Die Arbeit in erster Linie von der National Science Foundation (NSF) finanziert wurde, ist Chemie Division (prämiennummer CHE-1507370) anerkannt. Ayman M. Karim und Wenhui Li erkennen teilweisen finanzielle Unterstützung von 3M Non-Tenured Faculty Award. Diese Forschung verwendeten Ressourcen der Advanced Photon Source (Strahlrohr 12-ID-C, Benutzer Vorschlag GUP-45774), eine US-Department of Energy (DOE) Büro der Wissenschaft Benutzer Anlage betrieben für das DOE Office of Science vom Argonne National Laboratory unter Vertragsnr. DE-AC02-06CH11357. Die Autoren möchten Yubing Lu, eine Doktorandin im Bereich chemische Verfahrenstechnik an der Virginia Tech für seine freundliche Hilfe mit den Maßen SAXS danken. Die vorgestellte Arbeit wurde teilweise im Zentrum für integrierte Nanotechnologien hingerichtet, ein Büro der Wissenschaft Benutzer Anlage betrieben für das US Department of Energy (DOE) Office of Science. Los Alamos National Laboratory, Affirmative Action Equal Opportunity Employer, wird von Los Alamos National Security, LLC, für die National Nuclear Security Administration des US Department of Energy unter Vertrag DE-AC52-06NA25396 betrieben.

Es gibt kein Interessenkonflikt zu berichten.

In dieser Studie haben wir eine mächtige Methode untersuchen die Wirkung der Liganden auf die Keimbildung und das Wachstum von Metall-Nanopartikeln Deckelung vorgestellt. Wir synthetisiert Pd Nanopartikel in verschiedenen Lösungsmitteln (Toluol und Pyridin) mit Pd Acetat als Metall Vorläufer und TOP als Liganden. Wir haben in Situ SAXS, die Konzentration der reduzierten Atome (Kernbildung und Wachstum Veranstaltungen) sowie die Konzentration der Nanopartikel (Keimbildung Event), extrahieren wo beide experimen...

