman scattering (SERS), that provides good opportunities for the design and fabrication of new optoelectronic devices and sensors. Highlights: Black-Right-Pointing-Pointer We can tune the extinction spectra of P3HT/PMMA by manipulating the medium arrays. Black-Right-Pointing-Pointer These optical behaviors of P3HT/PMMA medium arrays are well described by FDTD simulation results. Black-Right-Pointing-Pointer Adding the Au nanoparticles can give more functionalities for sensing applications.

Synthesis and characterization of colloidal fluorescent silver nanoclusters.

Science.gov (United States)

Huang, Sherry; Pfeiffer, Christian; Hollmann, Jana; Friede, Sebastian; Chen, Justin Jin-Ching; Beyer, Andreas; Haas, Benedikt; Volz, Kerstin; Heimbrodt, Wolfram; Montenegro Martos, Jose Maria; Chang, Walter; Parak, Wolfgang J

2012-06-19

Ultrasmall water-soluble silver nanoclusters are synthesized, and their properties are investigated. The silver nanoclusters have high colloidal stability and show fluorescence in the red. This demonstrates that like gold nanoclusters also silver nanoclusters can be fluorescent.

Highly stable colloidal TiO2 nanocrystals with strong violet-blue emission

International Nuclear Information System (INIS)

Ghamsari, Morteza Sasani; Gaeeni, Mohammad Reza; Han, Wooje; Park, Hyung-Ho

2016-01-01

Improved sol–gel method has been applied to prepare highly stable colloidal TiO 2 nanocrystals. The synthesized titania nanocrystals exhibit strong emission in the violet-blue wavelength region. Very long evolution time was obtained by preventing the sol to gel conversion with reflux process. FTIR, XRD, UV–vis absorption, photoluminescence and high resolution transmission electron microscope (HRTEM) were used to study the optical properties, crystalline phase, morphology, shape and size of prepared TiO 2 colloidal nanocrystals. HRTEM showed that the diameter of TiO 2 colloidal nanocrystals is about 5 nm. Although the PL spectra show similar spectral features upon excitation wavelengths at 280, 300 and 350 nm, but their emission intensities are significantly different from each other. Photoluminescence quantum yield for TiO 2 colloidal nanocrystals is estimated to be 49% with 280 nm excitation wavelength which is in agreement and better than reported before. Obtained results confirm that the prepared colloidal TiO 2 sample has enough potential for optoelectronics applications.

Radioactive colloids

International Nuclear Information System (INIS)

Bergqvist, L.

1987-01-01

Different techniques for the characterization of radioactive colloids, used in nuclear medicine, have been evaluated and compared. Several radioactive colloids have been characterized in vitro and in vivo and tested experimentally. Colloid biokinetics following interstitial or intravenous injection were evaluated with a scintillation camera technique. Lymphoscintigraphy with a Tc-99-labelled antimony sulphur colloid was performed in 32 patients with malignant melanoma in order to evaluate the technique. Based on the biokinetic results, absorbed doses in tissues and organs were calculated. The function of the reticuloendothelial system has been evaluated in rats after inoculation with tumour cells. Microfiltration and photon correlation spectroscopy were found to be suitable in determining activity-size and particle size distributions, respectively. Maximal lymph node uptake following subcutaneous injection was found to correspond to a colloid particle size between 10 and 50 nm. Lymphoscintigraphy was found to be useful in the study of lymphatic drainage from the primary tumour site in patients with malignant melanoma on the trunk. Quantitative analysis of ilio-inguinal lymph node uptake in patients with malignant melanoma on the lower extremities was, however, found to be of no value for the detection of metastatic disease in lymph nodes. High absorbed doses may be received in lymph nodes (up to 1 mGy/MBq) and at the injection site (about 10 mGy/MBq). In an experimental study it was found that the relative colloid uptake in bone marrow and spleen depended on the total number of intravenously injected particles. This may considerably affect the absorbed dose in these organs. (author)

Antibacterial nanocarriers of resveratrol with gold and silver nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Park, Sohyun [College of Pharmacy, Inje University, 197 Inje-ro Gimhae, Gyeongnam 621-749 (Korea, Republic of); Cha, Song-Hyun [National Creative Research Initiatives (NCRI) Center for Isogeometric Optimal Design, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Cho, Inyoung [School of Civil, Environmental and Architecture Engineering, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 136-701 (Korea, Republic of); Park, Soomin [National Creative Research Initiatives (NCRI) Center for Isogeometric Optimal Design, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Park, Yohan [College of Pharmacy, Inje University, 197 Inje-ro Gimhae, Gyeongnam 621-749 (Korea, Republic of); Cho, Seonho [National Creative Research Initiatives (NCRI) Center for Isogeometric Optimal Design, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Park, Youmie, E-mail: youmiep@inje.ac.kr [College of Pharmacy, Inje University, 197 Inje-ro Gimhae, Gyeongnam 621-749 (Korea, Republic of); National Creative Research Initiatives (NCRI) Center for Isogeometric Optimal Design, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of)

2016-01-01

This study focused on the preparation of resveratrol nanocarrier systems and the evaluation of their in vitro antibacterial activities. Gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs) for resveratrol nanocarrier systems were synthesized using green synthetic routes. During the synthesis steps, resveratrol was utilized as a reducing agent to chemically reduce gold and silver ions to AuNPs and AgNPs. This system provides green and eco-friendly synthesis routes that do not involve additional chemical reducing agents. Resveratrol nanocarriers with AuNPs (Res-AuNPs) and AgNPs (Res-AgNPs) were observed to be spherical and to exhibit characteristic surface plasmon resonance at 547 nm and at 412–417 nm, respectively. The mean size of the nanoparticles ranged from 8.32 to 21.84 nm, as determined by high-resolution transmission electron microscopy. The face-centered cubic structure of the Res-AuNPs was confirmed by high-resolution X-ray diffraction. Fourier-transform infrared spectra indicated that the hydroxyl groups and C=C in the aromatic ring of resveratrol were involved in the reduction reaction. Res-AuNPs retained excellent colloidal stability during ultracentrifugation and re-dispersion, suggesting that resveratrol also played a role as a capping agent. Zeta potentials of Res-AuNPs and Res-AgNPs were in the range of − 20.58 to − 48.54 mV. Generally, against Gram-positive and Gram-negative bacteria, the Res-AuNPs and Res-AgNPs exhibited greater antibacterial activity compared to that of resveratrol alone. Among the tested strains, the highest antibacterial activity of the Res-AuNPs was observed against Streptococcus pneumoniae. The addition of sodium dodecyl sulfate during the synthesis of Res-AgNPs slightly increased their antibacterial activity. These results suggest that the newly developed resveratrol nanocarrier systems with metallic nanoparticles show potential for application as nano-antibacterial agents with enhanced activities. - Highlights

Aqueous gold nanosols stabilized by electrostatic protection generated by X-ray irradiation assisted radical reduction

International Nuclear Information System (INIS)

Wang, C.-H.; Hua, Tzu-En; Chien, C.-C.; Yu, Y.-L.; Yang, T.-Y.; Liu, C.-J.; Leng, W.-H.; Hwu, Y.; Yang, Y.-C.; Kim, Chong-Cook; Je, Jung-Ho; Chen, C.-H.; Lin, H.-M.; Margaritondo, G.

2007-01-01

Reductant, stabilizer-free colloidal gold solutions were fabricated by a new room-temperature synchrotron X-ray irradiation method. The influence of process parameters such as the pH value and the exposure time on the structure of gold nanoparticles was investigated. The mechanisms underlying the X-ray-triggered reduction of gold ions and the formation of gold clusters are discussed in detail. The X-ray irradiation derived highly concentrated gold nanoparticles are readily to be re-dispersed and possess suitable colloidal stability within cellular environment. The characterization included a study of the possible cytotoxicity for the EMT-6 tumor cell line: the negative results indicate that the gold clusters produced with our approach are biocompatible

Synthesis of oxocarbon-encapsulated gold nanoparticles with blue-shifted localized surface plasmon resonance by pulsed laser ablation in water with CO2 absorbers

Science.gov (United States)

Del Rosso, T.; Rey, N. A.; Rosado, T.; Landi, S.; Larrude, D. G.; Romani, E. C.; Freire Junior, F. L.; Quinteiro, S. M.; Cremona, M.; Aucelio, R. Q.; Margheri, G.; Pandoli, O.

2016-06-01

Colloidal suspensions of oxocarbon-encapsulated gold nanoparticles have been synthesized in a one-step procedure by pulsed-laser ablation (PLA) at 532 nm of a solid gold target placed in aqueous solution containing CO2 absorbers, but without any stabilizing agent. Multi-wavelength surface enhanced Raman spectroscopy allows the identification of adsorbed amorphous carbon and graphite, Au-carbonyl, Au coordinated CO2-derived bicarbonates/carbonates and hydroxyl groups around the AuNPs core. Scanning electron microscopy, energy dispersive x-ray analysis and high resolution transmission electron microscopy highlight the organic shell structure around the crystalline metal core. The stability of the colloidal solution of nanocomposites (NCs) seems to be driven by solvation forces and is achieved only in neutral or basic pH using monovalent hydroxide counter-ions (NaOH, KOH). The NCs are characterized by a blue shift of the localized surface plasmon resonance (LSPR) band typical of metal-ligand stabilization by terminal π-back bonding, attributed to a core charging effect caused by Au-carbonyls. Total organic carbon measurements detect the final content of organic carbon in the colloidal solution of NCs that is about six times higher than the value of the water solution used to perform PLA. The colloidal dispersions of NCs are stable for months and are applied as analytical probes in amino glycoside antibiotic LSPR based sensing.

Influence of the synthesis conditions of gold nanoparticles on the structure and architectonics of dipeptide composites

Energy Technology Data Exchange (ETDEWEB)

Loskutov, Alexander I., E-mail: ailoskutov@yandex.ru [Moscow State Technological University STANKIN (Russian Federation); Guskova, Olga A. [Leibniz Institute of Polymer Research Dresden (Germany); Grigoriev, Sergey N.; Oshurko, Vadim B. [Moscow State Technological University STANKIN (Russian Federation); Tarasiuk, Aleksei V. [Russian Academy of Medical Sciences, FSBI “Zakusov Institute of Pharmacology” (Russian Federation); Uryupina, Olga Ya. [Russian Academy of Sciences, Frumkin Institute of Physical Chemistry and Electrochemistry (Russian Federation)

2016-08-15

A wide variety of peptides and their natural ability to self-assemble makes them very promising candidates for the fabrication of solid-state devices based on nano- and mesocrystals. In this work, we demonstrate an approach to form peptide composite layers with gold nanoparticles through in situ reduction of chloroauric acid trihydrate by dipeptide and/or dipeptide/formaldehyde mixture in the presence of potassium carbonate at different ratios of components. Appropriate composition of components for the synthesis of highly stable gold colloidal dispersion with particle size of 34–36 nm in dipeptide/formaldehyde solution is formulated. Infrared spectroscopy results indicate that dipeptide participates in the reduction process, conjugation with gold nanoparticles and the self-assembly in 2D, which accompanied by changing peptide chain conformations. The structure and morphology of the peptide composite solid layers with gold nanoparticles on gold, mica and silica surfaces are characterized by atomic force microscopy. In these experiments, the flat particles, dendrites, chains, mesocrystals and Janus particles are observed depending on the solution composition and the substrate/interface used. The latter aspect is studied on the molecular level using computer simulations of individual peptide chains on gold, mica and silica surfaces.

Bentonite as a colloid source in groundwaters at Olkiluoto

International Nuclear Information System (INIS)

Vuorinen, U.; Hirvonen, H.

2005-02-01

addition to the ultrafiltrations some Nuclepore filter membranes with different cut-off values (0.4 μm, 0.2 μm, 0.1 μm and 0.05 μm) were prepared for SEM/EDS examination. The results of the groundwater samples collected before interaction with bentonite indicated that iron and aluminium were also associated with colloidal species, for example with SiO 2 , clay mineral or/and calcite colloids. The estimated size range of the colloids was from 50nm up to 400nm in PVA1 and in the more saline PVA3 up to 300nm (SEM). The estimate of Fe-associated colloids in PVA1 was 0.8mg/L and Alassociated colloids 0.004mg/L, whereas, in PVA3 the corresponding concentrations were clearly lower, 0.07mg/L and 0.001mg/L, respectively. After bentonite interaction bentonite colloids were detected (EDS) only in PVA1 groundwater. The size of the colloids varied from about 50nm up to about 200nm (SEM). However, the upper size limit was difficult to estimate due to large aggregates. No clear indication of bentonite colloids was obtained in PVA3 samples, but the element composition (EDS) indicated that minor amounts could be present. In PVA1 the estimated amount of Fe-associated colloids was 0.4mg/L and the amount of Al associated colloids was 0.001mg/L, whereas, in PVA3 the contents were 0.06mg/L and 0.001mg/L, respectively. Overall, the estimated concentrations of colloids in the studied size range (<0.45 μm) were small in both groundwaters and interaction with bentonite somewhat decreased the amount of Fe- and Al-associated colloids. However, the decrease in the colloid amount was more prominent in the case of the fresh PVA1 groundwater, which contained a little more to begin with. The salinity of groundwater affected the amount of colloids; more saline - less colloids. Bentonite colloids released from the bentonite source were detected only in the fresh PVA1 groundwater, but the amount was too small for obtaining an assessment of the concentration. (orig.)

Rapid green synthesis of spherical gold nanoparticles using Mangifera indica leaf

Science.gov (United States)

Philip, Daizy

2010-11-01

This paper reports the rapid biological synthesis of spherical gold nanoparticles at room temperature using fresh/dry leaf extract of Mangifera indica. This is a simple, cost-effective, stable for long time and reproducible aqueous synthesis method to obtain a self-assembly of nearly monodispersed Au nanoparticles of size ˜20 nm and 17 nm. The nanoparticles were obtained within 2 min of addition of the extract to the solution of HAuCl 4·3H 2O and the colloid is found to be stable for more than 5 months. Smaller and more uniformly distributed particles could be obtained with dried leaf extract. The nanoparticles obtained are characterized by UV-vis, transmission electron microscopy (TEM) and X-ray diffraction (XRD). Crystalline nature of the nanoparticles in the fcc structure is confirmed by the peaks in the XRD pattern corresponding to (1 1 1), (2 0 0), (2 2 0), (3 1 1) and (2 2 2) planes, bright circular spots in the selected area electron diffraction (SAED) and clear lattice fringes in the high-resolution TEM image. The possible biomolecules responsible for efficient stabilization are suggested by studying the FTIR spectrum of the sample. This environmentally benign method provides much faster synthesis and colloidal stability comparable to those of chemical reduction.

无铅、砷金红粉彩颜料的呈色机理%Colouration Mechanism of Lead and Arsenic Free Gold Ruby Famille-Rose Pigments

Institute of Scientific and Technical Information of China (English)

曹春娥; 卢希龙; 陈云霞; 沈华荣; 洪琛; 余峰

2011-01-01

The phase composition and micro-morphology of lead and arsenic free gold ruby famille-rose pigments before and after decoration firing were investigated by X-ray diffractometer,transmission electron microscope,and energy dispersive X-ray spectro-scope.The colorimetric and spectral analysis of the as-prepared samples was carried out using spectrophotometer to investigate the colouration mechanism of the pigments.The effect of the schedule of decoration firing on size of the colloidal gold particles was ana-lyzed.The results indicate that a large amount of colloidal gold particles with size of 20–30 nm are well dispersed in the glassy phase,appearing a ruby color,which is due to the strong absorption of green light of about 520 nm wavelength caused by the localized sur-face plasmon resonance of colloidal gold particles under visible light radiation.There was no clear dissolution and/or new phase forming reaction between Purple of Cassius and frit after decoration firing.The decoration firing schedule had little effect on the size of colloidal gold particles%采用X射线衍射、透射电子显微镜和能谱仪等研究了无铅、砷金红粉彩颜料彩烤前后的物相组成与显微形貌,用分光测色仪对样品进行色度及光谱分析,研究了其呈色机理,并探讨了彩烤制度对金胶粒子大小的影响。结果表明：无铅、砷金红颜料彩烤后呈红紫色是由于在光波作用下,金胶粒子产生局域表面等离子体共振,强烈吸收波长520 nm左右的绿色光所致。颜料彩烤后,大量粒径在20～30 nm的金胶粒子均匀分散于玻璃相中,色剂紫金泥与熔剂之间没有产生明显的溶解和生成新相,彩烤制度对金胶粒子大小影响不明显

Correlation between physical structure and magnetic anisotropy of a magnetic nanoparticle colloid

Science.gov (United States)

Dennis, C. L.; Jackson, A. J.; Borchers, J. A.; Gruettner, C.; Ivkov, R.

2018-05-01

We show the effects of a time-invariant magnetic field on the physical structure and magnetic properties of a colloid comprising 44 nm diameter magnetite magnetic nanoparticles, with a 24 nm dextran shell, in water. Structural ordering in this colloid parallel to the magnetic field occurs simultaneously with the onset of a colloidal uniaxial anisotropy. Further increases in the applied magnetic field cause the nanoparticles to order perpendicular to the field, producing unexpected colloidal unidirectional and trigonal anisotropies. This magnetic behavior is distinct from the cubic magnetocrystalline anisotropy of the magnetite and has its origins in the magnetic interactions among the mobile nanoparticles within the colloid. Specifically, these field-induced anisotropies and colloidal rearrangements result from the delicate balance between the magnetostatic and steric forces between magnetic nanoparticles. These magnetic and structural rearrangements are anticipated to influence applications that rely upon time-dependent relaxation of the magnetic colloids and fluid viscosity, such as magnetic hyperthermia and shock absorption.

Gold nanoparticles: BSA (Bovine Serum Albumin) coating and X-ray irradiation produce variable-spectrum photoluminescence

Energy Technology Data Exchange (ETDEWEB)

Lee, Kuo-Hao [Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan (China); Institute of Physics, Academia Sinica, Taipei 115, Taiwan (China); Lai, Sheng-Feng [Institute of Physics, Academia Sinica, Taipei 115, Taiwan (China); Department of Engineering Science, National Cheng Kung University, Tainan 701, Taiwan (China); Lin, Yan-Cheng; Chou, Wu-Ching [Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan (China); Ong, Edwin B.L. [Institute of Physics, Academia Sinica, Taipei 115, Taiwan (China); Tan, Hui-Ru [Institute of Materials Research and Engineering, 3 Research Link, 117602 (Singapore); Tok, Eng Soon [Physics Department, National University of Singapore, 117542 (Singapore); Yang, C.S. [Center for Nanomedicine, National Health Research Institutes, Miaoli 350, Taiwan (China); Margaritondo, G. [Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland); Hwu, Y., E-mail: phhwu@sinica.edu.tw [Institute of Physics, Academia Sinica, Taipei 115, Taiwan (China); Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 701, Taiwan (China); Institute of Optoelectronic Sciences, National Taiwan Ocean University, Keelung 202, Taiwan (China)

2015-01-15

We show that by using different x-ray irradiation times of BSA-coated Au nanoparticles (NPs) we can change their ultraviolet-stimulated photoluminescence and shift the spectral weight over the visible spectral range. This is due to the interplay of two emission bands, one due to BSA and the other related to gold. The emission properties did not change with time over a period of several months. - Highlights: • Gold nanoparticles (Au NPs) coated with Bovine Serum Albumin (BSA) are synthesized by x-ray irradiation. • BSA coated AuNPs with ∼1 nm size show strong photoluminescence in red by UV excitation. • The blue photoluminescence of BSA increase with x-ray irradiation. • Increase x-ray irradiation time during the synthesis shift the color of the colloid from red to blue.

Gold nanoparticles: BSA (Bovine Serum Albumin) coating and X-ray irradiation produce variable-spectrum photoluminescence

International Nuclear Information System (INIS)

Lee, Kuo-Hao; Lai, Sheng-Feng; Lin, Yan-Cheng; Chou, Wu-Ching; Ong, Edwin B.L.; Tan, Hui-Ru; Tok, Eng Soon; Yang, C.S.; Margaritondo, G.; Hwu, Y.

2015-01-01

We show that by using different x-ray irradiation times of BSA-coated Au nanoparticles (NPs) we can change their ultraviolet-stimulated photoluminescence and shift the spectral weight over the visible spectral range. This is due to the interplay of two emission bands, one due to BSA and the other related to gold. The emission properties did not change with time over a period of several months. - Highlights: • Gold nanoparticles (Au NPs) coated with Bovine Serum Albumin (BSA) are synthesized by x-ray irradiation. • BSA coated AuNPs with ∼1 nm size show strong photoluminescence in red by UV excitation. • The blue photoluminescence of BSA increase with x-ray irradiation. • Increase x-ray irradiation time during the synthesis shift the color of the colloid from red to blue

Oriented nanocomposites of ultrahigh-molecular-weight polyethylene and gold

NARCIS (Netherlands)

Heffels, W.; Bastiaansen, C.W.M.; Caseri, W.R.; Smith, P.

2000-01-01

Polymer nanocomposites were prepd. by mixing ultrahigh-mol.-wt. polyethylene and gold colloids coated with a self-assembled monolayer of dodecanethiol. Subsequently, these materials were oriented by solid state drawing which induced the formation of uniaxially oriented arrays of gold particles. As a

Method for the preparation of metal colloids in inverse micelles and product preferred by the method

Science.gov (United States)

Wilcoxon, Jess P.

1992-01-01

A method is provided for preparing catalytic elemental metal colloidal particles (e.g. gold, palladium, silver, rhodium, iridium, nickel, iron, platinum, molybdenum) or colloidal alloy particles (silver/iridium or platinum/gold). A homogeneous inverse micelle solution of a metal salt is first formed in a metal-salt solvent comprised of a surfactant (e.g. a nonionic or cationic surfactant) and an organic solvent. The size and number of inverse micelles is controlled by the proportions of the surfactant and the solvent. Then, the metal salt is reduced (by chemical reduction or by a pulsed or continuous wave UV laser) to colloidal particles of elemental metal. After their formation, the colloidal metal particles can be stabilized by reaction with materials that permanently add surface stabilizing groups to the surface of the colloidal metal particles. The sizes of the colloidal elemental metal particles and their size distribution is determined by the size and number of the inverse micelles. A second salt can be added with further reduction to form the colloidal alloy particles. After the colloidal elemental metal particles are formed, the homogeneous solution distributes to two phases, one phase rich in colloidal elemental metal particles and the other phase rich in surfactant. The colloidal elemental metal particles from one phase can be dried to form a powder useful as a catalyst. Surfactant can be recovered and recycled from the phase rich in surfactant.

Highly Tunable Complementary Micro/Submicro-Nanopatterned Surfaces Combining Block Copolymer Self-Assembly and Colloidal Lithography.

Science.gov (United States)

Chang, Tongxin; Du, Binyang; Huang, Haiying; He, Tianbai

2016-08-31

Two kinds of large-area ordered and highly tunable micro/submicro-nanopatterned surfaces in a complementary manner were successfully fabricated by elaborately combining block copolymer self-assembly and colloidal lithography. Employing a monolayer of polystyrene (PS) colloidal spheres assembled on top as etching mask, polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) or polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) micelle films were patterned into micro/submicro patches by plasma etching, which could be further transferred into micropatterned metal nanoarrays by subsequent metal precursor loading and a second plasma etching. On the other hand, micro/submicro-nanopatterns in a complementary manner were generated via preloading a metal precursor in initial micelle films before the assembly of PS colloidal spheres on top. Both kinds of micro/submicro-nanopatterns showed good fidelity at the micro/submicroscale and nanoscale; meanwhile, they could be flexibly tuned by the sample and processing parameters. Significantly, when the PS colloidal sphere size was reduced to 250 nm, a high-resolution submicro-nanostructured surface with 3-5 metal nanoparticles in each patch or a single-nanoparticle interconnected honeycomb network was achieved. Moreover, by applying gold (Au) nanoparticles as anchoring points, micronanopatterned Au arrays can serve as a flexible template to pattern bovine serum albumin (BSA) molecules. This facile and cost-effective approach may provide a novel platform for fabrication of micropatterned nanoarrays with high tunability and controllability, which are promising in the applications of biological and microelectronic fields.

Gold nanoparticle formation in diamond-like carbon using two different methods: Gold ion implantation and co-deposition of gold and carbon

International Nuclear Information System (INIS)

Salvadori, M. C.; Teixeira, F. S.; Araújo, W. W. R.; Sgubin, L. G.; Cattani, M.; Spirin, R. E.; Brown, I. G.

2012-01-01

We describe work in which gold nanoparticles were formed in diamond-like carbon (DLC), thereby generating a Au-DLC nanocomposite. A high-quality, hydrogen-free DLC thin film was formed by filtered vacuum arc plasma deposition, into which gold nanoparticles were introduced using two different methods. The first method was gold ion implantation into the DLC film at a number of decreasing ion energies, distributing the gold over a controllable depth range within the DLC. The second method was co-deposition of gold and carbon, using two separate vacuum arc plasma guns with suitably interleaved repetitive pulsing. Transmission electron microscope images show that the size of the gold nanoparticles obtained by ion implantation is 3-5 nm. For the Au-DLC composite obtained by co-deposition, there were two different nanoparticle sizes, most about 2 nm with some 6-7 nm. Raman spectroscopy indicates that the implanted sample contains a smaller fraction of sp 3 bonding for the DLC, demonstrating that some sp 3 bonds are destroyed by the gold implantation.

Gold nanoparticles: preparation, functionalisation and applications in biochemistry and immunochemistry

International Nuclear Information System (INIS)

Dykman, Lev A; Bogatyrev, Vladimir A

2007-01-01

The review summarises data on the synthesis and functionalisation of gold nanoparticles and their applications in biological investigations. Particular attention is given to applications of colloidal gold in solid-phase assays, immunoassay and studies of biologically active compounds by vibrational spectroscopy. A special section deals with the use of gold nanoparticles as antigen carriers in immunisation.

Search for an optimal colloid for sentinel node imaging

International Nuclear Information System (INIS)

Imam, S.K.; Killingsworth, M.

2005-01-01

This study aims at finding a cost-effective and stable colloid of appropriate size to replace antimony sulfide colloid which is now in routine use in Australia for sentinel lymph node (SLN) imaging. For this reason we evaluated three colloids; namely phytate, hepatate and stannous fluoride (SnF 2 ). As colloids of particle size of 100-200 nm seem to be appropriate for sentinel node imaging, the three radiolabelled colloid preparations were filtered through 0.1 and 0.22 μm filters and then studied on electron microscope. Electron microscopy showed that unlike phytate, the particle size of the hepatate and SnF 2 colloids did not increase beyond the size limit of 200 nm over a period of as long as 26 hours. Instead, they remained well within the size limits chosen. The stability of particle size is required for intra-operative gamma probe lymphatic mapping that sometimes may be performed on the following day. Hepatate and SnF 2 colloids appeared to be more suited for sentinel lymph node imaging, the latter being an inhouse product is more cost-effective. Further studies based on nodal uptake and the behavior of these two radiopharmaceuticals in animals is suggested in order to evaluate their potential for future wide-spread application in human sentinel node imaging. (author)

Tuning size and sensing properties in colloidal gold nanostars.

Science.gov (United States)

Barbosa, Silvia; Agrawal, Amit; Rodríguez-Lorenzo, Laura; Pastoriza-Santos, Isabel; Alvarez-Puebla, Ramón A; Kornowski, Andreas; Weller, Horst; Liz-Marzán, Luis M

2010-09-21

Gold nanostars are multibranched nanoparticles with sharp tips, which display extremely interesting plasmonic properties but require optimization. We present a systematic investigation of the influence of different parameters on the size, morphology, and monodispersity of Au nanostars obtained via seeded growth in concentrated solutions of poly(vinylpyrrolidone) in N,N-dimethylformamide. Controlled prereduction of Au(3+) to Au(+) was found to influence monodispersity (narrower plasmon bands), while the [HAuCl(4)]/[seed] molar ratio significantly affects the morphology and tip plasmon resonance frequency. We also varied the size of the seeds (2-30 nm) and found a clear influence on the final nanostar dimensions as well as on the number of spikes, while synthesis temperature notably affects the morphology of the particles, with more rounded morphologies formed above 60 °C. This rounding effect allowed us to confirm the importance of sharp tips on the optical enhancing behavior of these nanoparticles in surface-enhanced raman scattering (SERS). Additionally, the sensitivity toward changes in the local refractive index was found to increase for larger nanostars, though lower figure of merit (FOM) values were obtained because of the larger polydispersity.

Moessbauerspectroscopy on Gold Ruby Glass

International Nuclear Information System (INIS)

Haslbeck, S.

2005-01-01

In this thesis, the chemical states of gold and the physical mechanisms of the growing process of the particles under the influence of additional ingredients like tin, lead, antimony and selenium before, during and after the colouring process are investigated by using the Moessbauer spectroscopy on 197 Au, 119 Sn and 121 Sb, optical spectroscopy and X-ray-diffraction. Gold in an unnealed, colourless state of the glasses consists of monovalent forming linear bonds to two neighbouring oxygen atoms. The Lamb-Moessbauer factor of these gold oxide bondings is observed as 0.095 at 4.2 K. The gold in it's oxide state transforms to gold particles with a diameter of 3 nm to 60 nm. The size of the gold particles is quite definable within the optical spectra and certain sizes are also discernable within the Moessbauer spectra. One component of the Moessbauer spectra is assigned to the surface layer of the gold particles. By comparing this surface component with the amount of the bulk metallic core, one can calculate the size of the gold particles. In the Moessbauer spectra of the colourless glass one also can find parts of bulk metallic gold. Investigations with X-ray diffraction show that these are gold particles with a diameter of 100 nm to 300 nm and therefore have no additional colouring effect within the visible spectrum. The Moessbauer spectra on gold of the remelt glasses are similar to those which have been measured on the initial colourless glasses

Surface vertical deposition for gold nanoparticle film

International Nuclear Information System (INIS)

Diao, J J; Qiu, F S; Chen, G D; Reeves, M E

2003-01-01

In this rapid communication, we present the surface vertical deposition (SVD) method to synthesize the gold nanoparticle films. Under conditions where the surface of the gold nanoparticle suspension descends slowly by evaporation, the gold nanoparticles in the solid-liquid-gas junction of the suspension aggregate together on the substrate by the force of solid and liquid interface. When the surface properties of the substrate and colloidal nanoparticle suspension define for the SVD, the density of gold nanoparticles in the thin film made by SVD only depends on the descending velocity of the suspension surface and on the concentration of the gold nanoparticle suspension. (rapid communication)

Highly stable colloidal TiO{sub 2} nanocrystals with strong violet-blue emission

Energy Technology Data Exchange (ETDEWEB)

Ghamsari, Morteza Sasani, E-mail: msghamsari@yahoo.com [Laser & Optics Research School, NSTRI, 11155-3486 Tehran (Iran, Islamic Republic of); Gaeeni, Mohammad Reza [Laser & Optics Research School, NSTRI, 11155-3486 Tehran (Iran, Islamic Republic of); Han, Wooje; Park, Hyung-Ho [Department of Materials Science and Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749 (Korea, Republic of)

2016-10-15

Improved sol–gel method has been applied to prepare highly stable colloidal TiO{sub 2} nanocrystals. The synthesized titania nanocrystals exhibit strong emission in the violet-blue wavelength region. Very long evolution time was obtained by preventing the sol to gel conversion with reflux process. FTIR, XRD, UV–vis absorption, photoluminescence and high resolution transmission electron microscope (HRTEM) were used to study the optical properties, crystalline phase, morphology, shape and size of prepared TiO{sub 2} colloidal nanocrystals. HRTEM showed that the diameter of TiO{sub 2} colloidal nanocrystals is about 5 nm. Although the PL spectra show similar spectral features upon excitation wavelengths at 280, 300 and 350 nm, but their emission intensities are significantly different from each other. Photoluminescence quantum yield for TiO{sub 2} colloidal nanocrystals is estimated to be 49% with 280 nm excitation wavelength which is in agreement and better than reported before. Obtained results confirm that the prepared colloidal TiO{sub 2} sample has enough potential for optoelectronics applications.

Size-controllable synthesis of bare gold nanoparticles by femtosecond laser fragmentation in water

International Nuclear Information System (INIS)

Maximova, Ksenia; Aristov, Andrei; Sentis, Marc; Kabashin, Andrei V

2015-01-01

We report a size-controllable synthesis of stable aqueous solutions of ultrapure low-size-dispersed Au nanoparticles by methods of femtosecond laser fragmentation from preliminary formed colloids. Such approach makes possible the tuning of mean nanoparticle size between a few nm and several tens of nm under the size dispersion lower than 70% by varying the fluence of pumping radiation during the fragmentation procedure. The efficient size control is explained by 3D geometry of laser fragmentation by femtosecond laser-induced white light super-continuum and plasma-related phenomena. Despite the absence of any protective ligands, the nanoparticle solutions demonstrate exceptional stability due to electric repulsion effect associated with strong negative charging of formed nanoparticles. Stable aqueous solutions of bare gold nanoparticles present a unique object with a variety of potential applications in catalysis, surface-enhanced Raman spectroscopy, photovoltaics, biosensing and biomedicine. (paper)

Gold and gold-copper nanoparticles in 2-propanol: A radiation chemical study

International Nuclear Information System (INIS)

Dey, G.R.

2011-01-01

The studies on the reduction of Au 3+ to gold nanoparticles in presence and absence of Cu 2+ under deoxygenated conditions in 2-propanol by radiolytic method have been carried out. On γ-radiolysis, preliminary yellow colored solution of Au 3+ changed to purple color owing to gold nanoparticles formation, which exhibits an absorption peak at around 540 nm. In the presence of Cu 2+ , absorption of gold-copper nanoparticles, which was also produced during γ-radiolysis, was red shifted in contrast to the system containing no Cu 2+ . Under DLS studies the sizes of gold nanoparticles in the absence and the presence of Cu 2+ were found to be larger (>400 nm). However, in presence of polyethylene glycol, a stabilizer the nanoparticle sizes became smaller, sizes measured for gold and gold-copper nanoparticles are 40 and 140 nm, respectively. Moreover, the change in UV-vis spectra in the Cu 2+ and Au 3+ mixed system highlights the formation of gold-copper nanoparticles in core-shell type arrangement. - Highlights: → Present radiation chemical study highlights high reactivity of Au ·2+ with Cu 2+ . → Absorption of gold-copper nanoparticles is blue shifted as compared to copper nanoparticles. → Change in UV-vis spectra with dose emphasizes core-shell type arrangement of Au-Cu nanoparticles.

Quantification of the electrostatic forces involved in the directed assembly of colloidal nanoparticles by AFM nanoxerography.

Science.gov (United States)

Palleau, E; Sangeetha, N M; Ressier, L

2011-08-12

Directed assembly of 10 nm dodecanethiol stabilized silver nanoparticles in hexane and 14 nm citrate stabilized gold nanoparticles in ethanol was performed by AFM nanoxerography onto charge patterns of both polarities written into poly(methylmethacrylate) thin films. The quasi-neutral silver nanoparticles were grafted on both positive and negative charge patterns while the negatively charged gold nanoparticles were selectively deposited on positive charge patterns only. Numerical simulations were conducted to quantify the magnitude, direction and spatial range of the electrophoretic and dielectrophoretic forces exerted by the charge patterns on these two types of nanoparticles in suspension taken as models. The simulations indicate that the directed assembly of silver nanoparticles on both charge patterns is due to the predominant dielectrophoretic forces, while the selective assembly of gold nanoparticles only on positive charge patterns is due to the predominant electrophoretic forces. The study also suggests that the minimum surface potential of charge patterns required for obtaining effective nanoparticle assembly depends strongly on the charge and polarizability of the nanoparticles and also on the nature of the dispersing solvent. Attractive electrostatic forces of about 2 × 10( - 2) pN in magnitude just above the charged surface appear to be sufficient to trap silver nanoparticles in hexane onto charge patterns and the value is about 2 pN for gold nanoparticles in ethanol, under the present experimental conditions. The numerical simulations used in this work to quantify the electrostatic forces operating in the directed assembly of nanoparticles from suspensions onto charge patterns can easily be extended to any kind of colloid and serve as an effective tool for a better comprehension and prediction of liquid-phase nanoxerography processes.

Quantification of the electrostatic forces involved in the directed assembly of colloidal nanoparticles by AFM nanoxerography

International Nuclear Information System (INIS)

Palleau, E; Sangeetha, N M; Ressier, L

2011-01-01

Directed assembly of 10 nm dodecanethiol stabilized silver nanoparticles in hexane and 14 nm citrate stabilized gold nanoparticles in ethanol was performed by AFM nanoxerography onto charge patterns of both polarities written into poly(methylmethacrylate) thin films. The quasi-neutral silver nanoparticles were grafted on both positive and negative charge patterns while the negatively charged gold nanoparticles were selectively deposited on positive charge patterns only. Numerical simulations were conducted to quantify the magnitude, direction and spatial range of the electrophoretic and dielectrophoretic forces exerted by the charge patterns on these two types of nanoparticles in suspension taken as models. The simulations indicate that the directed assembly of silver nanoparticles on both charge patterns is due to the predominant dielectrophoretic forces, while the selective assembly of gold nanoparticles only on positive charge patterns is due to the predominant electrophoretic forces. The study also suggests that the minimum surface potential of charge patterns required for obtaining effective nanoparticle assembly depends strongly on the charge and polarizability of the nanoparticles and also on the nature of the dispersing solvent. Attractive electrostatic forces of about 2 x 10 -2 pN in magnitude just above the charged surface appear to be sufficient to trap silver nanoparticles in hexane onto charge patterns and the value is about 2 pN for gold nanoparticles in ethanol, under the present experimental conditions. The numerical simulations used in this work to quantify the electrostatic forces operating in the directed assembly of nanoparticles from suspensions onto charge patterns can easily be extended to any kind of colloid and serve as an effective tool for a better comprehension and prediction of liquid-phase nanoxerography processes.

Antifungal activity of gold nanoparticles prepared by solvothermal method

Energy Technology Data Exchange (ETDEWEB)

Ahmad, Tokeer, E-mail: tahmad3@jmi.ac.in [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi 110025 (India); Wani, Irshad A.; Lone, Irfan H.; Ganguly, Aparna [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi 110025 (India); Manzoor, Nikhat; Ahmad, Aijaz [Department of Biosciences, Jamia Millia Islamia, New Delhi 110025 (India); Ahmed, Jahangeer [Department of Chemistry, Michigan State University, East Lansing, MI 48824 (United States); Al-Shihri, Ayed S. [Department of Chemistry, Faculty of Science, King Khalid University, Abha 61413, P.O. Box 9004 (Saudi Arabia)

2013-01-15

Graphical abstract: Gold nanoparticles (7 and 15 nm) of very high surface area (329 and 269 m{sup 2}/g) have been successfully synthesized through solvothermal method by using tin chloride and sodium borohydride as reducing agents. As-prepared gold nanoparticles shows very excellent antifungal activity against Candida isolates and activity increases with decrease in the particle size. Display Omitted Highlights: ► Effect of reducing agents on the morphology of gold nanoparticles. ► Highly uniform and monodisperse gold nanoparticles (7 nm). ► Highest surface area of gold nanoparticles (329 m{sup 2/}g). ► Excellent antifungal activity of gold nanoparticles against Candida strains. -- Abstract: Gold nanoparticles have been successfully synthesized by solvothermal method using SnCl{sub 2} and NaBH{sub 4} as reducing agents. X-ray diffraction studies show highly crystalline and monophasic nature of the gold nanoparticles with face centred cubic structure. The transmission electron microscopic studies show the formation of nearly spherical gold nanoparticles of average size of 15 nm using SnCl{sub 2}, however, NaBH{sub 4} produced highly uniform, monodispersed and spherical gold nanoparticles of average grain size of 7 nm. A high surface area of 329 m{sup 2}/g for 7 nm and 269 m{sup 2}/g for 15 nm gold nanoparticles was observed. UV–vis studies assert the excitations over the visible region due to transverse and longitudinal surface plasmon modes. The gold nanoparticles exhibit excellent size dependant antifungal activity and greater biocidal action against Candida isolates for 7 nm sized gold nanoparticles restricting the transmembrane H{sup +} efflux of the Candida species than 15 nm sized gold nanoparticles.

