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https://www.readbyqxmd.com/read/28092122/how-size-determines-the-value-of-gold-economic-aspects-of-wet-chemical-and-laser-based-metal-colloid-synthesis
#1
Sandra Jendrzej, Bilal Gökce, Matthias Epple, Stephan Barcikowski
Gold is one of the most valuable materials, but its monetary value is even enhanced by size reduction from bullions to colloidal nanoparticles by a factor of 400. Wet-chemical reduction with subsequent centrifugation and pulsed laser ablation in liquids are frequently used for pure colloidal gold synthesis. Both methods provide similar physicochemical nanoparticle properties but are quite different synthesis techniques. However, surprisingly little is discussed about cost effects inherent to those methods. Both methods have in common that labor effort poses the majority of synthesis costs...
January 16, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28091991/trophic-transfer-and-effects-of-gold-nanoparticles-aunps-in-gammarus-fossarum-from-contaminated-periphytic-biofilm
#2
Magalie Baudrimont, Jennifer Andrei, Stéphane Mornet, Patrice Gonzalez, Nathalie Mesmer-Dudons, Pierre-Yves Gourves, Ali Jaffal, Odile Dedourge-Geffard, Alain Geffard, Olivier Geffard, Jeanne Garric, Agnès Feurtet-Mazel
This work addressed the trophic transfer and effects of functionalized gold nanoparticles (AuNPs) from periphytic biofilms to the crustacean Gammarus fossarum. Biofilms were exposed for 48 h to 10 nm positively charged functionalized AuNPs at two concentrations, 4.6 and 46 mg/L, and crustaceans G. fossarum grazed on these for 7 days, with daily biofilm renewal. Gold bioaccumulation in biofilm and crustacean were measured to estimate the trophic transfer ratio of these AuNP, and, for the first time, a transcriptomic approach and transmission electron microscopy observations in the crustacean were made...
January 13, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28091676/hemispherical-platinum%C3%A2-%C3%A2-silver-core%C3%A2-%C3%A2-shell-nanoparticles-for-mirna-detection
#3
Elaine Spain, Kellie Adamson, Mohammad Elshahawy, Isabella Bray, Tia E Keyes, Raymond L Stallings, Robert J Forster
Defects within a self-assembled monolayer (SAM) of dodecanethiol on gold have been used as nucleation sites for the electrodeposition of mushroom shaped platinum nanoparticles (PtNPs). The top surfaces of these PtNPs were then decorated with a layer of silver creating a hemispherical - platinum : silver core : shell nanoparticle (Pt-AgNP). Thiolated probe strand miRNA was then immobilised onto the upper silver surface. These regioselectively modified particles were desorbed by applying a current jump to yield nanoparticles capable of hybridising to a complementary miRNA target with electrocatalysis occurring on the non-functionalized lower surface...
January 16, 2017: Analyst
https://www.readbyqxmd.com/read/28091639/gold-nanoparticles-stabilized-by-cationic-carbosilane-dendrons-synthesis-and-biological-properties
#4
Cornelia E Peña-González, Elzbieta Pedziwiatr-Werbicka, Dzmitry Shcharbin, Carlos Guerrero-Beltrán, Viktar Abashkin, Svetlana Loznikova, José L Jiménez, M Ángeles Muñoz-Fernández, Maria Bryszewska, Rafael Gómez, Javier Sánchez-Nieves, F Javier de la Mata
Gold nanoparticles (AuNPs) and polycationic macromolecules are used as gene carriers. Their behaviour is dependent on several factors, such as the size and type of the framework, charge, etc. We have combined both types of systems and prepared AuNPs covered with cationic carbosilane dendrons with the aim to evaluate their biocompatibility. Water soluble dendronized cationic AuNPs were prepared following a straightforward procedure from dendrons, a gold precursor and a reducing agent in water and were characterized by (1)H NMR, transmission electron microscopy (TEM), dynamic light scattering (DLS), thermogravimetric analysis (TGA), ultraviolet spectroscopy (UV), and zeta potential (ZP)...
January 16, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28088280/comparative-study-of-colloidal-gold-and-quantum-dots-as-labels-for-multiplex-screening-tests-for-multi-mycotoxin-detection
#5
Astrid Foubert, Natalia V Beloglazova, Sarah De Saeger
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...