Kontrollierte Synthese von metallischen Nanopartikeln ist von großer Bedeutung aufgrund der großen Anwendungen von nanostrukturierten Materialien in der Katalyse, Photovoltaik, Photonik, Sensoren und Drug Delivery1,2,3, 4,5. Um die Nanopartikel mit bestimmten Größen und Größenverteilung zu synthetisieren, ist es wichtig zu verstehen, den zugrunde liegende Mechanismus für die Partikel Keimbildung und das Wachstum. Dennoch hat die Erlangung Nanopartikel mit solchen Kriterien die Nano-Synthese-Gemeinschaft durch die langsamen Fortschritte im Verständnis der Synthese-Mechanismen und der Mangel an robusten kinetische Modelle in der Literatur herausgefordert. In den 1950er-Jahren schlug LaMer ein Modell für die Keimbildung und das Wachstum von Schwefel-Sole, wo gibt es ein Ausbruch von Keimbildung, gefolgt von einer Diffusion kontrolliert Wachstum von Kernen6,7. In diesem vorgeschlagenen Modell, es wird postuliert, dass die monomerkonzentration (aufgrund der Reduzierung oder Zersetzung des Vorläufers) erhöht und einmal die Ebene oberhalb der kritischen Übersättigung, die Energiebarriere für Partikel Keimbildung überwunden werden kann, was zu einem Platzen Keimbildung (Homogene Keimbildung). Aufgrund der vorgeschlagenen platzen Nukleation, Monomer Konzentration Tropfen und wenn es unter das kritische Übersättigung Niveau fällt hält die Keimbildung. Als nächstes werden die gebildeten Kerne postuliert, wachsen über die Verbreitung der Monomere in Richtung der Nanopartikel-Oberfläche, während keine zusätzliche Keimbildung Ereignisse auftreten. Dadurch wird effektiv trennt die Keimbildung und das Wachstum in der Zeit und controlling der Partikelgrößenverteilung während der Wachstums-Prozess-8. Dieses Modell wurde verwendet, um die Bildung von verschiedenen Nanopartikeln einschließlich Ag9, Au10, CdSe11und Fe3O412beschreiben. Allerdings illustriert mehrere Studien, dass die klassische Nukleation Theorie (CNT) die Bildung von kolloidalen Nanopartikeln, insbesondere für metallische Nanopartikel nicht beschreiben wo die Überlappung der Keimbildung und das Wachstum wird1beobachtet, 13,14,15,16,17. In einer dieser Studien Watzky und Finke gegründet einen zweistufigen Mechanismus für die Bildung von Iridium-Nanopartikel13, in denen eine langsame kontinuierliche Keimbildung mit einem schnellen Nanopartikel Oberfläche Wachstum überlappt (wo autokatalytischen wächst). Die langsamen Keimbildung und schnell autokatalytischen Wachstum beobachtet auch für verschiedene Arten von Metall-Nanopartikeln, wie Pd14,15,18, Pt19,20und Rh21 ,22. Trotz der jüngsten Fortschritte bei der Entwicklung von Keimbildung und Wachstum Modelle1,23,24,25, die Rolle der Liganden in der vorgeschlagenen Modelle oft ignoriert. Dennoch sind Liganden gezeigt, um die Nanopartikel Größe14,15,26 und Morphologie19,27 , sowie die katalytische Aktivität und Selektivität28 beeinflussen , 29. Z. B. Yang Et Al. 30 kontrolliert die Pd nanopartikelgröße zwischen 9,5 und 15 nm durch Variation der Konzentration der Trioctylphosphine (oben). Bei der Synthese von magnetischen Nanopartikeln (Fe3O4) deutlich verkleinert, von 11 bis 5 nm bei der Liganden (Octadecylamine) Metall Vorläufer-Verhältnis von 1 auf 60 erhöht. Interessanterweise zeigte sich die Größe des Pt-Nanopartikel empfindlich auf die Kettenlänge von Amin Liganden (zB., n-Hexylamine und Octadecylamine), wo kleinere nanopartikelgröße mit längere Kette gewonnen werden konnte (i.e., Octadecylamine)31.
Die Größe Änderung verursacht durch unterschiedliche Konzentration und verschiedene Arten der Liganden ist ein klarer Beweis für den Beitrag der Liganden in die Keimbildung und das Wachstum Kinetik. Leider waren nur wenige Studien die Rolle des Liganden und in diesen Studien entfielen, mehrere oft der Einfachheit halber Annahmen, die wiederum diese Modelle nur für bestimmte Bedingungen32,33anwendbar zu machen. Genauer gesagt, entwickelt Rempel und Mitarbeiter ein kinetischen Modell, um die Bildung von Quantenpunkten (CdSe) beschreiben im Beisein von Kappung Liganden. In ihrer Studie ist jedoch die Bindung des Liganden mit Nanopartikel Oberfläche auszugehen, im Gleichgewicht zu jedem beliebigen Zeitpunkt32sein. Diese Annahme könnte zutreffen, wenn sich die Liganden in großen Überschuss. Unsere Gruppe entwickelt vor kurzem eine neue Liganden-basiertes Modell14 , die für die Bindung der Liganden mit der Vorläufer (Metallkomplex) und die Oberfläche der Nanopartikel als reversible Reaktionen14Deckelung entfielen. Darüber hinaus konnte unsere Liganden-basiertes Modell potenziell in anderen Metall-Nanopartikel-Systemen verwendet werden, wo die Synthese Kinetik scheinen durch die Anwesenheit der Liganden beeinflusst werden.
In der aktuellen Studie verwenden wir unsere neu entwickelte Liganden-basiertes Modell der Entstehung und dem Wachstum von Pd-Nanopartikeln in verschiedenen Lösungsmitteln wie Toluol und Pyridin vorherzusagen. Für unsere Modell-Input wurde in Situ SAXS genutzt, um die Konzentration der Nanopartikel und Größe Verteilung während der Synthese zu erhalten. Messung von Größe und Konzentration der Partikel, ergänzt durch kinetische Modellierung ermöglicht es uns, genauere Informationen über die Keimbildung und Wachstumsraten zu extrahieren. Weiter zeigen wir, dass unsere Liganden-basiertes Modell, das explizit für die Liganden-Metall-Bindung ausmacht, hoch prädiktiv ist und verwendet werden, kann um die Syntheseverfahren, die Nanopartikel mit gewünschten Größen zu erhalten zu entwerfen.

