Name: facile preparation of ultrafine aluminum hydroxide particles with or without mesoporous mcm-41 in ambient environments
Uploaded: 2017-05-11T15:00:00
Description: Watch this Scientific Journal Video about Facile Preparation of Ultrafine Aluminum Hydroxide Particles with or without Mesoporous MCM-41 in Ambient Environments at JoVE.com

The authors extend their appreciation to Dr. Thomas J. Emge and Wei Liu of Rutgers University for their analysis and expertise in small-angle X-ray diffraction and powder X-ray diffraction. Furthermore, the authors acknowledge Hao Wang for his support with the N2 adsorption experiments.

1. Al(OH)3 Nanoparticle Synthesis
<ol>
	<li>Dissolve 1.40 g of aluminum chloride hexahydrate in 5.822 g of deionized water.</li>
	<li>Add 2.778 g of L-arginine to the aqueous aluminum chloride solution while under magnetic stirring. Add the L-arginine slowly, so that the added arginine dissolves and does not form large clumps or chunks; furthermore, a slow addition reduces local concentrations of alkalinity and provides conditions for a more controllable hydrolysis.</li>
	<li>Once all the arginine dissolves ...

<ol>
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Rev. 106 (1), 1-16 (2006).</li><li>Lutzenkirchen, J., 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=Adsorption+of+Al13-Keggin+clusters+to+sapphire+c-plane+single+crystals:+Kinetic+observations+by+streaming+current+measurements.">Adsorption of Al13-Keggin clusters to sapphire c-plane single crystals: Kinetic observations by streaming current measurements.</a> Appl. Surf. Sci. 256 (17), 5406-5411 (2010).</li><li>Mokaya, R., Jones, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Efficient+post-synthesis+alumination+of+MCM-41+using+aluminum+chlorohydrate+containing+Al+polycations.">Efficient post-synthesis alumination of MCM-41 using aluminum chlorohydrate containing Al polycations.</a> J. Mater. Chem. 9 (2), 555-561 (1999).</li><li>Brunauer, S., Deming, L. S., Deming, W. E., Teller, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=On+a+Theory+of+the+van+der+Waals+adsorption+of+gases.">On a Theory of the van der Waals adsorption of gases.</a> J. Am. Chem. Soc. 62 (7), 1723-1732 (1940).</li><li>Kresge, C. T., Leonowicz, M. E., Roth, W. J., Vartuli, J. C., Beck, J. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ordered+mesoporous+molecular+sieves+synthesized+by+a+liquid-crystal+template+mechanism.">Ordered mesoporous molecular sieves synthesized by a liquid-crystal template mechanism.</a> Nature. 359 (6397), 710-712 (1992).</li><li>Zeng, Q., Nekvasil, H., Grey, C. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Proton+Environments+in+Hydrous+Aluminosilicate+Glasses:+A+1H+MAS,+1H/27Al,+and+1H/23Na+TRAPDOR+NMR+Study.">Proton Environments in Hydrous Aluminosilicate Glasses: A 1H MAS, 1H/27Al, and 1H/23Na TRAPDOR NMR Study.</a> J. Phys. Chem. B. 103 (35), 7406-7415 (1999).</li><li>Kao, H. M., Grey, C. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Probing+the+Bronsted+and+Lewis+acidity+of+zeolite+HY:+A+1H/27Al+and+15N/27Al+TRAPDOOR+NMR+study+of+mono-methylamine+adsorbed+on+HY.">Probing the Bronsted and Lewis acidity of zeolite HY: A 1H/27Al and 15N/27Al TRAPDOOR NMR study of mono-methylamine adsorbed on HY.</a> J. Phys. Chem. 100 (12), 5105-5117 (1996).</li><li>DeCanio, E. C., Edwards, J. C., Bruno, J. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Solid-state+1H+MAS+NMR+characterization+of+&#947;-alumina+and+modified+&#947;-aluminas.">Solid-state 1H MAS NMR characterization of &#947;-alumina and modified &#947;-aluminas.</a> J. Catal. 148 (1), 76-83 (1994).</li><li>Shafran, K. L., Deschaume, O., Perry, C. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+static+anion+exchange+method+for+generation+of+high+purity+aluminium+polyoxocations+and+monodisperse+aluminum+hydroxide+nanoparticles.">The static anion exchange method for generation of high purity aluminium polyoxocations and monodisperse aluminum hydroxide nanoparticles.</a> J. Mater. Chem. 15 (33), 3415-3423 (2005).</li><li>Vogels, R. J. M. J., Kloprogge, J. T., Geus, J. 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The preparation of an aqueous aluminum chloride solution entailed the use of a crystalline hexahydrate salt of aluminum chloride. Although the anhydrous form can also be used, it is not preferred due to its significant hygroscopic properties, which make it difficult to work with and to control the concentration of aluminum. It is noteworthy that aluminum chloride solution should be used within several days of preparation because over time, the [Al(H2O)6]3+ aqua acid hydrolyzes to yield un...

