Name: generation of zerovalent metal core nanoparticles using n-(2-aminoethyl)-3-aminosilanetriol
Uploaded: 2016-02-11T13:00:00
Description: Watch this Scientific Journal Video about Generation of Zerovalent Metal Core Nanoparticles Using n-2-aminoethyl-3-aminosilanetriol at JoVE.com

Dr. B.P.S. Chauhan would like to gratefully acknowledge William Paterson University for assigned release time (ART) award for part of the research described here and also for the research program in general.

Note: All reagents are used as is from manufacturer with no further purification. Reactions were monitored for up to one week via UV-Vis spectroscopy to ensure complete reduction. All reactions are carried out under a vent hood and appropriate safety attire is worn at all times, including gloves, eye goggles, and lab coats.
1. Synthesis of Silver Nanoparticles
<ol>
	<li>Weigh out 0.0169 g (0.1 mmol) of silver nitrate directly into a 50 ml Erlenmeyer flask.</li>
	<li>Add in 20 ml of 18.2 M&#9...

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Rev. 110, 1960-2004 (2010).</li><li>Wu, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preparation+and+Structural+Characterization+of+Novel+Nanohybrids+by+Cationic+3D+Silica+Nanoparticles+Sandwiched+between+2D+Anionic+Montmorillonite+Clay+through+Electrostatic+Attraction.">Preparation and Structural Characterization of Novel Nanohybrids by Cationic 3D Silica Nanoparticles Sandwiched between 2D Anionic Montmorillonite Clay through Electrostatic Attraction.</a> J. Phys. Chem. C. 113 (30), 13036-13044 (2009).</li><li>Spitalsky, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Carbon+nanotube-polymer+composites:+Chemistry,+Processing,+Mechanical+and+Electrical+Properties.">Carbon nanotube-polymer composites: Chemistry, Processing, Mechanical and Electrical Properties.</a> Prog. Polym. 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M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+of+silver+nanoparticles+by+microbial+method+and+their+characterization.">Synthesis of silver nanoparticles by microbial method and their characterization.</a> Arch. Phys. Res. 2 (3), 153-158 (2011).</li><li>Ghosh, S., Sarma, N., Mandal, M., Kundu, S., Esumi, K., Pal, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evolution+of+gold+nanoparticles+in+micelle+by+UV-irradiation:+A+conductometric+study.">Evolution of gold nanoparticles in micelle by UV-irradiation: A conductometric study.</a> Curr. Sci. 84 (6), 791-795 (2003).</li><li>Paul, B., Bhuyan, B., Purkayastha, D. D., Dey, M., Dhar, S. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Green+synthesis+of+gold+nanoparticles+using+Pogestemon+benghalensis+(B)+O.+Ktz+leaf+extract+and+studies+of+their+photocatalytic+activity+in+degradation+of+methylene.">Green synthesis of gold nanoparticles using Pogestemon benghalensis (B) O. Ktz leaf extract and studies of their photocatalytic activity in degradation of methylene.</a> Mater. Lett. 148, 37-40 (2015).</li><li>Chauhan, B. P. S., Rathore, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regioselective+Synthesis+of+Multifunctional+Hybrid+Polysiloxanes+Achieved+by+Pt-Nanocluster+Catalysis.">Regioselective Synthesis of Multifunctional Hybrid Polysiloxanes Achieved by Pt-Nanocluster Catalysis.</a> J. Am. Chem. Soc. 127, 5790-5791 (2005).</li><li>Chauhan, B. P. S., Rathore, S., Bandoo, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=&#34;Polysiloxane-Pd&#34;+Nanocomposites+as+Recyclable+Chemoselective+Hydrogenation+Catalysts.">&#34;Polysiloxane-Pd&#34; Nanocomposites as Recyclable Chemoselective Hydrogenation Catalysts.</a> J. Am. Chem. Soc. 126, 8493-8500 (2004).</li><li>Chauhan, B. P. S., Rathore, S., Chauhan, M., Krawicz, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+of+Polysiloxane+Stabilized+Palladium+Colloids+and+Evidence+of+Their+Participation+in+Silaesterification+Reactions.">Synthesis of Polysiloxane Stabilized Palladium Colloids and Evidence of Their Participation in Silaesterification Reactions.</a> J. Am. Chem. Soc. 125, 2876-2877 (2003).</li><li>Chauhan, B. P. S., Sardar, R., Tewari, P., Sharma, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> , 23-25 (2003).</li><li>Pouchert, C. J., Pouchert, C. .. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Non-Aromatic+Amines.">Non-Aromatic Amines.</a> The Aldrich Library of Infrared Spectra. , (1983).</li><li>Arkles, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Infrared+Analysis+of+Organosilicon+Compounds:+Spectra-Structure+Correlations.">Infrared Analysis of Organosilicon Compounds: Spectra-Structure Correlations.</a> Silicon Compounds Register and Review. , (1987).</li><li>Corriu, R. J. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hypervalent+Species+of+Silicon-structure+and+Reactivity.">Hypervalent Species of Silicon-structure and Reactivity.</a> J. Organomet. Chem. 400, 81-106 (1990).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Basic Instruction Manual: Hitachi HT7700 TEM. , 1-28 (2014).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> OMNIC User's Guide Version 7.3: Thermo Electron Corporation. , 151-216 (2006).</li></ol>