Antifungal activity of gold nanoparticles prepared by solvothermal method

International Nuclear Information System (INIS)

Ahmad, Tokeer; Wani, Irshad A.; Lone, Irfan H.; Ganguly, Aparna; Manzoor, Nikhat; Ahmad, Aijaz; Ahmed, Jahangeer; Al-Shihri, Ayed S.

2013-01-01

Graphical abstract: Gold nanoparticles (7 and 15 nm) of very high surface area (329 and 269 m 2 /g) have been successfully synthesized through solvothermal method by using tin chloride and sodium borohydride as reducing agents. As-prepared gold nanoparticles shows very excellent antifungal activity against Candida isolates and activity increases with decrease in the particle size. Display Omitted Highlights: ► Effect of reducing agents on the morphology of gold nanoparticles. ► Highly uniform and monodisperse gold nanoparticles (7 nm). ► Highest surface area of gold nanoparticles (329 m 2/ g). ► Excellent antifungal activity of gold nanoparticles against Candida strains. -- Abstract: Gold nanoparticles have been successfully synthesized by solvothermal method using SnCl 2 and NaBH 4 as reducing agents. X-ray diffraction studies show highly crystalline and monophasic nature of the gold nanoparticles with face centred cubic structure. The transmission electron microscopic studies show the formation of nearly spherical gold nanoparticles of average size of 15 nm using SnCl 2 , however, NaBH 4 produced highly uniform, monodispersed and spherical gold nanoparticles of average grain size of 7 nm. A high surface area of 329 m 2 /g for 7 nm and 269 m 2 /g for 15 nm gold nanoparticles was observed. UV–vis studies assert the excitations over the visible region due to transverse and longitudinal surface plasmon modes. The gold nanoparticles exhibit excellent size dependant antifungal activity and greater biocidal action against Candida isolates for 7 nm sized gold nanoparticles restricting the transmembrane H + efflux of the Candida species than 15 nm sized gold nanoparticles.

Macrocluster desorption effect caused by single MCI: charges of gold clusters (2-20 nm) desorbed due to electronic processes induced by fission fragment bombardment in nanodispersed gold targets

International Nuclear Information System (INIS)

Baranov, I.; Jarmiychuk, S.; Kirillov, S.; Novikov, A.; Obnorskii, V.; Pchelintsev, A.; Wien, K.; Reimann, C.

1999-01-01

In this work the charge state of the negatively charged gold nanocluster ions (2-20 nm) that were desorbed from nanodispersed gold islet targets by 252 Cf fission fragments via electronic processes is studied. Mean cluster charge was calculated as a ratio of mean cluster mass to mean mass-to-charge ratio . Cluster masses were measured by means of a collector technique employing transmission electron microscopy and scanning force microscopy, while m/q was measured by means of a tandem TOF-spectrometer. It is shown that the nanocluster ions are mostly multiply charged (2-16e) and the charge increases non-linearly with the cluster size. The results are discussed

Microscopic Investigation of Reversible Nanoscale Surface Size Dependent Protein Conjugation

Directory of Open Access Journals (Sweden)

Michael A. Carpenter

2009-05-01

Full Text Available Aβ1-40 coated 20 nm gold colloidal nanoparticles exhibit a reversible color change as pH is externally altered between pH 4 and 10. This reversible process may contain important information on the initial reversible step reported for the fibrillogenesis of Aβ (a hallmark of Alzheimer’s disease. We examined this reversible color change by microscopic investigations. AFM images on graphite surfaces revealed the morphology of Aβ aggregates with gold colloids. TEM images clearly demonstrate the correspondence between spectroscopic features and conformational changes of the gold colloid.

Field-scale colloid migration experiments in a granite fracture

International Nuclear Information System (INIS)

Vilks, P.; Frost, L.H.; Bachinski, D.B.

1997-01-01

An understanding of particle migration in fractured rock, required to assess the potential for colloid-facilitated transport of radionuclides, can best be evaluated when the results of laboratory experiments are demonstrated in the field. Field-scale migration experiments with silica colloids were carried out at AECL's Underground Research Laboratory (URL), located in southern Manitoba, to develop the methodology for large-scale migration experiments and to determine whether colloid transport is possible over distances up to 17 m. In addition, these experiments were designed to evaluate the effects of flow rate and flow path geometry, and to determine whether colloid tracers could be used to provide additional information on subsurface transport to that provided by conservative tracers alone. The colloid migration studies were carried out as part of AECL's Transport Properties in Highly Fractured Rock Experiment, the objective of which was to develop and demonstrate methods for evaluating the solute transport characteristics of zones of highly fractured rock. The experiments were carried out within fracture zone 2 as two-well recirculating, two-well non-recirculating, and convergent flow tests, using injection rates of 5 and 101 min -1 . Silica colloids with a 20 nm size were used because they are potentially mobile due to their stability, small size and negative surface charge. The shapes of elution profiles for colloids and conservative tracers were similar, demonstrating that colloids can migrate over distances of 17 m. The local region of drawdown towards the URL shaft affected colloid migration and, to a lesser extent, conservative tracer migration within the flow field established by the two-well tracer tests. These results indicate that stable colloids, with sizes as small as 20 nm, have different migration properties from dissolved conservative tracers. (author)

Bright infrared LEDs based on colloidal quantum-dots

KAUST Repository

Sun, Liangfeng; Choi, Joshua J.; Stachnik, David; Bartnik, Adam C.; Hyun, Byung-Ryool; Malliaras, George G.; Hanrath, Tobias; Wise, Frank W.

2013-01-01

Record-brightness infrared LEDs based on colloidal quantum-dots have been achieved through control of the spacing between adjacent quantum-dots. By tuning the size of quantum-dots, the emission wavelengths can be tuned between 900nm and 1650nm. © 2013 Materials Research Society.

Direct synthesis and morphological characterization of gold-dendrimer nanocomposites prepared using PAMAM succinamic acid dendrimers: preliminary study of the calcification potential.

Science.gov (United States)

Vasile, E; Serafim, A; Petre, D; Giol, D; Dubruel, P; Iovu, H; Stancu, I C

2014-01-01

Gold-dendrimer nanocomposites were obtained for the first time by a simple colloidal approach based on the use of polyamidoamine dendrimers with succinamic acid terminal groups and dodecanediamine core. Spherical and highly crystalline nanoparticles with dimensions between 3 nm and 60 nm, and size-polydispersity depending on the synthesis conditions, have been generated. The influence of the stoichiometric ratio and the structural and architectural features of the dendrimers on the properties of the nanocomposites has been described. The self-assembling behaviour of these materials produces gold-dendrimer nanostructured porous networks with variable density, porosity, and composition. The investigations of the reaction systems, by TEM, at two postsynthesis moments, allowed to preliminary establish the control over the properties of the nanocomposite products. Furthermore, this study allowed better understanding of the mechanism of nanocomposite generation. Impressively, in the early stages of the synthesis, the organization of gold inside the dendrimer molecules has been evidenced by micrographs. Growth and ripening mechanisms further lead to nanoparticles with typical characteristics. The potential of such nanocomposite particles to induce calcification when coating a polymer substrate was also investigated.

Direct Synthesis and Morphological Characterization of Gold-Dendrimer Nanocomposites Prepared Using PAMAM Succinamic Acid Dendrimers: Preliminary Study of the Calcification Potential

Directory of Open Access Journals (Sweden)

E. Vasile

2014-01-01

Full Text Available Gold-dendrimer nanocomposites were obtained for the first time by a simple colloidal approach based on the use of polyamidoamine dendrimers with succinamic acid terminal groups and dodecanediamine core. Spherical and highly crystalline nanoparticles with dimensions between 3 nm and 60 nm, and size-polydispersity depending on the synthesis conditions, have been generated. The influence of the stoichiometric ratio and the structural and architectural features of the dendrimers on the properties of the nanocomposites has been described. The self-assembling behaviour of these materials produces gold-dendrimer nanostructured porous networks with variable density, porosity, and composition. The investigations of the reaction systems, by TEM, at two postsynthesis moments, allowed to preliminary establish the control over the properties of the nanocomposite products. Furthermore, this study allowed better understanding of the mechanism of nanocomposite generation. Impressively, in the early stages of the synthesis, the organization of gold inside the dendrimer molecules has been evidenced by micrographs. Growth and ripening mechanisms further lead to nanoparticles with typical characteristics. The potential of such nanocomposite particles to induce calcification when coating a polymer substrate was also investigated.

Complex protein nanopatterns over large areas via colloidal lithography

DEFF Research Database (Denmark)

Kristensen, Stine H; Pedersen, Gitte Albinus; Ogaki, Ryosuke

2013-01-01

The patterning of biomolecules at the nanoscale provides a powerful method to investigate cellular adhesion processes. A novel method for patterning is presented that is based on colloidal monolayer templating combined with multiple and angled deposition steps. Patterns of gold and SiO2 layers...

Cyto- and genotoxicity assessment of Gold nanoparticles obtained by laser ablation in A549 lung adenocarcinoma cells

International Nuclear Information System (INIS)

Bucchianico, Sebastiano Di; Migliore, Lucia; Marsili, Paolo; Vergari, Chiara; Giammanco, Francesco; Giorgetti, Emilia

2015-01-01

Gold nanoparticles have attracted enormous interest in biomedical applications, based on their unique optical properties. However, their toxicity on human tissues is still an open issue. Beyond the potential intrinsic toxicity of nanostructured gold, a non-negligible contribution of stabilizers or reaction by-products related to current wet chemical synthesis procedures can be expected. Aimed at isolating gold contribution from that of any other contaminant, we produced colloidal suspensions of Gold nanoparticles having average size <10 nm in deionized water or acetone by pulsed laser ablation, that permits preparation of uncoated and highly stable Gold nanoparticles in pure solvents. Subsequently, we investigated the role of surface chemistry, size, and dispersivity of synthesized Gold nanoparticles in exerting toxicity in a cell model system of deep respiratory tract, representing the main route of exposure to NPs, namely adenocarcinoma epithelial A549 cells. Gold nanoparticles prepared in water showed no particular signs of cytotoxicity, cytostasis, and/or genotoxicity as assessed by MTT colorimetric viability test and Cytokinesis-block micronucleus cytome assay up to concentrations of the order of 5 μg/mL. In contrast, Gold nanoparticles produced in pure acetone and then transferred into deionized water showed impaired cell viability, apoptosis responses, micronuclei, and dicentric chromosomes induction as well as nuclear budding, as a function of the amount of surface contaminants like amorphous carbon and enolate ions

Cyto- and genotoxicity assessment of Gold nanoparticles obtained by laser ablation in A549 lung adenocarcinoma cells

Energy Technology Data Exchange (ETDEWEB)

Bucchianico, Sebastiano Di [Karolinska Institutet, Institute of Environmental Medicine (Sweden); Migliore, Lucia [University of Pisa, Department of Translational Research and New Technologies in Medicine and Surgery, Division of Medical Genetics (Italy); Marsili, Paolo [Institute of Complex Systems (ISC-CNR) (Italy); Vergari, Chiara [Plasma Diagnostics and Technologies s.r.l. (Italy); Giammanco, Francesco [University of Pisa, Department of Physics “E. Fermi” (Italy); Giorgetti, Emilia, E-mail: emilia.giorgetti@fi.isc.cnr.it [Institute of Complex Systems (ISC-CNR) (Italy)

2015-05-15

Gold nanoparticles have attracted enormous interest in biomedical applications, based on their unique optical properties. However, their toxicity on human tissues is still an open issue. Beyond the potential intrinsic toxicity of nanostructured gold, a non-negligible contribution of stabilizers or reaction by-products related to current wet chemical synthesis procedures can be expected. Aimed at isolating gold contribution from that of any other contaminant, we produced colloidal suspensions of Gold nanoparticles having average size <10 nm in deionized water or acetone by pulsed laser ablation, that permits preparation of uncoated and highly stable Gold nanoparticles in pure solvents. Subsequently, we investigated the role of surface chemistry, size, and dispersivity of synthesized Gold nanoparticles in exerting toxicity in a cell model system of deep respiratory tract, representing the main route of exposure to NPs, namely adenocarcinoma epithelial A549 cells. Gold nanoparticles prepared in water showed no particular signs of cytotoxicity, cytostasis, and/or genotoxicity as assessed by MTT colorimetric viability test and Cytokinesis-block micronucleus cytome assay up to concentrations of the order of 5 μg/mL. In contrast, Gold nanoparticles produced in pure acetone and then transferred into deionized water showed impaired cell viability, apoptosis responses, micronuclei, and dicentric chromosomes induction as well as nuclear budding, as a function of the amount of surface contaminants like amorphous carbon and enolate ions.

Fast microbial reduction of ferrihydrite colloids from a soil effluent

Science.gov (United States)

Fritzsche, Andreas; Bosch, Julian; Rennert, Thilo; Heister, Katja; Braunschweig, Juliane; Meckenstock, Rainer U.; Totsche, Kai U.

2012-01-01

Recent studies on the microbial reduction of synthetic iron oxide colloids showed their superior electron accepting property in comparison to bulk iron oxides. However, natural colloidal iron oxides differ in composition from their synthetic counterparts. Besides a potential effect of colloid size, microbial iron reduction may be accelerated by electron-shuttling dissolved organic matter (DOM) as well as slowed down by inhibitors such as arsenic. We examined the microbial reduction of OM- and arsenic-containing ferrihydrite colloids. Four effluent fractions were collected from a soil column experiment run under water-saturated conditions. Ferrihydrite colloids precipitated from the soil effluent and exhibited stable hydrodynamic diameters ranging from 281 (±146) nm in the effluent fraction that was collected first and 100 (±43) nm in a subsequently obtained effluent fraction. Aliquots of these oxic effluent fractions were added to anoxic low salt medium containing diluted suspensions of Geobacter sulfurreducens. Independent of the initial colloid size, the soil effluent ferrihydrite colloids were quickly and completely reduced. The rates of Fe2+ formation ranged between 1.9 and 3.3 fmol h-1 cell-1, and are in the range of or slightly exceeding previously reported rates of synthetic ferrihydrite colloids (1.3 fmol h-1 cell-1), but greatly exceeding previously known rates of macroaggregate-ferrihydrite reduction (0.07 fmol h-1 cell-1). The inhibition of microbial Fe(III) reduction by arsenic is unlikely or overridden by the concurrent enhancement induced by soil effluent DOM. These organic species may have increased the already high intrinsic reducibility of colloidal ferrihydrite owing to quinone-mediated electron shuttling. Additionally, OM, which is structurally associated with the soil effluent ferrihydrite colloids, may also contribute to the higher reactivity due to increasing solubility and specific surface area of ferrihydrite. In conclusion, ferrihydrite

Sampling silica and ferrihydrite colloids with fiberglass wicks under unsaturated conditions.

Science.gov (United States)

Shira, Jason M; Williams, Barbara C; Flury, Markus; Czigány, Szabolcs; Tuller, Markus

2006-01-01

The suitability of passive capillary samplers (PCAPS) for collection of representative colloid samples under partially saturated conditions was evaluated by investigating the transport of negatively and positively charged colloids in fiberglass wicks. A synthetic pore water solution was used to suspend silica microspheres (330 nm in diameter) and ferrihydrite (172 nm in diameter) for transport experiments on fiberglass wicks. Breakthrough curves were collected for three unsaturated flow rates with silica microspheres and one unsaturated flow rate with ferrihydrite colloids. A moisture characteristic curve, relating tensiometer measurements of matric potential to moisture content, was developed for the fiberglass wick. Results indicate that retention of the silica and the ferrihydrite on the wick occurred; that is, the wicks did not facilitate quantitative sampling of the colloids. For silica microspheres, 90% of the colloids were transmitted through the wicks. For ferrihydrite, 80 to 90% of the colloids were transmitted. The mechanisms responsible for the retention of the colloids on the fiberglass wicks appeared to be physicochemical attachment and not thin-film, triple-phase entrapment, or mechanical straining. Visualization of pathways by iron staining indicates that flow is preferential at the center of twisted bundles of filaments. Although axial preferential flow in PCAPS may enhance their hydraulic suitability for sampling mobile colloids, we conclude that without specific preparation to reduce attachment or retention, fiberglass wicks should only be used for qualitative sampling of pore water colloids.

Deposition kinetics of nanocolloidal gold particles

NARCIS (Netherlands)

Brouwer, E.A.M.; Kooij, Ernst S.; Hakbijl, Mark; Wormeester, Herbert; Poelsema, Bene

2005-01-01

The deposition kinetics of the irreversible adsorption of citrate-stabilized, nanocolloidal gold particles on Si/SiO2 surfaces, derivatized with (aminopropyl)triethoxysilane (APTES), is investigated in situ using single wavelength optical reflectometry. A well-defined flow of colloids towards the

SU-E-T-63: A Preliminary Study of Gold Nanoparticles Enhanced Cone Beam Computed Tomography

International Nuclear Information System (INIS)

Chen, K; Sha, H; Yang, Y

2015-01-01

Purpose: Gold nanoparticles (GNPs) have potential of being used as a new-generation contrast agent to enhance CT imaging of cancer. This feasibility study is to determine the GNP concentration required to provide sufficient image contrast in small animal cone beam CT (CBCT) imaging. Methods: The GNPs used are nanorods with 10nm diameter and 44nm length. A 50µl GNP colloid with an original GNP concentration of 3.6mg/ml was diluted to five different concentrations at 2.4, 2.1, 2.0, 1.9 and 1.8mg/ml, respectively. The GNP colloid was enclosed in a 150µl vial, and the GNP colloid vial was submerged in a water bottle for CBCT. CBCTs were acquired with x-ray energy of 65kVp and tube current of 1.5mA. In addition, to evaluate the optimal x-ray energy for GNP detection in CBCT, the GNP colloid of 1.8mg/ml was also imaged at x-ray energy of 45kVp and 85kVp. Regions of interest were placed in axial CBCT slices contouring the GNP colloid volume and a same volume in the surrounding water to calculate the signal and contrast. Results: For the GNP colloid at concentrations of 3.6, 2.4, 2.1, 2.0, 1.9 and 1.8mg/ml, the image contrasts between GNP colloid and water were 68±4, 33±4, 23±3, 20±3, 13±4, and 10±3 HU, respectively. At 1.8mg/ml concentration level, the image contrasts were 16±3 and 7±4 HU, respectively, when the x-ray energy was set at 45kVp and 85kVp. Conclusion: The minimal GNP concentration required on our small animal CBCT was estimated to be around 1.8mg/ml due to the fact that the minimum image contrast for adequate differentiation in CT is about 8 HU. CBCT at lower x-ray energy, i.e. 45kVp, can provide better image contrast than at higher energies, i.e., 65kVp and 85kVp. A study of GNP enhanced CBCT for in vivo small animal imaging is ongoing efforts in our group

Eco-friendly microwave-assisted green and rapid synthesis of well-stabilized gold and core-shell silver-gold nanoparticles.

Science.gov (United States)

El-Naggar, Mehrez E; Shaheen, Tharwat I; Fouda, Moustafa M G; Hebeish, Ali A

2016-01-20

Herein, we present a new approach for the synthesis of gold nanoparticles (AuNPs) individually and as bimetallic core-shell nanoparticles (AgNPs-AuNPs). The novelty of the approach is further maximized by using curdlan (CRD) biopolymer to perform the dual role of reducing and capping agents and microwave-aided technology for affecting the said nanoparticles with varying concentrations in addition to those affected by precursor concentrations. Thus, for preparation of AuNPs, curdlan was solubilized in alkali solution followed by an addition of tetrachloroauric acid (HAuCl4). The curdlan solution containing HAuCl4 was then subjected to microwave radiation for up to 10 min. The optimum conditions obtained with the synthesis of AuNPs were employed for preparation of core-shell silver-gold nanoparticles by replacing definite portion of HAuCl4 with an equivalent portion of silver nitrate (AgNO3). The portion of AgNO3 was added initially and allowed to be reduced by virtue of the dual role of curdlan under microwave radiation. The corresponding portion of HAuCl4 was then added and allowed to complete the reaction. Characterization of AuNPs and AgNPs-AuNPs core-shell were made using UV-vis spectra, TEM, FTIR, XRD, zeta potential, and AFM analysis. Accordingly, strong peaks of the colloidal particles show surface plasmon resonance (SPR) at maximum wavelength of 540 nm, proving the formation of well-stabilized gold nanoparticles. TEM investigations reveal that the major size of AuNPs formed at different Au(+3)concentration lie below 20 nm with narrow size distribution. Whilst, the SPR bands of AgNPs-AuNPs core-shell differ than those obtained from original AgNPs (420 nm) and AuNPs (540 nm). Such shifting due to SPR of Au nanoshell deposited onto AgNPs core was significantly affected by the variation of bimetallic ratios applied. TEM micrographs show variation in contrast between dark silver core and the lighter gold shell. Increasing the ratio of silver ions leads to

Silver, gold, and alloyed silver-gold nanoparticles: characterization and comparative cell-biologic action

Science.gov (United States)

Mahl, Dirk; Diendorf, Jörg; Ristig, Simon; Greulich, Christina; Li, Zi-An; Farle, Michael; Köller, Manfred; Epple, Matthias

2012-10-01

Silver, gold, and silver-gold-alloy nanoparticles were prepared by citrate reduction modified by the addition of tannin during the synthesis, leading to a reduction in particle size by a factor of three. Nanoparticles can be prepared by this easy water-based synthesis and subsequently functionalized by the addition of either tris(3-sulfonatophenyl)phosphine or poly( N-vinylpyrrolidone). The resulting nanoparticles of silver (diameter 15-25 nm), gold (5-6 nm), and silver-gold (50:50; 10-12 nm) were easily dispersable in water and also in cell culture media (RPMI + 10 % fetal calf serum), as shown by nanoparticle tracking analysis and differential centrifugal sedimentation. High-resolution transmission electron microscopy showed a polycrystalline nature of all nanoparticles. EDX on single silver-gold nanoparticles indicated that the concentration of gold is higher inside a nanoparticle. The biologic action of the nanoparticles toward human mesenchymal stem cells (hMSC) was different: Silver nanoparticles showed a significant concentration-dependent influence on the viability of hMSC. Gold nanoparticles showed only a small effect on the viability of hMSC after 7 days. Surprisingly, silver-gold nanoparticles had no significant influence on the viability of hMSC despite the silver content. Silver nanoparticles and silver-gold nanoparticles in the concentration range of 5-20 μg mL-1 induced the activation of hMSC as indicated by the release of IL-8. In contrast, gold nanoparticles led to a reduction of the release of IL-6 and IL-8.

Eco-friendly synthesis of colloidal silver nanospheres, nanorings and nanonetworks

NARCIS (Netherlands)

Singh, A.K.; Rai, A.K.; Bicanic, D.D.

2009-01-01

Colloidal silver nanospheres, nanorings, and nanonetworks were synthesized by the nanosecond pulsed laser ablation of a silver metal plate in a pure distilled water (at room temperature) using the fundamental (1064 nm), second harmonic (532 nm), and third harmonic (355 nm) wavelengths of the Nd:YAG

Colloids and composite materials Au/Pvp and Ag/Pvp generated by laser ablation in polymeric liquid environment

Energy Technology Data Exchange (ETDEWEB)

Larez, J.; Rojas, C. [Universidad Central de Venezuela, Faculty of Science, Center of Experimental Solid State Physics, Paseo Los Ilustres, Los Chaguaramos, Apdo. Postal 20513, Caracas 1020-A (Venezuela, Bolivarian Republic of); Castell, R., E-mail: jlarez@fisica.ciens.ucv.ve [Universidad Simon Bolivar, Department of Physics, Plasma and Laser Spectroscopy Laboratory, Valle de Sartenejas, Baruta, Apdo. Postal 89000, Caracas 1080-A (Venezuela, Bolivarian Republic of)

2016-11-01

Pulsed laser ablation of silver and gold targets, immersed in a polymeric solution of Polyvinylpyrrolidone (Pvp), is used to generate colloids and composite metal-polymer. Solutions of Pvp in deionized water at different concentrations are employed. Two Pvp number average molecular weights were considered, 10000 g/mol and 55000 g/mol. The high purity targets are irradiated between 20 min and 40 min with the third harmonic (Thg) (λ = 335 nm) of a Nd:YAG laser operating at a rate of 10 Hz with pulses of 8 ns. Optical spectroscopy in UV and vis regions, scanning electron microscopy, high resolution scanning electron microscopy and X-ray are used to identify and determine the shape and size of the produced particles. Very stable sub-micrometric spherical particles for Au/Pvp and Ag/Pvp samples are obtained with diameters of 0.72 μm and 0.40 μm, respectively. The preparation of colloids is performed in one step and no surfactant or dispersing agent is used in this process. (Author)

Spectrophotometric Determination of 4-Hydroxy-2-mercapto-6-methylpyrimidine Based on Aggregation of Colloidal Gold Nanoparticles

Directory of Open Access Journals (Sweden)

M.Reza Hormozi-Nezhad

2014-12-01

Full Text Available We report herein the development of a highly sensitive colorimetric method for the detection of 4-hydroxy-2-mercapto-6-methylpyrimidine (MTU which acts as an anti-thyroid drug utilizing citrate capped gold nanoparticles (Au-NPs. This thiol-containing molecule exhibits intriguing affinity with Au-NPs. The reactivity involves the displacement of the citrate shell by the thiolate shell followed by intermolecular electrostatic interactions or hydrogen-bonding between the thiolate shells. The interparticle interactions depend on ionic strength, pH and Au-NPs concentration of the solution. The interparticle interactions lead to a small change in the plasmon band around 521 nm and the formation of a new red shifted band. The calibration curve is derived from the ratio of the absorption intensity changes at 650 nm to the changes at 520 nm. It was linear in the concentration range of 5.0 × 10-7-2.75 × 10-6 M. The detection limit (3σ for MTU was found to be 1.9 × 10-7 M.

Influence of gold nanoparticles on the 805 nm gain in Tm3+/Yb3+ codoped PbO-GeO2 pedestal waveguides

Science.gov (United States)

de Assumpção, T. A. A.; Camilo, M. E.; Alayo, M. I.; da Silva, D. M.; Kassab, L. R. P.

2017-10-01

The production and characterization of pedestal waveguides based on PbO-GeO2 amorphous thin films codoped with Tm3+/Yb3+, with and without gold nanoparticles (NPs), are reported. Pedestal structure was obtained by conventional photolithography and plasma etching. Tm3+/Yb3+ codoped PGO amorphous thin film was obtained by RF Magnetron Sputtering deposition and used as core layer in the pedestal optical waveguide. The minimum propagation losses in the waveguide were 3.6 dB/cm at 1068 nm. The internal gain at 805 nm was enhanced and increased to 8.67 dB due to the presence of gold NPs. These results demonstrate for the first time that Tm3+/Yb3+ codoped PbO-GeO2 waveguides are promising for first telecom window and integrated photonics, especially for applications on fiber network at short distances.

Application of a multi-method approach in characterization of natural aquatic colloids from different sources along Huangpu River in Shanghai, China

Energy Technology Data Exchange (ETDEWEB)

Yan, Caixia [School of Geography and Environment, Key Laboratory of Poyang Lake Wetland and Watershed Research, Ministry of Education, Jiangxi Normal University, 99 Ziyang Road, Nanchang 330022 (China); Center for Environmental Nanoscience and Risk, Arnold School of Public Health, University of South Carolina, 921 Assembly Street, Columbia 29208 (United States); State Key Laboratory of Estuarine and Coastal Research, East China Normal University, 3663 North Zhongshan Road, Shanghai 200062 (China); Nie, Minghua [School of Geography and Environment, Key Laboratory of Poyang Lake Wetland and Watershed Research, Ministry of Education, Jiangxi Normal University, 99 Ziyang Road, Nanchang 330022 (China); Lead, Jamie R. [Center for Environmental Nanoscience and Risk, Arnold School of Public Health, University of South Carolina, 921 Assembly Street, Columbia 29208 (United States); Yang, Yi [State Key Laboratory of Estuarine and Coastal Research, East China Normal University, 3663 North Zhongshan Road, Shanghai 200062 (China); Key Laboratory of Geographic Information Science of the Ministry of Education, Department of Geosciences, East China Normal University, 3663 North Zhongshan Road, Shanghai, 200062 (China); Zhou, Junliang [State Key Laboratory of Estuarine and Coastal Research, East China Normal University, 3663 North Zhongshan Road, Shanghai 200062 (China); Merrifield, Ruth [Center for Environmental Nanoscience and Risk, Arnold School of Public Health, University of South Carolina, 921 Assembly Street, Columbia 29208 (United States); Baalousha, Mohammed, E-mail: MBAALOUS@mailbox.sc.edu [Center for Environmental Nanoscience and Risk, Arnold School of Public Health, University of South Carolina, 921 Assembly Street, Columbia 29208 (United States)

2016-06-01

Natural colloid properties and the impact of human activities on these properties are important considerations for studies seeking to understand the fate and transport of pollutants. In this study, the relationship between size and fluorescence properties of natural colloids from 4 different sources were quantified using a multi-method analytical approach including UV–visible and fluorescence spectroscopy, flow field flow fractionation (FlFFF) coupled online to fluorescence spectrometer, and atomic force microscopy (AFM). Results indicate that colloids from pristine natural river water have higher aromaticity and humification, higher fluorescent intensity, and smaller size compared to those from the rivers impacted by livestock. The majority of colloids are smaller than 10 nm in size as measured by AFM and FlFFF. Colloid size measured by FlFFF coupled to fluorescence spectroscopy increases in the order peak C (Ex/Em at 300–340/400–460 nm) < peak D (Ex/Em at 210–230/340–360 nm) < peak T (Ex/Em at 270–280/330–370 nm) < peak A (Ex/Em at 210–250/400–460 nm), revealing that optical properties such as fluorescence are correlated with size. This trend is confirmed by the principal component analysis, which demonstrates that the first principal component (PC1) reflecting colloid optical properties decrease with the increase in PC3 which is correlated to the colloid size. - Highlights: • Natural aquatic colloids from different sources were isolated using cross flow ultrafiltration. • Multi-method approach is applied for colloidal characterization. • Colloids in pristine natural river water showed higher aromaticity, humification, fluorescent intensity, and smaller sizes. • Optical properties of colloids are size-dependent.

Preparation and characterization compatible pellets for immobilization of colloidal sulphur nanoparticles

Science.gov (United States)

Adlim, M.; Zarlaida, F.; Khaldun, I.; Dewi, R.; Jamilah, M.

2018-03-01

Mercury pollution in atmosphere is dominated by mercury vapour release from coal burning and gold-amalgam separation in gold mining. The initial steps in formulating a compatible mercury absorbent for mercury stabilization was fabrication of pellet supported colloidal sulphur. Sulphur is used to stabilize mercury vapour by formation of metacinnabar that has much lower toxicity. The sulphur reactivity toward mercury vapour can be enhanced by using colloidal sulphur nanoparticles immobilized on compatible pellets. Clay pellets would have heat resistance but in fact, they were less stable in aqueous solution although their stability increased with inclusion of rice husk ash and sawdust or pineapple leaf fibre in the composite. Pellets made of rice husk ash and polyvinyl acetate were stable in water at least for 24 hours. Sulphur from thiosulfate precursor that immobilized onto surface of pellet using chitosan as the stabilizer and the binding agent gave lower sulphur content compared to sulphur from other precursors (sulphur powder and sulphur-CS2). Sulphur from thiosulfate precursor was in form of colloid, has nanosize, and disperse particles on the surface of rice husk ash pellets. Sulphur immobilization methods affect on sulphur particles exposure on the pellet surface.

Double Layer of a Gold Electrode Probed by AFM Force Measurements

NARCIS (Netherlands)

Barten, D.; Kleijn, J.M.; Duval, J.F.L.; Leeuwen, van H.P.; Lyklema, J.; Cohen Stuart, M.A.

2003-01-01

Colloidal probe atomic force microscopy was used to determine the electric double layer interactions between a gold electrode and a spherical silica probe. The double layer properties of the gold/solution interface were varied through the pH and salt concentration of the electrolyte, as well as by

Towards conducting inks: Polypyrrole–silver colloids

International Nuclear Information System (INIS)

Omastová, Mária; Bober, Patrycja; Morávková, Zuzana; Peřinka, Nikola; Kaplanová, Marie; Syrový, Tomáš; Hromádková, Jiřina; Trchová, Miroslava; Stejskal, Jaroslav

2014-01-01

Graphical abstract: - Highlights: • Composite colloidal particles combining conducting polymer and metal have been prepared. • Conducting colloids are suitable for printing applications. • Polypyrrole/silver colloids are prepared in a single reaction step. • The conductivity control is discussed and still needs improvement. - Abstract: The oxidation of pyrrole with silver nitrate in the presence of suitable water-soluble polymers yields composite polypyrrole–silver colloids. The polypyrrole–silver nanoparticles stabilized with poly(N-vinylpyrrolidone) have a typical size around 350 nm and polydispersity index 0.20, i.e. a moderate polydispersity in size. Similar results have been obtained with poly(vinyl alcohol) as stabilizer. The effect of stabilizer concentration on the particle size is marginal. In the present study, several types of stabilizers have been tested in addition to currently used poly(N-vinylpyrrolidone). Transmission electron microscopy and optical microscopy revealed the gemini morphology of polypyrrole and silver colloidal nanoparticles and confirmed their size and size-distribution determined by dynamic light scattering. The use of colloidal dispersions provides an efficient tool for the UV–vis and FT Raman spectroscopic characterization of polypyrrole, including the transition between polypyrrole salt and corresponding polypyrrole base. The dispersions were used for the preparation of coatings on polyethylene terephthalate foils, and the properties for polypyrrole–silver composites have been compared with those produced from polypyrrole colloids alone

Comparative study of colloidal gold and quantum dots as labels for multiplex screening tests for multi-mycotoxin detection

Energy Technology Data Exchange (ETDEWEB)

Foubert, Astrid, E-mail: astrid.foubert@hotmail.com; Beloglazova, Natalia V.; De Saeger, Sarah

2017-02-22

Quantum dots (QDs) and colloidal gold nanoparticles (CG) were evaluated as labels for multiplex lateral flow immunoassay (LFIA) for determination of mycotoxins deoxynivalenol (DON), zearalenone (ZEN) and T2/HT2-toxin (T2/HT2) in cereal matrices. Both developed assays were based on the same immunoreagents (except for the labels), therefore their analytical characteristics could be objectively compared. For both LFIAs antigens (DON-ovalbumin (OVA), ZEN-OVA and T2-OVA) and rabbit anti-mouse immunoglobulin were immobilized on a nitrocellulose membrane as three test lines and one control line, respectively. Depending on the LFIA, monoclonal antibodies (mAb) against DON, ZEN and T2 were conjugated with CdSeS/ZnS QDs or CG. T2 and HT2 were detected by one test line (T2-OVA) with an anti-T2 mAb which showed 110% cross-reactivity with HT2. Both tests were developed in accordance with the legal limits and were developed in such a way that they had the same cut-off limits of 1000 μg kg{sup −1}, 80 μg kg{sup −1} and 80 μg kg{sup −1} for DON, ZEN and T2/HT2, respectively in order to allow a correct comparison. Applicability of these assays was demonstrated by analysis of naturally contaminated wheat samples. The results demonstrate that both the LFIAs can be used as rapid, cost-effective and convenient qualitative tool for on-site screening for simultaneous detection of DON, ZEN and HT2/T2 in wheat without special instrumentation. However, the QD-based LFIA consumed less immunoreagents and was more sensitive and economically beneficial. In addition, the results were easier to interpret, resulting in a lower false negative rate (<5%) which was in good agreement with Commission Decision 2002/657/EC regarding the performance of analytical methods intended for screening purposes. - Highlights: • Development of colloidal gold- and quantum dot-based multiplex lateral flow immunoassay. • Lateral flow immunoassays allow simultaneous detection of four mycotoxins. �

Silver, gold, and alloyed silver-gold nanoparticles: characterization and comparative cell-biologic action

Energy Technology Data Exchange (ETDEWEB)

Mahl, Dirk; Diendorf, Joerg; Ristig, Simon [University of Duisburg-Essen, Department of Inorganic Chemistry, Center for Nanointegration Duisburg-Essen (CeNIDE) (Germany); Greulich, Christina [Ruhr-University of Bochum, Bergmannsheil University Hospital/Surgical Research (Germany); Li Zian; Farle, Michael [University of Duisburg-Essen, Faculty of Physics, Center for Nanointegration Duisburg-Essen (CeNIDE) (Germany); Koeller, Manfred [Ruhr-University of Bochum, Bergmannsheil University Hospital/Surgical Research (Germany); Epple, Matthias, E-mail: matthias.epple@uni-due.de [University of Duisburg-Essen, Department of Inorganic Chemistry, Center for Nanointegration Duisburg-Essen (CeNIDE) (Germany)

2012-10-15

Silver, gold, and silver-gold-alloy nanoparticles were prepared by citrate reduction modified by the addition of tannin during the synthesis, leading to a reduction in particle size by a factor of three. Nanoparticles can be prepared by this easy water-based synthesis and subsequently functionalized by the addition of either tris(3-sulfonatophenyl)phosphine or poly(N-vinylpyrrolidone). The resulting nanoparticles of silver (diameter 15-25 nm), gold (5-6 nm), and silver-gold (50:50; 10-12 nm) were easily dispersable in water and also in cell culture media (RPMI + 10 % fetal calf serum), as shown by nanoparticle tracking analysis and differential centrifugal sedimentation. High-resolution transmission electron microscopy showed a polycrystalline nature of all nanoparticles. EDX on single silver-gold nanoparticles indicated that the concentration of gold is higher inside a nanoparticle. The biologic action of the nanoparticles toward human mesenchymal stem cells (hMSC) was different: Silver nanoparticles showed a significant concentration-dependent influence on the viability of hMSC. Gold nanoparticles showed only a small effect on the viability of hMSC after 7 days. Surprisingly, silver-gold nanoparticles had no significant influence on the viability of hMSC despite the silver content. Silver nanoparticles and silver-gold nanoparticles in the concentration range of 5-20 {mu}g mL{sup -1} induced the activation of hMSC as indicated by the release of IL-8. In contrast, gold nanoparticles led to a reduction of the release of IL-6 and IL-8.

Silver, gold, and alloyed silver–gold nanoparticles: characterization and comparative cell-biologic action

International Nuclear Information System (INIS)

Mahl, Dirk; Diendorf, Jörg; Ristig, Simon; Greulich, Christina; Li Zian; Farle, Michael; Köller, Manfred; Epple, Matthias

2012-01-01

Silver, gold, and silver–gold-alloy nanoparticles were prepared by citrate reduction modified by the addition of tannin during the synthesis, leading to a reduction in particle size by a factor of three. Nanoparticles can be prepared by this easy water-based synthesis and subsequently functionalized by the addition of either tris(3-sulfonatophenyl)phosphine or poly(N-vinylpyrrolidone). The resulting nanoparticles of silver (diameter 15–25 nm), gold (5–6 nm), and silver–gold (50:50; 10–12 nm) were easily dispersable in water and also in cell culture media (RPMI + 10 % fetal calf serum), as shown by nanoparticle tracking analysis and differential centrifugal sedimentation. High-resolution transmission electron microscopy showed a polycrystalline nature of all nanoparticles. EDX on single silver–gold nanoparticles indicated that the concentration of gold is higher inside a nanoparticle. The biologic action of the nanoparticles toward human mesenchymal stem cells (hMSC) was different: Silver nanoparticles showed a significant concentration-dependent influence on the viability of hMSC. Gold nanoparticles showed only a small effect on the viability of hMSC after 7 days. Surprisingly, silver–gold nanoparticles had no significant influence on the viability of hMSC despite the silver content. Silver nanoparticles and silver–gold nanoparticles in the concentration range of 5–20 μg mL −1 induced the activation of hMSC as indicated by the release of IL-8. In contrast, gold nanoparticles led to a reduction of the release of IL-6 and IL-8.

Sodium caseinate stabilized zein colloidal particles.