Materials made of aluminum hydroxide are promising candidates for a variety of industrial applications, including catalysis, pharmaceuticals, water treatment, and cosmetics.1,2,3,4 At elevated temperatures, aluminum hydroxide absorbs a substantial amount of heat during decomposition to yield alumina (Al2O3), making it a useful flame-retarding agent.5 The four known polymorphs of aluminum hydroxide (i.e., gibbsite, bayerite, nordstrandite, and doyleite) have been investigated using computational and experimental techniques to improve our understanding of the formation and structures thereof6. The preparation of nanoscale particles is of particular interest due to their potential to exhibit quantum effects and properties differing from those of their bulk counterparts. Nanogibbsite particles with dimensions on the order of 100 nm are easily prepared under various conditions7,8,9,10,11,12,13,14.
Overcoming inherent challenges associated with reducing the particle sizes further is difficult; therefore, only a few cases exist where nanogibbsite particles have dimensions on the order of 50 nm.14,15,16,17 To the best of our knowledge, there have been no reports of nanogibbsite particles smaller than 50 nm. In part, this is attributed to the fact that nanoparticles tend to agglomerate due to electrostatic instability and the high probability for the formation of hydrogen bonds between the colloidal particles, especially in polar protic solvents. Our objective was to synthesize small Al(OH)3 nanoparticles by using exclusively safe ingredients and precursors. In the current work, aqueous particle aggregation was inhibited by incorporating an amino acid (i.e., L-arginine) as a buffer and stabilizer. Moreover, it is reported that the guanidinium-containing arginine prevented aluminum hydroxide particle growth and aggregation to yield an aqueous colloidal suspension with average particle sizes of 10-30 nm. It is proposed here that the amphoteric and zwitterionic properties of arginine mitigated the surface charge of aluminum hydroxide nanoparticles during the mild hydrolysis to disfavor particle growth beyond 30 nm. Although arginine was not capable of reducing the particle size below 10 nm, such particles were achieved by taking advantage of the &#34;cage&#34; confinement effect within the mesopores of MCM-41. Characterization of the Al-MCM-41 composite material revealed ultrafine aluminum hydroxide nanoparticles within the mesoporous silica, which has an average pore size of 2.7 nm.

<table border="0" cellpadding="0" cellspacing="0" width="650">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:261px;">aluminum chloride hexahydrate</td>
			<td style="width:103px;">Alfa Aesar</td>
			<td align="right" style="width:119px;">12297</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:261px;">L-arginine</td>
			<td style="width:103px;">BioKyowa</td>
			<td style="width:119px;">N/A</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:261px;">aluminum hydroxide</td>
			<td style="width:103px;">Sigma Aldrich</td>
			<td align="right" style="width:119px;">239186</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:261px;">Bio-Gel P-4 Gel</td>
			<td style="width:103px;">Bio-Rad</td>
			<td style="width:119px;">150-4128</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:261px;">Mesoporous siica (MCM-41 type)</td>
			<td style="width:103px;">Sigma Aldrich</td>
			<td align="right" style="width:119px;">643645</td>
			<td></td>
		</tr>
	</tbody>
</table>

facile preparation of ultrafine aluminum hydroxide particles with or without mesoporous mcm-41 in ambient environments