<table border="0" cellpadding="0" cellspacing="0" width="778">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">palladium acetate (Pd(OAc)2)</td>
			<td style="width:203px;">ALDRICH</td>
			<td style="width:119px;">520764</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">anhydrous acetic acid</td>
			<td style="width:203px;">SIAL</td>
			<td style="width:119px;">338826</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">trioctylphosphine</td>
			<td style="width:203px;">ALDRICH</td>
			<td style="width:119px;">718165</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">pyridine</td>
			<td style="width:203px;">MilliporeSigma</td>
			<td style="width:119px;">PX2012-7</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">toluene</td>
			<td style="width:203px;">SIAL</td>
			<td style="width:119px;">244511</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">1-hexanol</td>
			<td style="width:203px;">SIAL</td>
			<td style="width:119px;">471402</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">N8 Horizon SAXS</td>
			<td style="width:203px;">Bruker</td>
			<td style="width:119px;">A32-X1</td>
			<td></td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;width:291px;">glovebox</td>
			<td style="width:203px;">Vaccum Atmospheres Co.</td>
			<td style="width:119px;">109035</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">MR HEI-TEC 115V Hotplate</td>
			<td style="width:203px;">Heidolph</td>
			<td style="width:119px;">5053000000</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">hotplate Monoblock insert</td>
			<td style="width:203px;">Heidolph</td>
			<td style="width:119px;">5058000800</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">heat-On 25-ml insert</td>
			<td style="width:203px;">Heidolph</td>
			<td style="width:119px;">5058006200</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">7 mL vials</td>
			<td style="width:203px;">SUPELCO</td>
			<td style="width:119px;">27518</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">micro stir bar PTFE&#160;</td>
			<td style="width:203px;">VWR</td>
			<td style="width:119px;">58948-353</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">egg-Shaped Bars&#160;</td>
			<td style="width:203px;">Fisherbrand&#8482;&#160;</td>
			<td style="width:119px;">14-512-121</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">25 mL round bottom flasks</td>
			<td style="width:203px;">ALDRICH</td>
			<td style="width:119px;">Z167495</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">quartz capillary</td>
			<td style="width:203px;">Hampton Research</td>
			<td style="width:119px;">HR6-148</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">MATLAB R2016b</td>
			<td style="width:203px;">MathWorks</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">Bruker SAXS 1.0v</td>
			<td style="width:203px;">Bruker</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">Diffrac Measurement Center 4.0v</td>
			<td style="width:203px;">Bruker</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
	</tbody>
</table>

ligand-mediated nucleation and growth of palladium metal nanoparticles

Größe, Größenverteilung und Stabilität von kolloidalen Nanopartikeln sind stark durch die Anwesenheit der Deckelung Liganden betroffen. Trotz der wesentliche Beitrag der Deckelung Liganden während der Synthese-Reaktion ist ihre Rolle bei der Regulierung der Keimbildung und Wachstumsraten von kolloidalen Nanopartikeln nicht gut verstanden. In dieser Arbeit zeigen wir eine mechanistische Untersuchung der Rolle der Trioctylphosphine (oben) in Pd Nanopartikel in verschiedenen Lösungsmitteln (Toluol und Pyridin) mittels in Situ SAXS und Liganden-basierte kinetische Modellierung. Unsere Ergebnisse unter verschiedenen synthetischen Bedingungen zeigen die Überlappung der Keimbildung und das Wachstum von Pd-Nanopartikeln während der Reaktion, die die Keimbildung und das Wachstum LaMer-Modell widerspricht. Das Modell macht die Kinetik der Pd-TOP verbindlich für die Vorstufe und die Oberfläche der Partikel, die wesentlich für die Größe-Entwicklung sowie die Konzentration der Partikel in Situzu erfassen ist. Darüber hinaus zeigen wir die Vorhersagekraft der unsere Liganden-basiertes Modell durch die synthetischen Bedingungen entwerfen, Nanopartikel mit gewünschten Größen zu erhalten. Die vorgeschlagene Methode kann auf andere Synthese-Systeme angewendet werden und dient somit als eine wirksame Strategie zur prädiktiven Synthese von kolloidalen Nanopartikeln.

