Search results for " Gold"
showing 10 items of 278 documents
Tetrazine Click Chemistry for the Modification of 1-Hydroxy-1,1-methylenebisphosphonic Acids: Towards Bio-orthogonal Functionalization of Gold Nanopa…
2016
Inverse electron demand Diels-Alder (iEDDA) was evaluated for the functionalization of gold nanoparticles. The reaction was first modelled with the free coating molecule 1-hydroxy-1,1-methylenebisphosphonate bearing an alkene functionality (HMBPene). A model tetrazine 3,6-dipyridin-2-yl-1,2,4,5-tetrazine (pyTz) was used, kinetic of the reaction was calculated and coupling products were analysed by NMR and HRMS. The reaction was then transposed at the nanoparticle surface. Gold nanoparticles bearing an alkene functionality were obtained using a one-pot methodology with HMBPene and the tetrazine click chemistry was evaluated at their surface using pyTz. The successful coupling was assessed by…
Novel patternable and conducting metal-polymer nanocomposites: a step towards advanced mutlifunctional materials
2013
In this work, we present a novel patternable conducting nanocomposite containing gold nanoparticles. Here, the in-situ polymerization of 3T is carried out using HAuCl 4 as oxidizing agent inside PMMA as host matrix. During the bake step, the gold salt is also reduced from Au(III) to Au(0) generating Au nanoparticles in the interpenetrating polymer network (IPN) system. We found that this novel multifunctional resist shows electrical conductivity and plasmonic properties as well as potential patterning capability provided by the host matrix. The resulting nanocomposite has been investigated by TEM and UV-Vis spectroscopy. Electrical characterization was also conducted for different concentra…
Fabrication of Single Cylindrical Au-Coated Nanopores with Non-Homogeneous Fixed Charge Distribution Exhibiting High Current Rectifications
2014
We have designed and characterized a cylindrical nanopore that exhibits high electrochemical current rectification ratios at low and intermediate electrolyte concentrations. For this purpose, the track-etched single cylindrical nanopore in polymer membrane is coated with a gold (Au) layer via electroless plating technique. Then, a non-homogeneous fixed charge distribution inside the Au-coated nanopore is obtained by incorporating thiol-terminated uncharged poly(N-isopropylacrylamide) (PNIPAM) chains in series to poly(4-vinyl pyridine) (PVP) chains, which are positively charged at acidic pH values. The functionalization reaction is checked by measuring the current–voltage (I–V) curves prior …
Versatile Synthesis of Functional Gold Nanoparticles: Grafting Polymers From and Onto
2008
Functionalized gold nanoparticles have been prepared in an organic solvent by a two-phase reduction method in ethyl acetate and water using bis(6-hydroxyhexyl) disulfide bis(2-bromoisobutyl) ester, bis(6-acetyloxyhexyl) disulfide, and bis(5-carboxypentyl) disulfide bis(pentafluorophenyl) ester as stabilizing ligands. This procedure features the advantages that no phase transfer agent was necessary during the preparation of the gold nanoparticles and that the reducing conditions were mild enough to utilize functional disulfide ligands. The obtained gold nanoparticles with typical sizes between 2 and 5 nm could be precipitated and redispersed without any irreversible aggregation. Using these nanop…
Functional Polymer-Opals from Core-Shell Colloids
2007
Colloidal photonic crystals were prepared from monodisperse core-shell particles. The shell is hereby formed from a functional monomer, such as glycidylmethacrylate or different reactive ester monomers, which can perform chemical reactions and the core from a standard monomer, which yields highly monodisperse colloids. It was possible to crystallize the core-shell particles into artificial opals with excellent optical properties. Reactions on the functional surface of the colloids were carried out, which lead to a dramatic rise in the mechanical stability or to a functionalization of His-tagged silicatein, which acts as nanoreactor to synthesize and immobilize gold nanoparticles from auric …
Hetero-Telechelic Dye-Labeled Polymer for Nanoparticle Decoration
2009
The synthesis of poly(methyl methacrylate) (PMMA) exhibiting one fluorescent dye (Texas Red) and one methyl disulfide end group is described. It is shown that the latter end group enabled the exchange of both oleic amine on gold nanoparticles (AuNP) and of oleic acid on CdSe/ZnS quantum dots (QD), allowing for a phase transfer of both types of nanoparticles (NP) from hexane into dimethylformamide due to the solubility provided by the PMMA chains. For AuNP, a fluorescence quenching of the dye was found due to fluorescence resonance energy transfer (FRET) from the dye to the AuNP, while QDs caused a fluorescence enhancement by FRET from the QD to the attached dyes. Due to the hetero-telecheli…
CO2 switchable nanoparticles: reversible water/organic-phase exchange of gold nanoparticles by gas bubbling
2013
Gold nanoparticles capped with oleylamine can be effectively transferred from an organic solvent to water in the presence of an acetamidine surfactant by CO2 bubbling and then effectively reverted back to the organic phase by N2 bubbling.
Cittadinanza e sua commodificazione: cittadinanza come diritto, cittadinanza come bene
2019
cittadinanza e sua commodificazione
The Color of Avant-Garde: Kenneth Goldsmith’s "The Body of Michael Brown"
2018
In the following paper, I put forth a claim that literary works created according to the rules of conceptualism, seemingly devoid of expression, often reveal that values are inseparable from any textual operations. This is visible in Kenneth Goldsmith’s recent project, “The Body of Michael Brown,” which follows the format of Goldsmith’s previous book—Seven American Deaths and Disasters—a transcription of news reports of American national disasters, such as the assassination of John F. Kennedy or the attacks of 9/11. The text rewrites the autopsy report issued by the St. Louis County Coroner’s Office on the shooting of Michael Brown, an African-American teenager shot and killed by a white po…
Latvijas ģimenes paaudzēs, 2018
2019
Pētījums aptver visas vecuma grupas: gan jaunus cilvēkus patstāvīgās dzīves sākumā (no 18 gadu vecuma), gan pieredzes bagātus — citās vecuma grupās (līdz 79 gadu vecumam), sniedzot precīzu informāciju par cilvēka dzīves galvenajiem demogrāfiskajiem notikumiem un cikliem vairāku paaudžu dzīvē, sākot jau no 1950. gadu vidus. Aptaujā tiek iegūta informācija par šādām tēmām: pāreja uz pieaugušo dzīvi (mācības un darbs, vecāku mājas atstāšana, pirmās partnerattiecības, jaunas ģimenes veidošana, labklājība un trūkums; kopdzīve un ģimenes stabilitāte (daudzveidīgās ģimenes formas, balanss starp darbu un ģimeni, pienākumu sadale starp vīriešiem un sievietēm,…