February 22, 2017: Analytica Chimica Acta
https://www.readbyqxmd.com/read/28087479/synthesis-and-characterization-of-gold-nanostructured-chorin-e6-for-photodynamic-therapy
#6
L Vieira, M L Castilho, I Ferreira, J Ferreira-Strixino, K C Hewitt, L Raniero
Photodynamic therapy is an alternative treatment for cancer based on cellular uptake of a photosensitizer, illuminated with an appropriate wavelength in the presence of oxygen. A cascade of reactions generates reactive oxygen species leading to cell death. Using carbodiimide chemistry, chlorin e6 (Ce6) was covalently bonded to thiourea, and (via the sulphur end group) to gold nanoparticles (AuNPs), forming the Ce6-AuNP complex. Ce6 absorbs in the range 650-680nm, where the coefficient of biological tissue absorption is low (part of the therapeutic window), which is ideal for biological application...
January 10, 2017: Photodiagnosis and Photodynamic Therapy
https://www.readbyqxmd.com/read/28081255/changes-in-dna-methylation-in-mouse-lungs-after-a-single-intra-tracheal-administration-of-nanomaterials
#7
Ali M Tabish, Katrien Poels, Hyang-Min Byun, Katrien Luyts, Andrea A Baccarelli, Johan Martens, Stef Kerkhofs, Sven Seys, Peter Hoet, Lode Godderis
AIMS: This study aimed to investigate the effects of nanomaterial (NM) exposure on DNA methylation. METHODS AND RESULTS: Intra-tracheal administration of NM: gold nanoparticles (AuNPs) of 5-, 60- and 250-nm diameter; single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) at high dose of 2.5 mg/kg and low dose of 0.25 mg/kg for 48 h to BALB/c mice. Study showed deregulations in immune pathways in NM-induced toxicity in vivo. NM administration had the following DNA methylation effects: AuNP 60 nm induced CpG hypermethylation in Atm, Cdk and Gsr genes and hypomethylation in Gpx; Gsr and Trp53 showed changes in methylation between low- and high-dose AuNP, 60 and 250 nm respectively, and AuNP had size effects on methylation for Trp53...
2017: PloS One
https://www.readbyqxmd.com/read/28081087/plasmonic-non-concentric-nanorings-array-as-an-unidirectional-nano-optical-conveyor-belt-actuated-by-polarization-rotation
#8
Min Jiang, Guanghui Wang, Wenxiang Jiao, Zhoufeng Ying, Ningmu Zou, Ho-Pui Ho, Tianyu Sun, Xuping Zhang
We report a nano-optical conveyor belt containing an array of gold plasmonic non-concentric nanorings (PNNRs) for the realization of trapping and unidirectional transportation of nanoparticles through rotating the polarization of an excitation beam. The location of hot spots within an asymmetric plasmonic nanostructure is polarization dependent, thus making it possible to manipulate a trapped target by rotating the incident polarization state. In the case of PNNR, the two poles have highly unbalanced trap potential...
January 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/28078889/quantification-of-free-polyelectrolytes-present-in-colloidal-suspension-revealing-a-source-of-toxic-responses-for-polyelectrolyte-wrapped-gold-nanoparticles
#9
Tian A Qiu, Marco D Torelli, Ariane M Vartanian, Nathan B Rackstraw, Joseph T Buchman, Lisa M Jacob, Catherine J Murphy, Robert J Hamers, Christy L Haynes
Polyelectrolyte (PE) wrapping of colloidal nanoparticles (NPs) is a standard method to control NP surface chemistry and charge. Because excess polyelectrolytes are usually employed in the surface modification process, it is critical to evaluate different purification strategies to obtain a clean final product and thus avoid ambiguities in the source of effects on biological systems. In this work, 4 nm diameter gold nanoparticles (AuNPs) were wrapped with 15 kDa poly(allylamine hydrochloride) (PAH), and three purification strategies were applied: (a) diafiltration or either (b) one round or (c) two rounds of centrifugation...
January 10, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28078525/chitosan-ceramide-coating-on-gold-nanorod-to-improve-its-physiological-stability-and-reduce-the-lipid-surface-related-toxicity
#10
Gantumur Battogtokh, Oyuntuya Gotov, Young Tag Ko
Gold nanoparticles are promising materials for many applications that include imaging, drug delivery, and photothermal therapy. However, AuNPs can be unstable and/or toxic. We purposed to improve the stability and reduce toxicity of gold nanorods (AuNR) upon coating with biocompatible polymer, chitosan-ceramide (CS-CE), without replacing the original layer, CTAB. CS-CE-coated AuNR was prepared by simple mixing for 24 h and purified by centrifugation. The coating was confirmed by UV-Vis absorption analysis and surface charge and size measurement...