Salts reported in this paper are the only salts that were tested of that metal. As a result, it is uncertain that this reaction strategy would work with all salts of the metals, particularly gold. The solubility of these salts in water may also affect the outcome of the reaction in terms of reaction time, morphology, and yields. In all reactions, the silane was added to an already dissolved metal salt solution.
It is worth noting that care must be taken to ensure accuracy for these reactions r...

As the demand and applications of designer nanomaterials increases, so do the various methods of synthesis. The &#34;top-down&#34; methods, such as laser ablation or chemical etching have been employed for their excellent controllability and capability of resolving materials reliably down to the sub-micron level. These methods rely on bulk materials being processed into finer components, which typically increase the cost of production as the desired nanostructure size decreases. An alternative method of synthesis to this is the &#34;bottom-up&#34; approach, which controls synthesis at the molecular level and builds up to the desired nanostructure. This imparts a significant degree of control on the desired self-assembly, functionality, passivity, and stability in the generation of these nanostructured materials1. By working from the molecular level, hybrid nanocomposites can be generated providing the benefits of both materials within the same structure.
As nanomaterials are synthesized through the bottom-up strategy, methods need to be employed to control particle size, shape, texture, hydrophobicity, porosity, charge, and functionality2. In metal core nanoparticle synthesis, the initial metal salt is reduced in an autocatalytic process to generate zero-valent particles, which in turn direct the nucleation of other particle. This leads to clustering and finally nanoparticle production3. In an effort to control the size of nanoparticles created and prevent them from precipitating out of solution, stabilizers such as ligands, surfactants, ionic charge, and large polymers are exploited for their ability to block nanoparticles from further agglomeration4-10. These materials inhibit the van der Waals attraction of the nanoparticles, either through steric hindrance due to the presence of bulky groups or through Coulombic repulsions3.
In this work, a facile, one pot, synthetic strategy for the generation of various metal core nanoparticles using the silane, n-(2-aminoethyl)-3-aminosilanetriol (2-AST) is presented (Figure 1). Ligands on this compound are capable of reducing metal precursors and stabilizing metal nanoparticles with a relatively high efficacy. The three silanol moieties present are also capable of crosslinking and this forms an interconnected network of organosilane polymer impregnated with nanoparticles within its matrix (Figure 2). Unlike most silanes, which readily undergo hydrolysis in the presence of water, this compound is stabilized in water, which is beneficial for hydrophobicity purposes, stability, and control.

<table border="0" cellpadding="0" cellspacing="0" width="644">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:287px;">n-(2-aminoethyl)-3-aminosilanetriol (2-AST)</td>
			<td style="width:209px;">Gelest</td>
			<td style="width:72px;">SIA0590.0</td>
			<td style="width:76px;">25% in H2O</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Silver nitrate</td>
			<td>Sigma Aldrich</td>
			<td>S6506</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Gold(III) chloride trihydrate</td>
			<td>Sigma Aldrich</td>
			<td align="right">520918</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Palladium(II) Nitrate</td>
			<td>Alfa Aesar</td>
			<td align="right">11035</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Deuterium Dioxide</td>
			<td>Cambridge Isotope Laboratories</td>
			<td>DLM-4-100</td>
			<td></td>
		</tr>
	</tbody>
</table>

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.

The reaction was monitored via UV-Vis spectrometry as nanoparticle formation should produce peaks characteristic for each individual metal nanoparticle. The final analysis of synthesized materials was accomplished through TEM and FTIR. The FTIR spectra was obtained from dried powder of samples. The particle size analysis can be accomplished by measuring nanoparticle diameter from images obtained via TEM and averaging results.
Co...

Watch this Scientific Journal Video about Generation of Zerovalent Metal Core Nanoparticles Using n-2-aminoethyl-3-aminosilanetriol at JoVE.com

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.

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 ...