Science.gov (United States)

Patel, Ashok R; Bouwens, Elisabeth C M; Velikov, Krassimir P

2010-12-08

The present work deals with the preparation and stabilization of zein colloidal particles using sodium caseinate as electrosteric stabilizer. Colloidal particles with well-defined size range (120-150 nm) and negative surface potential (-29 to -47 mV) were obtained using a simple antisolvent precipitation method. Due to the presence of caseinate, the stabilized colloidal particles showed a shift of isoelectric point (IEP) from 6.0 to around pH 5.0 and thus prevent the aggregation of zein near its native IEP (pH 6.2). The particles also showed good stability to varying ionic strength (15 mM-1.5 M NaCl). Furthermore, stabilized particles retained the property of redispersibility after drying. In vitro protein hydrolysis study confirmed that the presence of caseinate did not alter the digestibility of zein. Such colloidal particles could potentially serve as all-natural delivery systems for bioactive molecules in food, pharmaceutical, and agricultural formulations.

Electrode reactions of iron oxide-hydroxide colloids.

Science.gov (United States)

Mahmoudi, Leila; Kissner, Reinhard

2014-11-07

Small-sized FeO(OH) colloids stabilised by sugars, commercially available for the clinical treatment of iron deficiency, show two waves during cathodic polarographic sweeps, or two current maxima with stationary electrodes, in neutral to slightly alkaline aqueous medium. Similar signals are observed with Fe(III) in alkaline media, pH > 12, containing citrate in excess. Voltammetric and polarographic responses reveal a strong influence of fast adsorption processes on gold and mercury. Visible spontaneous accumulation was also observed on platinum. The voltammetric signal at more positive potential is caused by Fe(III)→Fe(II) reduction, while the one at more negative potential has previously been assigned to Fe(II)→Fe(0) reduction. However, the involvement of adsorption phenomena leads us to the conclusion that the second cathodic current is caused again by Fe(III)→Fe(II), of species deeper inside the particles than those causing the first wave. This is further supported by X-ray photoelectron spectra obtained after FeO(OH) particle adsorption and reduction on a gold electrode surface. The same analysis suggests that sucrose stabilising the colloid is still bound to the adsorbed material, despite dilution and rinsing.

Micro-rheology on (polymer-grafted) colloids using optical tweezers

International Nuclear Information System (INIS)

Gutsche, C; Elmahdy, M M; Kegler, K; Semenov, I; Stangner, T; Otto, O; Ueberschaer, O; Kremer, F; Keyser, U F; Krueger, M; Rauscher, M; Weeber, R; Harting, J; Kim, Y W; Lobaskin, V; Netz, R R

2011-01-01

Optical tweezers are experimental tools with extraordinary resolution in positioning (± 1 nm) a micron-sized colloid and in the measurement of forces (± 50 fN) acting on it-without any mechanical contact. This enables one to carry out a multitude of novel experiments in nano- and microfluidics, of which the following will be presented in this review: (i) forces within single pairs of colloids in media of varying concentration and valency of the surrounding ionic solution, (ii) measurements of the electrophoretic mobility of single colloids in different solvents (concentration, valency of the ionic solution and pH), (iii) similar experiments as in (i) with DNA-grafted colloids, (iv) the nonlinear response of single DNA-grafted colloids in shear flow and (v) the drag force on single colloids pulled through a polymer solution. The experiments will be described in detail and their analysis discussed.

Colloidal assemblies modified by ion irradiation

OpenAIRE

Snoeks, E.; Blaaderen, A. van; Dillen, T. van; Kats, C.M. van; Velikov, K.P.; Brongersma, M.L.; Polman, A.

2001-01-01

Spherical SiO2 and ZnS colloidal particles show a dramatic anisotropic plastic deformation under 4 MeV Xe ion irradiation, that changes their shape into oblate into oblate ellipsional, with an aspect ratio that can be precisely controlled by the ion fluence. The 290 nm and 1.1 um diameter colloids were deposited on a Si substrate and irradiated at 90 K, using fluences in the range 3*10^(13)-8*10^(14) cm^(-2). The transverse particle diameter shows a linear increase with ion fluence, while the...

Instant synthesis of gold nanoparticles at room temperature and SERS applications

International Nuclear Information System (INIS)

Britto Hurtado, R.; Cortez-Valadez, M.; Ramírez-Rodríguez, L.P.; Larios-Rodriguez, Eduardo; Alvarez, Ramón A.B.; Rocha-Rocha, O.; Delgado-Beleño, Y.; Martinez-Nuñez, C.E.; Arizpe-Chávez, H.; Hernández-Martínez, A.R.; Flores-Acosta, M.

2016-01-01

Nowadays, gold nanoparticles (AuNps) can be used in a variety of applications, thus efficient methods to produce them are necessary. Several methods have been proposed in this area, but NPs production time is one limitation of these approaches. In this study, we propose a high competitive method to synthesize gold colloidal nanoparticles, instantaneously, using no-toxic reducing agents. These substances allow the instantaneous synthesis at room temperature, even without magnetic stirrers, ovens or ultrasonic baths. Optic analysis showed two absorption bands, associated with surface Plasmon as function of HAuCl_4 concentration. The nanoparticles synthesized have a 10–20 nm size, seen by the transmission electron microscopy (TEM). Therefore, it was possible to obtain several geometric patterns of AuNps, and the synthesis was performed reducing significantly processing time. Additionally, Mie and Fuchs theories were used to predict the location of the absorption bands linked to the plasmon surface in gold nanoparticles. The Surface Enhanced Raman Spectroscopy (SERS) effect was analyzed considering natural zeolite (Chabazite) as analyte, in order to determinate its possible application in soil analysis. - Highlights: • Cubic and spherical morphologies in AuNp. • Surface plasmon prediction in cubic and spherical AuNp. • Instant synthesis of AuNp. • SERS applications in soil analysis.

Instant synthesis of gold nanoparticles at room temperature and SERS applications

Energy Technology Data Exchange (ETDEWEB)

Britto Hurtado, R. [Departamento de Investigación en Física, Universidad de Sonora, Apdo. Postal 5-88, 83190, Hermosillo, Sonora (Mexico); Cortez-Valadez, M., E-mail: jose.cortez@unison.mx [CONACYT-Departamento de Investigación en Física, Universidad de Sonora, Apdo. Postal 5-88, 83190, Hermosillo, Sonora (Mexico); Ramírez-Rodríguez, L.P. [Departamento de Física, Universidad de Sonora, Apdo. Postal 5-88, 83190, Hermosillo, Sonora (Mexico); Larios-Rodriguez, Eduardo [Departamento de Ingeniería Química y Metalurgia, Universidad de Sonora, Rosales y Luis Encinas S/N, Hermosillo, Sonora (Mexico); Alvarez, Ramón A.B.; Rocha-Rocha, O.; Delgado-Beleño, Y.; Martinez-Nuñez, C.E.; Arizpe-Chávez, H. [Departamento de Investigación en Física, Universidad de Sonora, Apdo. Postal 5-88, 83190, Hermosillo, Sonora (Mexico); Hernández-Martínez, A.R. [Centro de Física Aplicada y Tecnología Avanzada (CFATA), Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro C.P. 76130 (Mexico); Flores-Acosta, M. [Departamento de Investigación en Física, Universidad de Sonora, Apdo. Postal 5-88, 83190, Hermosillo, Sonora (Mexico)

2016-08-06

Nowadays, gold nanoparticles (AuNps) can be used in a variety of applications, thus efficient methods to produce them are necessary. Several methods have been proposed in this area, but NPs production time is one limitation of these approaches. In this study, we propose a high competitive method to synthesize gold colloidal nanoparticles, instantaneously, using no-toxic reducing agents. These substances allow the instantaneous synthesis at room temperature, even without magnetic stirrers, ovens or ultrasonic baths. Optic analysis showed two absorption bands, associated with surface Plasmon as function of HAuCl{sub 4} concentration. The nanoparticles synthesized have a 10–20 nm size, seen by the transmission electron microscopy (TEM). Therefore, it was possible to obtain several geometric patterns of AuNps, and the synthesis was performed reducing significantly processing time. Additionally, Mie and Fuchs theories were used to predict the location of the absorption bands linked to the plasmon surface in gold nanoparticles. The Surface Enhanced Raman Spectroscopy (SERS) effect was analyzed considering natural zeolite (Chabazite) as analyte, in order to determinate its possible application in soil analysis. - Highlights: • Cubic and spherical morphologies in AuNp. • Surface plasmon prediction in cubic and spherical AuNp. • Instant synthesis of AuNp. • SERS applications in soil analysis.

Colloidal gold-based immunochromatographic strip assay for the rapid detection of three natural estrogens in milk.

Science.gov (United States)

Wang, Zhongxing; Guo, Lingling; Liu, Liqiang; Kuang, Hua; Xu, Chuanlai

2018-09-01

In this study, we developed highly sensitive and specific monoclonal antibodies (mAbs) against estrone (E 1 ), 17β-estradiol (17β-E 2 ), and estriol (E 3 ). The half-maximal inhibitory concentration values of anti-E 1 , anti-17β-E 2 , and anti-E 3 mAbs were 0.46, 0.36, and 0.39 ng/mL, respectively, based on competitive enzyme-linked immunosorbent assay (ic-ELISA) results. A rapid colloidal gold-based immunoassay strip assay was developed for the determination of E 1, 17β-E 2 , and E 3 residues in milk samples. The assay had a visual cut-off value of 5 ng/mL, and required 10 min to assess with the naked eye. The results obtained from the immunochromatographic strip assay were consistent with those obtained from ic-ELISA and gas chromatography-mass spectrometry. The immunochromatographic strip assay is useful and rapid for the detection of E 1 , 17β-E 2 , and E 3 in milk. Copyright © 2018 Elsevier Ltd. All rights reserved.

MICROSCOPIC USES OF NANOGOLD.

Energy Technology Data Exchange (ETDEWEB)

HAINFELD,J.F.POWELL,R.D.FURUYA,F.R.

2003-04-17

Gold has been used for immunocytochemistry since 1971 when Faulk and Taylor discovered adsorption of antibodies to colloidal gold. It is an ideal label for electron microscopy (EM) due to its high atomic number, which scatters electrons efficiently, and the fact that preparative methods have been developed to make uniform particles in the appropriate size range of 5 to 30 nm. Use in light microscopy (LM) generally requires silver enhancement (autometallography; AMG) of these small gold particles. Significant advances in this field since that time have included a better understanding of the conditions for best antibody adsorption, more regular gold size production, adsorption of other useful molecules, like protein A, and advances in silver enhancement. Many studies have also been accomplished showing the usefulness of these techniques to cell biology and biomedical research. A further advance in this field was the development of Nanogold{trademark}, a 1.4 nm gold cluster. A significant difference from colloidal gold is that Nanogold is actually a coordination compound containing a gold core covalently linked to surface organic groups. These in turn may be covalently attached to antibodies. This approach to immunolabeling has several advantages compared to colloidal gold such as vastly better penetration into tissues, generally greater sensitivity, and higher density of labeling. Since Nanogold is covalently coupled to antibodies, it may also be directly coupled to almost any protein, peptide, carbohydrate, or molecule of interest, including molecules which do not adsorb to colloidal gold. This increases the range of probes possible, and expands the applications of gold labeling.

Colloidal silver nanoparticles prepared by UV-light induced citrate reduction technique for the quantitative detection of uric acid

Science.gov (United States)

Maity, Anupam; Panda, Sovan Kumar

2018-04-01

Reddish-yellow color colloid consisting of silver nanoparticles (Ag NPs) has been synthesized by reducing aqueous AgNO3 solution by photo-induced citrate reduction technique under UV light. As prepared colloid exhibits single and intense plasmonic absorption peak in the violet region of the visible spectra with the peak centered at 405 nm. The NPs are fine and spherical with diameter ranging from 5 to 10 nm. These colloidal NPs have been used for the quantitative detection of uric acid by UV-VIS spectroscopy. A linear red shifting of the characteristics Plasmonic absorption peak of Ag NPs is observed with uric acid concentration. Uric acid can be detected by UV-VIS spectroscopy down to 5 nM limit using the prepared colloid.

Ultrafast, 2 min synthesis of monolayer-protected gold nanoclusters (d < 2 nm)

Science.gov (United States)

Martin, Matthew N.; Li, Dawei; Dass, Amala; Eah, Sang-Kee

2012-06-01

An ultrafast synthesis method is presented for hexanethiolate-coated gold nanoclusters (d gold nanoclusters are separated from the reaction byproducts fast and easily without any need for post-synthesis cleaning.An ultrafast synthesis method is presented for hexanethiolate-coated gold nanoclusters (d gold nanoclusters are separated from the reaction byproducts fast and easily without any need for post-synthesis cleaning. Electronic supplementary information (ESI) available: Experimental details of gold nanocluster synthesis and mass-spectrometry. See DOI: 10.1039/c2nr30890h

The effect of gold nanoparticles modified electrode on the glucose sensing performance

Science.gov (United States)

Zulkifli, Zulfa Aiza; Ridhuan, Nur Syafinaz; Nor, Noorhashimah Mohamad; Zakaria, Nor Dyana; Razak, Khairunisak Abdul

2017-07-01

In this work, 20 nm, 30 nm, 40 nm, 50 nm and 60 nm colloidal gold nanoparticles (AuNPs) were synthesized using the seeding growth method. AuNPs produced had spherical shape with uniform size. The AuNPs also are well dispersed in colloidal form that was proven by low polydispersity index. The produced AuNPs were used to modify electrode for glucose sensor. The produced AuNPs were deposited on indium tin oxide substrate (ITO), followed by immobilization of glucose oxidase (GOx) on it. After that, Nafion was deposited on the GOx/AuNPs/ITO. Electrooxidation of glucose with AuNPs-modified electrode was examined by cyclic voltammeter (CV) in 15 mM glucose mixed with 0.01 M PBS. The optimum size of AuNPs was 30 nm with optical density 3.0. AuNPs were successfully immobilized with glucose oxidase (GOx) and proved to work well as a glucose sensor. Based on the high electrocatalytic activity of Nafion/GOx/AuNPs/ITO, the sensitivity of the glucose sensors was further examined by varying the concentration of glucose solution from 2 mM to 20 mM in 0.01 M phosphate buffer solution (PBS) solution. Good linear relationship was observed between the catalytic current and glucose concentration in the range of 2 mM to 20 mM. The sensitivity of the Nafion/GOx/AuNPs/ITO electrode calculated from the slope of linear square calibration was 0.909 µA mM-1 cm-2 that is comparable with other published work. The linear fitting to the experimental data gives R-square of 0.991 at 0.9 V and a detection limit of 2.03 mM. This detection range is sufficient to be medically useful in monitoring human blood glucose level in which the normal blood glucose level is in the range of 4.4 to 6.6 mM and diabetic blood glucose level is above 7 mM.

Nanocomposite scaffold fabrication by incorporating gold nanoparticles into biodegradable polymer matrix: Synthesis, characterization, and photothermal effect

Energy Technology Data Exchange (ETDEWEB)

Abdelrasoul, Gaser N.; Farkas, Balazs; Romano, Ilaria; Diaspro, Alberto; Beke, Szabolcs, E-mail: szabolcs.beke@iit.it

2015-11-01

Nanoparticle incorporation into scaffold materials is a valuable route to deliver various therapeutic agents, such as drug molecules or large biomolecules, proteins (e.g. DNA or RNA) into their targets. In particular, gold nanoparticles (Au NPs) with their low inherent toxicity, tunable stability and high surface area provide unique attributes facilitating new delivery strategies. A biodegradable, photocurable polymer resin, polypropylene fumarate (PPF) along with Au NPs were utilized to synthesize a hybrid nanocomposite resin, directly exploitable in stereolithography (SL) processes. To increase the particles' colloidal stability, the Au NP nanofillers were coated with polyvinyl pyrrolidone (PVP). The resulting resin was used to fabricate a new type of composite scaffold via mask projection excimer laser stereolithography. The thermal properties of the nanocomposite scaffolds were found to be sensitive to the concentration of NPs. The mechanical properties were augmented by the NPs up to 0.16 μM, though further increase in the concentration led to a gradual decrease. Au NP incorporation rendered the biopolymer scaffolds photosensitive, i.e. the presence of Au NPs enhanced the optical absorption of the scaffolds as well, leading to possible localized temperature rise when irradiated with 532 nm laser, known as the photothermal effect. - Highlights: • Gold nanoparticle incorporation into biopolymer resin was realized. • Gold incorporation into biopolymer resin is a big step in tissue engineering. • Composite scaffolds were synthesized and thoroughly characterized. • Gold nanoparticles are remarkable candidates to be utilized as “transport vehicles”. • The photothermal effect was demonstrated using a 532-nm laser.

Electron beam patterning for writing of positively charged gold colloidal nanoparticles

Science.gov (United States)

Zafri, Hadar; Azougi, Jonathan; Girshevitz, Olga; Zalevsky, Zeev; Zitoun, David

2018-02-01

Synthesis at the nanoscale has progressed at a very fast pace during the last decades. The main challenge today lies in precise localization to achieve efficient nanofabrication of devices. In the present work, we report on a novel method for the patterning of gold metallic nanoparticles into nanostructures on a silicon-on-insulator (SOI) wafer. The fabrication makes use of relatively accessible equipment, a scanning electron microscope (SEM), and wet chemical synthesis. The electron beam implants electrons into the insulating material, which further anchors the positively charged Au nanoparticles by electrostatic attraction. The novel fabrication method was applied to several substrates useful in microelectronics to add plasmonic particles. The resolution and surface density of the deposition were tuned, respectively, by the electron energy (acceleration voltage) and the dose of electronic irradiation. We easily achieved the smallest written feature of 68 ± 18 nm on SOI, and the technique can be extended to any positively charged nanoparticles, while the resolution is in principle limited by the particle size distribution and the scattering of the electrons in the substrate. [Figure not available: see fulltext.

Ordered Nanopillar Structured Electrodes for Depleted Bulk Heterojunction Colloidal Quantum Dot Solar Cells

KAUST Repository

Kramer, Illan J.; Zhitomirsky, David; Bass, John D.; Rice, Philip M.; Topuria, Teya; Krupp, Leslie; Thon, Susanna M.; Ip, Alexander H.; Debnath, Ratan; Kim, Ho-Cheol; Sargent, Edward H.

2012-01-01

A bulk heterojunction of ordered titania nanopillars and PbS colloidal quantum dots is developed. By using a pre-patterned template, an ordered titania nanopillar matrix with nearest neighbours 275 nm apart and height of 300 nm is fabricated and subsequently filled in with PbS colloidal quantum dots to form an ordered depleted bulk heterojunction exhibiting power conversion efficiency of 5.6%. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ordered Nanopillar Structured Electrodes for Depleted Bulk Heterojunction Colloidal Quantum Dot Solar Cells

KAUST Repository

Kramer, Illan J.

2012-03-30

A bulk heterojunction of ordered titania nanopillars and PbS colloidal quantum dots is developed. By using a pre-patterned template, an ordered titania nanopillar matrix with nearest neighbours 275 nm apart and height of 300 nm is fabricated and subsequently filled in with PbS colloidal quantum dots to form an ordered depleted bulk heterojunction exhibiting power conversion efficiency of 5.6%. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Gold/silver core-shell 20 nm nanoparticles extracted from citrate solution examined by XPS

Energy Technology Data Exchange (ETDEWEB)

Engelhard, Mark H.; Smith, Jordan N.; Baer, Donald R.

2016-06-01

Silver nanoparticles of many types are widely used in consumer and medical products. The surface chemistry of particles and the coatings that form during synthesis or use in many types of media can significantly impact the behaviors of particles including dissolution, transformation and biological or environmental impact. Consequently it is useful to be able to extract information about the thickness of surface coatings and other attributes of nanoparticles produced in a variety of ways. It has been demonstrated that X-ray Photoelectron Spectroscopy (XPS) can be reliably used to determine the thickness of organic and other nanoparticles coatings and shells. However, care is required to produce reliable and consistent information. Here we report the XPS spectra from gold/silver core-shell nanoparticles of nominal size 20 nm removed from a citrate saturated solution after one and two washing cycles. The Simulation of Electron Spectra for Surface Analysis (SESSA) program had been used to model peak amplitudes to obtain information on citrate coatings that remain after washing and demonstrate the presence of the gold core. This data is provided so that others can compare use of SESSA or other modeling approaches to quantify the nature of coatings to those already published and to explore the impacts particle non-uniformities on XPS signals from core-shell nanoparticles.

Optical trapping of gold aerosols

DEFF Research Database (Denmark)

Schmitt, Regina K.; Pedersen, Liselotte Jauffred; Taheri, S. M.

2015-01-01

Aerosol trapping has proven challenging and was only recently demonstrated.1 This was accomplished by utilizing an air chamber designed to have a minimum of turbulence and a laser beam with a minimum of aberration. Individual gold nano-particles with diameters between 80 nm and 200 nm were trapped...... in air using a 1064 nm laser. The positions visited by the trapped gold nano-particle were quantified using a quadrant photo diode placed in the back focal plane. The time traces were analyzed and the trapping stiffness characterizing gold aerosol trapping determined and compared to aerosol trapping...... of nanometer sized silica and polystyrene particles. Based on our analysis, we concluded that gold nano-particles trap more strongly in air than similarly sized polystyrene and silica particles. We found that, in a certain power range, the trapping strength of polystyrene particles is linearly decreasing...

Design and synthesis of magnetic nanoparticles with gold shells for single particle optical tracking

Science.gov (United States)

Lim, Jitkang

The design, synthesis, and characterization of iron oxide core, gold shell nanoparticles are studied in this thesis. Firstly, nanoparticles with 18 +/- 1.7 nm diameter iron oxide cores with ˜5 nm thick gold shells were synthesized via a new seed-mediated electroless deposition method. The nanoparticles were superparamagnetic at room temperature and could be reversibly collected by a permanent magnet. These nanoparticles displayed a sharp localized surface plasmon resonance peak at 605 nm, as predicted by scattering theory, and their large scattering cross-section allowed them to be individually resolved in darkfield optical microscopy while undergoing Brownian motion in aqueous suspension. Later, commercially available 38 +/- 3.8 nm diameter spherical iron oxide nanoparticles (from Ocean Nanotech, Inc) were employed to make core-shell particles. These particles were decorated with cationic poly(diallyldimethylammonium chloride) (PDDA) which further promotes the attachment of small gold clusters. After gold seeding, the average hydrodynamic diameter of the core-shell particles is 172 +/- 65.9 nm. The magnetophoretic motion of these particles was guided by a piece of magnetized mu-metal. Individual particle trajectories were observed by darkfield optical microscopy. The typical magnetophoretic velocity achieved was within the range of 1--10 mum/sec. Random walk analysis performed on these particles while undergoing Brownian motion confirmed that individual particles were indeed being imaged. The particle size variation within the observed sample obtained through random walk analysis was within the size distribution obtained by dynamic light scattering. When the current to the solenoid used to magnetize the mu-metal was turned off, all the collected core-shell particles were readily redispersed by diffusion back into the surrounding environment. A Peclet number analysis was performed to probe the convective motion of nanospheres and nanorods under the influence of

Electrosynthesis and characterization of gold nanoparticles for electronic capacitance sensing of pollutants

International Nuclear Information System (INIS)

Cioffi, Nicola; Colaianni, Lorenzo; Ieva, Eliana; Pilolli, Rosa; Ditaranto, Nicoletta; Angione, Maria Daniela; Cotrone, Serafina; Buchholt, Kristina; Spetz, Anita Lloyd; Sabbatini, Luigia; Torsi, Luisa

2011-01-01

In the present study, gold/surfactant core/shell colloidal nanoparticles with a controlled morphology and chemical composition have been obtained via the so-called sacrificial anode technique, carried out in galvanostatic mode. As synthesized Au-NPs had an average core diameter comprised between 4 and 8 nm, as a function of the electrochemical process experimental conditions. The UV-Vis characterization of gold nanocolloids showed clear spectroscopic size effects, affecting both the position and width of the nanoparticle surface plasmon resonance peak. The nanomaterial surface spectroscopic characterization showed the presence of two chemical states, namely nanostructured Au(0) (its abundance being higher than 90%) and Au(I). Au-NPs were then deposited on the top of a capacitive field effect sensor and subjected to a mild thermal annealing aiming at removing the excess of stabilizing surfactant molecules. Au-NP sensors were tested towards some gases found in automotive gas exhausts. The sensing device showed the largest response towards NO x , and much smaller - if any - responses towards interferent species such as NH 3 , H 2 , CO, and hydrocarbons.

Effects of Quebracho Tannin on Recovery of Colloidal Gold from ...

African Journals Online (AJOL)

This paper considered effects of Quebracho Tannin (QT) on recovery of gold from the oxidized flotation concentrate wash liquor. The effect of Quebracho Tannin on Total Suspended Solids (TSS) was also established. This research established that the gold lost to tailings was not soluble in the effluent but was mainly in the ...

Agro-industrial waste-mediated synthesis and characterization of gold and silver nanoparticles and their catalytic activity for 4-nitroaniline hydrogenation

Energy Technology Data Exchange (ETDEWEB)

Dauthal, Preeti; Mukhopadhyay, Mausumi [S.V. National Institute of Technology, Surat (India)

2015-05-15

The biosynthesis of gold (Au-NPs) and silver nanoparticles (Ag-NPs) using agro-industrial waste Citrus aurantifolia peel extract as a bio-reducing agent is reported. Catalytic activity of nanoparticles (NPs) was evaluated for hydrogenation of anthropogenic pollutant 4-nitroaniline (4-NA). Both synthesized NPs were nearly spherical and distributed in size range of 6-46 and 10-32 nm for Au-NPs and Ag-NPs, respectively. XRD analysis revealed face centered cubic (fcc) structure of both NPs. ζ potential value obtained from colloidal solution of Au-NPs and Ag-NPs was −28.0 and −26.1mV, respectively, indicating the stability of the NPs in colloidal solution. FTIR spectra supported the role of citric and ascorbic acids of peel extract for biosynthesis and stabilization of NPs. The biosynthesized NPs exhibited excellent catalytic activity for hydrogenation of 4-NA in the presence of NaBH{sub 4}.

Laser induced breakdown detection for the assessment of colloid mediated radionuclide migration

CERN Document Server

Walther, C; Hauser, W; Kim, J I; Scherbaum, F J

2002-01-01

Colloids play an important role in the transport of pollutants in the environment. Harmful substances can undergo transport over large distances if bound to colloids in aqueous surrounding. One important example is the migration of Pu(IV) at unexpectedly high rates over several miles at a Nevada nuclear detonation test site. For long term safety assessments of radioactive waste repositories, it is hence crucial to know about the amount, size distribution and chemical composition of colloids in the ground water. Standard methods (e.g. light scattering) can be applied for high concentrations and large sizes of particles. Colloids smaller than 50 nm, however, are detected with very low efficiency. Laser induced breakdown detection (LIBD) can fill this gap. A new instrumentation is presented, which as compared to previous instruments, opens up a much wider operational dynamic range, now covering three orders of magnitude in size (5-1000 nm) and seven orders of magnitude in particle concentration (1 ppt - several ...

Laser induced photoacoustic spectroscopy applied to a study on coagulation processes of Tc(IV) colloid

International Nuclear Information System (INIS)

Sekine, T.; Kino, S.; Kino, Y.; Kudo, H.

2001-01-01

Quantitative determination of size and concentration of colloid particles in aqueous solutions was performed by laser induced photoacoustic spectroscopy (LPAS), and this technique was applied to a study on coagulation processes of Tc(IV) colloids. The intensity of photoacoustic signals from colloid particles (polystyrene, gold sols) was successfully calculated as a product of the number of particles and the absorption cross section per particle based on the Mie's light scattering theory. With this technique, the coagulation of Tc(IV) colloids prepared by the reduction of TcO 4 with Sn(II) was observed. The observed growth rate of colloid particles was successfully analyzed by a newly developed collision model, in which both the distribution of the kinetic energy of particles and the potential barrier between the two particles played significant roles. (author)

Effect of pH on ionic liquid mediated synthesis of gold nanoparticle using elaiseguineensis (palm oil) kernel extract

Science.gov (United States)

Irfan, Muhammad; Ahmad, Tausif; Moniruzzaman, Muhammad; Abdullah, Bawadi

2017-05-01

This study was conducted for microwave assisted synthesis of stable gold nanoparticles (AuNPs) by reduction of chloroauric acid with Elaeis Guineensis (palm oil) kernel (POK) extract which was prepared in aqueous solution of ionic liquid, [EMIM][OAc], 1-Ethyl-3-methylimidazolium acetate. Effect of initial pH of reaction mixture (3.5 - 8.5) was observed on SPR absorbance, maximum wavelength (λmax ) and size distribution of AuNPs. Change of pH of reaction mixture from acidic to basic region resulted in appearance of strong SPR absorption peaks and blue shifting of λmax from 533 nm to 522 nm. TEM analysis revealed the formation of predominantly spherical AuNPs with mean diameter of 8.51 nm. Presence of reducing moieties such as flavonoids, phenolic and carboxylic groups in POK extract was confirmed by FTIR analysis. Colloidal solution of AuNPs was remained stable at room temperature and insignificant difference in zeta value was recorded within experimental tenure of 4 months.

Radiation induced synthesis of colloidal silver nanoparticles stabilized by PVP/chitosan

International Nuclear Information System (INIS)

Dang Van Phu; Nguyen Trieu; Vo Thi Kim Lang; Nguyen Quoc Hien; Bui Duy Du

2008-01-01

Colloidal silver nanoparticle solution (10 mmol) was prepared by gamma 60 Co irradiation using polyvinyl pyrrolidone (PVP), water soluble chitosan (WSC) and mixture of PVP/WSC as stabilizers. Saturated conversion doses (Ag + → Ag 0 ) and maximum absorption wavelengths (λ max ) were determined by UV-vis spectra to be of 28 kGy (405.5 nm), 20 kGy (418.5 nm), 24 kGy (415.0 nm) and 24 kGy (407.0 nm) for PVP 1% (C1), WSC 0.5% (C2), PVP 1%/WSC 0.5% (C3) and PVP 1%/ethanol 1 M (C4), respectively. Results of the conversion doses indicated that WSC and ethanol plays a role in scavenging the OH* and H* arising from radiolysis of water, which reduced the conversion dose from 28 kGy (C1) to 20 kGy (C2). The average size of silver nanoparticles was characterized by Transmission Electron Microscopy (TEM) as 15.96 ± 0.51, 5.55 ± 0.25, 2.92 ± 0.05, and 11.44 ±2.07 nm for C1, C2, C3 and C4, respectively. The obtained result of silver nanoparticle sizes showed that WSC exhibited the effect of reducing silver nanoparticle size in colloids, especially the mixture of PVP/WSC that reduced the size of silver nanoparticle from ∼16 nm (C1) to about 3 nm (C3). The effect of NaNO 3 on stability of colloidal silver nanoparticles has been also investigated. (author)

Scintigraphic study of gastric emptying with colloidal tin

International Nuclear Information System (INIS)

Rodríguez Paleo, Lester; Nuez Vilar, Maricela; Machado Lois, Marisel; López González, María Karla; Torres Leyva, Oscar; Izquierdo Izquierdo, Yimel; García González, Idelsy; Conesa Gonzalez, Ana Ibis

2016-01-01

Gastroparesis is defined as a delay in gastric emptying in the absence of mechanical obstruction, associated with symptoms such as nausea and / or vomiting, feeling of postprandial gastric fullness, early satiety or epigastric pain for more than 3 months. The gold standard in the diagnosis of delayed gastric emptying scintigraphy is gastric emptying and radiopharmaceutical has been used more 99m Tc-sulfur colloid not available in the country. In order to evaluate the usefulness of colloidal tin in the scintigraphic gastric emptying study, a descriptive study was conducted in 64 patients over 18 years using as radiopharmaceutical 99m Tc-Sn colloid. 31% of patients had symptoms. The emptying time was normal in 50 cases and the association of gastroparesis symptoms was observed in 20 (15 diabetic and 5 non-diabetic), 9 patients had a delayed emptying, but reported no symptoms. Gastroparesis was more frequent in women than in men (35% versus 21%). 21% of patients had a moderate delayed gastric emptying. Conclusions: The results obtained with 99m Tc-Sn colloid are comparable to those reported by other authors using 99m Tc-SC in the scintigraphic assessment of gastric emptying. (author)

Ligand-free gold atom clusters adsorbed on graphene nano sheets generated by oxidative laser fragmentation in water

Science.gov (United States)

Lau, Marcus; Haxhiaj, Ina; Wagener, Philipp; Intartaglia, Romuald; Brandi, Fernando; Nakamura, Junji; Barcikowski, Stephan

2014-08-01

Over three decades after the first synthesis of stabilized Au55-clusters many scientific questions about gold cluster properties are still unsolved and ligand-free colloidal clusters are difficult to fabricate. Here we present a novel route to produce ultra-small gold particles by using a green technique, the laser ablation and fragmentation in water, without using reductive or stabilizing agents at any step of the synthesis. For fabrication only a pulsed laser, a gold-target, pure water, sodium hydroxide and hydrogen peroxide are deployed. The particles are exemplarily hybridized to graphene supports showing that these carbon-free colloidal clusters might serve as versatile building blocks.

Synthesis and antimicrobial activity of gold nanoparticle conjugates with cefotaxime

Science.gov (United States)

Titanova, Elena O.; Burygin, Gennady L.

2016-04-01

Gold nanoparticles (GNPs) have attracted significant interest as a novel platform for various applications to nanobiotechnology and biomedicine. The conjugates of GNPs with antibiotics and antibodies were also used for selective photothermal killing of protozoa and bacteria. Also the conjugates of some antibiotics with GNPs decreased the number of bacterial growing cells. In this work was made the procedure optimization for conjugation of cefotaxime (a third-generation cephalosporin antibiotic) with GNPs (15 nm) and we examined the antimicrobial properties of this conjugate to bacteria culture of E. coli K-12. Addition of cefotaxime solution to colloidal gold does not change their color and extinction spectrum. For physiologically active concentration of cefotaxime (3 μg/mL), it was shown that the optimum pH for the conjugation was more than 9.5. A partial aggregation of the GNPs in saline medium was observed at pH 6.5-7.5. The optimum concentration of K2CO3 for conjugation cefotaxime with GNPs-15 was 5 mM. The optimum concentration of cefotaxime was at 0.36 μg/mL. We found the inhibition of the growth of E. coli K12 upon application cefotaxime-GNP conjugates.

Thermally Stable Gold Nanoparticles with a Crosslinked Diblock Copolymer Shell

Science.gov (United States)

Jang, Se Gyu; Khan, Anzar; Hawker, Craig J.; Kramer, Edward J.

2010-03-01

The use of polymer-coated Au nanoparticles prepared using oligomeric- or polymeric-ligands tethered by Au-S bonds for incorporation into block copolymer templates under thermal processing has been limited due to dissociation of the Au-S bond at T > 100^oC where compromises their colloidal stability. We report a simple route to prepare sub-5nm gold nanoparticles with a thermally stable polymeric shell. An end-functional thiol ligand consisting of poly(styrene-b-1,2&3,4-isoprene-SH) is synthesized by anionic polymerization. After a standard thiol ligand synthesis of Au nanoparticles, the inner PI block is cross-linked through reaction with 1,1,3,3-tetramethyldisiloxane. Gold nanoparticles with the cross-linked shell are stable in organic solvents at 160^oC as well as in block copolymer films of PS-b-P2VP annealed in vacuum at 170^oC for several days. These nanoparticles can be designed to strongly segregate to the PS-P2VP interface resulting in very large Au nanoparticle volume fractions φp without macrophase separation as well as transitions between lamellar and bicontinuous morphologies as φp increases.

Synthesis of gold nanoparticles with graphene oxide.

Science.gov (United States)

Wang, Wenshuo; He, Dawei; Zhang, Xiqing; Duan, Jiahua; Wu, Hongpeng; Xu, Haiteng; Wang, Yongsheng

2014-05-01

Single sheets of functionalized graphene oxide are derived through chemical exfoliation of natural flake graphite. We present an effective synthetic method of graphene-gold nanoparticles hybrid nanocomposites. AFM (Atomic Force Microscope) was used to measure the thickness of the individual GO nanosheet. FTIR (Fourier transform infrared) spectroscopy was used to verify the attachment of oxygen functionalities on the surface of graphene oxide. TEM (Transmission Electron Microscope) data revealed the average diameters of the gold colloids and characterized the composite particles situation. Absorption spectroscopy showed that before and after synthesis the gold particle size did not change. Our studies indicate that the hybrid is potential substrates for catalysts and biosensors.

Rapid immune colloidal gold strip for cetacean meat restraining illegal trade and consumption: implications for conservation and public health.

Science.gov (United States)

Lo, Chieh; Chin, Li-Te; Chu, Chi-Shih; Wang, Yu-Ting; Chan, Kun-Wei; Yang, Wei-Cheng

2013-01-01

The consumption of cetacean meat is geographically common and often of undetermined sustainability. Besides, it can expose humans to contaminants and zoonotic pathogens. The illegality of possessing cetacean meat was likely under-reported in some countries due to lack of attention paid by the officials although DNA analysis of market products helped to show such practices. We developed two monoclonal antibodies against synthetic peptides of myoglobin (Mb) for constructing a rapid immune colloidal gold strip. Only cetacean Mb is capable of binding to both antibodies and presents positive signal while the Mb from other animals can bind only 1 of the antibodies and presents negative result. The strip for cetacean meat would be an applicable and cost-effective test for field inspectors and even the general public. It contributes to increase the reporting capacity and coverage of illegal cetacean meat possession, which has implications for global cetacean conservation and public health.

Confined palladium colloids in mesoporous frameworks for carbon nanotube growth

NARCIS (Netherlands)

Berenguer-Murcia, A.; Rebrov, E.V.; Cabaj, M.; Wheatley, A.E.H.; Johnson, B.F.G.; Robertson, J.; Schouten, J.C.

2009-01-01

Palladium colloidal nanoparticles with an average size of approximately 2.4 nm have been incorporated into mesoporous inorganic thin films following a multistep approach. This involves the deposition of mesoporous titania thin films with a thickness of 200 nm by spin-coating on titanium plates with

Synthesis and characterization of gold nanoparticles as diagnostic and therapeutic tool

International Nuclear Information System (INIS)

Costa, Pryscila Rodrigues da

2012-01-01

Nanomedicine covers the use of nanoparticles to the targeted site of action as platforms for building imaging and therapeutic agents against cancer and other human diseases. In particular, gold nanoparticles (AuNp's) have proven to be efficient for the diagnosis and therapy. Interest in the development of AuNp's is due to their extraordinary physical and chemical properties resulting from the effect of its size in the nanoscale, to have an area of easy modification and the radioactive γ and β emitter ( 198 Au; Eγ = 0,411 MeV, β max = 0,96 MeV; T 1/2 = 2,69 days), having the advantage of being able to be applied as a diagnostic tool for molecular photon emission tomography (SPECT) using only a small amount of radioactive gold . In this study were synthesized AuNp's, whose surface is functionalized with a biocompatible polymer (modified polyethylene glycol) and folic acid in order to render them stealth and specific tumors that over express the folate receptors. The techniques of Dynamic Light Scattering (DLS), zeta potential (ζ), transmission electron microscopy (TEM) and UV-Visible absorption spectroscopy were employed to characterization of the size and geometry of the nanoparticles, in addition to confirming its binding to thiol -PEG and PEG-thiol Folate. The results of UV-Visible and TEM showed the formation of dispersed AuNp's ranging in size from 8-12 nm with a strong absorption around 520 nm, relating to a maximum of surface plasmon resonance. DLS results showed a hydrodynamic diameter of 10 and 14 nm. The (pH ∼ 5.0 to 6.0) ranged ζ potential values of the dispersions prepared between -16.2 and -42.1 mV, indicating stable colloidal suspensions. To determine the real concentration of gold in the samples, it was used neutron activation in the nuclear reactor TRIGA MARK I IPR-R1 CDTN / CNEN of Belo Horizonte. Biocompatibility studies in vitro and in vivo of the samples were carried out showing that they have low toxicity in the models used. We evaluated

The treatment of rheumatoid arthritis, osteoarthritis, and non-specific synovitis by intra-articular injection of radioactive colloidal gold (198Au)

International Nuclear Information System (INIS)

Kim, S.J.