January 11, 2017: Archives of Pharmacal Research
https://www.readbyqxmd.com/read/28076887/in-vivo-bone-tunnel-evaluation-of-nanoparticle-grafts-using-an-acl-reconstruction-rabbit-model
#11
S A Grant, S E Smith, H Schmidt, F Pfeiffer, K Kuroki, S Sherman, R A White, D A Grant
Acellular human gracilis tendons conjugated with gold nanoparticles (AuNP) and hydroxyapatite nanoparticles (nano-HAp) were used as a graft in an anterior cruciate ligament (ACL) reconstruction rabbit model. The ACLs of 11 New Zealand rabbits were reconstructed using grafts conjugated without nanoparticles, with AuNP only, and with both AuNP and nano-HAp. Semi-quantitative histological scoring of bone tunnel portion of grafts was performed after 14 weeks. Bone tunnels were scored for graft degeneration, graft remodeling, percentage of new host fibrous connective, collateral connection, head-to-head connection, graft collagen fiber organization, new host fibrous connective tissue organization, and graft and interface vascularity...
January 11, 2017: Journal of Biomedical Materials Research. Part A
https://www.readbyqxmd.com/read/28075134/dynamic-optical-switching-of-polymer-plasmonic-nanoparticle-hybrids-with-sparse-loading
#12
Zhaoxia Qian, Kathryn N Guye, David J Masiello, David S Ginger
Responsive plasmonic nanomaterials composed of gold nanoparticles (AuNPs) and temperature-responsive poly(N-isopropylacrylamide) (PNIPAM) hydrogels offer the promise of designing smart materials that can change color in response to varying thermal, or photothermal stimuli. Typical AuNP/PNIPAM hybrids are heavily loaded with AuNPs. Here we demonstrate that PNIPAM spheres with small number AuNP loadings exhibit significant extinction shifts and a broad range of color changes with varying temperature. Hybrids with an average loading of 3 to 5 AuNPs per PNIPAM sphere exhibit peak extinction shifts of over 150 nm and color change from red to purple to gray, with very large extinction changes in the NIR, as the temperature increases from 25oC to 50oC...
January 11, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28074833/shifting-molecular-localization-by-plasmonic-coupling-in-a-single-molecule-mirage
#13
Mario Raab, Carolin Vietz, Fernando Daniel Stefani, Guillermo Pedro Acuna, Philip Tinnefeld
Over the last decade, two fields have dominated the attention of sub-diffraction photonics research: plasmonics and fluorescence nanoscopy. Nanoscopy based on single-molecule localization offers a practical way to explore plasmonic interactions with nanometre resolution. However, this seemingly straightforward technique may retrieve false positional information. Here, we make use of the DNA origami technique to both control a nanometric separation between emitters and a gold nanoparticle, and as a platform for super-resolution imaging based on single-molecule localization...
January 11, 2017: Nature Communications
https://www.readbyqxmd.com/read/28074781/mechanically-tunable-sub-10-nm-metal-gap-by-stretching-pdms-substrate
#14
Wenjie Liu, Yang Shen, Guohui Xiao, Xiaoyi She, Jianfang Wang, Chongjun Jin
Manipulating light in sub-10 nm or subnanometer metal nanogaps is crucial to study the strong interaction between electromagnetic waves and matters. However, the fabrication of metallic nanogaps with precisely controlled size and high-throughput still remains a challenge. Here, we developed an approach to actively control the gap distance between adjacent metal nanoparticles from 140 nm to sub-10 nm or even 0 nm via mechanical stretching process. To demonstrate this method, we manufactured the gold disk arrays in a square lattice on the polydimethylsiloxane (PDMS) substrate through interference lithography and gold deposition, and sub-10 nm interparticle gap was achieved as exerting a strain of 100% to the PDMS substrate...