An aqueous suspension of nanogibbsite was synthesized via the titration of aluminum aqua acid [Al(H2O)6]3+ with L-arginine to pH 4.6. Since the hydrolysis of aqueous aluminum salts is known to produce a wide array of products with a wide range of size distributions, a variety of state-of-the-art instruments (i.e., 27Al/1H NMR, FTIR, ICP-OES, TEM-EDX, XPS, XRD, and BET) were used to characterize the synthesis products and identification of byproducts. The product, which was comprised of nanoparticles (10-30 nm), was isolated using gel permeation chromatography (GPC) column technique. Fourier transform infrared (FTIR) spectroscopy and powder X-ray diffraction (PXRD) identified the purified material as the gibbsite polymorph of aluminum hydroxide. The addition of inorganic salts (e.g., NaCl) induced electrostatic destabilization of the suspension, thereby agglomerating the nanoparticles to yield Al(OH)3 precipitate with large particle sizes. By utilizing the novel synthetic method described here, Al(OH)3 was partially loaded inside the highly ordered mesoporous framework of MCM-41, with average pore dimensions of 2.7 nm, producing an aluminosilicate material with both octahedral and tetrahedral Al (Oh/Td = 1.4). The total Al content, measured using energy-dispersive X-ray spectrometry (EDX), was 11% w/w with a Si/Al molar ratio of 2.9. A comparison of bulk EDX with surface X-ray photoelectron spectroscopy (XPS) elemental analysis provided insight into the distribution of Al within the aluminosilicate material. Furthermore, a higher ratio of Si/Al was observed on the external surface (3.6) as compared to the bulk (2.9). Approximations of O/Al ratios suggest a higher concentration of Al(O)3 and Al(O)4 groups near the core and external surface, respectively. The newly developed synthesis of Al-MCM-41 yields a relatively high Al content while maintaining the integrity of the ordered silica framework and can be used for applications where hydrated or anhydrous Al2O3 nanoparticles are advantageous.

Nanogibbsite Synthesis
Nanogibbsite was prepared by titrating AlCl3&#183;6H2O (14 wt%) with L-arginine to a final Arg/Al molar ratio of 2.75. The synthesis of nanogibbsite particles was monitored via SEC, which is a widely used analysis technique for partially hydrolyzed aluminum chloride solutions, capable of discerning five domains arbitrarily designated as peaks 1, 2, 3, 4, and 51...

Watch this Scientific Journal Video about Facile Preparation of Ultrafine Aluminum Hydroxide Particles with or without Mesoporous MCM-41 in Ambient Environments at JoVE.com

Facile Preparation of Ultrafine Aluminum Hydroxide Particles with or without Mesoporous MCM-41 in Ambient Environments

An ultrafine aluminum hydroxide nanoparticle suspension was prepared via the controlled titration of [Al(H2O)]3+ with L-arginine to pH 4.6 with and without cage-effect confinement within mesoporous channels of MCM-41.

An aqueous suspension of nanogibbsite was synthesized via the titration of aluminum aqua acid [Al(H2O)6]3+ with L-arginine to pH 4.6. Since the hydrolysis ...