1981-01-01

In this study, thirty-nine knee and three ankle effusions and pains unresponsive to the usual methods of therapy were treated by intra-articular injection of radioactive colloidal gold from November 1964 to January 1979 and followed up. Thirteen cases had classical rheumatoid arthritis: fifteen non-specific synovitis: two pigmented villonodular synovitis: one post-synovectomy, and one tuberculous arthritis. The results were as follows: 1) In eleven cases (84.6 %) of rheumatoid arthritis fourteen cases (93.3 %) of non-specific synovitis, and five cases (50.0 %) of osteoarthritis, the effusion disappeared. 2) In twelve cases (92.3 %) of rheumatoid arthritis, thirteen cases (86.7 %) of non-specific synovitis, and only two cases (20.0 %) of oseoarthritis, the pain disappeared. 3) As a whole, in thirty-three cases (78.6 %), the effusion disappeared and in twenty-eight cases (66.7 %) the pain disappeared. (author)

Formation and optical characterisation of colloidal gold monolayers

NARCIS (Netherlands)

Kooij, Ernst S.; Brouwer, E.A.M.; Wormeester, Herbert; Poelsema, Bene

2003-01-01

We study the deposition of charge-stabilised gold nanocolloids on silicon substrates, which have been derivatised with (aminopropyl)triethoxysilane. Atomic force microscopy (AFM) and spectroscopic ellipsometry are employed to investigate the nanocrystal monolayers ex situ. Analysis of AFM images

Analytical scale purification of zirconia colloidal suspension using field programmed sedimentation field flow fractionation.

Science.gov (United States)

Van-Quynh, Alexandra; Blanchart, Philippe; Battu, Serge; Clédat, Dominique; Cardot, Philippe

2006-03-03

Sedimentation field flow fractionation was used to obtain purified fractions from a polydispersed zirconia colloidal suspension in the potential purpose of optical material hybrid coating. The zirconia particle size ranged from 50/70 nm to 1000 nm. It exhibited a log-Gaussian particle size distribution (in mass or volume) and a 115% polydispersity index (P.I.). Time dependent eluted fractions of the original zirconia colloidal suspension were collected. The particle size distribution of each fraction was determined with scanning electron microscopy and Coulter sub-micron particle sizer (CSPS). These orthogonal techniques generated similar data. From fraction average elution times and granulometry measurements, it was shown that zirconia colloids are eluted according to the Brownian elution mode. The four collected fractions have a Gaussian like distribution and respective average size and polydispersity index of 153 nm (P.I. = 34.7%); 188 nm (P.I. = 27.9%); 228 nm (P.I. = 22.6%), and 276 nm (P.I. = 22.3%). These data demonstrate the strong size selectivity of SdFFF operated with programmed field of exponential profile for sorting particles in the sub-micron range. Using this technique, the analytical production of zirconia of given average size and reduced polydispersity is possible.

Ionic Strength Dependent Kinetics of Nanocolloidal Gold Deposition

NARCIS (Netherlands)

Brouwer, E.A.M.; Kooij, Ernst S.; Wormeester, Herbert; Poelsema, Bene

2003-01-01

The deposition kinetics of the irreversible adsorption of citrate-stabilized, nanocolloidal gold particles on Si/SiO2 surfaces, derivatized with (aminopropyl)triethoxysilane, is investigated in situ using single wavelength reflectometry. A well-defined flow of colloids toward the surface is realized

Suppression of gold nanoparticle agglomeration and its separation via nylon membranes

Institute of Scientific and Technical Information of China (English)

Ayyavoo Jayalakshmi; In-Chul Kim; Young-Nam Kwon

2017-01-01

Use of ultraporous nylon membrane is one of the most widely employed techniques for removal of hard and soft nanoparticles in the semiconductor industry,and the accurate determination of membrane pore size is necessary in order to avoid manufacturing defects caused by contamination.The gold nanoparticle has several benefits for the evaluation of polymeric membranes;however,the nanoparticles agglomerate easily on the nylon membrane and make it difficult to evaluate the membrane precisely.The properties of 2-amino-2-hydroxymethyl-1,3-propanediol (ADP) ligand in gold nanoparticle solution were systematically investigated,and ADP was utilized for improved evaluation of the nylon membranes.Nylon membrane used in this study was prepared by phase inversion techniques.Ultrathin dense layer on top of the membrane surface and Darcy structures in the microporous membrane support were observed.The gold particle rejection was carried out at various pH values from 4 to 14 and higher rejection was observed at pH 4 and 8.The suppression of gold colloid agglomeration using ADP and monodispersity of gold colloids was also analyzed by confocal laser scanning microscopy (CLSM),transmission electron microscopy (TEM),and scanning electron microscopy (SEM).van der Waals interaction energy of the particles was reduced in the addition of ADP.The presence ofADP ligand in the gold solutions prevented the agglomeration of gold nanoparticles and reduced the adsorption of the particles on the nylon membrane surface,leading to precise evaluation of membrane pore sizes.

Synthesis and characterization of core-shell gold nanoparticles with poly(vinyl pyrrolidone) from a new precursor salt

Science.gov (United States)

Behera, M.; Ram, S.

2013-02-01

In this article, we report a facile one-step chemical synthesis of gold (Au) nanoparticles (GNPs) from a new precursor salt i.e., gold hydroxide in the presence of poly(vinyl pyrrolidone) (PVP) polymer. The non-aqueous dispersion of GNPs was comprehensively characterized by UV-Visible, FTIR, zeta potential, and transmission electron microscope (TEM). A strong surface plasmon resonance band at 529 nm in the UV-Visible spectrum confirms the formation of GNPs in the Au colloid. The FTIR spectroscopic results showed that PVP molecules get chemisorbed onto the surface of GNP via O-atom of carbonyl group. A negative zeta potential of (-)16 mV reveals accumulation of nonbonding electrons of O-atom of carbonyl group of PVP molecules on the nanosurface of GNP. TEM images demonstrate a core-shell nanostructure with an Au-crystalline core covered by a thin amorphous PVP-shell. PVP-capped GNPs could be a potential candidate for bio-sensing, catalysis, and other applications.

Species selection for the design of gold nanobioreactor by photosynthetic organisms

Energy Technology Data Exchange (ETDEWEB)

Dahoumane, Si Amar [Universite Paris Diderot, Interfaces, Traitements, Organisation et Dynamique des Systemes (ITODYS), UMR 7086, CNRS, Sorbonne Paris Cite (France); Djediat, Chakib; Yepremian, Claude; Coute, Alain [Museum National d' Histoire Naturelle, Departement RDDM, FRE 3206, USM 505 (France); Fievet, Fernand [Universite Paris Diderot, Interfaces, Traitements, Organisation et Dynamique des Systemes (ITODYS), UMR 7086, CNRS, Sorbonne Paris Cite (France); Coradin, Thibaud, E-mail: thibaud.coradin@upmc.fr [UPMC Universites Paris 06, CNRS, Chimie de la Matiere Condensee de Paris (LCMCP), College de France (France); Brayner, Roberta, E-mail: roberta.brayner@univ-paris-diderot.fr [Universite Paris Diderot, Interfaces, Traitements, Organisation et Dynamique des Systemes (ITODYS), UMR 7086, CNRS, Sorbonne Paris Cite (France)

2012-06-15

The design of cell-based bioreactors for inorganic particles formation requires both a better understanding of the underlying processes and the identification of most suitable organisms. With this purpose, the process of Au{sup 3+} incorporation, intracellular reduction, and Au{sup 0} nanoparticle release in the culture medium was compared for four photosynthetic microorganisms, Klebsormidium flaccidum and Cosmarium impressulum green algae, Euglena gracilis euglenoid and Anabaena flos-aquae cyanobacteria. At low gold content, the two green algae show maintained photosynthetic activity and recovered particles (ca. 10 nm in size) are similar to internal colloids, indicating a full biological control over the whole process. In similar conditions, the euglenoid exhibits a rapid loss of biological activity, due to the absence of protective extracellular polysaccharide, but could grow again after an adaptation period. This results in a larger particle size dispersity but larger reduction yield. The cyanobacteria undergo rapid cell death, due to their prokaryotic nature, leading to high gold incorporation rate but poor control over released particle size. Similar observations can be made after addition of a larger gold salt concentration when all organisms rapidly die, suggesting that part of the process is not under biological control anymore but also involves extracellular chemical reactions. Overall, fruitful information on the whole biocrystallogenesis process is gained and most suitable species for further bioreactor design can be identified, i.e., green algae with external coating.

Species selection for the design of gold nanobioreactor by photosynthetic organisms

International Nuclear Information System (INIS)

Dahoumane, Si Amar; Djediat, Chakib; Yéprémian, Claude; Couté, Alain; Fiévet, Fernand; Coradin, Thibaud; Brayner, Roberta

2012-01-01

The design of cell-based bioreactors for inorganic particles formation requires both a better understanding of the underlying processes and the identification of most suitable organisms. With this purpose, the process of Au 3+ incorporation, intracellular reduction, and Au 0 nanoparticle release in the culture medium was compared for four photosynthetic microorganisms, Klebsormidium flaccidum and Cosmarium impressulum green algae, Euglena gracilis euglenoid and Anabaena flos-aquae cyanobacteria. At low gold content, the two green algae show maintained photosynthetic activity and recovered particles (ca. 10 nm in size) are similar to internal colloids, indicating a full biological control over the whole process. In similar conditions, the euglenoid exhibits a rapid loss of biological activity, due to the absence of protective extracellular polysaccharide, but could grow again after an adaptation period. This results in a larger particle size dispersity but larger reduction yield. The cyanobacteria undergo rapid cell death, due to their prokaryotic nature, leading to high gold incorporation rate but poor control over released particle size. Similar observations can be made after addition of a larger gold salt concentration when all organisms rapidly die, suggesting that part of the process is not under biological control anymore but also involves extracellular chemical reactions. Overall, fruitful information on the whole biocrystallogenesis process is gained and most suitable species for further bioreactor design can be identified, i.e., green algae with external coating.

Species selection for the design of gold nanobioreactor by photosynthetic organisms

Science.gov (United States)

Dahoumane, Si Amar; Djediat, Chakib; Yéprémian, Claude; Couté, Alain; Fiévet, Fernand; Coradin, Thibaud; Brayner, Roberta

2012-06-01

The design of cell-based bioreactors for inorganic particles formation requires both a better understanding of the underlying processes and the identification of most suitable organisms. With this purpose, the process of Au3+ incorporation, intracellular reduction, and Au0 nanoparticle release in the culture medium was compared for four photosynthetic microorganisms, Klebsormidium flaccidum and Cosmarium impressulum green algae, Euglena gracilis euglenoid and Anabaena flos- aquae cyanobacteria. At low gold content, the two green algae show maintained photosynthetic activity and recovered particles (ca. 10 nm in size) are similar to internal colloids, indicating a full biological control over the whole process. In similar conditions, the euglenoid exhibits a rapid loss of biological activity, due to the absence of protective extracellular polysaccharide, but could grow again after an adaptation period. This results in a larger particle size dispersity but larger reduction yield. The cyanobacteria undergo rapid cell death, due to their prokaryotic nature, leading to high gold incorporation rate but poor control over released particle size. Similar observations can be made after addition of a larger gold salt concentration when all organisms rapidly die, suggesting that part of the process is not under biological control anymore but also involves extracellular chemical reactions. Overall, fruitful information on the whole biocrystallogenesis process is gained and most suitable species for further bioreactor design can be identified, i.e., green algae with external coating.

[AgBr colloids prepared by electrolysis and their SERS activity research].

Science.gov (United States)

Si, Min-Zhen; Fang, Yan; Dong, Gang; Zhang, Peng-Xiang

2008-01-01

Ivory-white AgBr colloids were prepared by means of electrolysis. Two silver rods 1.0 cm in diameter and 10.0 cm long were respectively used as the negative and positive electrodes, the aqueous solution of hexadecyl trimethyl ammonium bromide was used as the electrolyte, and a 7 V direct current was applied on the silver rods for three hours. The obtained AgBr colloids were characterized by UV-Vis spectroscopy, transmission electron microscopy, and SERS using a 514. 5 nm laser line on Renishaw 2000 Raman spectrometer. These particles are about nanometer size and their shapes are as spherical or elliptic, with a slight degree of particle aggregation. The UV-Vis spectra exhibit a large plasmon resonance band at about 292.5 nm, similar to that reported in the literature. The AgBr colloids were very stable at room temperature for months. In order to test if these AgBr colloids can be used for SERS research, methyl orange, Sudan red and pyridine were used. It was found that AgBr colloids have SERS activity to these three molicules. For methyl orange, the intense Raman peaks are at 1 123, 1 146, 1 392, 1 448 and 1 594 cm(-1); for Sudan red, the intense Raman peaks are at 1 141, 1 179, 1 433 and 1 590 cm(-1); and for pyridine, the intense Raman peaks are at 1 003, 1 034 and 1 121 cm(-1). It is noticeable that SERS of methyl orange was observed on AgBr colloids, but not on the gray and yellow silver colloids prepared by traditional means. The possible reason was explained. One major advantage of this means is the absence of the spectral interference such as citrate, BH4- arising from reaction products of the colloids formation process. On AgBr colloids, one can get some molecular SERS impossible to get on the gray and yellow silver colloids.

Pore water colloid properties in argillaceous sedimentary rocks.

Science.gov (United States)

Degueldre, Claude; Cloet, Veerle

2016-11-01

colloid concentration is expected to be very low (<1ppb, for 10-100nm) which restricts their relevance for radionuclide transport. Copyright © 2016. Published by Elsevier B.V.

Phage based green chemistry for gold ion reduction and gold retrieval.

Science.gov (United States)

Setyawati, Magdiel I; Xie, Jianping; Leong, David T

2014-01-22

The gold mining industry has taken its toll on the environment, triggering the development of more environmentally benign processes to alleviate the waste load release. Here, we demonstrate the use of bacteriophages (phages) for biosorption and bioreduction of gold ions from aqueous solution, which potentially can be applied to remediate gold ions from gold mining waste effluent. Phage has shown a remarkably efficient sorption of gold ions with a maximum gold adsorption capacity of 571 mg gold/g dry weight phage. The product of this phage mediated process is gold nanocrystals with the size of 30-630 nm. Biosorption and bioreduction processes are mediated by the ionic and covalent interaction between gold ions and the reducing groups on the phage protein coat. The strategy offers a simple, ecofriendly and feasible option to recover of gold ions to form readily recoverable products of gold nanoparticles within 24 h.

Ulex europaeus agglutinin-I binding to dental primary afferent projections in the spinal trigeminal complex combined with double immunolabeling of substance P and GABA elements using peroxidase and colloidal gold.

Science.gov (United States)

Matthews, M A; Hoffmann, K D; Hernandez, T V

1989-01-01

have a comparable distribution; however, many extended into the dorsal portion of the caudal half of Vi and the ventromedial quadrant of rostral Vi. Electron-microscopic analysis showed that transganglionically labeled dental pulp terminals contained ovoid, complex membrane-bound vacuoles laden with transported HRP. The preterminal axon and synaptic membranes of those dental pulp terminals located in zones of Vc and Vi displaying an affinity for UEA-I were usually characterized by a patchy, electron-dense coating of the peroxidase tag. SP was demonstrated ultrastructurally with Protein-A colloidal gold (3-nm particles), whereas GABA immunoreactivity was revealed by the avidin-biotin-peroxidase method.(ABSTRACT TRUNCATED AT 400 WORDS)

Synthesis of flower-like gold nanoparticles and their electrocatalytic activity towards the oxidation of methanol and the reduction of oxygen.

Science.gov (United States)

Jena, Bikash Kumar; Raj, C Retna

2007-03-27

This article describes the synthesis of branched flower-like gold (Au) nanocrystals and their electrocatalytic activity toward the oxidation of methanol and the reduction of oxygen. Gold nanoflowers (GNFs) were obtained by a one-pot synthesis using N-2-hydroxyethylpiperazine-N-2-ethanesulphonic acid (HEPES) as a reducing/stabilizing agent. The GNFs have been characterized by UV-visible spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), and electrochemical measurements. The UV-visible spectra show two bands corresponding to the transverse and longitudinal surface plasmon (SP) absorption at 532 and 720 nm, respectively, for the colloidal GNFs. The GNFs were self-assembled on a sol-gel-derived silicate network, which was preassembled on a polycrystalline Au electrode and used for electrocatalytic applications. The GNFs retain their morphology on the silicate network; the UV-visible diffuse reflectance spectra (DRS) of GNFs on the silicate network show longitudinal and transverse bands as in the case of colloidal GNFs. The GNFs show excellent electrocatalytic activity toward the oxidation of methanol and the reduction of oxygen. Oxidation of methanol in alkaline solution was observed at approximately 0.245 V, which is much less positive than that on an unmodified polycrystalline gold electrode. Reduction of oxygen to H2O2 and the further reduction of H2O2 to water in neutral pH were observed at less negative potentials on the GNFs electrode. The electrocatalytic activity of GNFs is significantly higher than that of the spherically shaped citrate-stabilized Au nanoparticles (SGNs).

Gold-Decorated Supraspheres of Block Copolymer Micelles

Science.gov (United States)

Kim, M. P.; Kang, D. J.; Kannon, A. G.; Jung, D.-W.; Yi, G. R.; Kim, B. J.

2012-02-01

Gold-decorated supraspheres displaying various surface morphologies were prepared by infiltration of gold precursor into polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP) supraspheres under acidic condition. The supraspheres were fabricated by emulsifying PS-b-P2VP polymer solution into surfactant solution. Selective swelling of P2VP in the suprasphere by gold precursor under acidic condition resulted in the formation of gold-decorated supraspheres with various surface structures. As evidenced by TEM and SEM images, dot pattern was formed in the case of smaller supraspheres than 800 nm; whereas fingerprint-like pattern was observed in larger supraspheres than 800 nm. Gold nanoparticles were located inside P2VP domains near the surface of prepared supraspheres as confirmed by TEM. The optical property of the supraspheres was characterized using UV-vis absorption spectroscopy and the maximum absorption peak at around 580 nm was observed, which means that gold nanoparticles densely packed into P2VP domain on the suprasphere. Our approach to prepare gold-decorated supraspheres can be extended to other metallic particles such as iron oxide or platinum nanoparticles, and those precursors can be also selectively incorporated into the P2VP domain.

Microbial deposition of gold nanoparticles by the metal-reducing bacterium Shewanella algae

International Nuclear Information System (INIS)

Konishi, Y.; Tsukiyama, T.; Tachimi, T.; Saitoh, N.; Nomura, T.; Nagamine, S.

2007-01-01

Microbial reduction and deposition of gold nanoparticles was achieved at 25 deg. C over the pH range 2.0-7.0 using the mesophilic bacterium Shewanella algae in the presence of H 2 as the electron donor. The reductive deposition of gold by the resting cells of S. algae was a fast process: 1 mM AuCl 4 - ions were completely reduced to elemental gold within 30 min. At a solution pH of 7, gold nanoparticles 10-20 nm in size were deposited in the periplasmic space of S. algae cells. At pH 2.8, gold nanoparticles 15-200 nm in size were deposited on the bacterial cells, and the biogenic nanoparticles exhibited a variety of shapes that included nanotriangles: in particular, single crystalline gold nanotriangles 100-200 nm in size were microbially deposited. At a solution pH of 2.0, gold nanoparticles about 20 nm in size were deposited intracellularly, and larger gold particles approximately 350 nm in size were deposited extracellularly. The solution pH was an important factor in controlling the morphology of the biogenic gold particles and the location of gold deposition. Microbial deposition of gold nanoparticles is potentially attractive as an environmentally friendly alternative to conventional methods

A tunable colloidal quantum dot photo field-effect transistor

KAUST Repository

Ghosh, Subir; Hoogland, Sjoerd; Sukhovatkin, Vlad; Levina, Larissa; Sargent, Edward H.

2011-01-01

We fabricate and investigate field-effect transistors in which a light-absorbing photogate modulates the flow of current along the channel. The photogate consists of colloidal quantum dots that efficiently transfer photoelectrons to the channel across a charge-separating (type-II) heterointerface, producing a primary and sustained secondary flow that is terminated via electron back-recombination across the interface. We explore colloidal quantum dot sizes corresponding to bandgaps ranging from 730 to 1475 nm and also investigate various stoichiometries of aluminum-doped ZnO (AZO) channel materials. We investigate the role of trap state energies in both the colloidal quantum dot energy film and the AZO channel. © 2011 American Institute of Physics.

Enzymatic formation of gold nanoparticles by submerged culture of the basidiomycete Lentinus edodes.

Science.gov (United States)

Vetchinkina, Elena P; Loshchinina, Ekaterina A; Burov, Andrey M; Dykman, Lev A; Nikitina, Valentina E

2014-07-20

We report for the first time that the medicinal basidiomycete Lentinus edodes can reduce Au(III) from chloroauric acid (HAuCl4) to elemental Au [Au(0)], forming nanoparticles. Several methods, including transmission electron microscopy, electron energy loss spectroscopy, X-ray fluorescence, and dynamic light scattering, were used to show that when the fungus was grown submerged, colloidal gold accumulated on the surface of and inside the mycelial hyphae as electron-dense particles mostly spherical in shape, with sizes ranging from 5 to 50nm. Homogeneous proteins (the fungal enzymes laccase, tyrosinase, and Mn-peroxidase) were found for the first time to be involved in the reduction of Au(III) to Au(0) from HAuCl4. A possible mechanism forming Au nanoparticles is discussed. Copyright © 2014 Elsevier B.V. All rights reserved.

Morphology dependent electrical transport behavior in gold nanostructures

International Nuclear Information System (INIS)

Alkhatib, A.; Souier, T.; Chiesa, M.

2011-01-01

The mechanism of electron transport in ultra-thin gold films is investigated and its dependence on the gold islands size is reported. For gold films of thickness below 38 nm, the electrical transport occurs by tunneling within electrically discontinuous islands of gold. Simmons model for metal-insulator-metal junction describes the non-ohmic experimental current-voltage curves obtained by means of conductive atomic force microscopy. Field emission is the predominant transport for thicknesses below 23 nm while direct tunneling occurs in thicker films. The transition between the two regimes is controlled by the gold islands size and their inter-distance.

Interaction between manufactured gold nanoparticles and naturally occurring organic macromolecules

International Nuclear Information System (INIS)

Diegoli, Sara; Manciulea, Adriana L.; Begum, Shakiela; Jones, Ian P.; Lead, Jamie R.; Preece, Jon A.

2008-01-01

The increasing exploitation of nanomaterials into many consumer and other products is raising concerns as these nanomaterials are likely to be released into the environment. Due to our lack of knowledge about the environmental chemistry, transport and ecotoxicology of nanomaterials, it is of paramount importance to study how natural aquatic colloids can interact with manufactured gold nanoparticles as these interactions will determine their environmental fate and behaviour. In this context, our work aims to quantify the effect of naturally occurring riverine macromolecules - International Humic Substances Society (IHSS) Suwannee River Humic Acid Standard (SRHA) - on citrate- and acrylate-stabilized gold nanoparticles. The influence of SRHA on the stability of the gold colloids was studied as a function of pH by UV-visible absorption spectroscopy, dynamic light scattering (DLS) and transmission electron microscopy (TEM). At high ionic strengths (0.1 M), extensive and rapid aggregation occurred, while more subtle effects were observed at lower ionic strength values. Evidence was found that SRHA enhances particle stability at extreme pH values (ionic strength < 0.01 M) by substituting and/or over-coating the original stabilizer on the gold nanoparticle surface, thus affecting surface charge and chemistry. These findings have important implications for the fate and behaviour of nanoparticles in the environment and their ecotoxicity

Exciton dynamics in near-surface InGaN quantum wells coupled to colloidal nanocrystals

DEFF Research Database (Denmark)

Kopylov, Oleksii; Shirazi, Roza; Yvind, Kresten

2013-01-01

We study non-radiative energy transfer between InGaN quantum wells and colloidal InP nanocrystals separated by sub-10nm distance. A significant non-radiative energy transfer between the two layers is accompanied by reduced surface recombination in InGaN.......We study non-radiative energy transfer between InGaN quantum wells and colloidal InP nanocrystals separated by sub-10nm distance. A significant non-radiative energy transfer between the two layers is accompanied by reduced surface recombination in InGaN....

Tuning adhesion forces between functionalized gold colloidal nanoparticles and silicon AFM tips: role of ligands and capillary forces.

Science.gov (United States)

Oras, Sven; Vlassov, Sergei; Berholts, Marta; Lõhmus, Rünno; Mougin, Karine

2018-01-01

Adhesion forces between functionalized gold colloidal nanoparticles (Au NPs) and scanning probe microscope silicon tips were experimentally investigated by atomic force microscopy (AFM) equipped with PeakForce QNM (Quantitative Nanoscale Mechanics) module. Au NPs were synthesized by a seed-mediated process and then functionalized with thiols containing different functional groups: amino, hydroxy, methoxy, carboxy, methyl, and thiol. Adhesion measurements showed strong differences between NPs and silicon tip depending on the nature of the tail functional group. The dependence of the adhesion on ligand density for different thiols with identical functional tail-group was also demonstrated. The calculated contribution of the van der Waals (vdW) forces between particles was in good agreement with experimentally measured adhesive values. In addition, the adhesion forces were evaluated between flat Au films functionalized with the same molecular components and silicon tips to exclude the effect of particle shape on the adhesion values. Although adhesion values on flat substrates were higher than on their nanoparticle counterparts, the dependance on functional groups remained the same.

Spherical aggregates composed of gold nanoparticles

International Nuclear Information System (INIS)

Chen, C-C; Kuo, P-L; Cheng, Y-C

2009-01-01

Alkylated triethylenetetramine (C12E3) was synthesized and used as both a reductant in the preparation of gold nanoparticles by the reduction of HAuCl 4 and a stabilizer in the subsequent self-assembly of the gold nanoparticles. In acidic aqueous solution, spherical aggregates (with a diameter of about 202 ± 22 nm) of gold nanoparticles (with the mean diameter of ∼18.7 nm) were formed. The anion-induced ammonium adsorption of the alkylated amines on the gold nanoparticles was considered to provide the electrostatic repulsion and steric hindrance between the gold nanoparticles, which constituted the barrier that prevented the individual particles from coagulating. However, as the amino groups became deprotonated with increasing pH, the ammonium adsorption was weakened, and the amino groups were desorbed from the gold surface, resulting in discrete gold particles. The results indicate that the morphology of the reduced gold nanoparticles is controllable through pH-'tunable' aggregation under the mediation of the amino groups of alkylated amine to create spherical microstructures.

Formation of Polyelectrolyte Complex Colloid Particles between Chitosan and Pectin with Different Degree of Esterification

Science.gov (United States)

Wang, Hui; Sun, Hongyuan; He, Jieyu

2017-12-01

The effects of degree of esterification, pectin/chitosan ratio and pH on the formation of polyelectrolyte complex colloid particles between chitosan (CS) and pectin (PE) were investigated. Low methoxyl pectin (LPE) was achieved by de-esterifying high methoxyl pectin (HPE) with pectin methyl esterase. Turbidity titration and colorimetric method was used to determine the stability of complex colloid particles. The structure and morphology of complex particles were characterized by FTIR and TEM. When pectin solution was dropped into chitosan solution, complex colloidal dispersion was stable as PE/CS mass ratio was no more than 3:2. Colloidal particles of HPE-CS complex coagulated at larger ratio of PE/CS than LPE-CS. The maximum complex occurred at pH 6.1 for HPE-CS and pH 5.7 for LPE-CS, and decreasing pH leaded to the dissociation of complex particles. Electrostatic interactions between carboxyl groups on pectin and amino groups on chitosan were confirmed by FTIR. Colloidal particle sizes ranged from about 100 nm to 400 nm with spherical shape.

Analytical detection and biological assay of antileukemic drug using gold nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Selvaraj, V. [Department of Chemical Engineering, Alagappa College of Technology, Anna University, Chennai 600025 (India)]. E-mail: rajselva_77@yahoo.co.in; Alagar, M. [Department of Chemical Engineering, Alagappa College of Technology, Anna University, Chennai 600025 (India)]. E-mail: mkalagar@yahoo.com; Hamerton, I. [Chemistry Division, School of Biomedical and Molecular Sciences, University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom)

2006-11-12

Gold nanoparticles are reported and evaluated as probes for the detection of anticancer drug 6-mercaptopurine (6-MP). The nature of binding between 6-MP and the gold nanoparticles via complexation is investigated using ultraviolet-visible spectrum, cyclic voltammetry, transmission electron microscopy, fluorescence and Fourier transform infrared (FT-IR) spectroscopy. The bound antileukemic drug is fluorescent and the quenching property of gold nanoparticles could be exploited for biological investigations. The 6-MP-colloidal gold complex is observed to have appreciable antibacterial and antifungal activity against Micrococcus luteus, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Aspergillus fumigatus, and Aspergillus niger. The experimental studies suggest that gold nanoparticles have the potential to be used as effective carriers for anticancer drugs.

Sorption behavior of cesium onto bentonite colloid

International Nuclear Information System (INIS)

Iijima, Kazuki; Masuda, Tsuguya; Tomura, Tsutomu

2004-01-01

It is considered that bentonite colloid might be generated from bentonite which will be used as buffer material in geological disposal system, and can facilitate the migration of radionuclides by means of sorption. In order to examine this characteristic, sorption and desorption experiments of Cs onto bentonite colloid were carried out to obtain its distribution coefficient (Kd) and information on the reversibility of its sorption. In addition, particle size distribution and shape of colloid were investigated and their effect on the sorption behavior was discussed. Kds for Cs were around 20 m 3 /kg for sorption and 30 m 3 /kg for desorption, in which sorbed Cs was desorbed by 8.4x10 -4 mol/l of NaCl solution. These values did not show any dependencies on Cs concentration and duration of sorption and desorption. The first 20% of sorbed Cs was desorbed reversibly at least. Most of colloidal particles were larger than 200 nm and TEM micrographs showed they had only several sheets of the clay crystal. Obtained Kds for colloidal bentonite were larger than those for powdered bentonite. This can be caused by difference of competing ions in the solution, characteristics of contained smectite, or sorption site density. (author)

Purification of rhamnolipid using colloidal magnetic nanoparticles ...

African Journals Online (AJOL)

Phospholipid-coated colloidal magnetic nanoparticles with mean magnetite core size of 9 nm are shown to be effective ion exchange media for the recovery and purification of Rhaminolipid from culture mixtures. These particles have high adsorption capacity for purification (an order of magnitude larger than the best ...

Green synthesis of gold nanoparticles by Allium sativum extract and their assessment as SERS substrate

Science.gov (United States)

Coman, Cristina; Leopold, Loredana Florina; Rugină, Olivia Dumitriţa; Barbu-Tudoran, Lucian; Leopold, Nicolae; Tofană, Maria; Socaciu, Carmen

2014-01-01

A green synthesis was used for preparing stable colloidal gold nanoparticles by using Allium sativum aqueous extract both as reducing and capping agent. The obtained nanoparticles were characterized by UV-Vis spectroscopy, Fourier-transform infrared spectroscopy (FTIR), and transmission electron microscopy. Moreover, their potential to be used as surface-enhanced Raman scattering (SERS) substrate was investigated. The obtained gold nanoparticles have spherical shape with mean diameters of 9-15 nm (depending on the amount of reducing agent used under boiling conditions) and are stable up to several months. FTIR spectroscopy shows that the nanoparticles are capped by protein molecules from the extract. The protein shell offers a protective coating, relatively impervious to external molecules, thus, rendering the nanoparticles stable and quite inert. These nanoparticles have the potential to be used as SERS substrates, both in solution and inside human fetal lung fibroblast HFL-1 living cells. We were able to demonstrate both the internalization of the nanoparticles inside HFL-1 cells and their ability to preserve the SERS signal after cellular internalization.

Modified gold electrodes based on thiocytosine/guanine-gold nanoparticles for uric and ascorbic acid determination

International Nuclear Information System (INIS)

Vulcu, Adriana; Grosan, Camelia; Muresan, Liana Maria; Pruneanu, Stela; Olenic, Liliana

2013-01-01

The present paper describes the preparation of new modified surfaces for electrodes based on guanine/thiocytosine and gold nanoparticles. The gold nanoparticles were analyzed by UV–vis spectroscopy and transmission electron microscopy (TEM) and it was found that they have diameters between 30 and 40 nm. The layers were characterized by specular reflectance infrared spectroscopy (FTIR-RAS) and by atomic force microscopy (AFM). The thickness of layers was found to be approximately 30 nm for TC layers and 300 nm for GU layers. Every layer was characterized as electrochemical sensor (by cyclic voltammetry) both for uric acid and ascorbic acid determinations, separately and in their mixture. The modified sensors have good calibration functions with good sensitivity (between 1.145 and 1.406 mA cm −2 /decade), reproducibility ( t hiocytosine (Au T C) and gold g uanine (Au G U) layers

Surface modification of silica particles with gold nanoparticles as an augmentation of gold nanoparticle mediated laser perforation

Science.gov (United States)

Kalies, Stefan; Gentemann, Lara; Schomaker, Markus; Heinemann, Dag; Ripken, Tammo; Meyer, Heiko

2014-01-01

Gold nanoparticle mediated (GNOME) laser transfection/perforation fulfills the demands of a reliable transfection technique. It provides efficient delivery and has a negligible impact on cell viability. Furthermore, it reaches high-throughput applicability. However, currently only large gold particles (> 80 nm) allow successful GNOME laser perforation, probably due to insufficient sedimentation of smaller gold nanoparticles. The objective of this study is to determine whether this aspect can be addressed by a modification of silica particles with gold nanoparticles. Throughout the analysis, we show that after the attachment of gold nanoparticles to silica particles, comparable or better efficiencies to GNOME laser perforation are reached. In combination with 1 µm silica particles, we report laser perforation with gold nanoparticles with sizes down to 4 nm. Therefore, our investigations have great importance for the future research in and the fields of laser transfection combined with plasmonics. PMID:25136494

Chemistry and stability of thiol based polyethylene glycol surface coatings on colloidal gold and their relationship to protein adsorption and clearance in vivo

Science.gov (United States)

Carpinone, Paul

Nanomaterials have presented a wide range of novel biomedical applications, with particular emphasis placed on advances in imaging and treatment delivery. Of the many particulate nanomaterials researched for biomedical applications, gold is one of the most widely used. Colloidal gold has been of great interest due to its chemical inertness and its ability to perform multiple functions, such as drug delivery, localized heating of tissues (hyperthermia), and imaging (as a contrast agent). It is also readily functionalized through the use of thiols, which spontaneously form sulfur to gold bonds with the surface. Polyethylene glycol (PEG) is the most widely used coating material for these particles as it provides both steric stability to the suspension and protein resistance. These properties extend the circulation time of the particles in blood, and consequently the efficacy of the treatment. Despite widespread use of PEG coated gold particles, the coating chemistry and stability of these particles are largely unknown. The goal of this work was to identify the mechanisms leading to degradation and stability of thiol based polyethylene glycol coatings on gold particles and to relate this behavior to protein adsorption and clearance in vivo. The results indicate that the protective PEG coating is susceptible to sources of oxidation (including dissolved oxygen) and competing adsorbates, among other factors. The quality of commercially available thiolated PEG reagents was also found to play a key role in the quality and protein resistance of the final PEG coating. Analysis of the stability of these coatings indicated that they rapidly degrade under physiological conditions, leading to the onset of protein adsorption when exposed to plasma or blood. Paralleling the protein adsorption behavior and onset of coating degradation observed in vitro, blood clearance of parenterally administered PEG coated particles in mice began after approximately 2h of circulation time. Taken

Nanostructured progesterone immunosensor using a tyrosinase-colloidal gold-graphite-Teflon biosensor as amperometric transducer

International Nuclear Information System (INIS)

Carralero, Veronica; Gonzalez-Cortes, Araceli; Yanez-Sedeno, Paloma; Pingarron, Jose M.

2007-01-01

A novel progesterone immunosensor using a colloidal gold-graphite-Teflon-tyrosinase composite biosensor as amperometric transducer is reported. A sequential competitive configuration between the analyte and progesterone labelled with alkaline phosphatase (AP) was used. Phenyl phosphate was employed as the AP-substrate and the enzyme reaction product, phenol, was oxidized by tyrosinase to o-quinone, which is subsequently reduced at -0.1 V at the biocomposite electrode. Variables such as the concentration of phenyl phosphate, the amount of antibody attached to the electrode surface, immersion time in a 2% BSA solution, working pH and incubation times in progesterone and AP conjugate were optimized. A linear calibration graph for progesterone was obtained between 0 and 40 ng mL -1 with a slope value of -82.3 nA ng -1 mL, and a detection limit of 0.43 ng mL -1 . The time needed to reach the steady-state current from the addition of phenyl phosphate was 30-40 s. These analytical characteristics improve substantially those reported for other progesterone immunosensors. A lifetime of 14 days with no need to apply any regeneration procedure was also achieved. The usefulness of the immunosensor was evaluated by determining progesterone in milk samples spiked with the analyte at 5.0 and 1.5 ng mL -1 concentration levels. Following a very simple procedure, involving only sample dilution, mean recoveries (n = 7) of 98 ± 3% and 99 ± 3%, respectively, were obtained

Nanostructured progesterone immunosensor using a tyrosinase-colloidal gold-graphite-Teflon biosensor as amperometric transducer

Energy Technology Data Exchange (ETDEWEB)

Carralero, Veronica [Department of Analytical Chemistry, Faculty of Chemistry, University Complutense of Madrid, 28040 Madrid (Spain); Gonzalez-Cortes, Araceli [Department of Analytical Chemistry, Faculty of Chemistry, University Complutense of Madrid, 28040 Madrid (Spain); Yanez-Sedeno, Paloma [Department of Analytical Chemistry, Faculty of Chemistry, University Complutense of Madrid, 28040 Madrid (Spain)]. E-mail: yseo@quim.ucm.es; Pingarron, Jose M. [Department of Analytical Chemistry, Faculty of Chemistry, University Complutense of Madrid, 28040 Madrid (Spain)

2007-07-16

A novel progesterone immunosensor using a colloidal gold-graphite-Teflon-tyrosinase composite biosensor as amperometric transducer is reported. A sequential competitive configuration between the analyte and progesterone labelled with alkaline phosphatase (AP) was used. Phenyl phosphate was employed as the AP-substrate and the enzyme reaction product, phenol, was oxidized by tyrosinase to o-quinone, which is subsequently reduced at -0.1 V at the biocomposite electrode. Variables such as the concentration of phenyl phosphate, the amount of antibody attached to the electrode surface, immersion time in a 2% BSA solution, working pH and incubation times in progesterone and AP conjugate were optimized. A linear calibration graph for progesterone was obtained between 0 and 40 ng mL{sup -1} with a slope value of -82.3 nA ng{sup -1} mL, and a detection limit of 0.43 ng mL{sup -1}. The time needed to reach the steady-state current from the addition of phenyl phosphate was 30-40 s. These analytical characteristics improve substantially those reported for other progesterone immunosensors. A lifetime of 14 days with no need to apply any regeneration procedure was also achieved. The usefulness of the immunosensor was evaluated by determining progesterone in milk samples spiked with the analyte at 5.0 and 1.5 ng mL{sup -1} concentration levels. Following a very simple procedure, involving only sample dilution, mean recoveries (n = 7) of 98 {+-} 3% and 99 {+-} 3%, respectively, were obtained.

Green synthesis of gold nanoparticles using Citrus maxima peel extract and their catalytic/antibacterial activities.

