Thanks to Mr. Jason Adkins for expert technical assistance.

1. Defatting Commercial Gliadin
<ol>
	<li>Measure 150 ml of acetone with a graduated cylinder and pour into 250 ml Erlenmeyer flask.
	<ol>
		<li>While stirring with a spin bar on a magnetic stirrer at RT, add 30 g of commercial gliadin powder. Seal the opening of flask with aluminum foil, and keep on stirring O/N in the hood.</li>
	</ol>
	</li>
	<li>Filtrate the solution with a filter paper.
	<ol>
		<li>Wash the filtrate with fresh acetone (ca. 50 ml). Let stand for 10 min to allow the acetone to drain.</li>
		<li>Transfer the filtrate together with the filter paper underneath to a large dish such as a cell culture square dish. Cover the whole dish with a large filter paper to slow down the evaporation of residual acetone.</li>
		<li>Allow the filtrate to dry completely in the hood O/N. Store the defatted gliadin in an air-tight container at RT.</li>
	</ol>
	</li>
</ol>
2. Preparation of Purified Gliadin
<ol>
	<li>Measure 150 ml of water with a graduated cylinder and pour into 1,000 ml Erlenmeyer flask.
	<ol>
		<li>Measure 350 ml of absolute ethanol with a mess cylinder and pour into the same 1,000 ml Erlenmeyer flask. Stir vigorously (800 - 1,000 rpm) with a spin bar until no bubble is generated from the solution mixture.</li>
	</ol>
	</li>
	<li>While stirring, add 20 g of defatted-commercial gliadin powder. Add gliadin in small amounts at a time to avoid the formation of lumps that contains air in the middle. Keep on stirring O/N.</li>
	<li>Transfer the whole solution to a 1,000 ml mess cylinder. Let stand for two days. During this time, impurities will be precipitated at the bottom of the cylinder.</li>
	<li>Transfer the supernatant to a rotary evaporator with a pipette, and remove ethanol from the supernatant as much as possible. As the percentage of ethanol is reduced, gliadin will appear in the solution as aggregate.</li>
	<li>Freeze the solution containing gliadin aggregates by immersing/rotating in methanol/dry ice mixture and freeze-dry at -70 &#176;C under vacuum. Before freeze-drying, make sure the whole solution is frozen without any liquid. 
	NOTE: The freeze-dried gliadin will form a porous solid.</li>
	<li>Crush the freeze-dried gliadin with mortar and pestle, and grind with a coffee grinder to obtain a fine power (&#60;0.5 mm). Transfer the product into an air-tight container and store at RT.</li>
</ol>
3. Polymerization Reaction of ECA with Gliadin
<ol>
	<li>Place a scintillation vial (volume is around 20 ml) in a weighing balance, and tare. Add 3.2 g distilled water and 6.8 g absolute ethanol in the scitillation vial.</li>
	<li>Move the scintillation vial on to a magnetic stirrer, put a magnetic spin bar (20&#160;x 3 mm) into the vial, and stir vigorously (800 - 1,000 rpm) until no air bubble is generated from the aqueous ethanol mixture.</li>
	<li>Add 40 &#181;l of 4 N HCl into the vial while stirring. Add 20 mg of gliadin into the vial while stirring, and keep on stirring until gliadin powder is fully dissolved in the aqueous ethanol mixture.</li>
	<li>After making sure the gliadin solution is clear to the naked eyes, slowly add 80 - 100 &#181;l of ECA while stirring speed is still 800 - 1,000 rpm.
	<ol>
		<li>Lower the stirring speed to 500 rpm, and continue stirring for 1 hr. As the reaction proceeds, observe turbidity which indicates that the polymerization reaction is in progress.</li>
	</ol>
	</li>
	<li>When the reaction is terminated, transfer the solution into centrifuge tubes, and balance the weight of the tubes. Centrifuge the reaction product at 10,000 x g for 20 min. During this time, side product precipitates and nanoparticles remain in the supernantant. The major component of side product is PACA homopolymer.</li>
	<li>After the centrifuge, transfer the produced nanoparticle suspension (supernatant) with a pipette to a scintillation vial (or any air-tight container), and store it at RT.</li>
</ol>
4. Characterization of the Product
<ol>
	<li>Prepare 10 g of 68 wt% aqueous ethanol by mixing 3.2 g water and 6.8 g absolute ethanol in 20 ml scintillation vial and stir until no bubble is generated from the solution mixture.
	<ol>
		<li>Add 40 &#181;l of 4 N HCl to the solution mixture while stirring. Add 50 &#181;l of nanoparticle suspension to the prepared ethanol solution while stirring.</li>
	</ol>
	</li>
	<li>Measure the size of nanoparticle with Dynamic Light Scattering (DLS) by using the sample solution prepared above and follow manufacturer&#39;s instructions. 
	NOTE: The size of the final product has to be smaller than 200 nm. If it is larger than 200 nm, the product will not be stable for an extended period of time. Larger nanoparticles are produced when the employed ECA is not fresh.</li>
</ol>
5. Examination of the Product
<ol>
	<li>Prepare a glass plate such as a hand mirror.&#160;Wash the surface of glass plate with soap water. Rinse the surface of glass plate with flowing water. Dry the cleaned surface or use without drying for the next step.</li>
	<li>Spray the nanoparticle suspension obtained in 3.6) on a part of the glass plate, and rinse off the surface with flowing water immediately.</li>
	<li>Spray pure water on the surface of glass plate. Observe the coated (sprayed with nanoparticle suspension) surface hold water layer while the uncoated surface is clear.</li>
</ol>