The overall goal of this experiment is to develop a green methodology for the facile synthesis of stabilized ultra-fine aluminum hydroxide particles, which can be used to effectively introduce aluminum hydroxide or aluminum oxide onto a wide variety of materials. The newly developed synthesis produces a novel phase of ultra-fine aluminum hydroxide by implementing arginene as a mild base source. The main advantage of this technique is taking arginene, an edible basic amino acid, to neutralize aluminum chloride, to form ultra-fine aluminum hydroxide, and stabilize the particles.We solve agglomeration. The ability to prepare stabilized ultra-fine aluminum hydroxide paves the way for further structural and mechanistic studies, in attempts to better understand hydrolysis of aluminum monomers to bulk aluminum hydroxide. Demonstrating the procedure will be our intern, Viktor Dubovoy.To begin this procedure, dissolve 1.4 grams of aluminum chloride hexahydrate in 5.822 grams of deionized water. Slowly add 2.778 grams of L-arginine under magnetic stirring. Once the L-arginine is complete dissolved, heat the solution at 50 degrees celsius for 72 hours.Then, prepare gel permeation chromatography column by packing the gel in successive steps of adding gel, and then allowing water to flow through the column, to ensure proper packing. Pack the gel to approximately 80%of the column. Next, use an HPLC pump with a 10ml injector loop, to introduce 10ml of the synthesized ultra-fine aluminum hydroxide suspension into the column.Collect the majority of the peak-1 fraction over 100 minutes. Once a peak emerges on the LI detector, collect the LU end in 30 minute intervals. After this, add one weight percent solution of sodium chloride drop-wise to 10ml of the purified ultra-fine aluminum hydroxide, to induce precipitation.To begin, use a vacuum oven to activate one gram of MCM-41 at 120 degrees celsius under vacuum for three hours. Next, combine 9.6926 grams of aluminum chloride hexahydrate and 40.3074 grams of deionized water. Add 0.74 grams of activated MCM-41 to this aluminum chloride solution.Mix for one hour, to ensure homogeneity of the aluminum chloride diffused throughout the MCM-41 channels. Slowly add L-arginine under stirring, such that the final arginine-aluminum molar ratio is 2.75. Once the mixture is homogenous, heat it to 50 degrees celsius for 72 hours.After this, use a buchner funnel equipped with qualitative 90mm filter paper circles to filter the solution under vacuum. Wash the obtained aluminum MCM-41 material with excess deionized water. In this study, an ultra-fine aluminum hydroxide suspension is prepared, via the controlled titration of aluminum aqua acid with L-arginine.Magic angle spinning and MR analysis of the prepared aluminum MCM-41 material shows the presence of both octahedral and tetrahedral aluminum environments, which are commonly observed in mesoporus silica-modified aluminum species. Bulk and surface elemental composition data suggests that most of the aluminum penetrated into the pores, as opposed to building up on the surface. Small angle X-ray diffraction patterns are measured before and after aluminum loading, and are indexed based on hexagonal symmetry.Lattice reflections of 100, 110, 200 are observed in both samples, indicating that the insertion of aluminum had no significant impact on the highly-ordered porosity of MCM-41. Transmission electron microscopy of aluminum MCM-41 particles reveals that the silica framework remains intact after loading aluminum hydroxide particles. This technology can be feasibly scaled to synthesize commercial quantities of ultra-fine aluminum hydroxide, or aluminum functionized high-grade materials.This acid synthesis is not just extendable to aluminum hydroxide. It is also extendable to other metal oxides, which has far reaching applications in drug-delivery, catalysis, and personal care products. Why the synthesized repeat the amino acids but to generate the same purity and yield.

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Chemistry

Particles without a Box: Brush-first Synthesis of Photodegradable PEG Star Polymers under Ambient Conditions

Convenient methods for the rapid, parallel synthesis of diversely functionalized nanoparticles will enable discovery of novel formulations for drug delivery, biological imaging, and supported catalysis. In this report, we demonstrate parallel synthesis of brush-arm star polymer (BASP) nanoparticles by the &#34;brush-first&#34; method. In this method, a norbornene-terminated poly(ethylene glycol) (PEG) macromonomer (PEG-MM) is first polymerized via ring-opening metathesis polymerization (ROMP) to generate a living brush macroinitiator. Aliquots of this initiator stock solution are added to vials that contain varied amounts of a photodegradable bis-norbornene crosslinker. Exposure to crosslinker initiates a series of kinetically-controlled brush+brush and star+star coupling reactions that ultimately yields BASPs with cores comprised of the crosslinker and coronas comprised of PEG. The final BASP size depends on the amount of crosslinker added. We carry out the synthesis of three BASPs on the benchtop with no special precautions to remove air and moisture. The samples are characterized by gel permeation chromatography (GPC); results agreed closely with our previous report that utilized inert (glovebox) conditions. Key practical features, advantages, and potential disadvantages of the brush-first method are discussed.