The overall goal of this protocol is to produce water-soluble metal core nanoparticles. This general method uses a silicon-based surfactant as both a reducing and a stabilizing agent. This method helps answer key questions about control of self-assembly functionality, passivity, and the stability of nanostructured materials.The main advantage of this technique is that a water-soluble silicon compound can reduce metal precursors to metal nanoparticles and efficiently stabilize them. It uses green conditions to create silox and metal nanocomposites which have applications in therapeutics drug delivery and heterogeneous catalyses. The implications of this technique are far-reaching because the surfactant can cross-link to form organo-silene gels impregnated with metallic nanoparticles.This method can be applied to create hybrids of most noble metals and can provide mechanistic insights into the formation of nanoparticles. By controlling the concentrations of salt and silene it is possible to control the reaction rates, particle size, and nanoparticle coating. To start the procedure first weigh out 16.9 milligrams of silver nitrate into a 50 milliliter erlenmyer flask equipped with a magnetic stir bar.Add 20 milliliters of 18.2 megaohm ultra-pure water to the flask and stopper it. Place the flask in an oil bath on a hot plate at 60 degrees Celsius and stir the solution. Next slowly add 144 microliters of 2-AST to the flask, using a precision micropipette.Flush the pipette several times with the mixture to ensure that all of the 2-AST is transferred. Every half-hour remove 100 microliters of the mixture using a precision micropipette and place it into a plastic cuvette for UV-Vis spectroscopy analysis. To the plastic cuvettes containing the sample add one milliliter of ultra-pure water and mix the sample in each of the cuvettes thoroughly by repeat pipetting.Transfer the cuvette to a UV-Vis spectrophotometer and record the absorbance spectrum. Discard the sample in an appropriate container when finished. After six hours, remove the flask from the oil bath and transfer the nanoparticle mixture to a 20 milliliter scintillation vial for storage.To begin the sample preparation for electron microscopy place a 200 carbon mesh Formvar coated copper grid onto a clean piece of filter paper. Once the sample has cooled to room temperature cast drop approximately 60 microliters of the nanoparticle mixture directly onto the grid using a one milliliter plastic Pasteur pipette. Allow the grid to dry for 24 hours.Load the grid into a transmission electron microscope and record images using 10 microampere current and 100 kilovolt accelerating voltage. To prepare the NMR sample, first use a precision pipette to transfer 50 microliters of deuterium oxide into a clean NMR tube. Next, slowly pipette 400 microliters of the nanoparticle mixture into the same NMR tube.Cap the tube and shake the top of the tube to force the mixture to the bottom. Mix the sample by shaking and repeatedly inverting the NMR tube. Insert the sample tube into the NMR magnet and record the NMR spectrum.To prepare the FTIR sample first place two milliliters of the nanoparticle mixture into a one dram glass vial. Continue by placing the vial into a vacuum dessicator. Connect the dessicator stopcock to a vacuum pump.Open it and then evacuate the dessicator. Use caution when drying the sample in a vacuum dessicator as rapid reduction of pressure may cause samples to flash boil, expelling some of the material out of the container. Once the vial no longer contains visible liquid, remove it from the dessicator, and scrape out the remaining solid sample using a clean spatula.Finally, place the sample onto an FTIR spectrometer fitted with zinc selenide crystal diode laser and record the FTIR spectrum. The formation of silver nanoparticles was monitored by UV-Vis Spectrometry analysis. The silver nanoparticles have a characteristic peak at 414 nanometers that increases with reaction time.Transmission electron microscopy was used to confirm the presence of silver nanoparticles. Analysis of the images shows that the majority of the nanoparticles were in the 10 nanometer size range. Fourier transform infrared spectroscopy was used to verify the complexation of the nanoparticles with 2-AST.Absorption at around 1000 reciprocal centimeters shows the presence of silicon-oxygen-silicon linkages and peaks at 3000 to 2750 reciprocal centimeters and 1550 to 1650 reciprocal centimeters are attributed to the amino group. Analysis of the NMR spectrum of the nanoparticles shows the coordination to the 2-AST by the shift in and appearance of new peaks between 2.72 to 3.40 parts per million. Once mastered, the reaction process can be set up within an hour.While performing this procedure, it's important to ensure the purity of the water. All experiments were carried out in ultra-pure, 18.2 megaohm water. Following this procedure, scanning electron microscopy or x-ray powder diffraction can be used to further elucidate structural features, such as morphology, size and particle roughness of the hybrid nanocomposites.After watching this video, you should have a good understanding of how to generate and analyze the stabilized metal-core nanoparticles. This method produces large quantities of water-soluble metal nanohybrids which can be capped with ligands for drug delivery applications. Don't forget that working with silver nitrate and other reagents can be hazardous.The use of protective equipment such as gloves, goggles and lab coats is strongly advised while performing this procedure. Thanks for watching, good luck with your experiments.