Science.gov (United States)

Yuan, Chun-Gang; Huo, Can; Gui, Bing; Cao, Wei-Ping

2017-08-01

The peel of Citrus maxima ( C. maxima ) is the primary byproducts during the process of fruit or juice in food industries, and it was always considered as biomass waste for further treatments. In this study, the authors reported a simple and eco-friendly method to synthesise gold nanoparticles (AuNPs) using C. maxima peel extract as reducing and capping agents. The synthesised AuNPs were characterised by UV-visible spectrum, X-ray diffraction (XRD), transmission electron microscope (TEM) and Fourier-transform infrared spectroscopy (FTIR). The UV-visible spectrum of the AuNPs colloid showed a characteristic peak at 540 nm. The peaks of XRD analysis at (2 θ ) 38.30°, 44.28°, 64.62°, 77.57° and 81.75° were assigned to (111), (200), (220), (311) and (222) planes of the face-centered cubic (fcc) lattice of gold. The TEM images showed that AuNPs were nearly spherical in shape with the size of 8-25 nm. The FTIR spectrum revealed that some bioactive compounds capped the surface of synthesised AuNPs. The biosynthesised AuNPs performed strong catalytic activity in degradation of 4-nitrophenol to 4-aminophenol and good antibacterial activity against both gram negative ( Escherichia coli ) and gram positive ( Staphylococcus aureus ) bacterium. The synthesis procedure was proved simple, cost effective and environment friendly.

Progress report on colloid-facilitated transport at Yucca Mountain: Yucca Mountain site characterization program milestone 3383

International Nuclear Information System (INIS)

Triay, I.R.; Degueldre, C.; Wistrom, A.O.; Cotter, C.R.; Lemons, W.W.

1996-06-01

To assess colloid-facilitated radionuclide transport in groundwaters at the potential nuclear waste repository at Yucca Mountain, it is very important to understand the generation and stability of colloids, including naturally occurring colloids. To this end, we measured the colloid concentration in waters from Well J-13, which is on the order of 106 particles per milliliter (for particle sizes larger than 100 manometers). At this low particle loading, the sorption of radionuclides to colloids would have to be extremely high before the colloids could carry a significant amount of radionuclides from the repository to the accessible environment. We also performed aggregation experiments to evaluate the stability of silica (particle diameter: 85 nm) and clay colloids (particle diameter: 140 nm) as a function of ionic strength in a carbonate-rich synthetic groundwater. When the concentration of electrolyte is increased to induce aggregation, the aggregation is irreversible and the rate of aggregation increases with increasing electrolyte strength. We used autocorrelation photon spectroscopy to estimate the rate of particle aggregation for both types of colloids. By relating the measured aggregation rate to the Smoluchowski rate expression, we determined the stability ratio, W. Aggregation of silica particles and kaolinite clay particles decreased dramatically for an electrolyte concentration, C NaCl , below 300 mM and 200 mM, respectively

THE RESPONSE OF DISSEMINATED RETICULUM CELL SARCOMA TO THE INTRAVENOUS INJECTION OF COLLOIDAL RADIOACTIVE GOLD

Energy Technology Data Exchange (ETDEWEB)

Rubin, Philip; Levitt, Seymour H.

1963-06-15

Case histories of two patients treated with colloidal radiogold for diffuse reticulum cell sarcoma are presented. Further analysis of the method is suggested by the unusually long survival time of one of the patients. It was concluded that, although external radiotherapy remains the treatment of choice in localized reticulum cell sarcoma, intravenous colloidal radiogold may be a useful agent in lymphosarcomas with diffuse minute neoplastic liver and spleen involvements. Intravenous colloidal radiogold can produce bone marrow depression and thrombocytopenia which can lead to death. This factor tends to argue against therapeutic use of the agent. It is suggested that no more than 50 mC Au/sup 198/ intravenously should be used for treatment of this disease. (R.M.G.)

Gradual growth of gold nanoseeds on silica for SiO2-gold homogeneous nano core/shell applications by the chemical reduction method

International Nuclear Information System (INIS)

Rezvani Nikabadi, H; Shahtahmasebi, N; Rezaee Rokn-Abadi, M; Bagheri Mohagheghi, M M; Goharshadi, E K

2013-01-01

In this paper, a facile method for the synthesis of gold nanoseeds on the functionalized surface of silica nanoparticles has been investigated. Mono-dispersed silica particles and gold nanoparticles were prepared by the chemical reduction method. The thickness of the Au shell was well controlled by repeating the reduction time of HAuCl 4 on silica/3-aminopropyltriethoxysilane (APTES)/initial gold nanoparticles. The prepared SiO 2 -gold core/shell nanoparticles were studied using x-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), Fourier transform infrared spectroscopy and ultraviolet visible (UV-Vis) spectroscopy. The TEM images indicated that the silica nanoparticles were spherical in shape with 100 nm diameters and functionalizing silica nanoparticles with a layer of bi-functional APTES molecules and tetrakis hydroxy methyl phosphonium chloride. The gold nanoparticles show a narrow size of up to 5 nm and by growing gold nanoseeds over the silica cores a red shift in the maximum absorbance of UV-Vis spectroscopy from 524 to 637 nm was observed.

A Novel Diagnostic Method to Detect Duck Tembusu Virus: A Colloidal Gold-Based Immunochromatographic Assay

Directory of Open Access Journals (Sweden)

Guanliu Yu

2018-05-01

Full Text Available Duck Tembusu virus (DTMUV is an emerging pathogenic flavivirus that has resulted in large economic losses to the duck-rearing industry in China since 2010. Therefore, an effective diagnostic approach to monitor the spread of DTMUV is necessary. Here, a novel diagnostic immunochromatographic strip (ICS assay was developed to detect DTMUV. The assay was carried out using colloidal gold coated with purified monoclonal antibody A12D3 against envelope E protein. Purified polyclonal C12D1 antibodies from BALB/c mice against the envelope E protein were used as the capture antibody. Goat anti-mouse IgG was used to detect DTMUV, which was also assembled on the ICS. Results showed that the ICS could specifically detect DTMUV within 10 min. It also could be stored 25 and 4°C for 4 and 6 months, respectively. The sensitivity of the ICS indicated that the dilution multiples of positive allantoic fluid of DTMUV (LD50: 104.33/0.2 ml was up to 200. Its specificity and sensibility showed no significant change under the above storage situations. Fifty clinical samples were simultaneously detected by ICS and reverse-transcription polymerase chain reaction with a 93.9% coincidence rate between them. It proved that the ICS in the present study was highly specific, sensitive, repeatable, and more convenient to rapidly detect DTMUV in clinical samples.

Formation and stability of aluminosilicate colloids by coprecipitation

Energy Technology Data Exchange (ETDEWEB)

Putri, Kirana Yuniati

2011-02-15

Colloids are ubiquitous in natural waters. Colloid-facilitated migration is of importance in safety assessment of a nuclear waste disposal. Aluminosilicate colloids are considered to be the kernel of aquatic colloids. Their stability is affected by a number of geochemical parameters. This work aims to study qualitatively and quantitatively the stability of aluminosilicate colloids formed by coprecipitation under various geochemical conditions, i.e. pH, concentration of Al and Si metal ions, ionic strength, and omnipresent cations (Na{sup +}, Ca{sup 2+}, and Mg{sup 2+}). The work is performed by colorimetric method and laser-induced breakdown detection (LIBD). Two consecutive phase separations at 450 nm and 1 kDa are applied to separate the precipitates and colloids from the ionic species. By means of colorimetry, Si and Al can be detected down to 5.8 x10{sup -8} M and 7.4x10{sup -7} M, respectively. On the other hand, LIBD is able to quantify the colloidal size and its number density down to several ppt. Depending on the concentration of Al and Si metal ions, the formation trend of aluminosilicate colloid changes following its solubility curve. The lower the concentration, the higher the pH range in which the colloids start to emerge. Furthermore, the colloids are stable at higher Al and Si concentration and at low ionic strength. In the low pH range, cations provide different effects at low and high ionic strengths. At high ionic strength, the colloids are stable in the presence of a larger cation, while all cations exhibit similar effects at low ionic strength. However, in the high pH range, valence seems to have a stronger effect than ionic radius; colloids are more stable in the presence of monovalent cations than divalent ones. Meanwhile, XRD shows non- and/or poor crystalline structure of the aluminosilicate species. Nevertheless, results from XPS may suggest that the chemical composition (Si/Al ∼ 0.6) of the aluminosilicate precipitates is sillimanite or

Silver nanoparticle colloids with γ-cyclodextrin: enhanced stability and Gibbs–Marangoni flow

Energy Technology Data Exchange (ETDEWEB)

Amiri, Setareh; Duroux, Laurent; Larsen, Kim Lambertsen, E-mail: kll@bio.aau.dk [Aalborg University, Department of Chemistry and Bioscience (Denmark)

2015-01-15

Although cyclodextrins (CD) are effective stabilizers for metal nanoparticle colloids, differences between α-, β- and γ-CD in stabilizing such colloids have not been previously reported. In this study, silver nanoparticles (AgNP) were synthesized using NaBH{sub 4} as reducing agent and cyclodextrins as stabilizers. Long-term stability of AgNP colloids in equilibrium conditions showed no marked differences between CD types. Transmission electron microscopy and quantitative image analysis revealed only marginal differences in particle sizes for CD-AgNP, although statistically significant. CD-AgNP colloids showed dispersed particles with average diameters of 7.3 ± 2.2, 6.3 ± 2.9 and 4.9 ± 1.9 nm for α-, β- and γ-CD, respectively, and with similar ζ-potentials about −25 to −30 mV. AgNP without CD showed bigger and aggregated particles of 15.0 ± 2.0 nm with lower ζ-potentials of about −40 mV. When subjected to centrifugal forces, i.e. non-equilibrium conditions, γ-CD was markedly more efficient than α- and β-CD in stabilizing the colloids. Drying patterns of colloid droplets showed a typical self-pinned coffee ring for all but the colloid stabilized by γ-CD, which showed a pattern resulting from a dominant Gibbs–Marangoni flow inside the drying droplet. Calculations using the Derjaguin, Landau, Verwey and Overbeek (DLVO) theory supported the stabilizing effect of CD in equilibrium conditions; it however did not provide clues for the superior stabilization by γ-CD in conditions of hydrodynamic stress.

Silver nanoparticle colloids with γ-cyclodextrin: enhanced stability and Gibbs–Marangoni flow

International Nuclear Information System (INIS)

Amiri, Setareh; Duroux, Laurent; Larsen, Kim Lambertsen

2015-01-01

Although cyclodextrins (CD) are effective stabilizers for metal nanoparticle colloids, differences between α-, β- and γ-CD in stabilizing such colloids have not been previously reported. In this study, silver nanoparticles (AgNP) were synthesized using NaBH 4 as reducing agent and cyclodextrins as stabilizers. Long-term stability of AgNP colloids in equilibrium conditions showed no marked differences between CD types. Transmission electron microscopy and quantitative image analysis revealed only marginal differences in particle sizes for CD-AgNP, although statistically significant. CD-AgNP colloids showed dispersed particles with average diameters of 7.3 ± 2.2, 6.3 ± 2.9 and 4.9 ± 1.9 nm for α-, β- and γ-CD, respectively, and with similar ζ-potentials about −25 to −30 mV. AgNP without CD showed bigger and aggregated particles of 15.0 ± 2.0 nm with lower ζ-potentials of about −40 mV. When subjected to centrifugal forces, i.e. non-equilibrium conditions, γ-CD was markedly more efficient than α- and β-CD in stabilizing the colloids. Drying patterns of colloid droplets showed a typical self-pinned coffee ring for all but the colloid stabilized by γ-CD, which showed a pattern resulting from a dominant Gibbs–Marangoni flow inside the drying droplet. Calculations using the Derjaguin, Landau, Verwey and Overbeek (DLVO) theory supported the stabilizing effect of CD in equilibrium conditions; it however did not provide clues for the superior stabilization by γ-CD in conditions of hydrodynamic stress

Preparation of silver colloid and enhancement of dispersion stability in organic solvent

International Nuclear Information System (INIS)

Kim, Ki Young; Choi, Young Tai; Seo, Dae Jong; Park, Seung Bin

2004-01-01

Silver colloid of nanometer size was prepared in liquid phase by a reduction method. AgNO 3 , FeSO 4 .7H 2 O, and Na 3 C 6 H 5 O 7 .2H 2 O were used as silver precursor, reducing agent and dispersing agent, respectively. As precursor concentration was decreased or the concentration of dispersing agent was increased, the prepared particle size was decreased from 180 nm to 20 nm. Apparently, the particle size seemed to be decreased with the increase of stirring rate, but it was confirmed by TEM that the size of primary particle remained the same. This result indicates that the uniformity of precursor concentration in the reactor affects the particle size and the stirring rate should be kept higher than the critical value to prevent the agglomeration of particles. In order to make the dispersion stability of the prepared silver colloid maintained even in non-polar organic solvent, electrodialysis technique was applied. As ionic species in colloidal solution were removed by electrodialysis, the dispersability of the colloid in the organic solvent of long carbon chain was confirmed to be increased

Gold-coated copper cone detector as a new standard detector for F2 laser radiation at 157 nm

International Nuclear Information System (INIS)

Kueck, Stefan; Brandt, Friedhelm; Taddeo, Mario

2005-01-01

A new standard detector for high-accuracy measurements of F2 laser radiation at 157 nm is presented. This gold-coated copper cone detector permits the measurement of average powers up to 2 W with an uncertainty of ∼1%. To the best of our knowledge, this is the first highly accurate standard detector for F2 laser radiation for this power level. It is fully characterized according to Guide to the Expression of Uncertainty in Measurement of the International Organization for Standardization and is connected to the calibration chain for laser radiation established by the German National Metrology Institute

Synthesis of Silver-Chitosan Nanocomposites Colloidal by Glucose as Reducing Agent

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Endang Susilowati

2015-03-01

Full Text Available Silver-chitosan nanocomposites colloidal was successfully performed by chemical reduction method at room temperature using glucose as reducing agent, sodium hydroxide (NaOH as accelerator reagent, silver nitrate (AgNO3 as metal precursor and chitosan as stabilizing agent. Compared to other synthetic methods, this work is green and simple. The effect of the amount of NaOH, molar ratio of AgNO3 to glucose and AgNO3 concentration towards Localized Surface Plasmon Resonance (LSPR absorption band of silver nanoparticles was investigated using UV-Vis spectrophotometer. The stability of the colloid was also studied for the first 16 weeks of storage at ambient temperature. The formation of silver nanoparticles was confirmed by the appearance of LSPR absorption peak at 402.4–414.5 nm. It is also shown that the absorption peak of LSPR were affected by NaOH amount, ratio molar AgNO3/glucose and concentration of AgNO3. The produced silver nanoparticles were spherical with dominant size range of 6 to 18 nm as shown by TEM images. All colloidals were stable without any aggregation for 16 weeks after preparation. The newly prepared silver-chitosan nanocomposites colloidal may have potential for antibacterial applications.

Modeling for Colloid and Chelator Facilitated Nuclide Transport in Radioactive Waste Disposal System

International Nuclear Information System (INIS)

Lee, Youn Myoung; Jeong, Jong Tae

2010-08-01

A modeling study and development of a total system performance assessment (TSPA) program template, by which assessment of safety and performance for a radioactive waste repository with normal and/or abnormal nuclide release cases can be made has been developed. Colloid and chelator facilitated transport that is believed to result for faster nuclide transport in various mediabothinthegeosphereandbiospherehas been evaluated deterministically and probabilistically to demonstrate the capability of the template developed through this study. To this end colloid and chelator facilitated nuclide transport has been modeled rather strainghtforwardly with assumed data through this study by utilizing some powerful function offered by GoldSim. An evaluation in view of apparent influence of colloid and chelator on the nuclide transport in the various media in and around a repository system with data assumed are illustrated

Preparation of 2 nm gold nanoparticles for in vitro and in vivo applications

OpenAIRE

Moyano, Daniel F.; Duncan, Bradley; Rotello, Vincent M.

2013-01-01

Gold nanoparticles have been a versatile tool in recent years for the exploration of biological systems. However, challenges with purification and adequate surface coverage limit the biocompatibility of gold nanoparticles. Here, we describe a detailed procedure for the synthesis, purification, and functionalization of biologically compatible gold nanoparticles for in vitro and in vivo studies.

UV-Visible intensity ratio (aggregates/single particles) as a measure to obtain stability of gold nanoparticles conjugated with protein A

Energy Technology Data Exchange (ETDEWEB)

Rios-Corripio, M. A. [Instituto Politecnico Nacional, CIBA-Tlaxcala (Mexico); Garcia-Perez, B. E. [Instituto Politecnico Nacional, Departamento de Inmunologia, ENCB (Mexico); Jaramillo-Flores, M. E. [Instituto Politecnico Nacional, Departamento de Ingenieria Bioquimica, ENCB (Mexico); Gayou, V. L.; Rojas-Lopez, M., E-mail: marlonrl@yahoo.com.mx [Instituto Politecnico Nacional, CIBA-Tlaxcala (Mexico)

2013-05-15

We have analyzed the titration process of gold nanoparticles with several amounts of protein A (0.3, 0.5, 1, 3, 6, and 9 {mu}g/ml) in the presence of NaCl, which induces aggregation if the surface of particles is not fully covered with protein A. The colloidal solutions with different particle size (16, 18, 20, 33 nm) were synthesized by citrate reduction to be conjugated with protein A. UV-Visible spectroscopy was used to measure the absorption of the surface plasmon resonance of gold nanoparticles as a function of the concentration of protein A. Such dependence shows an aggregation region (0 < x<6 {mu}g/ml), where the amount of protein A was insufficient to cover the surface of particles, obtaining aggregation caused by NaCl. The next part is the stability region (x {>=} 6 {mu}g/ml), where the amount of protein used covers the surface of particles and protects it from the aggregation. In addition to that the ratio between the intensities of both: the aggregates and of the gold nanoparticle bands was plotted as a function of the concentration of protein A. It was determined that 6 {mu}g/ml is a sufficient value of protein A to stabilize the gold nanoparticle-protein A system. This method provides a simple way to stabilize gold nanoparticles obtained by citrate reduction, with protein A.

The action of NIR (808nm) laser radiation and gold nanorods labeled with IgA and IgG human antibodies on methicillin-resistant and methicillin sensitive strains of Staphylococcus aureus

Science.gov (United States)

Tuchina, Elena S.; Petrov, Pavel O.; Ratto, Fulvio; Centi, Sonia; Pini, Roberto; Tuchin, Valery V.

2015-03-01

The effect of NIR laser radiation (808 nm) on methicillin-sensitive and methicillin resistant strains of Staphylococcus aureus incubated with gold nanorods is studied. Nanorods having length of 44 (± 4) nm and diameter of 10 (± 3) nm with the absorption maximum in the NIR (800 nm), functionalized with human immunoglobulins IgA and IgG, were synthesized and used in the studies. The killing ability up to 97% of the microorganism populations by using this nanotechnology was shown.

Surface-stabilized gold nanocatalysts

Science.gov (United States)

Dai, Sheng [Knoxville, TN; Yan, Wenfu [Oak Ridge, TN

2009-12-08

A surface-stabilized gold nanocatalyst includes a solid support having stabilizing surfaces for supporting gold nanoparticles, and a plurality of gold nanoparticles having an average particle size of less than 8 nm disposed on the stabilizing surfaces. The surface-stabilized gold nanocatalyst provides enhanced stability, such as at high temperature under oxygen containing environments. In one embodiment, the solid support is a multi-layer support comprising at least a first layer having a second layer providing the stabilizing surfaces disposed thereon, the first and second layer being chemically distinct.

Characterization, origin and aggregation behavior of colloids in eutrophic shallow lake.

Science.gov (United States)

Xu, Huacheng; Xu, Mengwen; Li, Yani; Liu, Xin; Guo, Laodong; Jiang, Helong

2018-05-31

Stability of colloidal particles contributes to the turbidity in the water column, which significantly influences water quality and ecological functions in aquatic environments especially shallow lakes. Here we report characterization, origin and aggregation behavior of aquatic colloids, including natural colloidal particles (NCPs) and total inorganic colloidal particles (TICPs), in a highly turbid shallow lake, via field observations, simulation experiments, ultrafiltration, spectral and microscopic, and light scattering techniques. The colloidal particles were characterized with various shapes (spherical, polygonal and elliptical) and aluminum-, silicon-, and ferric-containing mineralogical structures, with a size range of 20-200 nm. The process of sediment re-suspension under environmentally relevant conditions contributed 78-80% of TICPs and 54-55% of NCPs in Lake Taihu, representing an important source of colloids in the water column. Both mono- and divalent electrolytes enhanced colloidal aggregation, while a reverse trend was observed in the presence of natural organic matter (NOM). The influence of NOM on colloidal stability was highly related to molecular weight (MW) properties with the high MW fraction exhibiting higher stability efficiency than the low MW counterparts. However, the MW-dependent aggregation behavior for NCPs was less significant than that for TICPs, implying that previous results on colloidal behavior using model inorganic colloids alone should be reevaluated. Further studies are needed to better understand the mobility/stability and transformation of aquatic colloids and their role in governing the fate and transport of pollutants in natural waters. Copyright © 2018. Published by Elsevier Ltd.

Rapid extra-/intracellular biosynthesis of gold nanoparticles by the fungus Penicillium sp.

Science.gov (United States)

Du, Liangwei; Xian, Liang; Feng, Jia-Xun

2011-03-01

In this work, the fungus Penicillium was used for rapid extra-/intracellular biosynthesis of gold nanoparticles. AuCl4 - ions reacted with the cell filtrate of Penicillium sp. resulting in extracellular biosynthesis of gold nanoparticles within 1 min. Intracellular biosynthesis of gold nanoparticles was obtained by incubating AuCl4 - solution with fungal biomass for 8 h. The gold nanoparticles were characterized by means of visual observation, UV-Vis absorption spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). The extracellular nanoparticles exhibited maximum absorbance at 545 nm in UV-Vis spectroscopy. The XRD spectrum showed Bragg reflections corresponding to the gold nanocrystals. TEM exhibited the formed spherical gold nanoparticles in the size range from 30 to 50 nm with an average size of 45 nm. SEM and TEM revealed that the intracellular gold nanoparticles were well dispersed on the cell wall and within the cell, and they are mostly spherical in shape with an average diameter of 50 nm. The presence of gold was confirmed by EDX analysis.

Transport of uranium in water and soil: colloidal-isotopic combined approach

International Nuclear Information System (INIS)

Harguindeguy, Stephanie

2013-01-01

Mechanisms of interaction between uranium and colloids were studied by samples taken from a site of interest for the 'French Nuclear Agency' (CEA). The mobilization of uranium from soils was apprehended by static and dynamic leaching experiments. The transfer and transport have been studied by considering pond waters and drain waters. Results confirm that anthropogenic uranium is more mobile than natural uranium. However mechanisms of mobilization and distribution of uranium, does not differ depending on its origin. The colloidal fraction plays an important role on the migration in soil and the transfer into water by representing from 10 to 90 % uranium depending on samples. The colloidal fractions of uranium are in a continuum of size up to about 200 nm hydrodynamic diameter. They are mainly composed of organic material, iron and aluminum. Along the drain, from the upstream to the downstream of the site, rearrangement of colloidal associations between uranium and organic material occurs in disfavor of colloidal associations between uranium and iron, the proportion of colloidal uranium bound to aluminum remains unchanged. (author) [fr

Formation of stable uranium(VI) colloidal nanoparticles in conditions relevant to radioactive waste disposal.

Science.gov (United States)

Bots, Pieter; Morris, Katherine; Hibberd, Rosemary; Law, Gareth T W; Mosselmans, J Frederick W; Brown, Andy P; Doutch, James; Smith, Andrew J; Shaw, Samuel

2014-12-09

The favored pathway for disposal of higher activity radioactive wastes is via deep geological disposal. Many geological disposal facility designs include cement in their engineering design. Over the long term, interaction of groundwater with the cement and waste will form a plume of a hyperalkaline leachate (pH 10-13), and the behavior of radionuclides needs to be constrained under these extreme conditions to minimize the environmental hazard from the wastes. For uranium, a key component of many radioactive wastes, thermodynamic modeling predicts that, at high pH, U(VI) solubility will be very low (nM or lower) and controlled by equilibrium with solid phase alkali and alkaline-earth uranates. However, the formation of U(VI) colloids could potentially enhance the mobility of U(VI) under these conditions, and characterizing the potential for formation and medium-term stability of U(VI) colloids is important in underpinning our understanding of U behavior in waste disposal. Reflecting this, we applied conventional geochemical and microscopy techniques combined with synchrotron based in situ and ex situ X-ray techniques (small-angle X-ray scattering and X-ray adsorption spectroscopy (XAS)) to characterize colloidal U(VI) nanoparticles in a synthetic cement leachate (pH > 13) containing 4.2-252 μM U(VI). The results show that in cement leachates with 42 μM U(VI), colloids formed within hours and remained stable for several years. The colloids consisted of 1.5-1.8 nm nanoparticles with a proportion forming 20-60 nm aggregates. Using XAS and electron microscopy, we were able to determine that the colloidal nanoparticles had a clarkeite (sodium-uranate)-type crystallographic structure. The presented results have clear and hitherto unrecognized implications for the mobility of U(VI) in cementitious environments, in particular those associated with the geological disposal of nuclear waste.

Stabilizing Protein Effects on the Pressure Sensitivity of Fluorescent Gold Nanoclusters

Science.gov (United States)

2016-01-13

affected by the environment of the stabilizing protein, allowing these hybrid systems to act as sensors in many applications.2,9,14–19 This has led...Biosens Bioelectron. 2012;32:297–299. 8. Joseph D, Geckeler KE. Synthesis of highly fluorescent gold nanoclusters using egg white proteins. Colloids Surf...Chang HW, Chien YC, Hsiao JK, Cheng JT, Chou PT. Insulin -directed synthesis of fluorescent gold nanoclusters: preservation of insulin bioactivity and

Synthesis, Structure, Stability and Redispersion of Gold-based Nanoparticles

Science.gov (United States)

Tiruvalam, Ram Chandra

Nanoscale gold has been shown to possess an intriguing combination of unexpected optical, photochemical and catalytic properties. The ability to control the size, shape, morphology, composition and dispersion of gold-based nanostructures is key to optimizing their performance for nanotechnology applications. The advanced electron microscopy studies described in this thesis analyze three important aspects of gold and gold-palladium alloy nanoparticles: namely, (i) the ability to synthesize gold nanoparticles of controlled size and shape in an aqueous medium; (ii) the colloidal preparation of designer gold-palladium alloys for selective oxidation catalysis; and (iii) the ability to disperse gold as finely and homogeneously as possible on a metal oxide or carbon support. The ability to exploit the nanoscale properties of gold for various engineering applications often depends on our ability to control size and shape of the nanoscale entity by careful manipulation of the synthesis parameters. We have explored an aqueous based synthesis route, using oleylamine as both a reductant and surfactant, for preparing gold nanostructures. By systematically varying synthesis parameters such as oleylamine concentration, reaction temperature, and aging time it is possible to identify processing regimens that generate Au nanostructures having either pseudo-spherical, faceted polyhedral, nanostar or wire shaped morphologies. Furthermore, by quenching the reaction partway through it is possible to create a class of metastable Au-containing structures such as nanocubes, nanoboxes and nanowires. Possible formation mechanisms for these gold based nano-objects are discussed. There is a growing interest in using supported bimetallic AuPd alloy nanoparticles for selective oxidation reactions. In this study, a systematic series of size controlled AuPd bimetallic particles have been prepared by colloidal synthesis methods. Particles having random alloy structures, as well as `designer

Physico-chemical studies on a new production method of radioactive gold colloids

International Nuclear Information System (INIS)

Barrabin, H.; Caro, R.A.; Ihlo, J.E.; Richards, D.E.; Radicella, R.

1975-04-01

The preparation of gelatin protected radiogold colloids with small particles is described. A simplified procedure is utilized by which it is possible to eliminate the complicate equipment used until now. Some of the physicochemical parameters which affect the process are also analyzed. (author)

Phospholipid-assisted synthesis of size-controlled gold nanoparticles

International Nuclear Information System (INIS)

He Peng; Zhu Xinyuan

2007-01-01

Morphology and size control of gold nanoparticles (AuNPs) by phospholipids (PLs) has been reported. It was found that gold entities could form nanostructures with different sizes controlled by PLs in an aqueous solution. During the preparation of 1.5 nm gold seeds, AuNPs were obtained from the reduction of gold complex by sodium borohydride and capped by citrate for stabilization. With the different ratios between seed solution and growth solution, which was composed by gold complex and PLs, gold seeds grew into larger nanoparticles step by step until enough large size up to 30 nm. The main discovery of this work is that common biomolecules, such as PLs can be used to control nanoparticle size. This conclusion has been confirmed by transmission electron micrographs, particle size analysis, and UV-vis spectra

Synthesis and characterization of pHLIP® coated gold nanoparticles.

Science.gov (United States)

Daniels, Jennifer L; Crawford, Troy M; Andreev, Oleg A; Reshetnyak, Yana K

2017-07-01

Novel approaches in synthesis of spherical and multispiked gold nanoparticles coated with polyethylene glycol (PEG) and pH Low Insertion Peptide (pHLIP ® ) were introduced. The presence of a tumor-targeting pHLIP ® peptide in the nanoparticle coating enhances the stability of particles in solution and promotes a pH-dependent cellular uptake. The spherical particles were prepared with sodium citrate as a gold reducing agent to form particles of 7.0±2.5 nm in mean metallic core diameter and ∼43 nm in mean hydrodynamic diameter. The particles that were injected into tumors in mice (21 µg of gold) were homogeneously distributed within a tumor mass with no staining of the muscle tissue adjacent to the tumor. Up to 30% of the injected gold dose remained within the tumor one hour post-injection. The multispiked gold nanoparticles with a mean metallic core diameter of 146.0±50.4 nm and a mean hydrodynamic size of ~161 nm were prepared using ascorbic acid as a reducing agent and disk-like bicelles as a template. Only the presence of a soft template, like bicelles, ensured the appearance of spiked nanoparticles with resonance in the near infrared region. The irradiation of spiked gold nanoparticles by an 805 nm laser led to the time- and concentration-dependent increase of temperature. Both pHLIP ® and PEG coated gold spherical and multispiked nanoparticles might find application in radiation and thermal therapies of tumors.

Synthesis and characterization of pHLIP® coated gold nanoparticles

Directory of Open Access Journals (Sweden)

Jennifer L. Daniels

2017-07-01

Full Text Available Novel approaches in synthesis of spherical and multispiked gold nanoparticles coated with polyethylene glycol (PEG and pH Low Insertion Peptide (pHLIP® were introduced. The presence of a tumor-targeting pHLIP® peptide in the nanoparticle coating enhances the stability of particles in solution and promotes a pH-dependent cellular uptake. The spherical particles were prepared with sodium citrate as a gold reducing agent to form particles of 7.0±2.5 nm in mean metallic core diameter and ∼43 nm in mean hydrodynamic diameter. The particles that were injected into tumors in mice (21 µg of gold were homogeneously distributed within a tumor mass with no staining of the muscle tissue adjacent to the tumor. Up to 30% of the injected gold dose remained within the tumor one hour post-injection. The multispiked gold nanoparticles with a mean metallic core diameter of 146.0±50.4 nm and a mean hydrodynamic size of ~161 nm were prepared using ascorbic acid as a reducing agent and disk-like bicelles as a template. Only the presence of a soft template, like bicelles, ensured the appearance of spiked nanoparticles with resonance in the near infrared region. The irradiation of spiked gold nanoparticles by an 805 nm laser led to the time- and concentration-dependent increase of temperature. Both pHLIP® and PEG coated gold spherical and multispiked nanoparticles might find application in radiation and thermal therapies of tumors.

Improvement of colloid sampling techniques in groundwater and actinide characterisation of the groundwater systems at Gorleben (FRG) and El Berrocal (E)

International Nuclear Information System (INIS)

Dearlove, J.P.L.; Longworth, G.; Ivanovich, M.

1990-08-01

Two sites, the Gorleben site (FRG) and the El Berrocal Experimental station (E) have been studied to evaluate different sampling and analytical techniques for the characterisation of particulates (> 1000 nm size), colloids (1-1000 nm size) and the solution phase (<1 nm) in groundwaters in terms of their physical, chemical and actinide composition. The uptake characteristics of the field ultrafiltration system used to separate the colloid fraction from the solution phase in the groundwater have also been studied. (Author)

A nanoporous gold membrane for sensing applications

Directory of Open Access Journals (Sweden)

Swe Zin Oo

2016-03-01

Full Text Available Design and fabrication of three-dimensionally structured, gold membranes containing hexagonally close-packed microcavities with nanopores in the base, are described. Our aim is to create a nanoporous structure with localized enhancement of the fluorescence or Raman scattering at, and in the nanopore when excited with light of approximately 600 nm, with a view to provide sensitive detection of biomolecules. A range of geometries of the nanopore integrated into hexagonally close-packed assemblies of gold micro-cavities was first evaluated theoretically. The optimal size and shape of the nanopore in a single microcavity were then considered to provide the highest localized plasmon enhancement (of fluorescence or Raman scattering at the very center of the nanopore for a bioanalyte traversing through. The optimized design was established to be a 1200 nm diameter cavity of 600 nm depth with a 50 nm square nanopore with rounded corners in the base. A gold 3D-structured membrane containing these sized microcavities with the integrated nanopore was successfully fabricated and ‘proof of concept’ Raman scattering experiments are described. Keywords: Nanopore, Polymer sphere, Gold membrane, Plasmons, Sensing, SERS

In vivo integrity of polymer-coated gold nanoparticles

Science.gov (United States)

Kreyling, Wolfgang G.; Abdelmonem, Abuelmagd M.; Ali, Zulqurnain; Alves, Frauke; Geiser, Marianne; Haberl, Nadine; Hartmann, Raimo; Hirn, Stephanie; de Aberasturi, Dorleta Jimenez; Kantner, Karsten; Khadem-Saba, Gülnaz; Montenegro, Jose-Maria; Rejman, Joanna; Rojo, Teofilo; de Larramendi, Idoia Ruiz; Ufartes, Roser; Wenk, Alexander; Parak, Wolfgang J.

2015-07-01

Inorganic nanoparticles are frequently engineered with an organic surface coating to improve their physicochemical properties, and it is well known that their colloidal properties may change upon internalization by cells. While the stability of such nanoparticles is typically assayed in simple in vitro tests, their stability in a mammalian organism remains unknown. Here, we show that firmly grafted polymer shells around gold nanoparticles may degrade when injected into rats. We synthesized monodisperse radioactively labelled gold nanoparticles (198Au) and engineered an 111In-labelled polymer shell around them. Upon intravenous injection into rats, quantitative biodistribution analyses performed independently for 198Au and 111In showed partial removal of the polymer shell in vivo. While 198Au accumulates mostly in the liver, part of the 111In shows a non-particulate biodistribution similar to intravenous injection of chelated 111In. Further in vitro studies suggest that degradation of the polymer shell is caused by proteolytic enzymes in the liver. Our results show that even nanoparticles with high colloidal stability can change their physicochemical properties in vivo.

Polydispersity effects in the crystallisation of hard-sphere colloidal samples

International Nuclear Information System (INIS)

Martin, S.; Bryant, G.

2002-01-01

Full text: Colloidal particles mimicking hard-sphere behaviour have been shown to undergo the freezing and melting transition as predicted from computer simulations. Due to the large size and slow movement of the colloidal particles, it is possible to measure the time dependence of the growth of the main Bragg reflection using laser light scattering. The new data presented here was taken on a newly built crystallisation spectrometer which averages the Bragg reflections over the whole Debye-Scherrer cone, where previous work has mostly been done with the detector fixed in one plane. This new apparatus allows us to observe the crystallisation process at earlier times, on lower density samples than had previously been possible. Measurements have been made on samples made from colloidal particles with radii 320nm and 247 nm and polydispersities of ∼6.9% and >8% respectively. The results have been compared with other results from particles with >4% polydispersity. The results show that increasing the polydispersity in the particles increases the time lag before significant crystal growth occurs, but polydispersity doesn't appear to directly affect the rate of crystal growth

Extracellular mycosynthesis of gold nanoparticles using Fusarium solani

Science.gov (United States)

Gopinath, K.; Arumugam, A.

2014-08-01

The development of eco-friendly methods for the synthesis of nanomaterial shape and size is an important area of research in the field of nanotechnology. The present investigation deals with the extracellular rapid biosynthesis of gold nanoparticles using Fusarium solani culture filtrate. The UV-vis spectra of the fungal culture filtrate medium containing gold ion showed peak at 527 nm corresponding to the plasmon absorbance of gold nanoparticles. FTIR spectra provide an evidence for the presence of heterocyclic compound in the culture filtrate, which increases the stability of the synthesized gold nanoparticles. The X-ray analysis respects the Bragg's law and confirmed the crystalline nature of the gold nanoparticles. AFM analysis showed the results of particle sizes (41 nm). Transmission electron microscopy (TEM) showed that the gold nanoparticles are spherical in shape with the size range from 20 to 50 nm. The use of F. solani will offer several advantages since it is considered as a non-human pathogenic organism. The fungus F. solani has a fast growth rate, rapid capacity of metallic ions reduction, NPs stabilization and facile and economical biomass handling. Extracellular biosynthesis of gold nanoparticles could be highly advantageous from the point of view of synthesis in large quantities, time consumption, eco-friendly, non-toxic and easy downstream processing.

T cells enhance gold nanoparticle delivery to tumors in vivo

Science.gov (United States)

Kennedy, Laura C.; Bear, Adham S.; Young, Joseph K.; Lewinski, Nastassja A.; Kim, Jean; Foster, Aaron E.; Drezek, Rebekah A.

2011-12-01

Gold nanoparticle-mediated photothermal therapy (PTT) has shown great potential for the treatment of cancer in mouse studies and is now being evaluated in clinical trials. For this therapy, gold nanoparticles (AuNPs) are injected intravenously and are allowed to accumulate within the tumor via the enhanced permeability and retention (EPR) effect. The tumor is then irradiated with a near infrared laser, whose energy is absorbed by the AuNPs and translated into heat. While reliance on the EPR effect for tumor targeting has proven adequate for vascularized tumors in small animal models, the efficiency and specificity of tumor delivery in vivo, particularly in tumors with poor blood supply, has proven challenging. In this study, we examine whether human T cells can be used as cellular delivery vehicles for AuNP transport into tumors. We first demonstrate that T cells can be efficiently loaded with 45 nm gold colloid nanoparticles without affecting viability or function (e.g. migration and cytokine production). Using a human tumor xenograft mouse model, we next demonstrate that AuNP-loaded T cells retain their capacity to migrate to tumor sites in vivo. In addition, the efficiency of AuNP delivery to tumors in vivo is increased by more than four-fold compared to injection of free PEGylated AuNPs and the use of the T cell delivery system also dramatically alters the overall nanoparticle biodistribution. Thus, the use of T cell chaperones for AuNP delivery could enhance the efficacy of nanoparticle-based therapies and imaging applications by increasing AuNP tumor accumulation.

Rapid Detection and Identification of Overdose Drugs in Saliva by Surface-Enhanced Raman Scattering Using Fused Gold Colloids

Directory of Open Access Journals (Sweden)

Frank Inscore

2011-07-01

Full Text Available The number of drug-related emergency room visits in the United States doubled from 2004 to 2009 to 4.6 million. Consequently there is a critical need to rapidly identify the offending drug(s, so that the appropriate medical care can be administered. In an effort to meet this need we have been investigating the ability of surface-enhanced Raman spectroscopy (SERS to detect and identify numerous drugs in saliva at ng/mL concentrations within 10 minutes. Identification is provided by matching measured spectra to a SERS library comprised of over 150 different drugs, each of which possess a unique spectrum. Trace detection is provided by fused gold colloids trapped within a porous glass matrix that generate SERS. Speed is provided by a syringe-driven sample system that uses a solid-phase extraction capillary combined with a SERS-active capillary in series. Spectral collection is provided by a portable Raman analyzer. Here we describe successful measurement of representative illicit, prescribed, and over-the-counter drugs by SERS, and 50 ng/mL cocaine in saliva as part of a focused study.