Um systematisch prüfen, ob die Deckelung Liganden die Kinetik der Keimbildung und Wachstum verändern, nahmen wir die beiden folgenden Ansätze: (i) die Bindung des Liganden mit dem Metall galt nicht in den kinetischen Modell ähnlich wie bei früheren Studien (zB., die Keimbildung und das autokatalytischen Wachstum) (Ii) die reversible Bindung von Liganden mit dem Vorläufer und Oberfläche der Nanopartikel Deckelung berücksichtigt wurde im Modell (i.e., Liganden-basi...

Watch this Scientific Journal Video about Ligand-Mediated Nucleation and Growth of Palladium Metal Nanoparticles at JoVE.com

Ligand-Mediated Nucleation and Growth of Palladium Metal Nanoparticles

Liganden-vermittelten Keimbildung und das Wachstum von Palladium Metall-Nanopartikeln

Das Hauptziel dieser Arbeit ist es, die Rolle des Agenten bei der Regulierung der Größe der Nanopartikel Palladium indem ichn Situ kleine Winkel Röntgenstreuung (SAXS) und Liganden-basierte kinetische Modellierung Deckelung aufzuklären.

The size, size distribution and stability of colloidal nanoparticles are greatly affected by the presence of capping ligands. Despite the key contribution ...

ligand-mediated-nucleation-and-growth-of-palladium-metal-nanoparticles

Research

Education

JoVE Journal

JoVE Core

Chemistry

Transition Metals and Coordination Complexes

SCIENTISTS IN ACTION

10.3K Aufrufe.  Virginia Polytechnic Institute and State University. Das Hauptziel dieser Arbeit ist es, die Rolle des Agenten bei der Regulierung der Größe der Nanopartikel Palladium indem ichn Situ kleine Winkel Röntgenstreuung (SAXS) und Liganden-basierte kinetische Modellierung Deckelung aufzuklären.

Serie: Ligand-Mediated Nucleation and Growth of Palladium Metal Nanoparticles

Synthesis and Characterization of Functionalized Metal-organic Frameworks

Metal-organic frameworks have attracted extraordinary amounts of research attention, as they are attractive candidates for numerous industrial and technological applications. Their signature property is their ultrahigh porosity, which however imparts a series of challenges when it comes to both constructing them and working with them. Securing desired MOF chemical and physical functionality by linker/node assembly into a highly porous framework of choice can pose difficulties, as less porous and more thermodynamically stable congeners (e.g., other crystalline polymorphs, catenated analogues) are often preferentially obtained by conventional synthesis methods. Once the desired product is obtained, its characterization often requires specialized techniques that address complications potentially arising from, for example, guest-molecule loss or preferential orientation of microcrystallites. Finally, accessing the large voids inside the MOFs for use in applications that involve gases can be problematic, as frameworks may be subject to collapse during removal of solvent molecules (remnants of solvothermal synthesis). In this paper, we describe synthesis and characterization methods routinely utilized in our lab either to solve or circumvent these issues. The methods include solvent-assisted linker exchange, powder X-ray diffraction in capillaries, and materials activation (cavity evacuation) by supercritical CO2 drying. Finally, we provide a protocol for determining a suitable pressure region for applying the Brunauer-Emmett-Teller analysis to nitrogen isotherms, so as to estimate surface area of MOFs with good accuracy.

Synthesis, activation, and characterization of intentionally designed metal-organic framework materials is challenging, especially when building blocks are incompatible or unwanted polymorphs are thermodynamically favored over desired forms. We describe how applications of solvent-assisted linker exchange, powder X-ray diffraction in capillaries and activation via supercritical CO2 drying, can address some of these challenges.