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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;.

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.

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

Synthesis, Characterization, and Functionalization of Hybrid Au/CdS and Au/ZnS Core/Shell Nanoparticles

Plasmonic nanoparticles are an attractive material for light harvesting applications due to their easily modified surface, high surface area and large extinction coefficients which can be tuned across the visible spectrum. Research into the plasmonic enhancement of optical transitions has become popular, due to the possibility of altering and in some cases improving photo-absorption or emission properties of nearby chromophores such as molecular dyes or quantum dots. The electric field of the plasmon can couple with the excitation dipole of a chromophore, perturbing the electronic states involved in the transition and leading to increased absorption and emission rates. These enhancements can also be negated at close distances by energy transfer mechanism, making the spatial arrangement of the two species critical. Ultimately, enhancement of light harvesting efficiency in plasmonic solar cells could lead to thinner and, therefore, lower cost devices. The development of hybrid core/shell particles could offer a solution to this issue. The addition of a dielectric spacer between a gold nanoparticles and a chromophore is the proposed method to control the exciton plasmon coupling strength and thereby balance losses with the plasmonic gains. A detailed procedure for the coating of gold nanoparticles with CdS and ZnS semiconductor shells is presented. The nanoparticles show high uniformity with size control in both the core gold particles and shell species allowing for a more accurate investigation into the plasmonic enhancement of external chromophores.

The synthesis of uniform gold nanoparticles coated with semiconductor shells of CdS or ZnS is performed. The semiconductor coating is conducted by first depositing a silver sulfide shell and exchanging the silver cations for zinc or cadmium cations.

Plasmonic nanoparticles are an attractive material for light harvesting applications due to their easily modified surface, high surface area and large ...

Sediment Core Extrusion Method at Millimeter Resolution Using a Calibrated, Threaded-rod

Aquatic sediment core subsampling is commonly performed at cm or half-cm resolution. Depending on the sedimentation rate and depositional environment, this resolution provides records at the annual to decadal scale, at best. An extrusion method, using a calibrated, threaded-rod is presented here, which allows for millimeter-scale subsampling of aquatic sediment cores of varying diameters. Millimeter scale subsampling allows for sub-annual to monthly analysis of the sedimentary record, an order of magnitude higher than typical sampling schemes. The extruder consists of a 2 m aluminum frame and base, two core tube clamps, a threaded-rod, and a 1 m piston. The sediment core is placed above the piston and clamped to the frame. An acrylic sampling collar is affixed to the upper 5 cm of the core tube and provides a platform from which to extract sub-samples. The piston is rotated around the threaded-rod at calibrated intervals and gently pushes the sediment out the top of the core tube. The sediment is then isolated into the sampling collar and placed into an appropriate sampling vessel (e.g., jar or bag). This method also preserves the unconsolidated samples (i.e., high pore water content) at the surface, providing a consistent sampling volume. This mm scale extrusion method was applied to cores collected in the northern Gulf of Mexico following the Deepwater Horizon submarine oil release. Evidence suggests that it is necessary to sample at the mm scale to fully characterize events that occur on the monthly time-scale for continental slope sediments.

An extrusion method using a calibrated threaded-rod is presented, which allows for mm scale subsampling of aquatic sediment cores. Millimeter-scale sampling is necessary to fully characterize recent event stratigraphy in sediment records.

Aquatic sediment core subsampling is commonly performed at cm or half-cm resolution. Depending on the sedimentation rate and depositional environment, ...

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.

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

Determination of Thermodynamic Properties of Alkaline Earth-liquid Metal Alloys Using the Electromotive Force Technique

A novel electrochemical cell based on a CaF2 solid-state electrolyte has been developed to measure the electromotive force (emf) of binary alkaline earth-liquid metal alloys as functions of both composition and temperature in order to acquire thermodynamic data. The cell consists of a chemically stable solid-state CaF2-AF2 electrolyte (where A is the alkaline-earth element such as Ca, Sr, or Ba), with binary A-B alloy (where B is the liquid metal such as Bi or Sb) working electrodes, and a pure A metal reference electrode. Emf data are collected over a temperature range of 723 K to 1,123 K in 25 K increments for multiple alloy compositions per experiment and the results are analyzed to yield activity values, phase transition temperatures, and partial molar entropies/enthalpies for each composition.