Peptide-functionalized iron oxide magnetic nanoparticle for gold mining

Energy Technology Data Exchange (ETDEWEB)

Shen, Wei-Zheng; Cetinel, Sibel; Sharma, Kumakshi; Borujeny, Elham Rafie; Montemagno, Carlo, E-mail: montemag@ualberta.ca [Ingenuity Lab, 1-070C (Canada)

2017-02-15

Here, we present our work on preparing a novel nanomaterial composed of inorganic binding peptides and magnetic nanoparticles for inorganic mining. Two previously selected and well-characterized gold-binding peptides from cell surface display, AuBP1 and AuBP2, were exploited. This nanomaterial (AuBP-MNP) was designed to fulfill the following two significant functions: the surface conjugated gold-binding peptide will recognize and selectively bind to gold, while the magnetic nano-sized core will respond and migrate according to the applied external magnetic field. This will allow the smart nanomaterial to mine an individual material (gold) from a pool of mixture, without excessive solvent extraction, filtration, and concentration steps. The working efficiency of AuBP-MNP was determined by showing a dramatic reduction of gold nanoparticle colloid concentration, monitored by spectroscopy. The binding kinetics of AuBP-MNP onto the gold surface was determined using surface plasmon resonance (SPR) spectroscopy, which exhibits around 100 times higher binding kinetics than peptides alone. The binding capacity of AuBP-MNP was demonstrated by a bench-top mining test with gold microparticles.

A concetration-dependent model for silver colloids in nanostructured sol-gel materials

Science.gov (United States)

Garcia-Macedo, Jorge A.; Franco, Alfredo; Renteria, Victor; Valverde-Aguilar, Guadalupe

2005-08-01

We report on the physical modelling of the photoconductive response of nanostructured sol-gel films in function of the silver nitrate concentration (ions and colloids). This model considers several factors as the silver nitrate concentration and the transport parameters obtained. The model is compared with others commonly used. 2d-hexagonal nanostructured sol-gel thin films were prepared by dip-coating method using a non-ionic diblock copolymer Brij58 (surfactant) to produce channels into the film. Silver colloids (metallic Ag0 nanoparticles ) were obtained by spontaneous reduction process of Ag+ ions to Ag0. These nanoparticles were deposited into the channels formed by the surfactant. The structure was identified by X-ray diffraction and TEM. An absorption band located at 430 nm was detected by optical absorption; it corresponds to the plasmon surface. Fit to this band with modified Gans theory is presented. Photoconductivity studies were performed on films with silver ions and films with silver colloids to characterized their mechanisms of charge transport in the darkness and under illumination at 420, 633 nm wavelengths. Transport parameters were calculated. The films with silver colloids exhibit a photovoltaic effect stronger than the films with silver ions. While, the last ones possesses a photoconductivity behaviour.

In Situ Scanning Tunneling Microscopy Topography Changes of Gold (111) in Aqueous Sulfuric Acid Produced by Electrochemical Surface Oxidation and Reduction and Relaxation Phenomena

Science.gov (United States)

Pasquale, M. A.; Nieto, F. J. Rodríguez; Arvia, A. J.

The electrochemical formation and reduction of O-layers on gold (111) films in 1 m sulfuric acid under different potentiodynamic routines are investigated utilizing in situ scanning tunneling microscopy. The surface dynamics is interpreted considering the anodic and cathodic reaction pathways recently proposed complemented with concurrent relaxation phenomena occurring after gold (111) lattice mild disruption (one gold atom deep) and moderate disruption (several atoms deep). The dynamics of both oxidized and reduced gold topographies depends on the potentiodynamic routine utilized to form OH/O surface species. The topography resulting from a mild oxidative disruption is dominated by quasi-2D holes and hillocks of the order of 5 nm, involving about 500-600 gold atoms each, and their coalescence. A cooperative turnover process at the O-layer, in which the anion ad-layer and interfacial water play a key role, determines the oxidized surface topography. The reduction of these O-layers results in gold clusters, their features depending on the applied potential routine. A moderate oxidative disruption produces a surface topography of hillocks and holes several gold atoms high and deep, respectively. The subsequent reduction leads to a spinodal gold pattern. Concurrent coalescence appears to be the result of an Ostwald ripening that involves the surface diffusion of both gold atoms and clusters. These processes produce an increase in surface roughness and an incipient gold faceting. The dynamics of different topographies can be qualitatively explained employing the arguments from colloidal science theory. For 1.1 V ≤ E ≅ Epzc weak electrostatic repulsions favor gold atom/cluster coalescence, whereas for E < Epzc the attenuated electrostatic repulsions among gold surfaces stabilize small clusters over the substrate producing string-like patterns.

Ball-milled nano-colloids of rare-earth compounds as liquid gain media for capillary optical amplifiers and lasers

Science.gov (United States)

Patel, Darayas; Blockmon, Avery; Ochieng, Vanesa; Lewis, Ashley; Wright, Donald M.; Lewis, Danielle; Valentine, Rueben; Valentine, Maucus; Wesley, Dennis; Sarkisov, Sergey S.; Darwish, Abdalla M.; Sarkisov, Avedik S.

2017-02-01

Nano-colloids and nano-crystals doped with ions of rare-earth elements have recently attracted a lot of attention in the scientific community due to their potential applications as biomarkers, fluorescent inks, gain media for lasers and optical amplifiers. Many rare-earth doped materials of different compositions, shapes and size distribution have been prepared by different synthetic methods, such as chemical vapor deposition, sol-gel process, micro-emulsion techniques, gas phase condensation methods, hydrothermal methods and laser ablation. In this paper micro-crystalline powder of the rare-earthdoped compound NaYF4:Yb3+, Er3+ was synthesized using a simple wet process followed by baking in open air. Under 980 nm diode laser excitation strong fluorescence in the 100 nm band around 1531-nm peak was observed from the synthesized micro-powder. The micro-powder was pulverized using a ball mill and prepared in the form of nano-colloids in different liquids. The particle size of the obtained nano-colloids was measured using an atomic force microscope and a dynamic light scatterometer. The size of the nano-particles was close to 100-nm. The nano-colloids were utilized as a filling media in capillary optical amplifiers and lasers. The gain of a 7-cm-long capillary optical amplifier (150-micron inner diameter) was as high as 6 dB at 200 mW pump power. The synthesized nano-colloids and the active optical components using them can be potentially used in optical communication, signal processing, optical computing, and other applications.

Spontaneous formation of gold nanostructures in aqueous microdroplets.

Science.gov (United States)

Lee, Jae Kyoo; Samanta, Devleena; Nam, Hong Gil; Zare, Richard N

2018-04-19

The synthesis of gold nanostructures has received widespread attention owing to many important applications. We report the accelerated synthesis of gold nanoparticles (AuNPs), as well as the reducing-agent-free and template-free synthesis of gold nanoparticles and nanowires in aerosol microdroplets. At first, the AuNP synthesis are carried out by fusing two aqueous microdroplet streams containing chloroauric acid and sodium borohydride. The AuNPs (~7 nm in diameter) are produced within 60 µs at the rate of 0.24 nm µs -1 . Compared to bulk solution, microdroplets enhance the size and the growth rate of AuNPs by factors of about 2.1 and 1.2 × 10 5 , respectively. Later, we find that gold nanoparticles and nanowires (~7 nm wide and >2000 nm long) are also formed in microdroplets in the absence of any added reducing agent, template, or externally applied charge. Thus, water microdroplets not only accelerate the synthesis of AuNPs by orders of magnitude, but they also cause spontaneous formation of gold nanostructures.

Influence of Temperature on the Colloidal Stability of Polymer-Coated Gold Nanoparticles in Cell Culture Media.

Science.gov (United States)

Zyuzin, Mikhail V; Honold, Tobias; Carregal-Romero, Susana; Kantner, Karsten; Karg, Matthias; Parak, Wolfgang J

2016-04-06

The temperature-dependence of the hydrodynamic diameter and colloidal stability of gold-polymer core-shell particles with temperature-sensitive (poly(N-isopropylacrylamide)) and temperature-insensitive shells (polyallylaminine hydrochloride/polystyrensulfonate, poly(isobutylene-alt-maleic anhydride)-graft-dodecyl) are investigated in various aqueous media. The data demonstrate that for all nanoparticle agglomeration, i.e., increase in effective nanoparticle size, the presence of salts or proteins in the dispersion media has to be taken into account. Poly(N-isopropylacrylamide) coated nanoparticles show a reversible temperature-dependent increase in size above the volume phase transition of the polymer shell when they are dispersed in phosphate buffered saline or in media containing protein. In contrast, the nanoparticles coated with temperature-insensitive polymers show a time-dependent increase in size in phosphate buffered saline or in medium containing protein. This is due to time-dependent agglomeration, which is particularly strong in phosphate buffered saline, and induces a time-dependent, irreversible increase in the hydrodynamic diameter of the nanoparticles. This demonstrates that one has to distinguish between temperature- and time-induced agglomerations. Since the size of nanoparticles regulates their uptake by cells, temperature-dependent uptake of thermosensitive and non-thermosensitive nanoparticles by cells lines is compared. No temperature-specific difference between both types of nanoparticles could be observed. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Optical Manipulation of Shape-Morphing Elastomeric Liquid Crystal Microparticles Doped with Gold Nanocrystals

Energy Technology Data Exchange (ETDEWEB)

Sun, Y. R.; Evans, J. S.; Lee, T.; Senyuk, B.; Keller, P.; He, S. L.; Smalyukh, I. I.

2012-06-11

We demonstrate facile optical manipulation of shape of birefringent colloidal microparticles made from liquid crystal elastomers. Using soft lithography and polymerization, we fabricate elastomeric microcylinders with weakly undulating director oriented on average along their long axes. These particles are infiltrated with gold nanospheres acting as heat transducers that allow for an efficient localized transfer of heat from a focused infrared laser beam to a submicrometer region within a microparticle. Photothermal control of ordering in the liquid crystal elastomer using scanned beams allows for a robust control of colloidal particles, enabling both reversible and irreversible changes of shape. Possible applications include optomechanics, microfluidics, and reconfigurable colloidal composites with shape-dependent self-assembly.

Fluorosurfactant-capped gold nanoparticles-enhanced chemiluminescence from hydrogen peroxide-hydroxide and hydrogen peroxide-bicarbonate in presence of cobalt(II)

Science.gov (United States)

Li, Jinge; Li, Qianqian; Lu, Chao; Zhao, Lixia; Lin, Jin-Ming

2011-02-01

Nonionic fluorosurfactant (FSN)-capped gold nanoparticles (GNPs) remain excellently stable at a wider pH range and high ionic strength, which is useful to investigate some CL systems involved in high salt and a strict pH range. In this study, we utilized FSN-capped GNPs of different sizes to distinguish the emitting species from H 2O 2-Co 2+-NaOH and H 2O 2-Co 2+-NaHCO 3 systems. When the pH of FSN-capped gold colloidal solution was adjusted to 10.2 by dropwise addition of 0.05 M NaOH, the CL intensity of H 2O 2-Co 2+-NaHCO 3 system was enhanced 6-fold or 60-fold respectively in the presence of FSN-capped 14 nm or 69 nm GNPs with comparison to H 2O 2-Co 2+-NaOH. The variation of CL spectra and UV-vis spectra, as well as the quenching effect of reactive oxygen species scavengers were studied in detail to understand the CL enhancement mechanisms of FSN-capped GNPs on the two systems. For H 2O 2-Co 2+-NaOH system, the gold(I) complexes intermediate and singlet oxygen dimol species were proposed as the emitting species. The excited states of the carbon dioxide dimers and singlet oxygen dimol species were considered responsible for the light emission of H 2O 2-Co 2+-NaHCO 3 system. To our knowledge, this work is the first time to study the two CL systems simultaneously using nanoparticles.

Coating of gold nanoparticles for medical application: UV-VIS

Science.gov (United States)

Martínez Espinosa, Juan Carlos; Ramírez, Nayem Amtanus Chequer; Funes Oliva, Luis Enrique; Córdova Fraga, Teodoro; Bernal Alvarado, Jesús; Reyes Pablo, Aldelmo; Núñez, Anita Rosa Elvira

2014-11-01

The use of nanostructured materials has gained strength in recent years in the biomedical area; new applications such as the detection of components in living cells have been used in pharmaceutical area, specifically to study the interaction of various antitumor drugs in living tissues, the detection of genes that are closely related to some type of cancer, as well as the detections of protein biomarkers for diseases also have been studied in various research laboratories around of the world. In this work, we characterize the variation of the absorbance of gold nanoparticles (GNPs) coated with different concentration of Bovine Serum Albumin (BSA) protein. We use GNPS of 60 nm of the trademark-TED PELLA, the BSA protein trademark of Sigma Aldrich and based on that proposed protocol by Chithrani et al., 2009 with purposes to obtain an alternative model to determine the optimal stability of the nanoparticles coated with the protein. The colloidal solutions were prepared with BSA at different concentrations (0.25, 0.5, 0.75 and 1% M/V), and were centrifuged at 15,000 rpm for 90 minutes (centrifuge Model Z383K) and a constant temperature of 25 °C. All the spectra sets were obtained within the range from 400 to 700 nm using an UV-VIS spectrophotometer (Thermo Scientific Model 51118650). The results showed a R2 of 0.99 for an exponential curve correlation between the concentration of BSA, and the absorbance measured. We found at higher concentrations of BSA, there is a decrease in the intensity of the absorption spectra in the plasmon resonance. This preliminary model obtained can be used in the stabilization of gold nanoparticles with different proteins of biomedical interest in future experiments and support for functionalization of GNPs with specific membrane markers.

Preparation, Physicochemical Characterization and Performance Evaluation of Gold Nanoparticles in Radiotherapy

Directory of Open Access Journals (Sweden)

Ali Kamiar

2013-08-01

Full Text Available Purpose: The aim of the present study was preparation, physicochemical characterization and performance evaluation of gold nanoparticles (GNPs in radiotherapy. Another objective was the investigation of anti-bacterial efficacy of gold nanoparticle against E. coli clinical strains. Methods: Gold nanoparticles prepared by controlled reduction of an aqueous HAuCl4 solution using Tri sodium citrate. Particle size analysis and Transmission electron microscopy were used for physicochemical characterization. Polymer gel dosimetry was used for evaluation of the enhancement of absorbed dose. Diffusion method in agar media was used for investigation of anti-bacterial effect. Results: Gold nanoparticles synthesized in size range from 57 nm to 346 nm by planning different formulation. Gold nanoparticle in 57 nm size increased radiation dose effectiveness with the magnitude of about 21 %. At the concentration of 400 ppm, Nano gold exhibited significant anti-bacterial effect against E. coli clinical strains. Conclusion: It is concluded that gold nanoparticles can be applied as dose enhancer in radiotherapy. The Investigation of anti-bacterial efficacy showed that gold nanoparticle had significant effect against E. coli clinical strains.

Magnetic SiO2/Fe3O4 colloidal crystals

International Nuclear Information System (INIS)

Huang, C-K; Hou, C-H; Chen, C-C; Tsai, Y-L; Chang, L-M; Wei, H-S; Hsieh, K-H; Chan, C-H

2008-01-01

We proposed a novel technique to fabricate colloidal crystals by using monodisperse SiO 2 coated magnetic Fe 3 O 4 (SiO 2 /Fe 3 O 4 ) microspheres. The magnetic SiO 2 /Fe 3 O 4 microspheres with a diameter of 700 nm were synthesized in the basic condition with ferric sulfate, ferrous sulfate, tartaric acid and tetraethyl orthosilicate (TEOS) in the reaction system. Monodisperse SiO 2 /Fe 3 O 4 superparamagnetic microspheres have been successfully used to fabricate colloidal crystals under the existing magnetic field

Seeded Growth Synthesis of Gold Nanotriangles: Size Control, SAXS Analysis, and SERS Performance.

Science.gov (United States)

Kuttner, Christian; Mayer, Martin; Dulle, Martin; Moscoso, Ana; López-Romero, Juan Manuel; Förster, Stephan; Fery, Andreas; Pérez-Juste, Jorge; Contreras-Cáceres, Rafael

2018-04-04

We studied the controlled growth of triangular prismatic Au nanoparticles with different beveled sides for surface-enhanced Raman spectroscopy (SERS) applications. First, in a seedless synthesis using 3-butenoic acid (3BA) and benzyldimethylammonium chloride (BDAC), gold nanotriangles (AuNTs) were synthesized in a mixture with gold nanooctahedra (AuNOCs) and separated by depletion-induced flocculation. Here, the influence of temperature, pH, and reducing agent on the reaction kinetics was initially investigated by UV-vis and correlated to the size and yield of AuNT seeds. In a second step, the AuNT size was increased by seed-mediated overgrowth with Au. We show for the first time that preformed 3BA-synthesized AuNT seeds can be overgrown up to a final edge length of 175 nm and a thickness of 80 nm while maintaining their triangular shape and tip sharpness. The NT morphology, including edge length, thickness, and tip rounding, was precisely characterized in dispersion by small-angle X-ray scattering and in dry state by transmission electron microscopy and field-emission scanning electron microscopy. For sensor purposes, we studied the size-dependent SERS performance of AuNTs yielding analytical enhancement factors between 0.9 × 10 4 and 5.6 × 10 4 and nanomolar limit of detection (10 -8 -10 -9 M) for 4-mercaptobenzoic acid and BDAC. These results confirm that the 3BA approach allows the fabrication of AuNTs in a whole range of sizes maintaining the NT morphology. This enables tailoring of localized surface plasmon resonances between 590 and 740 nm, even in the near-infrared window of a biological tissue, for use as colloidal SERS sensing agents or for optoelectronic applications.

Colloids or artefacts? A TVO/SKB cooperation project in Olkiluoto, Finland

International Nuclear Information System (INIS)

Laaksoharju, M.; Vuorinen, U.; Snellman, M.; Helenius, J.; Allard, B.; Pettersson, C.; Hinkkanen, H.

1993-12-01

TVO (Teollisuuden Voima Oy, Finland) initiated a co-operative task with SKB (Swedish Nuclear Fuel and Waste Management Co.) to critically evaluate colloid sampling methods at the test site in Olkiluoto, SW Finland. Three different colloid sampling methods were compared when sampling borehole OL-KR1 at 613-618 m depth. One possible way to make a conservative in-situ colloid estimation is to omit the contribution from calcite precipitation which is considered to be the main artefact. When this is made the inorganic colloid content (size 1-1000 nm) in Olkiluoto is 184 ±177 ppb consisting of clay minerals, silica, pyrite, goethite and magnesium oxide; the concentration of organic substances are around 100 ppb. The in-situ colloid concentration seems to be low which is in good agreement with experiences from years of sampling in similar environment and depths. The exercise shows the many difficulties encountered when sampling colloids. Small error in the planning, pump rate selection, a lack of precautionary measures, artefact sensitivity of the method etc have a tendency to affect significantly the results on the measured ppb colliod level

Gold - Old Drug with New Potentials.

Science.gov (United States)

Faa, Gavino; Gerosa, Clara; Fanni, Daniela; Lachowicz, Joanna I; Nurchi, Valeria M

2018-01-01

Research into gold-based drugs for a range of human diseases has seen a revival in recent years. This article reviews the most important applications of gold products in different fields of human pathology. Au(I) and Au(III) compounds have been re-introduced in clinical practice for targeting the cellular components involved in the onset and progression of viral and parasitic diseases, rheumatoid arthritis and cancer. After some brief historical notes, this article takes into account the applications of gold compounds against Mycobacterium tuberculosis, and also in tuberculosis and in rheumatoid arthritis treatment. The use of gold containing drugs in the cure of cancer are then considered, with special emphasis to the use of nanoparticles and to the photo-thermal cancer therapy. The use of colloidal gold in diagnostics, introduced in the last decade is widely discussed. As a last point a survey on the adverse effects and on the toxicity of the various gold derivatives in use in medicine is presented. In this review, we described the surprisingly broad spectrum of possible uses of gold in diagnostics and in therapeutic approaches to multiple human diseases, ranging from degenerative to infectious diseases, and to cancer. In particular, gold nanoparticles appear as attractive elements in modern clinical medicine, combining high therapeutic properties, high selectivity in targeting cancer cells and low toxicity. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Quantitative analysis of gold nanorod alignment after electric field assisted deposition

NARCIS (Netherlands)

Ahmed, W.; Ahmed, Waqqar; Kooij, Ernst S.; van Silfhout, Arend; Poelsema, Bene

2009-01-01

We have studied the alignment of colloidal gold nanorods, deposited from solution onto well-defined substrates in the presence of an AC electric field generated by micrometer spaced electrodes. The field strengths employed in our experiments are sufficiently large to overcome Brownian motion and

Protracted elimination of gold nanoparticles from mouse liver

DEFF Research Database (Denmark)

Sadauskas, Evaldas; Wallin, Håkan; Stoltenberg, Meredin

2009-01-01

The present study aims at revealing the fate of 40-nm gold nanoparticles after intravenous injections. The gold nanoparticles were traced histochemically with light and transmission electron microscopy using autometallographic (AMG) staining, and the gold content in the liver was determined with ...

Hetero-Colloidal Metal Particle Multilayer Films Grown Using Electrostatic Interactions at the Air-water Interface

International Nuclear Information System (INIS)

Sastry, Murali; Mayya, K.S.

2000-01-01

The formation of nanoparticle multilayer films by electrostatic immobilization of surface-modified colloidal particles at the air-water interface has been recently demonstrated by us. In this paper, we extend our study to show that multilayer assemblies consisting of metal particles of different chemical nature (hetero-colloidal particle superlattices) and size can be deposited by the versatile Langmuir-Blodgett technique. Multilayer films consisting of a different number of bilayers of gold and silver colloidal particles have been deposited and characterized using quartz crystal microgravimetry and UV-visible spectroscopy measurements. It is observed that while layer-by-layer deposition of the different colloidal particle assemblies is possible by this technique without a detectable variation in the cluster density in the different layers, a degree of post-deposition reorganization of the clusters occurs in the film. In addition to this aging behavior, the effect of different organic solvents on the reorganization process has also been studied

Enhanced photocatalysis, colloidal stability and cytotoxicity of synchrotron X-ray synthesized Au/TiO2 nanoparticles

International Nuclear Information System (INIS)

Liu, Chi-Jen; Yang, Tsung-Yeh; Wang, Chang-Hai; Chien, Chia-Chi; Chen, Shin-Tai; Wang, Cheng-Liang; Leng, Wei-Hua; Hwu, Y.; Lin, Hong-Ming; Lee, Yao-Chang; Cheng, Chia-Liang; Je, J.H.; Margaritondo, G.

2009-01-01

Au/TiO 2 nanocomposite particles were synthesized by a method based on intense X-ray irradiation without adding any reducing agent or stabilizer. The nanocomposite exhibits promising photocatalytic and biological properties at physiologically relevant concentration ([Au] = 0.028 mM, [TiO 2 ] = 0.5 mM). The structure and photocatalysis were examined by X-ray diffraction, electron microscopy and ultraviolet-visible spectroscopy demonstrating that gold nanoparticles of 2-5 nm size were successfully deposited on TiO 2 nanoparticle surfaces. The nanocomposite exhibited good colloidal stability within a typical cellular environment and was nontoxic to cancer cell according to evaluations under controlled conditions. The Au/TiO 2 nanoparticles were also found to enhance the photocatalytic efficiency of UV radiation and even more that of X-ray radiation. In vitro studies indicated that the cell-killing effect under X-ray irradiation is more pronounced with the addition of Au/TiO 2 nanoparticles than of bare TiO 2 nanoparticles.

Synthesis of radioactive gold nanoparticle in surfactant medium

International Nuclear Information System (INIS)

Swadesh Mandal

2014-01-01

The present study describes the synthesis of radioactive gold nanoparticle in surfactant medium. Proton irradiated stable 197 Au and radioactive 198 Au were simultaneously used for production of radioactive gold nanoparticle. Face centered cubic gold nanoparticles with size of 4-50 nm were found in proton irradiated gold foil. However, the size of nanoparticle varies with pH using both stable and radioactive gold. (author)

Development of a Colloidal Gold-Based Immunochromatographic Strip for Rapid Detection of Klebsiella pneumoniae Serotypes K1 and K2.

Science.gov (United States)

Siu, L Kristopher; Tsai, Yu-Kuo; Lin, Jung-Chung; Chen, Te-Li; Fung, Chang-Phone; Chang, Feng-Yee

2016-12-01

In this study, a novel colloidal gold-based immunochromatographic strip (ICS) containing anti-Klebsiella pneumoniae capsular polysaccharide polyclonal antibodies was developed to specifically detect K. pneumoniae serotypes K1 and K2. Capsular polysaccharide K1 and K2 antigens were first used to produce polyclonal anti-K1 and anti-K2 antibodies. Reference strains with different serotypes, nontypeable K. pneumoniae strains, and other bacterial species were then used to assess the sensitivity and specificity of these test strips. The detection limit was found to be 10 5 CFU, and the ICSs were stable for 6 months when stored at room temperature. No false-positive or false-negative results were observed, and equivalent results were obtained compared to those of more conventional test methods, such as PCR or serum agglutination. In conclusion, the ICS developed here requires no technical expertise and allows for the specific, rapid, and simultaneous detection of K. pneumoniae serotypes K1 and K2. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Biodistribution of gold nanoparticles following intratracheal instillation in mouse lung

DEFF Research Database (Denmark)

Sadauskas, Evaldas; Jacobsen, Nicklas R.; Danscher, Gorm

2009-01-01

plasma mass spectrometry (ICP-MS) and neutron activation analysis (NAA). The liver is the major site of deposition of circulating gold nanoparticles. Therefore the degree of translocation was determined by the hepatic deposition of gold. Mice were instilled with 5 intratracheal doses of gold...... repeatedly during 3 weeks, the load was substantial. Ultrastructurally, AMG silver enhanced gold nanoparticles were found in lysosome-/endosome-like organelles of the macrophages and analysis with AMG, ICP-MS and NAA of the liver revealed an almost total lack of translocation of nanoparticles. In mice given...... repeated instillations of 2 nm gold nanoparticles, 1.4‰ (by ICP-MS) to 1.9‰ (by NAA) of the instilled gold was detected in the liver. With the 40 nm gold, no gold was detected in the liver (detection level 2 ng, 0.1‰) except for one mouse in which 3‰ of the instilled gold was found in the liver. No gold...

Biosynthesis, structural characterization and antimicrobial activity of gold and silver nanoparticles.

Science.gov (United States)

Ahmad, Tokeer; Wani, Irshad A; Manzoor, Nikhat; Ahmed, Jahangeer; Asiri, Abdullah M

2013-07-01

An eco friendly simple biosynthetic route was used for the preparation of monodisperse and highly crystalline gold and silver nanoparticles using cell free extract of fungus, Candida albicans. Transmission electron microscopic studies show the formation of gold and silver nanocrystals of average size of 5 nm and 30 nm with the specific surface areas of 18.9 m(2)/g and 184.4 m(2)/g respectively. The interaction of gold and silver nanoparticles with proteins has been formulated by FT-IR spectroscopy and thermal gravimetric analysis. The formation of gold and silver nanoparticles was also confirmed by the appearance of a surface plasmon band at 540 nm and 450 nm respectively. The antimicrobial activity of the synthesized gold and silver nanoparticles was investigated against both Staphylococcus aureus and Escherichia coli. The results suggest that these nanoparticles can be used as effective growth inhibitors against the test microorganisms. Greater bactericidal activity was observed for silver nanoparticles. The E. coli, a gram negative bacterium was found to be more susceptible to gold and silver nanoparticles than the S. aureus, a gram positive bacterium. Copyright © 2013 Elsevier B.V. All rights reserved.

Active colloids

International Nuclear Information System (INIS)

Aranson, Igor S

2013-01-01

A colloidal suspension is a heterogeneous fluid containing solid microscopic particles. Colloids play an important role in our everyday life, from food and pharmaceutical industries to medicine and nanotechnology. It is useful to distinguish two major classes of colloidal suspensions: equilibrium and active, i.e., maintained out of thermodynamic equilibrium by external electric or magnetic fields, light, chemical reactions, or hydrodynamic shear flow. While the properties of equilibrium colloidal suspensions are fairly well understood, active colloids pose a formidable challenge, and the research is in its early exploratory stage. One of the most remarkable properties of active colloids is the possibility of dynamic self-assembly, a natural tendency of simple building blocks to organize into complex functional architectures. Examples range from tunable, self-healing colloidal crystals and membranes to self-assembled microswimmers and robots. Active colloidal suspensions may exhibit material properties not present in their equilibrium counterparts, e.g., reduced viscosity and enhanced self-diffusivity, etc. This study surveys the most recent developments in the physics of active colloids, both in synthetic and living systems, with the aim of elucidation of the fundamental physical mechanisms governing self-assembly and collective behavior. (physics of our days)

Porous Gold Films Fabricated by Wet-Chemistry Processes

Directory of Open Access Journals (Sweden)

Aymeric Pastre

2016-01-01

Full Text Available Porous gold films presented in this paper are formed by combining gold electroless deposition and polystyrene beads templating methods. This original approach allows the formation of conductive films (2 × 106 (Ω·cm−1 with tailored and interconnected porosity. The porous gold film was deposited up to 1.2 μm on the silicon substrate without delamination. An original zirconia gel matrix containing gold nanoparticles deposited on the substrate acts both as an adhesion layer through the creation of covalent bonds and as a seed layer for the metallic gold film growth. Dip-coating parameters and gold electroless deposition kinetics have been optimized in order to create a three-dimensional network of 20 nm wide pores separated by 20 nm thick continuous gold layers. The resulting porous gold films were characterized by GIXRD, SEM, krypton adsorption-desorption, and 4-point probes method. The process is adaptable to different pore sizes and based on wet-chemistry. Consequently, the porous gold films presented in this paper can be used in a wide range of applications such as sensing, catalysis, optics, or electronics.

Ultrathin free-standing close-packed gold nanoparticle films: Conductivity and Raman scattering enhancement

Science.gov (United States)

Yu, Qing; Huang, Hongwen; Peng, Xinsheng; Ye, Zhizhen

2011-09-01

A simple filtration technique was developed to prepare large scale free-standing close-packed gold nanoparticle ultrathin films using metal hydroxide nanostrands as both barrier layer and sacrificial layer. As thin as 70 nm, centimeter scale robust free-standing gold nanoparticle thin film was obtained. The thickness of the films could be easily tuned by the filtration volumes. The electronic conductivities of these films varied with the size of the gold nanoparticles, post-treatment temperature, and thickness, respectively. The conductivity of the film prepared from 20 nm gold nanoparticles is higher than that of the film prepared from 40 nm gold nanoparticle by filtering the same filtration volume of their solution, respectively. Their conductivities are comparable to that of the 220 nm thick ITO film. Furthermore, these films demonstrated an average surface Raman scattering enhancement up to 6.59 × 105 for Rhodamine 6 G molecules on the film prepared from 40 nm gold nanoparticles. Due to a lot of nano interspaces generated from the close-packed structures, two abnormal enhancements and relative stronger intensities of the asymmetrical vibrations at 1534 and 1594 cm-1 of R6G were observed, respectively. These robust free-standing gold nanoparticle films could be easily transferred onto various solid substrates and hold the potential application for electrodes and surface enhanced Raman detectors. This method is applicable for preparation of other nanoparticle free-standing thin films.A simple filtration technique was developed to prepare large scale free-standing close-packed gold nanoparticle ultrathin films using metal hydroxide nanostrands as both barrier layer and sacrificial layer. As thin as 70 nm, centimeter scale robust free-standing gold nanoparticle thin film was obtained. The thickness of the films could be easily tuned by the filtration volumes. The electronic conductivities of these films varied with the size of the gold nanoparticles, post

Colloidal organization

CERN Document Server

Okubo, Tsuneo

2015-01-01

Colloidal Organization presents a chemical and physical study on colloidal organization phenomena including equilibrium systems such as colloidal crystallization, drying patterns as an example of a dissipative system and similar sized aggregation. This book outlines the fundamental science behind colloid and surface chemistry and the findings from the author's own laboratory. The text goes on to discuss in-depth colloidal crystallization, gel crystallization, drying dissipative structures of solutions, suspensions and gels, and similar-sized aggregates from nanosized particles. Special emphas

Generation of polypeptide-templated gold nanoparticles using ionizing radiation.

Science.gov (United States)

Walker, Candace Rae; Pushpavanam, Karthik; Nair, Divya Geetha; Potta, Thrimoorthy; Sutiyoso, Caesario; Kodibagkar, Vikram D; Sapareto, Stephen; Chang, John; Rege, Kaushal

2013-08-13

Ionizing radiation, including γ rays and X-rays, are high-energy electromagnetic radiation with diverse applications in nuclear energy, astrophysics, and medicine. In this work, we describe the use of ionizing radiation and cysteine-containing elastin-like polypeptides (C(n)ELPs, where n = 2 or 12 cysteines in the polypeptide sequence) for the generation of gold nanoparticles. In the presence of C(n)ELPs, ionizing radiation doses higher than 175 Gy resulted in the formation of maroon-colored gold nanoparticle dispersions, with maximal absorbance at 520 nm, from colorless metal salts. Visible color changes were not observed in any of the control systems, indicating that ionizing radiation, gold salt solution, and C(n)ELPs were all required for nanoparticle formation. The hydrodynamic diameters of nanoparticles, determined using dynamic light scattering, were in the range of 80-150 nm, while TEM imaging indicated the formation of gold cores 10-20 nm in diameter. Interestingly, C2ELPs formed 1-2 nm diameter gold nanoparticles in the absence of radiation. Our results describe a facile method of nanoparticle formation in which nanoparticle size can be tailored based on radiation dose and C(n)ELP type. Further improvements in these polypeptide-based systems can lead to colorimetric detection of ionizing radiation in a variety of applications.

The Stability of Supported Gold Catalysts

NARCIS (Netherlands)

Masoud, Nazila

2018-01-01

Gold has supreme cultural and financial value and, in form of nanoparticles smaller than 10 nm, is a unique catalyst for different industrially relevant reactions. Intriguing properties of the gold catalysts have spurred demand in the chemical industry for Au catalysts, the application of which

Photochemical modification of diamond powder with sulfur functionalities and its behavior on gold surfaces

International Nuclear Information System (INIS)

Nakamura, T; Ohana, T; Hagiwara, Y; Tsubota, T

2010-01-01

A useful method of modifying the surface of diamond powders with sulfur-containing functionalities was developed by the use of the photolysis of elemental sulfur. The introduction of sulfur-containing functional groups on the diamond surfaces was confirmed by means of XPS, DRIFT and mass spectroscopy analyses. The sulfur-modified diamond powders exhibited surface-attachment behavior to gold surfaces through the sulfur-containing linkage. In brief, exposure of the modified diamond powders to gold colloids resulted in gold nanoparticles being attached to the diamond powders. Treatment of the modified diamond powders with gold thin film on Si substrate afforded alignment of surface-attached diamond powders through sulfur linkages by self-assembly.

Self-Assembly on Gold and Graphene for Molecular Electronics

DEFF Research Database (Denmark)

Reeler, Nini Elisabeth Abildgaard

In this work, different bottom-up approaches were pursued to develop a method to mass produce dimers of gold nanorods (AuNRs) or large gold nanoparticles (AuNPs) bridged by a conducting molecule for later use in a device. Two types of AuNPs with a size of 3-5 nm and 50-75 nm respectively were syn...

Sampling and physical and actinide characterization of colloids from the Grimsel test site

International Nuclear Information System (INIS)

Longworth, G.; Ivanovich, M.

1990-01-01

Samples of groundwater from a granite fracture at the Grimsel test site in Switzerland have been collected as part of a second intercomparison of groundwater colloid sampling and characterization techniques carried out by members of the Coco Club (colloids and complexes) sponsored by the CEC. This report describes the Harwell contribution to this exercise. The bulk of naturally occurring actinides were found to reside in solution with 10 particles/I (detection limit ∼50 nm) for samples determined by three laboratories. The colloids were shown to be negatively charged using microelectrophoresis and to be relatively stable. There was evidence of a reduction in the pH of the water after storage due to air contamination. This work has served to identify the problems associated with colloid sampling and characterization techniques

Synthesis and characterization of silver colloidal nanoparticles with different coatings for SERS application

International Nuclear Information System (INIS)

Mikac, L.; Ivanda, M.; Gotić, M.; Mihelj, T.; Horvat, L.

2014-01-01

Silver colloids were produced by chemical reduction of silver salt (silver nitrate, AgNO 3 ) solution. As reducing agents, trisodium citrate, sodium borohydride, ascorbic acid, polyvinylpyrrolidone, and glucose were used. The colloids were characterized by UV–Vis, DLS, zeta potential measurements, and SEM. The colloids were stabilized with negative groups or large molecules attached to their surface. The surface-enhanced Raman scattering (SERS) effect of stabilized nanoparticles was measured by using pyridine and rhodamine 6G molecules as analytes and NaNO 3 , KCl, and KBr at different concentrations as aggregating agents. The best Raman signal enhancement was achieved using silver nanoparticles of 40 nm size reduced and stabilized with citrate. The SERS signal of analyte molecules was further enhanced with the addition of sodium borohydride as an alternative aggregating agent. The borohydride had the strongest impact on the SERS effect of the colloid consistent of large (0.5 µm) silver nanoparticles stabilized with aminodextran. The mixture colloid-borohydride-pyridine was stable for hours. The mechanism of borohydride in the colloids is discussed

Synthesis and characterization of silver colloidal nanoparticles with different coatings for SERS application

Energy Technology Data Exchange (ETDEWEB)

Mikac, L.; Ivanda, M., E-mail: ivanda@irb.hr [Ruđer Bošković Institute, Laboratory for Molecular Physics (Croatia); Gotić, M. [Ruđer Bošković Institute, Laboratory for Synthesis of New Materials (Croatia); Mihelj, T. [Ruđer Bošković Institute, Laboratory for Synthesis and Processes of Self-assembling of Organic Molecules (Croatia); Horvat, L. [Ruđer Bošković Institute, Laboratory for Electron Microscopy (Croatia)

2014-12-15

Silver colloids were produced by chemical reduction of silver salt (silver nitrate, AgNO{sub 3}) solution. As reducing agents, trisodium citrate, sodium borohydride, ascorbic acid, polyvinylpyrrolidone, and glucose were used. The colloids were characterized by UV–Vis, DLS, zeta potential measurements, and SEM. The colloids were stabilized with negative groups or large molecules attached to their surface. The surface-enhanced Raman scattering (SERS) effect of stabilized nanoparticles was measured by using pyridine and rhodamine 6G molecules as analytes and NaNO{sub 3}, KCl, and KBr at different concentrations as aggregating agents. The best Raman signal enhancement was achieved using silver nanoparticles of 40 nm size reduced and stabilized with citrate. The SERS signal of analyte molecules was further enhanced with the addition of sodium borohydride as an alternative aggregating agent. The borohydride had the strongest impact on the SERS effect of the colloid consistent of large (0.5 µm) silver nanoparticles stabilized with aminodextran. The mixture colloid-borohydride-pyridine was stable for hours. The mechanism of borohydride in the colloids is discussed.

Development of a colloidal gold-immunochromatography assay to detect immunoglobulin G antibodies to Treponema pallidum with TPN17 and TPN47.

Science.gov (United States)

Lin, Li-Rong; Fu, Zuo-Gen; Dan, Bing; Jing, Guang-Jun; Tong, Man-li; Chen, De-Teng; Yu, Yang; Zhang, Chang-Gong; Yang, Tian-Ci; Zhang, Zhong-Ying

2010-11-01

Syphilis remains a worldwide public health problem; it is necessary to develop a new diagnostic approach that is easier and faster than conventional tests. Here, we report a new testing method named colloidal gold-immunochromatography assay (GICA) to detect syphilis instead of fluorescent treponemal antibody-absorption (FTA-Abs). Syphilis-specific immunoglobulin G (IgG) antibody was detected with GICA established on syphilis-specific recombinant proteins, TPN17 and TPN47. FTA-Abs Treponema pallidum (TP)-IgG was set as the gold standard. A GICA test was performed to detect the serum of 14 967 subjects who took a serologic test for syphilis at the Xiamen Center of Clinical Laboratory, Fujian, China, from March 2009 to February 2010, among which 1326 cases were diagnosed as syphilitic. The results showed that the sensitivity, specificity, and positive predictive value were 99.38% (1279/1287), 99.96% (12,975/12,980), and 99.61% (1279/1284), respectively. The positive rate between the 2 test methods had no significant difference (χ(2) = 0.003, P > 0.05). Detection on 500 interference specimens indicated that the biologic false-positive rate of the GICA test was extremely low and free from other biologic and chemical factors. The characteristics of GICA TP-IgG correspond to that of FTA-Abs TP-IgG (EUROIMMUN Medizinische Labordiagnostika, Germany). The GICA test is convenient, fast, and inexpensive, and it can be used both as a confirmatory test and a screening indicator, instead of FTA-Abs TP-IgG. Copyright © 2010 Elsevier Inc. All rights reserved.