Synthese und Charakterisierung von funktionalisierten Metall-organische Gerüste

Metal-organic frameworks have attracted extraordinary amounts of research attention, as they are attractive candidates for numerous industrial and ...

Forschung

Chemie

Using Polystyrene-block-poly(acrylic acid)-coated Metal Nanoparticles as Monomers for Their Homo- and Co-polymerization

We present a template-free method for &#8220;polymerizing&#8221; nanoparticles into long chains without side branches. A variety of nanoparticles are encapsulated in polystyrene-block-poly(acrylic acid) (PSPAA) shells and then used as monomers for their self-assembly. Spherical PSPAA micelles upon acid treatment are known to assemble into cylindrical micelles. Exploiting this tendency, the core-shell nanoparticles are induced to aggregate, coalesce, and then transform into long chains. When more than one type of nanoparticles are used, random and block &#8220;copolymers&#8221; of nanoparticles can be obtained. Detailed procedures are reported for the PSPAA encapsulation of nanoparticles, homo- and co-polymerization of the core-shell nanoparticles, separation and purification of the resulting nanoparticle chains. Transformations of single-line chains into double- and triple-line chains are also presented. The synergy between the polymer shell and the embedded nanoparticles leads to an unusual chain-growth polymerization mode, giving long nanoparticle chains that are distinct from the products of the traditional step-growth aggregation process.

Using Polystyrene-block-polyacrylic acid-coated Metal Nanoparticles as Monomers for Their Homo- and Co-polymerization

We report protocols for &#8220;polymerizing&#8221; various types of polymer-encapsulated metal nanoparticles into long chains of &#8220;homo-&#8220; and &#8220;co-polymers&#8221;.

Verwendung Polystyrol-<em&gt; Block</em&gt; -Poly (Acrylsäure) beschichteten Metallnanopartikel als Monomere für ihre Homo- und Polymerisation

We present a template-free method for &#8220;polymerizing&#8221; nanoparticles into long chains without side branches. A variety of nanoparticles are ...

Reverse Microemulsion-mediated Synthesis of Monometallic and Bimetallic Early Transition Metal Carbide and Nitride Nanoparticles

A reverse microemulsion is used to encapsulate monometallic or bimetallic early transition metal oxide nanoparticles in microporous silica shells. The silica-encapsulated metal oxide nanoparticles are then carburized in a methane/hydrogen atmosphere at temperatures over 800 &#176;C to form silica-encapsulated early transition metal carbide nanoparticles. During the carburization process, the silica shells prevent the sintering of adjacent carbide nanoparticles while also preventing the deposition of excess surface carbon. Alternatively, the silica-encapsulated metal oxide nanoparticles can be nitridized in an ammonia atmosphere at temperatures over 800 &#176;C to form silica-encapsulated early transition metal nitride nanoparticles. By adjusting the reverse microemulsion parameters, the thickness of the silica shells, and the carburization/nitridation conditions, the transition metal carbide or nitride nanoparticles can be tuned to various sizes, compositions, and crystal phases. After carburization or nitridation, the silica shells are then removed using either a room-temperature aqueous ammonium bifluoride solution or a 0.1 to 0.5 M NaOH solution at 40-60 &#176;C. While the silica shells are dissolving, a high surface area support, such as carbon black, can be added to these solutions to obtain supported early transition metal carbide or nitride nanoparticles. If no high surface area support is added, then the nanoparticles can be stored as a nanodispersion or centrifuged to obtain a nanopowder.

A &#8220;removable ceramic coating method&#8221; is presented in visual format for the synthesis of non-sintered and metal-terminated monometallic and bimetallic early transition metal carbide and nitride nanoparticles with tunable sizes and crystal structures.

Umkehrmikroemulsion-vermittelte Synthese von Monometallische und Bimetall frühes Übergangsmetall Carbide und Nitride Nanopartikel

A reverse microemulsion is used to encapsulate monometallic or bimetallic early transition metal oxide nanoparticles in microporous silica shells. The ...