Poly(ethylene glycol) (PEG) brush-arm star polymers (BASPs) with narrow mass distributions and tunable nanoscopic sizes are synthesized in via ring opening metathesis polymerization (ROMP) of a PEG-norbornene macromonomer followed by transfer of portions of the resulting living brush initiator to vials containing varied amounts of a rigid, photo-cleavable bis-norbornene crosslinker.

Convenient methods for the rapid, parallel synthesis of diversely functionalized nanoparticles will enable discovery of novel formulations for drug ...

Activating Molecules, Ions, and Solid Particles with Acoustic Cavitation

The chemical and physical effects of ultrasound arise not from a direct interaction of molecules with sound waves, but rather from the acoustic cavitation: the nucleation, growth, and implosive collapse of microbubbles in liquids submitted to power ultrasound. The violent implosion of bubbles leads to the formation of chemically reactive species and to the emission of light, named sonoluminescence. In this manuscript, we describe the techniques allowing study of extreme intrabubble conditions and chemical reactivity of acoustic cavitation in solutions. The analysis of sonoluminescence spectra of water sparged with noble gases provides evidence for nonequilibrium plasma formation. The photons and the "hot" particles generated by cavitation bubbles enable to excite the non-volatile species in solutions increasing their chemical reactivity. For example the mechanism of ultrabright sonoluminescence of uranyl ions in acidic solutions varies with uranium concentration: sonophotoluminescence dominates in diluted solutions, and collisional excitation contributes at higher uranium concentration. Secondary sonochemical products may arise from chemically active species that are formed inside the bubble, but then diffuse into the liquid phase and react with solution precursors to form a variety of products. For instance, the sonochemical reduction of Pt(IV) in pure water provides an innovative synthetic route for monodispersed nanoparticles of metallic platinum without any templates or capping agents. Many studies reveal the advantages of ultrasound to activate the divided solids. In general, the mechanical effects of ultrasound strongly contribute in heterogeneous systems in addition to chemical effects. In particular, the sonolysis of PuO2 powder in pure water yields stable colloids of plutonium due to both effects.

Acoustic cavitation in liquids submitted to power ultrasound creates transient extreme conditions inside the collapsing bubbles, which are the origin of unusual chemical reactivity and light emission, known as sonoluminescence. In the presence of noble gases, nonequilibrium plasma is formed. The "hot" particles and the photons generated by collapsing bubbles are able to excite species in solution.

The chemical and physical effects of ultrasound arise not from a direct interaction of molecules with sound waves, but rather from the acoustic ...

Synthesis and Catalytic Performance of Gold Intercalated in the Walls of Mesoporous Silica

As a promising catalytically active nano reactor, gold nanoparticles intercalated in mesoporous silica (GMS) were successfully synthesized and properties of the materials were investigated. We used a one pot sol-gel approach to intercalate gold nano particles in the walls of mesoporous silica. To start with the synthesis, P123 was used as template to form micelles. Then TESPTS was used as a surface modification agent to intercalate gold nano particles. Following this process, TEOS was added in as a silica source which underwent a polymerization process in acid environment. After hydrothermal processing and calcination, the final product was acquired. Several techniques were utilized to characterize the porosity, morphology and structure of the gold intercalated mesoporous silica. The results showed a stable structure of mesoporous silica after gold intercalation. Through the oxidation of benzyl alcohol as a benchmark reaction, the GMS materials showed high selectivity and recyclability.

Here, we present a protocol with a sol-gel process to synthesize gold intercalated in the walls of mesoporous materials (GMS), which is confirmed to possess a mesoporous matrix with gold intercalated in the walls imparting great stability and recyclability.

As a promising catalytically active nano reactor, gold nanoparticles intercalated in mesoporous silica (GMS) were successfully synthesized and properties ...