Hanging colloidal drop: A new photonic crystal synthesis route

Science.gov (United States)

Sandu, Ion; Dumitru, Marius; Fleaca, Claudiu Teodor; Dumitrache, Florian

2018-05-01

High-quality photonic crystals (hundreds of micrometres in thickness) were grown by the free evaporation of a colloidal drop consisting of silica and polystyrene nanospheres with dimensions of 300 nm, 500 nm, and 1000 nm. The essence of experimental findings is that the drop has to hang on a pillar. This leads to the inhibition of the droplet spreading, the minimisation of the convective force, and the zeroing of the static frictional force between nanospheres and the liquid/air interface, where the first layer is formed. The theoretical essence is the continuous adjustment of nanospheres positions during the growth of photonic crystal, a key condition of the self-assembling phenomenon.

Effect of surface roughness on substrate-tuned gold nanoparticle gap plasmon resonances.

Science.gov (United States)

Lumdee, Chatdanai; Yun, Binfeng; Kik, Pieter G

2015-03-07

The effect of nanoscale surface roughness on the gap plasmon resonance of gold nanoparticles on thermally evaporated gold films is investigated experimentally and numerically. Single-particle scattering spectra obtained from 80 nm diameter gold particles on a gold film show significant particle-to-particle variation of the peak scattering wavelength of ±28 nm. The experimental results are compared with numerical simulations of gold nanoparticles positioned on representative rough gold surfaces, modeled based on atomic force microscopy measurements. The predicted spectral variation and average resonance wavelength show good agreement with the measured data. The study shows that nanometer scale surface roughness can significantly affect the performance of gap plasmon-based devices.

Colloid transport in model fracture filling materials

Science.gov (United States)

Wold, S.; Garcia-Garcia, S.; Jonsson, M.

2010-12-01

Colloid transport in model fracture filling materials Susanna Wold*, Sandra García-García and Mats Jonsson KTH Chemical Science and Engineering Royal Institute of Technology, SE-100 44 Stockholm, Sweden *Corresponding author: E-mail: wold@kth.se Phone: +46 8 790 6295 In colloid transport in water-bearing fractures, the retardation depends on interactions with the fracture surface by sorption or filtration. These mechanisms are difficult to separate. A rougher surface will give a larger area available for sorption, and also when a particle is physically hindered, it approaches the surface and enables further sorption. Sorption can be explained by electrostatics were the strongest sorption on minerals always is observed at pH below pHpzc (Filby et al., 2008). The adhesion of colloids to mineral surfaces is related to the surface roughness according to a recent study (Darbha et al., 2010). There is a large variation in the characteristics of water-bearing fractures in bedrock in terms of aperture distribution, flow velocity, surface roughness, mineral distributions, presence of fracture filling material, and biological and organic material, which is hard to implement in modeling. The aim of this work was to study the transport of negatively charged colloids in model fracture filling material in relation to flow, porosity, mineral type, colloid size, and surface charge distribution. In addition, the impact on transport of colloids of mixing model fracture filling materials with different retention and immobilization capacities, determined by batch sorption experiments, was investigated. The transport of Na-montmorillonite colloids and well-defined negatively charged latex microspheres of 50, 100, and 200 nm diameter were studied in either columns containing quartz or quartz mixed with biotite. The ionic strength in the solution was exclusively 0.001 and pH 6 or 8.5. The flow rates used were 0.002, 0.03, and 0.6 mL min-1. Sorption of the colloids on the model fracture

Scalable creation of gold nanostructures on high performance engineering polymeric substrate

Science.gov (United States)

Jia, Kun; Wang, Pan; Wei, Shiliang; Huang, Yumin; Liu, Xiaobo

2017-12-01

The article reveals a facile protocol for scalable production of gold nanostructures on a high performance engineering thermoplastic substrate made of polyarylene ether nitrile (PEN) for the first time. Firstly, gold thin films with different thicknesses of 2 nm, 4 nm and 6 nm were evaporated on a spin-coated PEN substrate on glass slide in vacuum. Next, the as-evaporated samples were thermally annealed around the glass transition temperature of the PEN substrate, on which gold nanostructures with island-like morphology were created. Moreover, it was found that the initial gold evaporation thickness and annealing atmosphere played an important role in determining the morphology and plasmonic properties of the formulated Au NPs. Interestingly, we discovered that isotropic Au NPs can be easily fabricated on the freestanding PEN substrate, which was fabricated by a cost-effective polymer solution casting method. More specifically, monodispersed Au nanospheres with an average size of ∼60 nm were obtained after annealing a 4 nm gold film covered PEN casting substrate at 220 °C for 2 h in oxygen. Therefore, the scalable production of Au NPs with controlled morphology on PEN substrate would open the way for development of robust flexible nanosensors and optical devices using high performance engineering polyarylene ethers.

Determination of hepatic fractional clearance of radioactive gold colloids for a measure of effective hepatic blood flow

International Nuclear Information System (INIS)

Fujii, Masahiro

1979-01-01

For a measure of effective blood flow, a hepatic fractional clearance of 198 Au-colloids was determined, which was obtained from the disappearance rate multiplied by the fraction of injected dose taken up by the liver. The hepatic uptake was determined with a gamma camera. The counts over the liver was corrected for body weight and height. The method was considered sufficiently simple for routine use. 198 Au-colloids were obtained from Dainabot Lab. and CIS. The former gave 64% higher values of disappearance rate than the latter, without any change in the organ distribution. A quality control tests were applied over a six-year period to the disappearance rates. Reproducibility within 95 to confidence limits was found for both groups. In 28 normal control subjects, hepatic fractional clearance of the colloids from Dainabot Lab. was 18.5 +- 3.4%/min. In patients with progressed hepatic disease, both hepatic fractional clearance and final hepatic uptake were decreased, showing that the determination of hepatic uptake is necessary in measuring effective hepatic blood flow by the colloidal clearance method. The influence of splenic uptake is discussed in relation to hepatic blood flow measurement. (author)

Serum protein identification and quantification of the corona of 5, 15 and 80 nm gold nanoparticles

International Nuclear Information System (INIS)

Schäffler, Martin; Semmler-Behnke, Manuela; Takenaka, Shinji; Wenk, Alexander; Schleh, Carsten; Johnston, Blair D; Kreyling, Wolfgang G; Sarioglu, Hakan; Hauck, Stefanie M

2013-01-01

When nanoparticles (NP) enter the body they come into contact with body fluids containing proteins which can adsorb to their surface. These proteins may influence the NP interactions with the biological vicinity, eventually determining their biological fate inside the body. Adsorption of the most abundantly binding proteins was studied after an in vitro 24 hr incubation of monodisperse, negatively charged 5, 15 and 80 nm gold spheres (AuNP) in mouse serum by a two-step analysis: proteomic protein identification and quantitative protein biochemistry. The adsorbed proteins were separated from non-adsorbed proteins by centrifugation and gel electrophoresis and identified using a MALDI-TOF-MS-Proteomics-Analyzer. Quantitative analysis of proteins in gel bands by protein densitometry, required the focus on predominantly binding serum proteins. Numerous proteins adsorbed to the AuNP depending on their size, e.g. apolipoproteins or complement C3. The qualitative and quantitative amount of adsorbed proteins differed between 5, 15 and 80 nm AuNP. Band intensities of adsorbed proteins decreased with increasing AuNP sizes based not only on their mass but also on their surface area. Summarizing, the AuNP surface is covered with serum proteins containing transport and immune related proteins among others. Hence, protein binding depends on the size, surface area and curvature of the AuNP. (paper)

Observation of enhanced infrared absorption in silicon supersaturated with gold by pulsed laser melting of nanometer-thick gold films

Science.gov (United States)

Chow, Philippe K.; Yang, Wenjie; Hudspeth, Quentin; Lim, Shao Qi; Williams, Jim S.; Warrender, Jeffrey M.

2018-04-01

We demonstrate that pulsed laser melting (PLM) of thin 1, 5, and 10 nm-thick vapor-deposited gold layers on silicon enhances its room-temperature sub-band gap infrared absorption, as in the case of ion-implanted and PLM-treated silicon. The former approach offers reduced fabrication complexity and avoids implantation-induced lattice damage compared to ion implantation and pulsed laser melting, while exhibiting comparable optical absorptance. We additionally observed strong broadband absorptance enhancement in PLM samples made using 5- and 10-nm-thick gold layers. Raman spectroscopy and Rutherford backscattering analysis indicate that such an enhancement could be explained by absorption by a metastable, disordered and gold-rich surface layer. The sheet resistance and the diode electrical characteristics further elucidate the role of gold-supersaturation in silicon, revealing the promise for future silicon-based infrared device applications.

Au, Ag and Au:Ag colloidal nanoparticles synthesized by pulsed laser ablation as SERS substrates

Directory of Open Access Journals (Sweden)

M. Vinod

2014-12-01

Full Text Available Chemically pure colloidal suspensions of gold and silver nanoparticles were synthesized using pulsed laser ablation. The dependence of laser fluence on the surface plasmon characteristics of the nanoparticles was investigated. Au:Ag colloidal suspensions were prepared by mixing highly monodisperse Au and Ag nanocolloids. The plasmon band of these mixtures was found to be highly sensitive to Au:Ag concentration ratio and wavelength of the laser beam used in the ablation process. The Au:Ag mixture consists of almost spherical shaped nanostructures with a tendency to join with adjacent ones. The surface enhanced Raman scattering activity of the Au, Ag and Au:Ag colloidal suspensions was tested using crystal violet as probe molecules. Enhancement in Raman signal obtained with Au:Ag substrates was found to be promising and strongly depends on its plasmon characteristics.

Controlling the reproducibility of Coulomb blockade phenomena for gold nanoparticles on an organic monolayer/silicon system.

Science.gov (United States)

Caillard, L; Sattayaporn, S; Lamic-Humblot, A-F; Casale, S; Campbell, P; Chabal, Y J; Pluchery, O

2015-02-13

Two types of highly ordered organic layers were prepared on silicon modified with an amine termination for binding gold nanoparticles (AuNPs). These two grafted organic monolayers (GOMs), consisting of alkyl chains with seven or 11 carbon atoms, were grafted on oxide-free Si(111) surfaces as tunnel barriers between the silicon electrode and the AuNPs. Three kinds of colloidal AuNPs were prepared by reducing HAuCl4 with three different reactants: citrate (Turkevich synthesis, diameter ∼16 nm), ascorbic acid (diameter ∼9 nm), or NaBH4 (Natan synthesis, diameter ∼7 nm). Scanning tunnel spectroscopy (STS) was performed in a UHV STM at 40 K, and Coulomb blockade behaviour was observed. The reproducibility of the Coulomb behavior was analysed as a function of several chemical and physical parameters: size, crystallinity of the AuNPs, influence of surrounding surfactant molecules, and quality of the GOM/Si interface (degree of oxidation after the full processing). Samples were characterized with scanning tunneling microscope, STS, atomic force microscope, Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy (XPS), and high resolution transmission electronic microscope. We show that the reproducibility in observing Coulomb behavior can be as high as ∼80% with the Natan synthesis of AuNPs and GOMs with short alkyl chains.

Colloidal transport of uranium in soil: Size fractionation and characterization by field-flow fractionation-multi-detection

International Nuclear Information System (INIS)

Claveranne-Lamolere, C.; Lespes, G.; Dubascoux, St.; Potin-Gautier, M.; Claveranne-Lamolere, C.; Aupiais, J.; Pointurier, F.

2009-01-01

The aim of this study was to characterize colloids associated with uranium by using an on-line fractionation/multi-detection technique based on asymmetrical flow field-flow fractionation (As-Fl-FFF) hyphenated with UV detector, multi angle laser light scattering (MALLS) and inductively coupling plasma-mass spectrometry (ICP-MS). Moreover, thanks to the As-Fl-FFF, the different colloidal fractions were collected and characterized by a total organic carbon analyzer (TOC). Thus it is possible to determine the nature (organic or inorganic colloids), molar mass, size (gyration and hydrodynamic radii) and quantitative uranium distribution over the whole colloidal phase. In the case of the site studied, two populations are highlighted. The first population corresponds to humic-like substances with a molar mass of (1500 ± 300) g mol -1 and a hydrodynamic diameter of (2. 0 ± 0. 2) nm. The second one has been identified as a mix of carbonated nano-particles or clays with organic particles (aggregates and/or coating of the inorganic particles) with a size range hydrodynamic diameter between 30 and 450 nm. Each population is implied in the colloidal transport of uranium: maximum 1% of the uranium content in soil leachate is transported by the colloids in the site studied, according to the depth in the soil. Indeed, humic substances are the main responsible of this transport in sub-surface conditions whereas nano-particles drive the phenomenon in depth conditions. (authors)

Simultaneous synthesis of anatase colloidal and multiple-branched rutile TiO{sub 2} nanostructures

Energy Technology Data Exchange (ETDEWEB)

Nguyen, Trong Tung; Duong, Ngoc Huyen [School of Engineering Physics, Hanoi University of Science and Technology, Hanoi (Viet Nam); Mai, Xuan Dung [Dept. of Chemistry, Hanoi Pedagogical University No2, Vinh Phuc (Viet Nam)

2017-03-15

Facile synthesis of titanium dioxide (TiO{sub 2} ) nanostructures with controllability over their cystallinity, dimensions, and shape is in demand for diverse optoelectronic applications. Anatase colloidal particles and precipitates of rutile bundles were synthesized simultaneously using HCl catalyzed sol–gel process with titanium tetrachloride as Ti precursor. The crystallinity and the morphology of these two separable TiO{sub 2} phases were studied by X-ray diffraction, Raman spectroscopy, and transmission electron microscopy. The results show that by varying HCl concentration during synthesis, dimensions of colloidal anatase can be tuned from spherical particles with a diameter of 2–5 nm to nanorods of dimension of 4 nm (width) × 14 nm (length). The rutile bundles whose size increased with aging time consisted of multiple branches with elongation along c-axis. Both anatase nanorods and rutile bundles can be applied as highly efficient photocatalysts or electron conduits.

Gold Nanostructures for Surface-Enhanced Raman Spectroscopy, Prepared by Electrodeposition in Porous Silicon

Directory of Open Access Journals (Sweden)

Yukio H. Ogata

2011-04-01

Full Text Available Electrodeposition of gold into porous silicon was investigated. In the present study, porous silicon with ~100 nm in pore diameter, so-called medium-sized pores, was used as template electrode for gold electrodeposition. The growth behavior of gold deposits was studied by scanning electron microscope observation of the gold deposited porous silicon. Gold nanorod arrays with different rod lengths were prepared, and their surface-enhanced Raman scattering properties were investigated. We found that the absorption peak due to the surface plasmon resonance can be tuned by changing the length of the nanorods. The optimum length of the gold nanorods was ~600 nm for surface-enhanced Raman spectroscopy using a He-Ne laser. The reason why the optimum length of the gold nanorods was 600 nm was discussed by considering the relationship between the absorption peak of surface plasmon resonance and the wavelength of the incident laser for Raman scattering.

Colloidal CsPbBr3 Perovskite Nanocrystals: Luminescence beyond Traditional Quantum Dots.

Science.gov (United States)

Swarnkar, Abhishek; Chulliyil, Ramya; Ravi, Vikash Kumar; Irfanullah, Mir; Chowdhury, Arindam; Nag, Angshuman

2015-12-14

Traditional CdSe-based colloidal quantum dots (cQDs) have interesting photoluminescence (PL) properties. Herein we highlight the advantages in both ensemble and single-nanocrystal PL of colloidal CsPbBr3 nanocrystals (NCs) over the traditional cQDs. An ensemble of colloidal CsPbBr3 NCs (11 nm) exhibits ca. 90 % PL quantum yield with narrow (FWHM=86 meV) spectral width. Interestingly, the spectral width of a single-NC and an ensemble are almost identical, ruling out the problem of size-distribution in PL broadening. Eliminating this problem leads to a negligible influence of self-absorption and Förster resonance energy transfer, along with batch-to-batch reproducibility of NCs exhibiting PL peaks within ±1 nm. Also, PL peak positions do not alter with measurement temperature in the range of 25 to 100 °C. Importantly, CsPbBr3 NCs exhibit suppressed PL blinking with ca. 90 % of the individual NCs remain mostly emissive (on-time >85 %), without much influence of excitation power. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Large area nano-patterning /writing on gold substrate using dip - pen nanolithography (DPN)

Science.gov (United States)

Saini, Sudhir Kumar; Vishwakarma, Amit; Agarwal, Pankaj B.; Pesala, Bala; Agarwal, Ajay

2014-10-01

Dip Pen Nanolithography (DPN) is utilized to pattern large area (50μmX50μm) gold substrate for application in fabricating Nano-gratings. For Nano-writing 16-MHA ink coated AFM tip was prepared using double dipping procedure. Gold substrate is fabricated on thermally grown SiO2 substrate by depositing ˜5 nm titanium layer followed by ˜30nm gold using DC pulse sputtering. The gratings were designed using period of 800nm and 25% duty cycle. Acquired AFM images indicate that as the AFM tip proceeds for nano-writing, line width decreases from 190nm to 100nm. This occurs probably due to depreciation of 16-MHA molecules in AFM tip as writing proceeds.

Combination of Q-switched and quasi long-pulsed 1064-nm Nd:YAG laser, non-ablative 1450-nm diode laser, and ablative 10 600-nm carbon dioxide fractional laser for enlarged pores.

Science.gov (United States)

Cho, Sung Bin; Noh, Seongmin; Lee, Sang Ju; Kang, Jin Moon; Kim, Young Koo; Lee, Ju Hee

2010-07-01

Currently, there is no gold standard for the treatment of enlarged facial pores. In this report, we describe a patient with enlarged nasal pores which were treated with a combination of a non-ablative 1450-nm diode laser, a Q-switched and quasi long-pulsed 1064-nm Nd:YAG laser, and an ablative 10 600-nm carbon dioxide fractional laser system. Four months after the final treatment, the condition of the patient's pores had markedly improved, and the patient was satisfied with the results.

Non-iridescent structural colors from uniform-sized SiO2 colloids

Science.gov (United States)

Topçu, Gökhan; Güner, Tuğrul; Demir, Mustafa M.

2018-05-01

Structural colors have recently attracted interest from diverse fields of research due to their ease of fabrication and eco-friendliness. These types of colors are, in principle, achieved by periodically arranged submicron-diameter colloidal particles. The interaction of light with a structure containing long-range ordered colloidal particles leads to coloration; this usually varies depending on the angle of observation (iridescence). However, the majority of the applications demand constant color that is independent of the viewing angle (non-iridescence). In this work, silica colloids were obtained using the Stöber method at different sizes from 150 to 300 nm in an alcoholic dispersion. The casting of the dispersion on a substrate leaves behind a photonic crystal showing a colorful iridescent film. However, centrifugation and redispersion of the SiO2 particles into fresh solvent may cause the formation of small, aggregated silica domains in the new dispersion. The casting of this dispersion allows for the development of photonic glass, presumably due to the accumulation of aggregates showing stable colloidal film independent of viewing angle. Moreover, depending on the size of the silica colloids, non-iridescent photonic glasses with various colors (violet, blue, green, and orange) are obtained.

Parameters for Fabricating Nano-Au Colloids through the Electric Spark Discharge Method with Micro-Electrical Discharge Machining.

Science.gov (United States)

Tseng, Kuo-Hsiung; Chung, Meng-Yun; Chang, Chaur-Yang

2017-06-02

In this study, the Electric Spark Discharge Method (ESDM) was employed with micro-electrical discharge machining (m-EDM) to create an electric arc that melted two electrodes in deionized water (DW) and fabricated nano-Au colloids through pulse discharges with a controlled on-off duration (T ON -T OFF ) and a total fabrication time of 1 min. A total of six on-off settings were tested under normal experimental conditions and without the addition of any chemical substances. Ultraviolet-visible spectroscopy (UV-Vis), Zetasizer Nano measurements, and scanning electron microscopy-energy dispersive X-ray (SEM-EDX) analyses suggested that the nano-Au colloid fabricated at 10-10 µs (10 µs on, 10 µs off) had higher concentration and suspension stability than products made at other T ON -T OFF settings. The surface plasmon resonance (SPR) of the colloid was 549 nm on the first day of fabrication and stabilized at 532 nm on the third day. As the T ON -T OFF period increased, the absorbance (i.e., concentration) of all nano-Au colloids decreased. Absorbance was highest at 10-10 µs. The SPR peaks stabilized at 532 nm across all T ON -T OFF periods. The Zeta potential at 10-10 µs was -36.6 mV, indicating that no nano-Au agglomeration occurred and that the particles had high suspension stability.

A low cost microwave synthesis method for preparation of gold nanoparticles

International Nuclear Information System (INIS)

Ngo Vo Ke Thanh; Lam Quang Vinh; Nguyen Dang Giang; Huynh Thanh Dat

2014-01-01

The gold nanoparticles (GNPs) in 15-20 nm size range have attention for fabrication of smart sensing devices in biomedical sciences as diagnostic tools. Citrate capped GNPs are negatively charged, which can be exploited for electrostatic interactions with some positively charged biomolecules like antibody. In this study, we are developing a low-cost technique by using a common microwave system with medium power for synthesizing gold nanoparticles with using sodium citrate (Na 3 Ct) reduction in chloroauric acid (HAuCl 4 .3H 2 O). It was found that the comparing with normal thermal method, the reaction by the microwave irradiation was much faster. Besides, the effects the sodium citrate concentration and optical properties of gold nanoparticles were studied. The optical properties of gold nanoparticles suspension were characterized by using transmission electron microscopy (TEM), X-ray diffraction (XRD), and UV-Vis absorption spectroscopy (UV-Vis). Maximum absorbance wavelengths (λ max ) for gold nanoparticles are ∼ 518-524 nm with the size of 12-25 nm. The size of gold nanoparticles decreases with increasing concentration of sodium citrate. Besides, the morphology of gold nanoparticles have a spherical shape with face-centered-cubic (fcc) crystalline structure. (author)

Study of preparation and survey of radioisotopes tracer applications of gold nanoparticles in the multi-phase industrial processes

International Nuclear Information System (INIS)

Huynh Thai Kim Ngan; Trinh Cong Son; Duong Thi Bich Chi; Tran Tri Hai; Nguyen Huu Quang; Bui Trong Duy; Le Trong Nghia; Ngo Duc Tin

2014-01-01

Gold nanoparticles (AuNPs) were prepared by Turkevich and Brust method. The labeled gold in liquids is the colloidal form with nano size particle of gold. This particles is of high dispersity in the liquid phase that makes them a good physical tracer. The stability and dissolve of AuNPs in solvents such as water, toluene are hereafter discussed. The size of AuNPs was determined through UV-Visible spectroscopy (UV-Vis) and transmission electron microscope (TEM). (author)

PVA stabilized gold nanoparticles by use of unexplored albeit conventional reducing agent

Energy Technology Data Exchange (ETDEWEB)

Khanna, P K [Nanomaterials Laboratory, Centre for Materials for Electronics Technology (C-MET), Panchwati, Off Pashan Road, Pune 411008 (India); Gokhale, R [Nanomaterials Laboratory, Centre for Materials for Electronics Technology (C-MET), Panchwati, Off Pashan Road, Pune 411008 (India); Subbarao, V V.V.S. [Nanomaterials Laboratory, Centre for Materials for Electronics Technology (C-MET), Panchwati, Off Pashan Road, Pune 411008 (India); Vishwanath, A Kasi [Nanomaterials Laboratory, Centre for Materials for Electronics Technology (C-MET), Panchwati, Off Pashan Road, Pune 411008 (India); Das, B K [Nanomaterials Laboratory, Centre for Materials for Electronics Technology (C-MET), Panchwati, Off Pashan Road, Pune 411008 (India); Satyanarayana, C V.V. [National Chemical Laboratory, Pashan Road, Pune 41108 (India)

2005-07-15

Poly(vinyl alcohol) (PVA) stabilized gold nanoparticles have been prepared in aqueous medium using two different reducing viz.; hydrazine hydrate, a stronger reducing agent and sodium formaldehydesulfoxylate (SFS), a slightly weaker reducing agent. SFS is used for first ever time for reduction of gold metal salt. The PVA stabilized gold nanoparticles solutions are wine red to blood red coloured and are stable over a long period of time with no indication of aggregation. The solution shows strong visible light absorptions in the range of 520-540 nm, characteristics of gold nanoparticles. Powder X-ray diffraction patterns of freshly prepared films containing gold nanoparticles indicated particles size to be about 15 nm. Transmission electron microscopy (TEM) of a more than two-week-old sample revealed well-defined non-agglomerated spherical particles of about 50 nm diameter in solutions.

PVA stabilized gold nanoparticles by use of unexplored albeit conventional reducing agent

International Nuclear Information System (INIS)

Khanna, P.K.; Gokhale, R.; Subbarao, V.V.V.S.; Vishwanath, A. Kasi; Das, B.K.; Satyanarayana, C.V.V.

2005-01-01

Poly(vinyl alcohol) (PVA) stabilized gold nanoparticles have been prepared in aqueous medium using two different reducing viz.; hydrazine hydrate, a stronger reducing agent and sodium formaldehydesulfoxylate (SFS), a slightly weaker reducing agent. SFS is used for first ever time for reduction of gold metal salt. The PVA stabilized gold nanoparticles solutions are wine red to blood red coloured and are stable over a long period of time with no indication of aggregation. The solution shows strong visible light absorptions in the range of 520-540 nm, characteristics of gold nanoparticles. Powder X-ray diffraction patterns of freshly prepared films containing gold nanoparticles indicated particles size to be about 15 nm. Transmission electron microscopy (TEM) of a more than two-week-old sample revealed well-defined non-agglomerated spherical particles of about 50 nm diameter in solutions

Superparamagnetic core/shell GoldMag nanoparticles: size-, concentration- and time-dependent cellular nanotoxicity on human umbilical vein endothelial cells and the suitable conditions for magnetic resonance imaging.

Science.gov (United States)

Gong, Mingfu; Yang, Hua; Zhang, Song; Yang, Yan; Zhang, Dong; Qi, Yueyong; Zou, Liguang

2015-03-25

GoldMag nanoparticles (GMNPs) possess the properties of colloid gold and superparamagnetic iron oxide nanoparticles, which make them useful for delivery, separation and molecular imaging. However, because of the nanometer effect, GMNPs are highly toxic. Thus, the biosafety of GMNPs should be fully studied prior to their use in biomedicine. The main purpose of this study was to evaluate the nanotoxicity of GMNPs on human umbilical vein endothelial cells (HUVECs) and determine a suitable size, concentration and time for magnetic resonance imaging (MRI). Transmission electron microscopy showed that GMNPs had a typical shell/core structure, and the shell was confirmed to be gold using energy dispersive spectrometer analysis. The average sizes of the 30 and 50 nm GMNPs were 30.65 ± 3.15 and 49.23 ± 5.01 nm, respectively, and the shell thickness were 6.8 ± 0.65 and 8.5 ± 1.36 nm, respectively. Dynamic light scattering showed that the hydrodynamic diameter of the 30 and 50 nm GMNPs were 33.2 ± 2.68 and 53.12 ± 4.56 nm, respectively. The r 2 relaxivity of the 50 nm GMNPs was 98.65 mM(-1) s(-1), whereas it was 80.18 mM(-1) s(-1) for the 30 nm GMNPs. The proliferation, cytoskeleton, migration, tube formation, apoptosis and ROS generation of labeled HUVECs depended on the size and concentration of GMNPs and the time of exposure. Because of the higher labeling rate, the 50 nm GMNPs exhibited a significant increase in nanotoxicity compared with the 30 nm GMNPs at the same concentration and time. At no more than 25 μg/mL and 12 hours, the 50 nm GMNPs exhibited no significant nanotoxicity in HUVECs, whereas no toxicity was observed at 50 μg/mL and 24 hours for the 30 nm GMNPs. These results demonstrated that the nanotoxicity of GMNPs in HUVECs depended on size, concentration and time. Exposure to larger GMNPs with a higher concentration for a longer period of time resulted in a higher labeling rate and ROS level for HUVECs. Coupled with r 2 relaxivity, it was suggested

Hardness and Elastic Modulus on Six-Fold Symmetry Gold Nanoparticles

Science.gov (United States)

Ramos, Manuel; Ortiz-Jordan, Luis; Hurtado-Macias, Abel; Flores, Sergio; Elizalde-Galindo, José T.; Rocha, Carmen; Torres, Brenda; Zarei-Chaleshtori, Maryam; Chianelli, Russell R.

2013-01-01

The chemical synthesis of gold nanoparticles (NP) by using gold (III) chloride trihydrate (HAuCl∙3H2O) and sodium citrate as a reducing agent in aqueous conditions at 100 °C is presented here. Gold nanoparticles areformed by a galvanic replacement mechanism as described by Lee and Messiel. Morphology of gold-NP was analyzed by way of high-resolution transmission electron microscopy; results indicate a six-fold icosahedral symmetry with an average size distribution of 22 nm. In order to understand the mechanical behaviors, like hardness and elastic moduli, gold-NP were subjected to nanoindentation measurements—obtaining a hardness value of 1.72 GPa and elastic modulus of 100 GPa in a 3–5 nm of displacement at the nanoparticle’s surface. PMID:28809302

Erbium-implanted silica colloids with 80% luminescence quantum efficiency

Science.gov (United States)

Slooff, L. H.; de Dood, M. J. A.; van Blaaderen, A.; Polman, A.

2000-06-01

Silica colloids with a diameter of 240-360 nm, grown by wet chemical synthesis using ethanol, ammonia, water, and tetraethoxysilane, were implanted with 350 keV Er ions, to peak concentrations of 0.2-1.1 at. % and put onto a silicon or glass substrate. After annealing at 700-900 °C the colloids show clear room-temperature photoluminescence at 1.53 μm, with lifetimes as high as 17 ms. By comparing data of different Er concentrations, the purely radiative lifetime is estimated to be 20-22 ms, indicating a high quantum efficiency of about 80%. This high quantum efficiency indicates that, after annealing, the silica colloids are almost free of OH impurities. Spinning a layer of polymethylmethacrylate over the silica spheres results in an optically transparent nanocomposite layer, that can be used as a planar optical waveguide amplifier at 1.5 μm that is fully compatible with polymer technology.

Optical tweezers with 2.5 kHz bandwidth video detection for single-colloid electrophoresis

Science.gov (United States)

Otto, Oliver; Gutsche, Christof; Kremer, Friedrich; Keyser, Ulrich F.

2008-02-01

We developed an optical tweezers setup to study the electrophoretic motion of colloids in an external electric field. The setup is based on standard components for illumination and video detection. Our video based optical tracking of the colloid motion has a time resolution of 0.2ms, resulting in a bandwidth of 2.5kHz. This enables calibration of the optical tweezers by Brownian motion without applying a quadrant photodetector. We demonstrate that our system has a spatial resolution of 0.5nm and a force sensitivity of 20fN using a Fourier algorithm to detect periodic oscillations of the trapped colloid caused by an external ac field. The electrophoretic mobility and zeta potential of a single colloid can be extracted in aqueous solution avoiding screening effects common for usual bulk measurements.

Surface-enhanced Raman spectroscopy on laser-engineered ruthenium dye-functionalized nanoporous gold

Science.gov (United States)

Schade, Lina; Franzka, Steffen; Biener, Monika; Biener, Jürgen; Hartmann, Nils

2016-06-01

Photothermal processing of nanoporous gold with a microfocused continuous-wave laser at λ = 532 nm provides a facile means in order engineer the pore and ligament size of nanoporous gold. In this report we take advantage of this approach in order to investigate the size-dependence of enhancement effects in surface-enhanced Raman spectroscopy (SERS). Surface structures with laterally varying pore sizes from 25 nm to ≥200 nm are characterized using scanning electron microscopy and then functionalized with N719, a commercial ruthenium complex, which is widely used in dye-sensitized solar cells. Raman spectroscopy reveals the characteristic spectral features of N719. Peak intensities strongly depend on the pore size. Highest intensities are observed on the native support, i.e. on nanoporous gold with pore sizes around 25 nm. These results demonstrate the particular perspectives of laser-fabricated nanoporous gold structures in fundamental SERS studies. In particular, it is emphasized that laser-engineered porous gold substrates represent a very well defined platform in order to study size-dependent effects with high reproducibility and precision and resolve conflicting results in previous studies.

Color and texture morphing with colloids on multilayered surfaces.

Science.gov (United States)

Chen, Ziguang; Li, Shumin; Arkebauer, Andrew; Gogos, George; Tan, Li

2015-05-20

Dynamic morphing of marine species to match with environment changes in color and texture is an advanced means for surviving, self-defense, and reproduction. Here we use colloids that are placed inside a multilayered structure to demonstrate color and texture morphing. The multilayer is composed of a thermal insulating base layer, a light absorbing mid layer, and a liquid top layer. When external light of moderate intensity (∼0.2 W cm(-2)) strikes the structure, colloids inside the liquid layer will be assembled to locations with an optimal absorption. When this system is exposed to continuous laser pulses, more than 18,000 times of reversible responses are recorded, where the system requests 20 ms to start the response and another 160 ms to complete. The flexibility of our concept further allows the system to be built on a variety of light-absorbing substrates, including dyed paper, gold thin film, and amorphous silicon, with the top layer even a solid.

Facile synthesis of gold nanomaterials with unusual crystal structures.

Science.gov (United States)

Fan, Zhanxi; Huang, Xiao; Chen, Ye; Huang, Wei; Zhang, Hua

2017-11-01

Gold (Au) nanomaterials have attracted wide research attention, owing to their high chemical stability, promising catalytic properties, excellent biocompatibility, unique electronic structure and outstanding localized surface plasmon resonance (LSPR) absorption properties; all of which are closely related to their size and shape. Recently, crystal-phase-controlled synthesis of noble metal nanomaterials has emerged as a promising strategy to tune their physicochemical properties. This protocol describes the detailed experimental procedures for the crystal-phase-controlled syntheses of Au nanomaterials with unusual crystal structures under mild conditions. Briefly, pure hexagonal close-packed (hcp) Au square sheets (AuSSs) with a thickness of ∼2.4 nm are synthesized using a graphene-oxide-assisted method in which HAuCl 4 is reduced by oleylamine in a mixture of hexane and ethanol. By using pure hexane as the solvent, well-dispersed ultrathin hcp/face-centered cubic (fcc) Au nanowires with a diameter of ∼1.6 nm on graphene oxide can be obtained. Meanwhile, hcp/fcc Au square-like plates with a side length of 200-400 nm are prepared via the secondary growth of Au on the hcp AuSSs. Remarkably, hexagonal (4H) Au nanoribbons with a thickness of 2.0-6.0 nm can be synthesized with a one-pot colloidal method in which HAuCl 4 is reduced by oleylamine in a mixed solvent of hexane and 1,2-dichloropropane. It takes 17-37 h for the synthesis of these Au nanomaterials with unusual crystal structures. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) are used to characterize the resultant Au nanomaterials, which could have many promising applications, such as biosensing, near-IR photothermal therapy, catalysis and surface-enhanced Raman scattering (SERS).

Concentration Dependence of Gold Nanoparticles for Fluorescence Enhancement

Science.gov (United States)

Solomon, Joel; Wittmershaus, Bruce

Noble metal nanoparticles possess a unique property known as surface plasmon resonance in which the conduction electrons oscillate due to incoming light, dramatically increasing their absorption and scattering of light. The oscillating electrons create a varying electric field that can affect nearby molecules. The fluorescence and photostability of fluorophores can be enhanced significantly when they are near plasmonic nanoparticles. This effect is called metal enhanced fluorescence (MEF). MEF from two fluorescence organic dyes, Lucifer Yellow CH and Riboflavin, was measured with different concentrations of 50-nm colloidal gold nanoparticles (Au-NP). The concentration range of Au-NP was varied from 2.5 to 250 pM. To maximize the interaction, the dyes were chosen so their emission spectra had considerable overlap with the absorption spectra of the Au-NP, which is common in MEF studies. If the dye molecules are too close to the surface of Au-NP, fluorescence quenching can occur instead of MEF. To try to observe this difference, silica-coated Au-NP were compared to citrate-based Au-NP; however, fluorescence quenching was observed with both Au-NP. This material is based upon work supported by the National Science Foundation under Grant Number NSF-ECCS-1306157.

Theoretical analysis of gold nano-strip gap plasmon resonators

Energy Technology Data Exchange (ETDEWEB)

Soendergaard, T; Jung, J; Bozhevolnyi, S I; Della Valle, G [Department of Physics and Nanotechnology, Aalborg University, Skjernvej 4A, DK-9220 Aalborg Oest (Denmark)], E-mail: ts@nano.aau.dk

2008-10-15

Gold gap plasmon resonators consisting of two nm-thin and sub-micron-wide gold strips separated by a nm-thin air or quartz gap are considered. Scattering resonances and resonant fields are related to a model of resonances being due to counter-propagating gap plasmon polaritons forming standing waves. A small gap ({approx}10 nm) is found to result in small resonance peaks in scattering spectra but large electric field magnitude enhancement ({approx}20), whereas a large gap ({approx}100 nm) is found to result in more pronounced scattering peaks but smaller field enhancement. Design curves are presented that allow construction of gap plasmon resonators with any desired resonance wavelength in the range from the visible to the infrared, including telecom wavelengths. The relation between resonance wavelength and resonator width is close to being linear. The field magnitude enhancement mid between the gold strips is systematically investigated versus gap size and wavelength.

Facile formation of dendrimer-stabilized gold nanoparticles modified with diatrizoic acid for enhanced computed tomography imaging applications.

Science.gov (United States)

Peng, Chen; Li, Kangan; Cao, Xueyan; Xiao, Tingting; Hou, Wenxiu; Zheng, Linfeng; Guo, Rui; Shen, Mingwu; Zhang, Guixiang; Shi, Xiangyang

2012-11-07

We report a facile approach to forming dendrimer-stabilized gold nanoparticles (Au DSNPs) through the use of amine-terminated fifth-generation poly(amidoamine) (PAMAM) dendrimers modified by diatrizoic acid (G5.NH(2)-DTA) as stabilizers for enhanced computed tomography (CT) imaging applications. In this study, by simply mixing G5.NH(2)-DTA dendrimers with gold salt in aqueous solution at room temperature, dendrimer-entrapped gold nanoparticles (Au DENPs) with a mean core size of 2.5 nm were able to be spontaneously formed. Followed by an acetylation reaction to neutralize the dendrimer remaining terminal amines, Au DSNPs with a mean size of 6 nm were formed. The formed DTA-containing [(Au(0))(50)-G5.NHAc-DTA] DSNPs were characterized via different techniques. We show that the Au DSNPs are colloid stable in aqueous solution under different pH and temperature conditions. In vitro hemolytic assay, cytotoxicity assay, flow cytometry analysis, and cell morphology observation reveal that the formed Au DSNPs have good hemocompatibility and are non-cytotoxic at a concentration up to 3.0 μM. X-ray absorption coefficient measurements show that the DTA-containing Au DSNPs have enhanced attenuation intensity, much higher than that of [(Au(0))(50)-G5.NHAc] DENPs without DTA or Omnipaque at the same molar concentration of the active element (Au or iodine). The formed DTA-containing Au DSNPs can be used for CT imaging of cancer cells in vitro as well as for blood pool CT imaging of mice in vivo with significantly improved signal enhancement. With the two radiodense elements of Au and iodine incorporated within one particle, the formed DTA-containing Au DSNPs may be applicable for CT imaging of various biological systems with enhanced X-ray attenuation property and detection sensitivity.

Inverse opal photonic crystals with photonic band gaps in the visible and near-infrared

Science.gov (United States)

Jarvis, Brandon C.; Gilleland, Cody L.; Renfro, Tim; Gutierrez, Jose; Parikh, Kunjal; Glosser, R.; Landon, Preston B.