Generation of Zerovalent Metal Core Nanoparticles Using n-(2-aminoethyl)-3-aminosilanetriol

In this work, a facile one-pot reaction for the formation of metal nanoparticles in a water solution through the use of n-(2-aminoethyl)-3-aminosilanetriol is presented. This compound can be used to effectively reduce and complex metal salts into metal core nanoparticles coated with the compound. By controlling the concentrations of salt and silane one is able to control reaction rates, particle size, and nanoparticle coating. The effects of these changes were characterized through transmission electron microscopy (TEM), UV-Vis spectrometry (UV-Vis), Nuclear Magnetic Resonance spectroscopy (NMR) and Fourier Transform Infrared spectroscopy (FTIR). A unique aspect to this reaction is that usually silanes hydrolyze and cross-link in water; however, in this system the silane is water-soluble and stable. It is known that silicon and amino moieties can form complexes with metal salts. The silicon is known to extend its coordination sphere to form penta- or hexa-coordinated species. Furthermore, the silanol group can undergo hydrolysis to form a Si-O-Si silica network, thereby transforming the metal nanoparticles into a functionalized nanocomposites.

Generation of Zerovalent Metal Core Nanoparticles Using n-2-aminoethyl-3-aminosilanetriol

A novel method for metal core nanoparticle synthesis using a water stable silanol is described.

Die Erzeugung von nullwertigen Metallkern Nanopartikel unter Verwendung von N- (2-Aminoethyl) -3-aminosilanetriol

In this work, a facile one-pot reaction for the formation of metal nanoparticles in a water solution through the use of ...

Photochemical Oxidative Growth of Iridium Oxide Nanoparticles on CdSe@CdS Nanorods

We demonstrate a procedure for the photochemical oxidative growth of iridium oxide catalysts on the surface of seeded cadmium selenide-cadmium sulfide (CdSe@CdS) nanorod photocatalysts. Seeded rods are grown using a colloidal hot-injection method and then moved to an aqueous medium by ligand exchange. CdSe@CdS nanorods, an iridium precursor and other salts are mixed and illuminated. The deposition process is initiated by absorption of photons by the semiconductor particle, which results with formation of charge carriers that are used to promote redox reactions. To insure photochemical oxidative growth we used an electron scavenger. The photogenerated holes oxidize the iridium precursor, apparently in a mediated oxidative pathway. This results in the growth of high quality crystalline iridium oxide particles, ranging from 0.5 nm to about 3 nm, along the surface of the rod. Iridium oxide grown on CdSe@CdS heterostructures was studied by a variety of characterization methods, in order to evaluate its characteristics and quality. We explored means for control over particle size, crystallinity, deposition location on the CdS rod, and composition. Illumination time and excitation wavelength were found to be key parameters for such control. The influence of different growth conditions and the characterization of these heterostructures are described alongside a detailed description of their synthesis. Of significance is the fact that the addition of iridium oxide afforded the rods astounding photochemical stability under prolonged illumination in pure water (alleviating the requirement for hole scavengers).

A protocol for the photochemical oxidative growth of small crystalline iridium oxide nanoparticles on the surface of CdSe@CdS seeded rod nanoparticles is presented.

Photochemische oxidative Wachstum von Iridium-Nanopartikel auf CdSe @ CdS-Nanostäbchen

We demonstrate a procedure for the photochemical oxidative growth of iridium oxide catalysts on the surface of seeded cadmium selenide-cadmium sulfide ...

In Situ Detection and Single Cell Quantification of Metal Oxide Nanoparticles Using Nuclear Microprobe Analysis