January 11, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28072878/signal-amplified-lateral-flow-test-strip-for-visual-detection-of-cu2
#15
Yulong Wang, Limin Wang, Juanjuan Xue, Jinbo Dong, Jia Cai, Xiude Hua, Minghua Wang, Cunzheng Zhang, Fengquan Liu
A signal-amplified lateral flow test strip (SA-LFTS) for the detection of Cu2+ in aqueous solution was constructed based on Cu+-catalyzed click chemistry and hybridization of single-stranded DNA (ssDNA). Alkyne and azide modified ssDNA acted as specific elements for Cu2+ recognition, and a chemical ligation product formed through Cu+-catalyzed alkyne-azide cycloaddition. Hybridization of ssDNA-labeled gold nanoparticles resulted in high sensitivity, and the output signal could be observed directly by the naked eye...
2017: PloS One
https://www.readbyqxmd.com/read/28070927/lead-sulfide-selenide-quantum-dots-and-gold-copper-alloy-nanoparticles-augment-light-harvesting-of-solar-cells
#16
Aparajita Das, Melepurath Deepa, Partha Ghosal
Lead-sulfide-selenide (PbSSe) quantum dots (QDs) and gold-copper (AuCu) alloy nanoparticles (NPs) are incorporated in a cadmium sulfide (CdS)/titanium oxide (TiO2) photoanode for the first time for enhanced conversion of solar energy to electricity. PbSSe QDs with a band gap of 1.02 eV, extend the light harvesting range of the photoanode from visible to the near infrared region. The conduction band (CB) edge of PbSSe QDs is wedged between the CBs of TiO2 and CdS; this additional level coupled with a good electrical conductivity of the dots facilitate charge transport and collection, for a high power conversion efficiency (PCE) of 4...
January 10, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28068467/exodisc-for-rapid-size-selective-and-efficient-isolation-and-analysis-of-nanoscale-extracellular-vesicles-from-biological-samples
#17
Hyun-Kyung Woo, Vijaya Sunkara, Juhee Park, Tae-Hyeong Kim, Ja-Ryoung Han, Chi-Ju Kim, Hyun-Il Choi, Yoon-Keun Kim, Yoon-Kyoung Cho
Extracellular vesicles (EVs) are cell-derived, nanoscale vesicles that carry nucleic acids and proteins from their cells of origin and show great potential as biomarkers for many diseases, including cancer. Efficient isolation and detection methods are prerequisites for exploiting their use in clinical settings and understanding their physiological functions. Here, we presented a rapid, label-free, and highly sensitive method for EV isolation and quantification using a lab-on-a-disc integrated with two nanofilters (Exodisc)...
January 9, 2017: ACS Nano
https://www.readbyqxmd.com/read/28068103/molecular-coatings-for-stabilizing-silver-and-gold-nanocubes-under-electron-beam-irradiation
#18
Shu Fen Tan, Michel Bosman, Christian A Nijhuis
We studied the degradation process of closely-spaced silver and gold nanocubes under high energy electron beam irradiation using transmission electron microscopy (TEM). The high aspect ratio gaps between silver and gold nanocubes degraded in many cases as a result of protrusion and filament formation during electron beam irradiation. We demonstrate that the molecular coating of the nanoparticles can act as a protective barrier to minimize electron beam-induced damage on passivated gold and silver nanoparticles...
January 9, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28068053/surface-modification-of-gold-nanoparticles-with-small-molecules-for-biochemical-analysis
#19
Yiping Chen, Yunlei Xianyu, Xingyu Jiang
As one of the major tools for and by chemical science, biochemical analysis is becoming increasingly important in fields like clinical diagnosis, food safety, environmental monitoring, and the development of chemistry and biochemistry. The advancement of nanotechnology boosts the development of analytical chemistry, particularly the nanoparticle (NP)-based approaches for biochemical assays. Functional NPs can greatly improve the performance of biochemical analysis because they can accelerate signal transduction, enhance the signal intensity, and enable convenient signal readout due to their unique physical and chemical properties...
January 9, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28067372/selective-turn-on-and-modulation-of-resonant-energy-transfer-in-single-plasmonic-hybrid-nanostructures
#20
Łukasz Bujak, Tatsuya Ishii, Dharmendar Kumar Sharma, Shuzo Hirata, Martin Vacha
Förster resonant energy transfer (FRET) is a nonradiative process by which the energy of light absorbed by a donor molecule is transferred to an acceptor molecule over a distance of several nanometers. FRET plays a crucial role in photosynthesis and nature-inspired artificial light-harvesting systems that are being explored for use in energy conversion applications. Localized plasmons of metal nanoparticles can potentially lead to a significant increase of FRET efficiency and effective donor-acceptor distance...
January 9, 2017: Nanoscale
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