2005-08-01

Colloidal silica spheres with 200nm, 250nm, and 290nm diameters were self-assembled with single crystal crystallites 4-5mm wide and 10-15mm long. Larger spheres with diameters between 1000-2300nm were self-assembled with single crystal crystallites up to 1.5mm wide and 2mm long. The silica opals self-assembled vertically along the [100] direction of the face centered cubic lattice resulting in self-templated opals. Inverse opal photonic crystals with a partial band gap possessing a maximum in the near infrared at 3.8μm were constructed from opal templates composed of 2300nm diameter spheres with chalcogenide Ge33As12Se55 (AMTIR-1), a transparent glass in the near infrared with high refractive index. Inverse gold and gold/ polypropylene composite photonic crystals were fabricated from synthetic opal templates composed of 200-290nm silica spheres. The reflectance spectra and electrical conductance of the resulting structures is presented. Gold was infiltrated into opal templates as gold chloride and heat converted to metallic gold. Opals partially infiltrated with gold were co-infiltrated with polypropylene plastic for mechanical support prior to removal of the silica template with hydrofluoric acid.

Migration of uranium in the presence of clay colloids in a sandy aquifer

International Nuclear Information System (INIS)

Le Cointe, P.; Grambow, B.; Piscitelli, A.; Montavon, G.; Van der Lee, J.; Giffaut, E.; Schneider, V.

2010-01-01

Document available in extended abstract form only. In France, low and medium level radioactive waste of short period (nuclides with a half-life less than 31 years and an activity ranging from 100 to 1,000,000 Bq/g) is stored in concrete constructions on a surface site in Soulaines-Dhuys (Aube). The site was chosen for its simple geology: it entirely lays on an aquifer formation, the Upper Aptian sands, above a Lower Aptian impermeable clay formation. The site is surrounded by the Noues d'Amance stream, which serves as the single outlet of the groundwater on the site. The objective of this study is to improve knowledge of radionuclides migration in the aquifer formation to improve safety, using U(VI) as an example and focusing on colloids, capable of transporting U(VI) on long distances. The sediment is composed of two main phases: quartz and clay minerals (glauconite, with a small fraction of kaolinite and smectite), with relative amounts of 91 and 6% in weight, respectively. The aquifer water contains clay colloids, invisible to the eye though observed with SEM and TEM in a non disturbed sample. No signal was measured with usual light diffusion techniques and Asymmetric Flow Field-Flow Fractionation (AF4). Only the Laser Induced Breakdown Detection (LIBD) technique could characterize the size (between 30 and 70 nm) and the concentration (around 10 ppb) of the clay colloids. Batch experiments were carried out to define U(VI)-Quartz and U(VI)-Clay interactions, with U(VI) concentration, pH and pCO 2 being the studied variables. The data were modelled with the Chess geochemistry code developed at the Paris School of Mines and compared to literature. Davis applied model for U(VI)-Quartz interaction and Bradbury and Baeyens applied model for U(VI)-Illite interaction adequately describe the experimental data. To know if clay colloids can move freely in the groundwater, pore size was measured using X-ray microtomography. Nanoparticles tracing was done with

Migration of uranium in the presence of clay colloids in a sandy aquifer

Energy Technology Data Exchange (ETDEWEB)

Le Cointe, P. [Laboratoire SUBATECH, UMR 6457 Ecole des Mines/CNRS/Universite, 4 rue A. Kastler, BP 20722, 44307 Nantes Cedex 03 (France); Centre de Geosciences, Ecole des Mines de Paris, 35 rue St-Honore, 77305 Fontainebleau Cedex (France); ANDRA 1/7 rue Jean Monnet - 92298 Chatenay Malabry Cedex (France); Grambow, B.; Piscitelli, A.; Montavon, G. [Laboratoire SUBATECH, UMR 6457 Ecole des Mines/CNRS/Universite, 4 rue A. Kastler, BP 20722, 44307 Nantes Cedex 03 (France); Van der Lee, J. [EDF R ete D, Site des Renardieres, Route de Sens - Ecuelles, 77250 Moret sur Loing (France); Giffaut, E.; Schneider, V. [ANDRA 1/7 rue Jean Monnet - 92298 Chatenay Malabry Cedex (France)

2010-07-01

Document available in extended abstract form only. In France, low and medium level radioactive waste of short period (nuclides with a half-life less than 31 years and an activity ranging from 100 to 1,000,000 Bq/g) is stored in concrete constructions on a surface site in Soulaines-Dhuys (Aube). The site was chosen for its simple geology: it entirely lays on an aquifer formation, the Upper Aptian sands, above a Lower Aptian impermeable clay formation. The site is surrounded by the Noues d'Amance stream, which serves as the single outlet of the groundwater on the site. The objective of this study is to improve knowledge of radionuclides migration in the aquifer formation to improve safety, using U(VI) as an example and focusing on colloids, capable of transporting U(VI) on long distances. The sediment is composed of two main phases: quartz and clay minerals (glauconite, with a small fraction of kaolinite and smectite), with relative amounts of 91 and 6% in weight, respectively. The aquifer water contains clay colloids, invisible to the eye though observed with SEM and TEM in a non disturbed sample. No signal was measured with usual light diffusion techniques and Asymmetric Flow Field-Flow Fractionation (AF4). Only the Laser Induced Breakdown Detection (LIBD) technique could characterize the size (between 30 and 70 nm) and the concentration (around 10 ppb) of the clay colloids. Batch experiments were carried out to define U(VI)-Quartz and U(VI)-Clay interactions, with U(VI) concentration, pH and pCO{sub 2} being the studied variables. The data were modelled with the Chess geochemistry code developed at the Paris School of Mines and compared to literature. Davis applied model for U(VI)-Quartz interaction and Bradbury and Baeyens applied model for U(VI)-Illite interaction adequately describe the experimental data. To know if clay colloids can move freely in the groundwater, pore size was measured using X-ray microtomography. Nanoparticles tracing was done with

Gold(III) biosorption and bioreduction with the brown alga Fucus vesiculosus.

Science.gov (United States)

Mata, Y N; Torres, E; Blázquez, M L; Ballester, A; González, F; Muñoz, J A

2009-07-30

In this paper, the bioreduction of Au(III) to Au(0) using biomass of the brown alga Fucus vesiculosus was investigated. The recovery and reduction process took place in two stages with an optimum pH range of 4-9 with a maximum uptake obtained at pH 7. In the first stage, an induction period previous to gold reduction, the variation of pH, redox potential and gold concentration in solution was practically negligible and no color change was observed. In the second stage, the gold reduction was followed by a sharp decrease of gold concentration, pH and redox potential of solution and a color change from yellow to reddish purple. Hydroxyl groups present in the algal polysaccharides were involved in the gold bioreduction. Metallic gold was detected as microprecipitates on the biomass surface and in colloidal form as nanoparticles in the solution. Bioreduction with F. vesiculosus could be an alternative and environmentally friendly process that can be used for recovering gold from dilute hydrometallurgical solutions and leachates of electronic scraps, and for the synthesis of gold nanoparticles of different size and shape.

Gold(III) biosorption and bioreduction with the brown alga Fucus vesiculosus

International Nuclear Information System (INIS)

Mata, Y.N.; Torres, E.; Blazquez, M.L.; Ballester, A.; Gonzalez, F.; Munoz, J.A.

2009-01-01

In this paper, the bioreduction of Au(III) to Au(0) using biomass of the brown alga Fucus vesiculosus was investigated. The recovery and reduction process took place in two stages with an optimum pH range of 4-9 with a maximum uptake obtained at pH 7. In the first stage, an induction period previous to gold reduction, the variation of pH, redox potential and gold concentration in solution was practically negligible and no color change was observed. In the second stage, the gold reduction was followed by a sharp decrease of gold concentration, pH and redox potential of solution and a color change from yellow to reddish purple. Hydroxyl groups present in the algal polysaccharides were involved in the gold bioreduction. Metallic gold was detected as microprecipitates on the biomass surface and in colloidal form as nanoparticles in the solution. Bioreduction with F. vesiculosus could be an alternative and environmentally friendly process that can be used for recovering gold from dilute hydrometallurgical solutions and leachates of electronic scraps, and for the synthesis of gold nanoparticles of different size and shape.

Optical limiting in gelatin stabilized Cu-PVP nanocomposite colloidal suspension

Science.gov (United States)

Tamgadge, Y. S.; Gedam, P. P.; Thakare, N. B.; Talwatkar, S. S.; Sunatkari, A. L.; Muley, G. G.

2018-05-01

This article illustrates investigations on optical limiting properties of Cu-PVP nanocomposite colloidal suspension. Gelatin stabilized Cu nanoparticles have been synthesized using chemical reduction method and thin films in PVP matrix have been obtained using spin coating technique. Thin films have been characterized by X-ray diffraction (XRD), Ultraviolet-visible (UV-vis) spectroscopy, etc. for structural and linear optical studies. Optical limiting properties of Colloidal Cu-PVP nanocomposites have been investigated at 808 nm diode CW laser. Minimum optical limiting threshold was found for GCu3-PVP nanocomposites sample. The strong optical limiting is thermal in origin as CW laser is used and effects are attributed to thermal lensing effect.

Leaching of natural colloids from forest topsoils and their relevance for phosphorus mobility.

Science.gov (United States)

Missong, Anna; Holzmann, Stefan; Bol, Roland; Nischwitz, Volker; Puhlmann, Heike; V Wilpert, Klaus; Siemens, Jan; Klumpp, Erwin

2018-09-01

The leaching of P from the upper 20cm of forest topsoils influences nutrient (re-)cycling and the redistribution of available phosphate and organic P forms. However, the effective leaching of colloids and associated P forms from forest topsoils was so far sparsely investigated. We demonstrated through irrigation experiments with undisturbed mesocosm soil columns, that significant proportions of P leached from acidic forest topsoils were associated with natural colloids. These colloids had a maximum size of 400nm. By means of Field-flow fractionation the leached soil colloids could be separated into three size fractions. The size and composition was comparable to colloids present in acidic forest streams known from literature. The composition of leached colloids of the three size classes was dominated by organic carbon. Furthermore, these colloids contained large concentrations of P which amounted between 12 and 91% of the totally leached P depending on the type of the forest soil. The fraction of other elements leached with colloids ranged between 1% and 25% (Fe: 1-25%; C org : 3-17%; Al: leaching. Leaching of total and colloid-associated P from the forest surface soil did not increase with increasing bulk soil P concentrations and were also not related to tree species. The present study highlighted that colloid-facilitated P leaching can be of higher relevance for the P leaching from forest surface soils than dissolved P and should not be neglected in soil water flux studies. Copyright © 2018 Elsevier B.V. All rights reserved.

Immobilization of rhodium complexes at thiolate monolayers on gold surfaces : Catalytic and structural studies

NARCIS (Netherlands)

Belser, T; Stöhr, Meike; Pfaltz, A

2005-01-01

Chiral rhodium-diphosphine complexes have been incorporated into self-assembled thiolate monolayers (SAMS) on gold colloids. Catalysts of this type are of interest because they combine properties of homogeneous and heterogeneous systems. In addition, it should be possible to influence the catalytic

Dependency of plasmon resonance sensitivity of colloidal gold nanoparticles on the identity of surrounding ionic media

Science.gov (United States)

Mehrdel, B.; Aziz, A. Abdul

2018-03-01

The plasmon resonance sensitivity of gold nanoparticles (AuNPs) in sodium chloride (NaCl) liquid in near-infrared to the visible spectral region was investigated. The correlation between NaCl concentration and refractive index was analyzed using concentration dependency and Lorenz-Lorenz methods. The first derivative method was applied to the measured absorption spectra to quantitatively evaluate the plasmon resonance sensitivity. To understand the influence of the identity of the surrounding medium on the plasmon resonance sensitivity, experiments were repeated by replacing NaCl with sodium hydroxide (NaOH), followed by phosphate buffered saline (PBS). Experimental results showed that NaCl is the most effective ionic surrounding medium, which gives prominent plasmon resonance response. AuNPs size can have a significant influence on the plasmon resonance sensitivity. For tiny AuNPs (∼10 nm AuNPs), the plasmon resonance is insensitive to the identity of the surrounding medium due to their low cross-section value.

Synthesis of gold nanoclusters: a fluorescent marker for water-soluble TiO2 nanotubes

International Nuclear Information System (INIS)

Ratanatawanate, Chalita; Yu Jing; Zhou Chen; Zheng Jie; Balkus, Kenneth J Jr

2011-01-01

The first example of a water-soluble wrapped titania nanotube (TNT) decorated with fluorescent gold nanoparticles has been prepared. Gold nanoparticles ∼ 1.6 nm in diameter were grown on the TiO 2 nanotubes using a thiolactic acid linker to control the size. The gold clusters emit at 660 nm in water and were imaged using confocal microscopy. The gold decorated TNTs were suspended in water by wrapping the nanotubes with poly-L-arginine.

Hybridization thermodynamics of DNA bound to gold nanoparticles

International Nuclear Information System (INIS)

Lang, Brian

2010-01-01

Isothermal Titration Calorimetry (ITC) was used to study the thermodynamics of hybridization on DNA-functionalized colloidal gold nanoparticles. When compared to the thermodynamics of hybridization of DNA that is free in solution, the differences in the values of the Gibbs free energy of reaction, Δ r G o , the enthalpy, Δ r H o , and entropy, Δ r S o , were small. The change in Δ r G o between the free and bound states was always positive but with statistical significance outside the 95% confidence interval, implying the free DNA is slightly more stable than when in the bound state. Additionally, ITC was also able to reveal information about the binding stoichiometry of the hybridization reactions on the DNA-functionalized gold nanoparticles, and indicates that there is a significant fraction of the DNA on gold nanoparticle surface that is unavailable for DNA hybridization. Furthermore, the fraction of available DNA is dependent on the spacer group on the DNA that is used to span the gold surface from that to the probe DNA.

Modeling of protein electrophoresis in silica colloidal crystals having brush layers of polyacrylamide

Science.gov (United States)

Birdsall, Robert E.; Koshel, Brooke M.; Hua, Yimin; Ratnayaka, Saliya N.; Wirth, Mary J.

2013-01-01

Sieving of proteins in silica colloidal crystals of mm dimensions is characterized for particle diameters of nominally 350 and 500 nm, where the colloidal crystals are chemically modified with a brush layer of polyacrylamide. A model is developed that relates the reduced electrophoretic mobility to the experimentally measurable porosity. The model fits the data with no adjustable parameters for the case of silica colloidal crystals packed in capillaries, for which independent measurements of the pore radii were made from flow data. The model also fits the data for electrophoresis in a highly ordered colloidal crystal formed in a channel, where the unknown pore radius was used as a fitting parameter. Plate heights as small as 0.4 μm point to the potential for miniaturized separations. Band broadening increases as the pore radius approaches the protein radius, indicating that the main contribution to broadening is the spatial heterogeneity of the pore radius. The results quantitatively support the notion that sieving occurs for proteins in silica colloidal crystals, and facilitate design of new separations that would benefit from miniaturization. PMID:23229163

Direct formation of gold nanorods on surfaces using polymer-immobilised gold seeds

Directory of Open Access Journals (Sweden)

Majid K. Abyaneh

2016-06-01

Full Text Available Herein, we present the formation of gold nanorods (GNRs on novel gold–poly(methyl methacrylate (Au–PMMA nanocomposite substrates with unprecedented growth control through the polymer molecular weight (Mw and gold-salt-to-polymer weight ratio. For the first time, GNRs have been produced by seed-mediated direct growth on surfaces that were pre-coated with polymer-immobilised gold seeds. A Au–PMMA nanocomposite formed by UV photoreduction has been used as the gold seed. The influence of polymer Mw and gold concentration on the formation of GNRs has been investigated and discussed. The polymer nanocomposite formed with a lower Mw PMMA and 20 wt % gold salt provides a suitable medium for growing well-dispersed GNRs. In this sample, the average dimension of produced GNRs is 200 nm in length with aspect ratios up to 10 and a distribution of GNRs to nanoparticles of nearly 22%. Suitable characterization techniques such as AFM and SEM have been used to support concept of the proposed growth method.

Investigation of Different Colloidal Porous Silicon Solutions and Their Composite Solid Matrix Rods by Optical Techniques

Science.gov (United States)

Khan, M. Naziruddin; Aldalbahi, Ali; Almohammedi, Abdullah

2018-03-01

Colloidal porous silicon (PSi) in different solvents was synthesized by simple chemical etching. Colloidal solutions were then prepared using different quantities of silicon wafer pieces (Pcs) and chloroplatinic (Pt) acid in catalyst solution. The effect on the properties of the colloidal solutions and composite rods were investigated using various optical characterization techniques. Absorption and photoluminescence (PL) intensity of the colloidal PSi solutions are observed to depend on the quantity of wafer Pcs, the Pt-solution, and the porosity formation on the wafer surface. The morphological structure of the PSi in a solvent and the solid-rod environments were studied using field-emission scanning electron microscopy (FE-SEM) and were observed to have different structures. A mono-oriented structure of PSi exists in tetrahydrofuran, which has stereo orientation in dioxane and dimethylsulfoxide (approximately 5-8 nm as confirmed using high resolution transmission electron microscopy). Subsequently, some colloidal PSi solutions were directly embedded in three types of sol-gel-based matrices, silica, ormosils (or organically modified silica) and polymer, which easily generated solid rods. Spontaneous emission (SE) of the PSi solutions and their composite rods were examined using a high power picosecond 355 nm laser source. The emitted PL and SE signals of the colloidal PSi solutions were dependent on the Pt volume, nature of the solvent, quantity of Si wafer piece, and pumping energy. The response of SE signals from the PSi composites rods is an interesting phenomenon, and such nanocomposites may be used for future research on light amplification.

Stability and biocompatibility of photothermal gold nanorods after lyophilization and sterilization

Energy Technology Data Exchange (ETDEWEB)

Gomez, Leyre [Department of Chemical Engineering, Nanoscience Institute of Aragon (INA), C/ Mariano Esquillor, R and D Building, University of Zaragoza, 50018 Zaragoza (Spain); Cebrian, Virginia [CIBER de Bioingeniería, Biomateriales y Nanomedicina, CIBER-BBN, Zaragoza (Spain); Hospital Universitario La Paz-IdiPAZ, Paseo de la Castellana 261, 28046 Madrid (Spain); Martin-Saavedra, Francisco [Hospital Universitario La Paz-IdiPAZ, Paseo de la Castellana 261, 28046 Madrid (Spain); CIBER de Bioingeniería, Biomateriales y Nanomedicina, CIBER-BBN, Zaragoza (Spain); Arruebo, Manuel, E-mail: arruebom@unizar.es [Department of Chemical Engineering, Nanoscience Institute of Aragon (INA), C/ Mariano Esquillor, R and D Building, University of Zaragoza, 50018 Zaragoza (Spain); CIBER de Bioingeniería, Biomateriales y Nanomedicina, CIBER-BBN, Zaragoza (Spain); Vilaboa, Nuria [Hospital Universitario La Paz-IdiPAZ, Paseo de la Castellana 261, 28046 Madrid (Spain); CIBER de Bioingeniería, Biomateriales y Nanomedicina, CIBER-BBN, Zaragoza (Spain); Santamaria, Jesus, E-mail: Jesus.Santamaria@unizar.es [Department of Chemical Engineering, Nanoscience Institute of Aragon (INA), C/ Mariano Esquillor, R and D Building, University of Zaragoza, 50018 Zaragoza (Spain); CIBER de Bioingeniería, Biomateriales y Nanomedicina, CIBER-BBN, Zaragoza (Spain)

2013-10-15

Graphical abstract: - Highlights: • Morphological changes are observed for CTABr capped gold nanorods over time. • Polystyrenesulfonate (PSS) and polyethyleneglycol (PEG) coated nanorods are stable. • Re-suspendible and sterilizable colloids are prepared using those capping agents. • Those materials are efficient heat sinks potentially used in photothermal therapy. - Abstract: Suspensions in phosphate buffered saline (PBS) of gold nanorods stabilized with cetyltrimethyl ammonium chloride (CTABr), polystyrenesulfonate (PSS) and methyl-polyethyleneglycol-thiol (m-PEG-SH) have been prepared and the evolution of their colloidal stability and plasmonic response over time has been evaluated. Their performance after lyophilization, alcoholic sterilization and resuspension has also been characterized. Sub-cytotoxic doses on HeLa cells were calculated for the three surface functionalizations used. Their heating efficiency at different exposure times was also evaluated after being irradiated with near infrared light. The best results were obtained for m-PEG-SH stabilized rods, which were not only stable, sterilizable and lyophilizable, but also biocompatible at all doses tested, showing potential as a stable, re-suspendible and biocompatible hyperthermic agent.

Stability and biocompatibility of photothermal gold nanorods after lyophilization and sterilization

International Nuclear Information System (INIS)

Gomez, Leyre; Cebrian, Virginia; Martin-Saavedra, Francisco; Arruebo, Manuel; Vilaboa, Nuria; Santamaria, Jesus

2013-01-01

Graphical abstract: - Highlights: • Morphological changes are observed for CTABr capped gold nanorods over time. • Polystyrenesulfonate (PSS) and polyethyleneglycol (PEG) coated nanorods are stable. • Re-suspendible and sterilizable colloids are prepared using those capping agents. • Those materials are efficient heat sinks potentially used in photothermal therapy. - Abstract: Suspensions in phosphate buffered saline (PBS) of gold nanorods stabilized with cetyltrimethyl ammonium chloride (CTABr), polystyrenesulfonate (PSS) and methyl-polyethyleneglycol-thiol (m-PEG-SH) have been prepared and the evolution of their colloidal stability and plasmonic response over time has been evaluated. Their performance after lyophilization, alcoholic sterilization and resuspension has also been characterized. Sub-cytotoxic doses on HeLa cells were calculated for the three surface functionalizations used. Their heating efficiency at different exposure times was also evaluated after being irradiated with near infrared light. The best results were obtained for m-PEG-SH stabilized rods, which were not only stable, sterilizable and lyophilizable, but also biocompatible at all doses tested, showing potential as a stable, re-suspendible and biocompatible hyperthermic agent

Anisotropic Model Colloids

NARCIS (Netherlands)

van Kats, C.M.

2008-01-01

The driving forces for fundamental research in colloid science are the ability to manage the material properties of colloids and to unravel the forces that play a role between colloids to be able to control and understand the processes where colloids play an important role. Therefore we are

Polymers at interfaces and in colloidal dispersions.

Science.gov (United States)

Fleer, Gerard J

2010-09-15

This review is an extended version of the Overbeek lecture 2009, given at the occasion of the 23rd Conference of ECIS (European Colloid and Interface Society) in Antalya, where I received the fifth Overbeek Gold Medal awarded by ECIS. I first summarize the basics of numerical SF-SCF: the Scheutjens-Fleer version of Self-Consistent-Field theory for inhomogeneous systems, including polymer adsorption and depletion. The conformational statistics are taken from the (non-SCF) DiMarzio-Rubin lattice model for homopolymer adsorption, which enumerates the conformational details exactly by a discrete propagator for the endpoint distribution but does not account for polymer-solvent interaction and for the volume-filling constraint. SF-SCF corrects for this by adjusting the field such that it becomes self-consistent. The model can be generalized to more complex systems: polydispersity, brushes, random and block copolymers, polyelectrolytes, branching, surfactants, micelles, membranes, vesicles, wetting, etc. On a mean-field level the results are exact; the disadvantage is that only numerical data are obtained. Extensions to excluded-volume polymers are in progress. Analytical approximations for simple systems are based upon solving the Edwards diffusion equation. This equation is the continuum variant of the lattice propagator, but ignores the finite segment size (analogous to the Poisson-Boltzmann equation without a Stern layer). By using the discrete propagator for segments next to the surface as the boundary condition in the continuum model, the finite segment size can be introduced into the continuum description, like the ion size in the Stern-Poisson-Boltzmann model. In most cases a ground-state approximation is needed to find analytical solutions. In this way realistic analytical approximations for simple cases can be found, including depletion effects that occur in mixtures of colloids plus non-adsorbing polymers. In the final part of this review I discuss a

Structural characterization and plasmonic properties of two-dimensional arrays of hydrophobic large gold nanoparticles fabricated by Langmuir-Blodgett technique

Energy Technology Data Exchange (ETDEWEB)

Ishida, Takuya; Tachikiri, Yuki; Sako, Takayuki [Department of Materials Physics and Chemistry, Graduate School of Engineering, Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395 (Japan); Takahashi, Yukina, E-mail: yukina@mail.cstm.kyushu-u.ac.jp [Department of Applied Chemistry, Faculty of Engineering, Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395 (Japan); Yamada, Sunao, E-mail: yamada@mail.cstm.kyushu-u.ac.jp [Department of Applied Chemistry, Faculty of Engineering, Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395 (Japan); Center for Future Chemistry, Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395 (Japan)

2017-05-15

Highlights: • Hydrophobic gold nanoparticles (AuNPs) by our method were large and stable enough. • Two-dimensional (2D) arrays of the AuNPs were obtained by Langmuir-Blodgett method with polyethylene glycol. • The plasmon resonant wavelength of the 2D arrays can be controlled by the diameter. - Abstract: We have succeeded in fabricating two-dimensional (2D) arrays of larger gold nanoparticles (AuNPs) (diameters 17, 28, and 48 nm) by Langmuir-Blodgett (LB) method. Although the particle size of AuNPs is one of the most important factors in order to control the optical properties of 2D arrays, there have been reported only the size of less than ∼20 nm. This is a first report on the bottom-up fabrication of 2D arrays consisting of hydrophobic AuNP with the diameter of ∼50 nm, of which the size is expected to obtain maximum near-field effects. Octadecylthiolate-capped AuNPs (ODT-AuNPs) which were prepared by our method could be re-dispersed in chloroform even after drying completely, realizing the spreading of the colloidal chloroform solution onto the water surface. Accordingly, densely-packed 2D LB films of ODT-AuNPs could be fabricated on an indium-tin-oxide substrate, when water as the subphase and polyethylene glycol (PEG) as an amphiphilic agent were used. PEG played an important role to form densely-packed film uniformly due to increasing affinity between hydrophobic AuNP and water. Absorption spectra of the films revealed that the resonance wavelengths of plasmon oscillation through interparticle plasmon coupling were clearly correlated with the particle sizes rather than deposition densities.

Laser induced photoluminescence from Ge{sub 28}Se{sub 60}Sb{sub 12} chalcogenide nano colloids

Energy Technology Data Exchange (ETDEWEB)

Tintu, R., E-mail: tintu_tillanivas@yahoo.co.in [School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam-686560 (India); Nampoori, V.P.N.; Radhakrishnan, P.; Thomas, Sheenu [International School of Photonics, Cochin University of Science and Technology, Cochin 689110 (India); Unnikrishnan, N.V. [School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam-686560 (India)

2013-04-01

We report the observation of two-photon induced photoluminescence from Ge{sub 28}Se{sub 60}Sb{sub 12} nano colloid solutions using frequency doubled Nd:YAG laser. Quadratic emission intensity dependence verifies the two photon absorption for the observed luminescence at an excitation of 532 nm. The optical band gap of the material is found to be tunable depending on the cluster size of the nano colloids. The cluster formation and the dependence of the cluster size with concentration were confirmed by the SEM analysis. Confocal imaging was done to confirm the emission from the clusters in the nano colloid solutions.

Gold nanoparticles supported on magnesium oxide for CO oxidation

Science.gov (United States)

Carabineiro, Sónia Ac; Bogdanchikova, Nina; Pestryakov, Alexey; Tavares, Pedro B.; Fernandes, Lisete Sg; Figueiredo, José L.

2011-06-01

Au was loaded (1 wt%) on a commercial MgO support by three different methods: double impregnation, liquid-phase reductive deposition and ultrasonication. Samples were characterised by adsorption of N2 at -96°C, temperature-programmed reduction, high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction. Upon loading with Au, MgO changed into Mg(OH)2 (the hydroxide was most likely formed by reaction with water, in which the gold precursor was dissolved). The size range for gold nanoparticles was 2-12 nm for the DIM method and 3-15 nm for LPRD and US. The average size of gold particles was 5.4 nm for DIM and larger than 6.5 for the other methods. CO oxidation was used as a test reaction to compare the catalytic activity. The best results were obtained with the DIM method, followed by LPRD and US. This can be explained in terms of the nanoparticle size, well known to determine the catalytic activity of gold catalysts.

Gold nanoparticles supported on magnesium oxide for CO oxidation

Directory of Open Access Journals (Sweden)

Bogdanchikova Nina

2011-01-01

Full Text Available Abstract Au was loaded (1 wt% on a commercial MgO support by three different methods: double impregnation, liquid-phase reductive deposition and ultrasonication. Samples were characterised by adsorption of N2 at -96°C, temperature-programmed reduction, high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction. Upon loading with Au, MgO changed into Mg(OH2 (the hydroxide was most likely formed by reaction with water, in which the gold precursor was dissolved. The size range for gold nanoparticles was 2-12 nm for the DIM method and 3-15 nm for LPRD and US. The average size of gold particles was 5.4 nm for DIM and larger than 6.5 for the other methods. CO oxidation was used as a test reaction to compare the catalytic activity. The best results were obtained with the DIM method, followed by LPRD and US. This can be explained in terms of the nanoparticle size, well known to determine the catalytic activity of gold catalysts.

Laser ablative nanostructuring of Au in liquid ambience in continuous wave illumination regime

Science.gov (United States)

Kucherik, A. O.; Kutrovskaya, S. V.; Arakelyan, S. M.; Ryabchikov, Y. V.; Al-Kattan, A.; Kabashin, A. V.; Itina, T. E.

2016-03-01

Gold nanoparticles (Au NPs) attract particular attention because of their unique size-dependent chemical, physicochemical and optical properties and, hence, their potential applications in catalysis, nanoelectronics, photovoltaics and medicine. In particular, laser-produced colloidal nanoparticles are not only biocompatible, but also reveal unique chemical properties. Different laser systems can be used for synthesis of these colloids, varying from continuous wave (CW) to ultra-short femtosecond lasers. The choice of an optimum laser system is still a challenge in application development. To bring more light at this issue, we investigate an influence of laser parameters on nanoparticle formation from a gold target immersed in deionized water. First, an optical diagnostics of laser-induced hydrodynamic processes taking place near the gold surface is performed. Then, gold nanoparticle colloids with average particle sizes smaller than 10 nm and a very narrow dispersion are shown to be formed by CW laser ablation. The obtained results are compared with the ones obtained by using the second harmonics and with previous results obtained by using femtosecond laser systems.

Emission dynamics of hybrid plasmonic gold/organic GaN nanorods

Science.gov (United States)

Mohammadi, F.; Schmitzer, H.; Kunert, G.; Hommel, D.; Ge, J.; Duscher, G.; Langbein, W.; Wagner, H. P.

2017-12-01

We studied the emission of bare and aluminum quinoline (Alq3)/gold coated wurtzite GaN nanorods by temperature- and intensity-dependent time-integrated and time-resolved photoluminescence (PL). The GaN nanorods of ˜1.5 μm length and ˜250 nm diameter were grown by plasma-assisted molecular beam epitaxy. Gold/Alq3 coated GaN nanorods were synthesized by organic molecular beam deposition. The near band-edge and donor-acceptor pair luminescence was investigated in bare GaN nanorods and compared with multilevel model calculations providing the dynamical parameters for electron-hole pairs, excitons, impurity bound excitons, donors and acceptors. Subsequently, the influence of a 10 nm gold coating without and with an Alq3 spacer layer was studied and the experimental results were analyzed with the multilevel model. Without a spacer layer, a significant PL quenching and lifetime reduction of the near band-edge emission is found. The behavior is attributed to surface band-bending and Förster energy transfer from excitons to surface plasmons in the gold layer. Inserting a 5 nm Alq3 spacer layer reduces the PL quenching and lifetime reduction which is consistent with a reduced band-bending and Förster energy transfer. Increasing the spacer layer to 30 nm results in lifetimes which are similar to uncoated structures, showing a significantly decreased influence of the gold coating on the excitonic dynamics.

Gold-Pluronic core-shell nanoparticles: synthesis, characterization and biological evaluation

Energy Technology Data Exchange (ETDEWEB)

Simon, Timea; Boca, Sanda [Babes-Bolyai University, Nanobiophotonics and Laser Microspectroscopy Center, Interdisciplinary Research Institute on Bio-Nano-Sciences and Faculty of Physics (Romania); Biro, Dominic [Sapientia University, Department of Mechanical Engineering, Faculty of Technical and Human Sciences (Romania); Baldeck, Patrice [Universite Joseph Fourier and CNRS, Laboratoire Interdisciplinaire de Physique, UMR 5588, CNRS (France); Astilean, Simion, E-mail: simion.astilean@phys.ubbcluj.ro [Babes-Bolyai University, Nanobiophotonics and Laser Microspectroscopy Center, Interdisciplinary Research Institute on Bio-Nano-Sciences and Faculty of Physics (Romania)

2013-04-15

This study presents the synthesis of gold-Pluronic core-shell nanoparticles by a two-step method and investigates their biological impact on cancer cells, specifically nanoparticle internalization and cytotoxicity. Uniform, 9-10-nm-sized, hydrophobic gold nanoparticles were synthesized in organic phase by reducing gold salt with oleylamine, after which oleylamine-protected gold nanoparticles were phase-transferred into aqueous medium using Pluronic F127 block copolymer, resulting in gold-Pluronic core-shell nanoparticles with a mean hydrodynamic diameter of {approx}35 nm. The formation and phase-transfer of gold nanoparticles were analyzed by UV-Vis absorption spectroscopy, transmission electron microscopy, and dynamic light scattering. The obtained gold-Pluronic core-shell nanoparticles proved to be highly stable in salted solution. Cytotoxicity tests showed no modification of cellular viability in the presence of properly purified particles. Furthermore, dark-field cellular imaging demonstrated that gold-Pluronic nanoparticles were able to be efficiently uptaken by cells, being internalized through nonspecific endocytosis. The high stability, proven biocompatibility, and imaging properties of gold-Pluronic core-shell nanoparticles hold promise for relevant intracellular applications, with such a design providing the feasibility to combine all multiple functionalities in one nanoparticle for simultaneous detection and imaging.

Impact of colloids on uranium transport in groundwater applied to the Aube radioactive waste disposal

International Nuclear Information System (INIS)

Le Cointe, Pierre

2011-01-01

The presence of colloids, known vectors of radionuclides and chemical contaminants in groundwater, has been identified in groundwater at the Aube radioactive waste disposal in 2004. This thesis aims to characterize these colloids, and to determine their potential impact in the transport of Uranium, chosen as the element of interest for this study. The identified 60 nm in diameter clay colloids and the fulvic and humic acids can move in Aptian groundwater, as indirectly evidenced by column experiments. A feasibility study of a in situ test has been done through a transport modeling to confirm the colloid mobility at the field scale. Using the conditions of the study, the clay colloids do not influence Uranium transport. Even with the greatest concentration assumed on site, they have a very limited impact on the mobilization of Uranium, in the pH range measured on site. On the contrary, the organic colloids, despite their low concentration, can facilitate Uranium transport, the uranyl - organic acid chemical bond being exceptionally strong. Therefore their low concentration in groundwater makes their impact on uranium mobility equally insignificant. (author)

Optics of colloidal quantum-confined CdSe nanoscrolls

Energy Technology Data Exchange (ETDEWEB)

Vasiliev, R B; Sokolikova, M S [M. V. Lomonosov Moscow State University, Moscow (Russian Federation); Vitukhnovskii, A G; Ambrozevich, S A; Selyukov, A S; Lebedev, V S [P N Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2015-09-30

Nanostructures in the form of 1.2-nm-thick colloidal CdSe nanoplatelets rolled into scrolls are investigated. The morphology of these scrolls is analysed and their basic geometric parameters are determined (diameter 29 nm, longitudinal size 100 – 150 nm) by TEM microscopy. Absorption and photoluminescence spectra of these objects are recorded, and the luminescence decay kinetics is studied. It is shown that the optical properties of CdSe nanoscrolls differ significantly from the properties of CdSe quantum dots and that these nanoscrolls are attractive for nanophotonic devices due to large oscillator strengths of the transition, small widths of excitonic peaks and short luminescence decay times. Nanoscrolls can be used to design hybrid organic–inorganic pure-color LEDs with a high luminescence quantum yield and low operating voltages. (optics and technology of nanostructures)

Microbial biosynthesis of nontoxic gold nanoparticles

International Nuclear Information System (INIS)

Roy, Swarup; Das, Tapan Kumar; Maiti, Guru Prasad; Basu, Utpal

2016-01-01

Graphical abstract: The manuscript deals with the fungus mediated optimized biologically synthesized GNPs using Aspergillus foetidus and characterization of biosynthesized GNPs using various physico-chemical methods. The fairly stable synthesized nanoparticles have size in the range of 10–40 nm. Cytotoxicity study of biosynthesized GNPs on Human lung cancer cell line A549 showed no significant toxicity of GNPs. - Highlights: • A novel biosynthesis process of GNPs using Aspergillus foetidus. • Biosynthesized GNPs are in the range of 10–40 nm as observed from TEM. • This process of synthesis is an optimized biosynthesis process of GNPs. • Biosynthesized GNPs are noncytotoxic against A549 cell line. - Abstract: We study the extracellular biosynthesis of gold nanoparticles (GNPs) using the fungal species Aspergillus foetidus. The formation of GNPs were initially monitored by visual observation and then characterized with the help of various characterization techniques. X-ray diffraction (XRD) results revealed distinctive formation of face centered cubic crystalline GNPs. From field emission scanning electron microscopy (FESEM) the morphology of the nanoparticles were found to be roughly spherical and within the size range of 30–50 nm. The spherical and polydispersed GNPs in the range of 10–40 nm were observed by transmission electron microscopy (TEM) analysis. It was established that alkaline pH, 1 mM gold salt concentration and 75 °C temperature were the respective optimum parameter for biosynthesis of GNPs. Cell cytotoxicity of GNP was compared with that of normal gold salt solution on A549 cell. The A549 cell growth in presence of GNPs was found to be comparatively less toxic than the gold ion.

Microbial biosynthesis of nontoxic gold nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Roy, Swarup, E-mail: swaruproy@klyuniv.ac.in [Department of Biochemistry and Biophysics, University of Kalyani, Kalyani 741235, West Bengal (India); Das, Tapan Kumar [Department of Biochemistry and Biophysics, University of Kalyani, Kalyani 741235, West Bengal (India); Maiti, Guru Prasad [Department of Molecular Biology and Biotechnology, University of Kalyani, Kalyani 741235, West Bengal (India); Department of Anesthesiology, Texas Tech University Health science Center, 3601 4th Street, Lubbock, TX 79430 (United States); Basu, Utpal [Department of Molecular Biology and Biotechnology, University of Kalyani, Kalyani 741235, West Bengal (India)

2016-01-15

Graphical abstract: The manuscript deals with the fungus mediated optimized biologically synthesized GNPs using Aspergillus foetidus and characterization of biosynthesized GNPs using various physico-chemical methods. The fairly stable synthesized nanoparticles have size in the range of 10–40 nm. Cytotoxicity study of biosynthesized GNPs on Human lung cancer cell line A549 showed no significant toxicity of GNPs. - Highlights: • A novel biosynthesis process of GNPs using Aspergillus foetidus. • Biosynthesized GNPs are in the range of 10–40 nm as observed from TEM. • This process of synthesis is an optimized biosynthesis process of GNPs. • Biosynthesized GNPs are noncytotoxic against A549 cell line. - Abstract: We study the extracellular biosynthesis of gold nanoparticles (GNPs) using the fungal species Aspergillus foetidus. The formation of GNPs were initially monitored by visual observation and then characterized with the help of various characterization techniques. X-ray diffraction (XRD) results revealed distinctive formation of face centered cubic crystalline GNPs. From field emission scanning electron microscopy (FESEM) the morphology of the nanoparticles were found to be roughly spherical and within the size range of 30–50 nm. The spherical and polydispersed GNPs in the range of 10–40 nm were observed by transmission electron microscopy (TEM) analysis. It was established that alkaline pH, 1 mM gold salt concentration and 75 °C temperature were the respective optimum parameter for biosynthesis of GNPs. Cell cytotoxicity of GNP was compared with that of normal gold salt solution on A549 cell. The A549 cell growth in presence of GNPs was found to be comparatively less toxic than the gold ion.