Facile and Efficient Preparation of Tri-component Fluorescent Glycopolymers via RAFT-controlled Polymerization

Synthetic glycopolymers are instrumental and versatile tools used in various biochemical and biomedical research fields. An example of a facile and efficient synthesis of well-controlled fluorescent statistical glycopolymers using reversible addition-fragmentation chain-transfer (RAFT)-based polymerization is demonstrated. The synthesis starts with the preparation of &#946;-galactose-containing glycomonomer 2-lactobionamidoethyl methacrylamide obtained by reaction of lactobionolactone and N-(2-aminoethyl) methacrylamide (AEMA). 2-Gluconamidoethyl methacrylamide (GAEMA) is used as a structural analog lacking a terminal &#946;-galactoside. The following RAFT-mediated copolymerization reaction involves three different monomers: N-(2-hydroxyethyl) acrylamide as spacer, AEMA as target for further fluorescence labeling, and the glycomonomers. Tolerant of aqueous systems, the RAFT agent used in the reaction is (4-cyanopentanoic acid)-4-dithiobenzoate. Low dispersities (&#8804;1.32), predictable copolymer compositions, and high reproducibility of the polymerizations were observed among the products. Fluorescent polymers are obtained by modifying the glycopolymers with carboxyfluorescein succinimidyl ester targeting the primary amine functional groups on AEMA. Lectin-binding specificities of the resulting glycopolymers are verified by testing with corresponding agarose beads coated with specific glycoepitope recognizing lectins. Because of the ease of the synthesis, the tight control of the product compositions and the good reproducibility of the reaction, this protocol can be translated towards preparation of other RAFT-based glycopolymers with specific structures and compositions, as desired.

An efficient, three-step synthesis of RAFT-based fluorescent glycopolymers, consisting of glycomonomer preparation, copolymerization, and post-modification, is demonstrated. This protocol can be used to prepare RAFT-based statistical glycopolymers with desired structures.

Synthetic glycopolymers are instrumental and versatile tools used in various biochemical and biomedical research fields. An example of a facile and ...

Facile Preparation of Internally Self-assembled Lipid Particles Stabilized by Carbon Nanotubes

We present a facile method to prepare nanostructured lipid particles stabilized by carbon nanotubes (CNTs). Single-walled (pristine) and multi-walled (functionalized) CNTs are used as stabilizers to produce Pickering type oil-in-water (O/W) emulsions. Lipids namely, Dimodan U and Phytantriol are used as emulsifiers, which in excess water self-assemble into the bicontinuous cubic Pn3m phase. This highly viscous phase is fragmented into smaller particles using a probe ultrasonicator in presence of conventional surfactant stabilizers or CNTs as done here. Initially, the CNTs (powder form) are dispersed in water followed by further ultrasonication with the molten lipid to form the final emulsion. During this process the CNTs get coated with lipid molecules, which in turn are presumed to surround the lipid droplets to form a particulate emulsion that is stable for months. The average size of CNT-stabilized nanostructured lipid particles is in the submicron range, which compares well with the particles stabilized using conventional surfactants. Small angle X-ray scattering data confirms the retention of the original Pn3m cubic phase in the CNT-stabilized lipid dispersions as compared to the pure lipid phase (bulk state). Blue shift and lowering of the intensities in characteristic G and G&#39; bands of CNTs observed in Raman spectroscopy characterize the interaction between CNT surface and lipid molecules. These results suggest that the interactions between the CNTs and lipids are responsible for their mutual stabilization in aqueous solutions. As the concentrations of CNTs employed for stabilization are very low and lipid molecules are able to functionalize the CNTs, the toxicity of CNTs is expected to be insignificant while their biocompatibility is greatly enhanced. Hence the present approach finds a great potential in various biomedical applications, for instance, for developing hybrid nanocarrier systems for the delivery of multiple functional molecules as in combination therapy or polytherapy.

We report on a smart application of carbon nanotubes for kinetic stabilization of lipid particles that contain self-assembled nanostructures in their cores. The preparation of lipid particles requires rather low concentrations of carbon nanotubes permitting their use in biomedical applications such as drug delivery.

We present a facile method to prepare nanostructured lipid particles stabilized by carbon nanotubes (CNTs). Single-walled (pristine) and multi-walled ...