This protocol describes the measurement of the electromotive force of alkaline-earth elements in liquid metal alloys at high temperatures (723-1,123 K) to determine their thermodynamic properties, including activity, partial molar entropy, partial molar enthalpy, and phase transition temperatures, over a wide composition range.

A novel electrochemical cell based on a CaF2 solid-state electrolyte has been developed to measure the electromotive force (emf) of binary alkaline ...

Ligand-Mediated Nucleation and Growth of Palladium Metal Nanoparticles

The size, size distribution and stability of colloidal nanoparticles are greatly affected by the presence of capping ligands. Despite the key contribution of capping ligands during the synthesis reaction, their role in regulating the nucleation and growth rates of colloidal nanoparticles is not well understood. In this work, we demonstrate a mechanistic investigation of the role of trioctylphosphine (TOP) in Pd nanoparticles in different solvents (toluene and pyridine) using in situ SAXS and ligand-based kinetic modeling. Our results under different synthetic conditions reveal the overlap of nucleation and growth of Pd nanoparticles during the reaction, which contradicts the LaMer-type nucleation and growth model. The model accounts for the kinetics of Pd-TOP binding for both, the precursor and the particle surface, which is essential to capture the size evolution as well as the concentration of particles in situ. In addition, we illustrate the predictive power of our ligand-based model through designing the synthetic conditions to obtain nanoparticles with desired sizes. The proposed methodology can be applied to other synthesis systems and therefore serves as an effective strategy for predictive synthesis of colloidal nanoparticles.

The main goal of this work is to elucidate the role of capping agents in regulating the size of palladium nanoparticles by combining in situ small angle x-ray scattering (SAXS) and ligand-based kinetic modeling.

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

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.

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

Imaging Corrosion at the Metal-Paint Interface Using Time-of-Flight Secondary Ion Mass Spectrometry

Corrosion developed at the paint and aluminum (Al) metal-paint interface of an aluminum alloy is analyzed using time-of-flight secondary ion mass spectrometry (ToF-SIMS), illustrating that SIMS is a suitable technique to study the chemical distribution at a metal-paint interface. The painted Al alloy coupons are immersed in a salt solution or exposed to air only. SIMS provides chemical mapping and 2D molecular imaging of the interface, allowing direct visualization of the morphology of the corrosion products formed at the metal-paint interface and mapping of the chemical after corrosion occurs. The experimental procedure of this method is presented to provide technical details to facilitate similar research and highlight pitfalls that may be encountered during such experiments.

Time-of-flight secondary ion mass spectrometry is applied to demonstrate the chemical mapping and corrosion morphology at the metal-paint interface of an aluminum alloy after being exposed to a salt solution compared with a specimen exposed to air.

Corrosion developed at the paint and aluminum (Al) metal-paint interface of an aluminum alloy is analyzed using time-of-flight secondary ion mass ...

A Microwave-Assisted Direct Heteroarylation of Ketones Using Transition Metal Catalysis

Heteroarylation introduces heteroaryl fragments to organic molecules. Despite the numerous available reactions reported for arylation via transition metal catalysis, the literature on direct heteroarylation is scarce. The presence of heteroatoms such as nitrogen, sulfur and oxygen often make heteroarylation a challenging research field due to catalyst poisoning, product decomposition and the rest. This protocol details a highly efficient direct &#945;-C(sp3) heteroarylation of ketones under microwave irradiation. Key factors for successful heteroarylation include the use of XPhos Palladacycle Gen. 4 Catalyst, excess base to suppress side reactions and the high temperature and pressure achieved in a sealed reaction vial under microwave irradiation. The heteroarylation compounds prepared by this method were fully characterized by proton nuclear magnetic resonance spectroscopy (1H NMR), carbon nuclear magnetic resonance spectroscopy (13C NMR) and high-resolution mass spectrometry (HRMS). This methodology has several advantages over literature precedents including broad substrate scope, rapid reaction time, greener procedure and operational simplicity by eliminating the preparation of intermediates such as silyl enol ether. Possible applications for this protocol include, but are not limited to, diversity-oriented synthesis for the discovery of biologically active small molecules, domino synthesis for the preparation of natural products and ligand development for new transition metal catalytic systems.

Heteroaryl compounds are important molecules utilized in organic synthesis, medicinal and biological chemistry. A microwave-assisted heteroarylation using palladium catalysis provides a rapid and efficient method to attach heteroaryl moieties directly to ketone substrates.

Heteroarylation introduces heteroaryl fragments to organic molecules. Despite the numerous available reactions reported for arylation via transition metal ...