Micro-analytical techniques based on chemical element imaging enable the localization and quantification of chemical composition at the cellular level. They offer new possibilities for the characterization of living systems and are particularly appropriate for detecting, localizing and quantifying the presence of metal oxide nanoparticles both in biological specimens and the environment. Indeed, these techniques all meet relevant requirements in terms of (i) sensitivity (from 1 up to 10 &#181;g.g-1 of dry mass), (ii) micrometer range spatial resolution, and (iii) multi-element detection. Given these characteristics, microbeam chemical element imaging can powerfully complement routine imaging techniques such as optical and fluorescence microscopy. This protocol describes how to perform a nuclear microprobe analysis on cultured cells (U2OS) exposed to titanium dioxide nanoparticles. Cells must grow on and be exposed directly in a specially designed sample holder used on the optical microscope and in the nuclear microprobe analysis stages. Plunge-freeze cryogenic fixation of the samples preserves both the cellular organization and the chemical element distribution. Simultaneous nuclear microprobe analysis (scanning transmission ion microscopy, Rutherford backscattering spectrometry and particle induced X-ray emission) performed on the sample provides information about the cellular density, the local distribution of the chemical elements, as well as the cellular content of nanoparticles. There is a growing need for such analytical tools within biology, especially in the emerging context of Nanotoxicology and Nanomedicine for which our comprehension of the interactions between nanoparticles and biological samples must be deepened. In particular, as nuclear microprobe analysis does not require nanoparticles to be labelled, nanoparticle abundances are quantifiable down to the individual cell level in a cell population, independently of their surface state.

In Situ Detection and Single Cell Quantification of Metal Oxide Nanoparticles Using Nuclear Microprobe Analysis

We describe a procedure for the detection of chemical elements present in situ in human cells as well as their in vitro quantification. The method is well-suited to any cell type and is particularly useful for quantitative chemical analyses in single cells following in vitro metal oxide nanoparticles exposure.

In Situ Erkennung und Quantifizierung der einzelnen Zelle von Metall-Oxid-Nanopartikel mit nuklearen Mikrosonde Analyse

Micro-analytical techniques based on chemical element imaging enable the localization and quantification of chemical composition at the cellular level. ...

High Resolution Physical Characterization of Single Metallic Nanoparticles

Individual molecules can be detected and characterized by measuring the degree by which they reduce the ionic current flowing through a single nanometer-scale pore. The signal is characteristic of the molecule&#39;s physicochemical properties and its interactions with the pore. We demonstrate that the nanopore formed by the bacterial protein exotoxin Staphylococcus aureus alpha hemolysin (&#945;HL) can detect polyoxometalates (POMs, anionic metal oxygen clusters), at the single molecule limit. Moreover, multiple degradation products of 12-phosphotungstic acid POM (PTA, H3PW12O40) in solution are simultaneously measured. The single molecule sensitivity of the nanopore method allows for POMs to be characterized at significantly lower concentrations than required for nuclear magnetic resonance (NMR) spectroscopy. This technique could serve as a new tool for chemists to study the molecular properties of polyoxometalates or other metallic clusters, to better understand POM synthetic processes, and possibly improve their yield. Hypothetically, the location of a given atom, or the rotation of a fragment in the molecule, and the metal oxidation state could be investigated with this method. In addition, this new technique has the advantage of allowing the real-time monitoring of molecules in solution.&#160;

Here, we present a protocol to detect discrete metal oxygen clusters, polyoxometalates (POMs), at the single molecule limit using a biological nanopore-based electronic platform. The method provides a complementary approach to traditional analytical chemistry tools used in the study of these molecules.

Physikalische Charakterisierung einzelner metallischer Nanopartikel in hoher Auflösung

Individual molecules can be detected and characterized by measuring the degree by which they reduce the ionic current flowing through a single ...

Molten-Salt Synthesis of Complex Metal Oxide Nanoparticles

The development of feasible synthesis methods is critical for the successful exploration of novel properties and potential applications of nanomaterials. Here, we introduce the molten-salt synthesis (MSS) method for making metal oxide nanomaterials. Advantages over other methods include its simplicity, greenness, reliability, scalability, and generalizability. Using pyrochlore lanthanum hafnium oxide (La2Hf2O7) as a representative, we describe the MSS protocol for the successful synthesis of complex metal oxide nanoparticles (NPs). Furthermore, this method has the unique ability to produce NPs with different material features by changing various synthesis parameters such as pH, temperature, duration, and post-annealing. By fine-tuning these parameters, we are able to synthesize highly uniform, non-agglomerated, and highly crystalline NPs. As a specific example, we vary the particle size of the La2Hf2O7&#160;NPs by changing the concentration of the ammonium hydroxide solution used in the MSS process, which allows us to further explore the effect of particle size on various properties. It is expected that the MSS method will become a more popular synthesis method for nanomaterials and more widely employed in the nanoscience and nanotechnology community in the upcoming years.