Facile Preparation of 4-Substituted Quinazoline Derivatives

Reported in this paper is a very simple method for direct preparation of 4-substituted quinazoline derivatives from a reaction between substituted 2-aminobenzophenones and thiourea in the presence of dimethyl sulfoxide (DMSO). This is a unique complementary reaction system in which thiourea undergoes thermal decomposition to form carbodiimide and hydrogen sulfide, where the former reacts with 2-aminobenzophenone to form 4-phenylquinazolin-2(1H)-imine intermediate, whilst hydrogen sulfide reacts with DMSO to give methanethiol or other sulfur-containing molecule which then functions as a complementary reducing agent to reduce 4-phenylquinazolin-2(1H)-imine intermediate into 4-phenyl-1,2-dihydroquinazolin-2-amine. Subsequently, the elimination of ammonia from 4-phenyl-1,2-dihydroquinazolin-2-amine affords substituted quinazoline derivative. This reaction usually gives quinazoline derivative as a single product arising from 2-aminobenzophenone as monitored by GC/MS analysis, along with small amount of sulfur-containing molecules such as dimethyl disulfide, dimethyl trisulfide, etc. The reaction usually completes in 4-6 hr at 160 &#186;C in small scale but may last over 24 hr when carried out in large scale. The reaction product can be easily purified by means of washing off DMSO with water followed by column chromatography or thin layer chromatography.

A protocol for facile preparation of 4-substituted quinazoline derivatives from 2-aminobenzophenones, thiourea and dimethyl sulfoxide is presented.

Reported in this paper is a very simple method for direct preparation of 4-substituted quinazoline derivatives from a reaction between substituted ...

Visualization of Ambient Mass Spectrometry with the Use of Schlieren Photography

This manuscript outlines how to visualize mass spectrometry ambient ionization sources using schlieren photography. In order to properly optimize the mass spectrometer, it is necessary to characterize and understand the physical principles of the source. Most commercial ambient ionization sources utilize jets of nitrogen, helium, or atmospheric air to facilitate the ionization of the analyte. As a consequence, schlieren photography can be used to visualize the gas streams by exploiting the differences in refractive index between the streams and ambient air for visualization in real time. The basic setup requires a camera, mirror, flashlight, and razor blade. When properly configured, a real time image of the source is observed by watching its reflection. This allows for insight into the mechanism of action in the source, and pathways to its optimization can be elucidated. Light is shed on an otherwise invisible situation.

This paper presents a protocol for the visualization of gaseous streams of an ambient ionization source using schlieren photography and mass spectrometry.

This manuscript outlines how to visualize mass spectrometry ambient ionization sources using schlieren photography. In order to properly optimize the mass ...

Facile Synthesis of Worm-like Micelles by Visible Light Mediated Dispersion Polymerization Using Photoredox Catalyst

Presented herein is a protocol for the facile synthesis of worm-like micelles by visible light mediated dispersion polymerization. This approach begins with the synthesis of a hydrophilic poly(oligo(ethylene glycol) methyl ether methacrylate) (POEGMA) homopolymer using reversible addition-fragmentation chain-transfer (RAFT) polymerization. Under mild visible light irradiation (&#955; = 460 nm, 0.7 mW/cm2), this macro-chain transfer agent (macro-CTA) in the presence of a ruthenium based photoredox catalyst, Ru(bpy)3Cl2 can be chain extended with a second monomer to form a well-defined block copolymer in a process known as Photoinduced Electron Transfer RAFT (PET-RAFT). When PET-RAFT is used to chain extend POEGMA with benzyl methacrylate (BzMA) in ethanol (EtOH), polymeric nanoparticles with different morphologies are formed in situ according to a polymerization-induced self-assembly (PISA) mechanism. Self-assembly into nanoparticles presenting POEGMA chains at the corona and poly(benzyl methacrylate) (PBzMA) chains in the core occurs in situ due to the growing insolubility of the PBzMA block in ethanol. Interestingly, the formation of highly pure worm-like micelles can be readily monitored by observing the onset of a highly viscous gel in situ due to nanoparticle entanglements occurring during the polymerization. This process thereby allows for a more reproducible synthesis of worm-like micelles simply by monitoring the solution viscosity during the course of the polymerization. In addition, the light stimulus can be intermittently applied in an ON/OFF manner demonstrating temporal control over the nanoparticle morphology.