Here, we demonstrate a unique, relatively low-temperature, molten-salt synthesis method for preparing uniform complex metal oxide lanthanum hafnate nanoparticles.

Salzschmelze Synthese von komplexen Metall-Oxid-Nanopartikel

The development of feasible synthesis methods is critical for the successful exploration of novel properties and potential applications of nanomaterials. ...

Synthesis and Characterization of Amphiphilic Gold Nanoparticles

Gold nanoparticles covered with a mixture of 1-octanethiol (OT) and 11-mercapto-1-undecane sulfonic acid (MUS) have been extensively studied because of their interactions with cell membranes, lipid bilayers, and viruses. The hydrophilic ligands make these particles colloidally stable in aqueous solutions and the combination with hydrophobic ligands creates an amphiphilic particle that can be loaded with hydrophobic drugs, fuse with the lipid membranes, and resist nonspecific protein adsorption. Many of these properties depend on nanoparticle size and the composition of the ligand shell. It is, therefore, crucial to have a reproducible synthetic method and reliable characterization techniques that allow the determination of nanoparticle properties and the ligand shell composition. Here, a one-phase chemical reduction, followed by a thorough purification to synthesize these nanoparticles with diameters below 5 nm, is presented. The ratio between the two ligands on the surface of the nanoparticle can be tuned through their stoichiometric ratio used during synthesis. We demonstrate how various routine techniques, such as transmission electron microscopy (TEM), nuclear magnetic resonance (NMR), thermogravimetric analysis (TGA), and ultraviolet-visible (UV-Vis) spectrometry, are combined to comprehensively characterize the physicochemical parameters of the nanoparticles.

Amphiphilic gold nanoparticles can be used in many biological applications. A protocol to synthesize gold nanoparticles coated by a binary mixture of ligands and a detailed characterization of these particles is presented.

Synthese und Charakterisierung von amphiphilen Gold-Nanopartikeln

Gold nanoparticles covered with a mixture of 1-octanethiol (OT) and 11-mercapto-1-undecane sulfonic acid (MUS) have been extensively studied because of ...

Synthesis Method for Cellulose Nanofiber Biotemplated Palladium Composite Aerogels

Here, a method to synthesize cellulose nanofiber biotemplated palladium composite aerogels is presented. Noble metal aerogel synthesis methods often result in fragile aerogels with poor shape control. The use of carboxymethylated cellulose nanofibers (CNFs) to form a covalently bonded hydrogel allows for the reduction of metal ions such as palladium on the CNFs with control over both nanostructure and macroscopic aerogel monolith shape after supercritical drying. Crosslinking the carboxymethylated cellulose nanofibers is achieved using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) in the presence of ethylenediamine. The CNF hydrogels maintain their shape throughout synthesis steps including covalent crosslinking, equilibration with precursor ions, metal reduction with high concentration reducing agent, rinsing in water, ethanol solvent exchange, and CO2 supercritical drying. Varying the precursor palladium ion concentration allows for control over the metal content in the final aerogel composite through a direct ion chemical reduction rather than relying on the relatively slow coalescence of pre-formed nanoparticles used in other sol-gel techniques. With diffusion as the basis to introduce and remove chemical species into and out of the hydrogel, this method is suitable for smaller bulk geometries and thin films. Characterization of the cellulose nanofiber-palladium composite aerogels with scanning electron microscopy, X-ray diffractometry, thermal gravimetric analysis, nitrogen gas adsorption, electrochemical impedance spectroscopy, and cyclic voltammetry indicates a high surface area, metallized palladium porous structure.

A synthesis method for cellulose nanofiber biotemplated palladium composite aerogels is presented.The resulting composite aerogel materials offer potential for catalysis, sensing, and hydrogen gas storage applications.

Synthesemethode für Cellulose Nanofaser Biotemplated Palladium Composite Aerogels

Here, a method to synthesize cellulose nanofiber biotemplated palladium composite aerogels is presented. Noble metal aerogel synthesis methods often ...