This article describes a process for producing polymeric self-assembled nanoparticles using visible light mediated dispersion polymerization. Using low energy visible light to control the polymerization allows for the reproducible formation of self-assembled worm-like micelles at high solids content.

Presented herein is a protocol for the facile synthesis of worm-like micelles by visible light mediated dispersion polymerization. This approach begins ...

Facile Preparation of (2Z,4E)-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate

Direct cross-coupling between two alkenes via vinylic C-H bond activation represents an efficient strategy for the synthesis of butadienes with high atomic and step economy. However, this functionality-directed cross-coupling reaction has not been developed, as there are still limited directing groups in practical use. In particular, a stoichiometric amount of oxidant is usually required, producing a large amount of waste. Due to our interest in novel 1,3-butadiene synthesis, we describe the ruthenium-catalyzed olefination of electron-deficient alkenes using allyl acetate and without external oxidant. The reaction of 2-phenyl acrylamide and allyl acetate was chosen as a model reaction, and the desired diene product was obtained in 80% isolated yield with good stereoselectivity (Z,E/Z,Z = 88:12) under optimal conditions: [Ru(p-cymene) Cl2]2 (3 mol %) and AgSbF6 (20 mol %) in DCE at 110 &#186;C for 16 h. With the optimized catalytic conditions in hand, representative &#945;- and/or &#946;-substituted acrylamides were investigated, and all reacted smoothly, regardless of aliphatic or aromatic groups. Also, differently N-substituted acrylamides have proven to be good substrates. Moreover, we examined the reactivity of different allyl derivatives, suggesting that the chelation of acetate oxygen to the metal is crucial for the catalytic process. Deuterium-labeled experiments were also conducted to investigate the reaction mechanism. Only Z-selective H/D exchanges on acrylamide were observed, indicating a reversible cyclometalation event. In addition, a kinetic isotope effect (KIE) of 3.2 was observed in the intermolecular isotopic study, suggesting that the olefinic C-H metalation step is probably involved in the rate-determining step.

Facile Preparation of 2Z,4E-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate

The ruthenium-catalyzed olefination of electron-deficient alkenes with allyl acetate is described here. By using aminocarbonyl as a directing group, this external oxidant-free protocol has high efficiency and good stereo- and regioselectivity, opening a novel synthetic route to (Z,E)-butadiene skeletons.

Direct cross-coupling between two alkenes via vinylic C-H bond activation represents an efficient strategy for the synthesis of butadienes with high ...

In Situ Characterization of Boehmite Particles in Water Using Liquid SEM

In situ imaging and elemental analysis of boehmite (AlOOH) particles in water is realized using the System for Analysis at the Liquid Vacuum Interface (SALVI) and Scanning Electron Microscopy (SEM). This paper describes the method and key steps in integrating the vacuum compatible SAVLI to SEM and obtaining secondary electron (SE) images of particles in liquid in high vacuum. Energy dispersive x-ray spectroscopy (EDX) is used to obtain elemental analysis of particles in liquid and control samples including deionized (DI) water only and an empty channel as well. Synthesized boehmite (AlOOH) particles suspended in liquid are used as a model in the liquid SEM illustration. The results demonstrate that the particles can be imaged in the SE mode with good resolution (i.e., 400 nm). The AlOOH EDX spectrum shows significant signal from the aluminum (Al) when compared with the DI water and the empty channel control. In situ liquid SEM is a powerful technique to study particles in liquid with many exciting applications. This procedure aims to provide technical know-how in order to conduct liquid SEM imaging and EDX analysis using SALVI and to reduce potential pitfalls when using this approach.

In Situ Characterization of Boehmite Particles in Water Using Liquid SEM

We present a procedure for real-time imaging and elemental composition analysis of boehmite particles in deionized water by in situ liquid Scanning Electron Microscopy.

In situ imaging and elemental analysis of boehmite (AlOOH) particles in water is realized using the System for Analysis at the Liquid Vacuum Interface ...