<ol>
	<li>Vauthier, C., Dubernet, C., Fattal, E., Pinto-Alphandary, H., Couvreur, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Poly(alkylcyanoacrylates)+as+biodegradable+materials+for+biomedical+applications.">Poly(alkylcyanoacrylates) as biodegradable materials for biomedical applications.</a> Adv. Drug Deliver. Rev. 55, 519-548 (2003).</li><li>Wieser, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chemistry+of+gluten+proteins.">Chemistry of gluten proteins.</a> Food Microbiol. 24, 115-119 (2007).</li><li>Bietz, J. A., Wall, 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=Identity+of+high+molecular+weight+gliadin+and+ethanol+soluble+glutenin+subunits+of+wheat:+Relation+to+gluten+structure.">Identity of high molecular weight gliadin and ethanol soluble glutenin subunits of wheat: Relation to gluten structure.</a> Cereal Chem. 57, 415-421 (1980).</li><li>Kim, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Production+of+composites+by+using+gliadin+as+a+bonding+material.">Production of composites by using gliadin as a bonding material.</a> J. Cereal Sci. 54, 168-172 (2011).</li><li>Kim, S., Kim, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Production+of+gliadin-poly(ethyl+cyanoacrylate)+nanoparticles+for+hydrophilic+coating.">Production of gliadin-poly(ethyl cyanoacrylate) nanoparticles for hydrophilic coating.</a> J. Nanopart. Res. 16, 1-10 (2014).</li><li>Behan, N., Birkinshaw, C., Clarke, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Poly+n-butyl+cyanoacrylate+nanoparticles:+a+mechanistic+study+of+polymerisation+and+particle+formation.">Poly n-butyl cyanoacrylate nanoparticles: a mechanistic study of polymerisation and particle formation.</a> Biomaterials. 22, 1335-1344 (2001).</li><li>Nicolas, J., Couvreur, P. <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+poly(alkyl+cyanoacrylate)-based+colloidal+nanomedicines.">Synthesis of poly(alkyl cyanoacrylate)-based colloidal nanomedicines.</a> Wiley Interdiscip. Rev. Nanomed. Nanobiotechnol. 1, 111-127 (2009).</li><li>Kim, S., Evans, K., Biswas, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Production+of+BSA-poly(ethyl+cyanoacrylate)+nanoparticles+as+a+coating+material+that+improves+wetting+property.">Production of BSA-poly(ethyl cyanoacrylate) nanoparticles as a coating material that improves wetting property.</a> Colloid Surface. B. 107, 68-75 (2013).</li><li>Lander, L. M., Siewierski, L. M., Brittain, W. J., Vogler, E. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+systematic+comparison+of+contact+angle+methods.">A systematic comparison of contact angle methods.</a> Langmuir. 9, 2237-2239 (1993).</li><li>Davies, J., Nunnerley, C. S., Brisley, A. C., Edwards, J. C., Finlayson, S. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Use+of+Dynamic+Contact+Angle+Profile+Analysis+in+Studying+the+Kinetics+of+Protein+Removal+from+Steel+Glass,+Polytetrafluoroethylene,+Polypropylene,+Ethylenepropylene+Rubber,+and+Silicone+Surfaces.">Use of Dynamic Contact Angle Profile Analysis in Studying the Kinetics of Protein Removal from Steel Glass, Polytetrafluoroethylene, Polypropylene, Ethylenepropylene Rubber, and Silicone Surfaces.</a> J. Colloid Interf. Sci. 182, 437-443 (1996).</li><li>Giolando, D. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nano-crystals+of+titanium+dioxide+in+aluminum+oxide:+A+transparent+self-cleaning+coating+applicable+to+solar+energy.">Nano-crystals of titanium dioxide in aluminum oxide: A transparent self-cleaning coating applicable to solar energy.</a> Sol. Energy. 97, 195-199 (2013).</li></ol>

Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture. USDA is an equal opportunity provider and employer.

There are several critical steps in the production of the nanoparticle suspension. If the purified gliadin contains impurities, the reaction with ECA will produce side products. Although these unwanted products can be removed from the reaction medium during the centrifugation stage, it lowers the yield of the major product. If the gliadin solution prepared during experimental step 2.3) does not show clear separation between supernatant and precipitate after two days, the solution needs to stand for longer time. Using fre...

The goal of this article is to show the protocol for the preparation of nanoparticle suspension that modifies the wetting property of materials by a simple spray. The presented nanoparticle suspension is made from alkyl cyanoacrylate1 and a cereal protein, gliadin2,3. During the manufacturing process, protein aggregates are formed in aqueous ethanol4. Subsequent reaction with monomer (alkyl cyanoacrylate) produces the nanoparticle that is comprised of a protein core surrounded by linear polymer chains [poly(alkyl cyanoacrylate)]5.
Poly(alkyl cyanoacrylate)s are biodegradable and have been used for the production of nanoparticles via emulsion polymerization6. This reaction is spontaneously initiated by the hydroxyl groups dissociated from water or by other nucleophilic groups in the reaction medium7. In the case of the reaction presented in this article, the amine groups on the surface of protein aggregates initiate the polymerization reaction of alkyl cyanoacrylate monomers5,8. As a result of this reaction, nanoparticles are formed in the reaction medium. The core of the nanoparticle is protein aggregates and the outer layer is poly(alkyl cyanoacrylate) (PACA) chains. The prepared nanoparticle has a strong affinity on most materials (more precisely, any material which PACA can adsorb to) and adheres onto their surface to form a thin coating on a nanometer scale. A simple spray coating instantly turns the surface of the materials hydrophilic.
Gliadin is one of the main fractions of gluten, which is in the endosperms of wheat. Gliadins are mainly monomeric proteins with molecular weights around 28,000 - 55,000. Non-covalent bonds such as hydrogen bonds, ionic bonds and hydrophobic bonds are responsible for the aggregation of gliadins2. Although gliadin is chosen as a reactant in this article, many other proteins can also be used for the same purpose. However, the reaction condition needs to be modified accordingly because the condition for inducing aggregation is dependent on the type of protein to be employed8. Compared with other proteins, gliadin is more readily available, purification is simple, and production cost is low. Although ethyl cyanoacrylate (ECA) is chosen as a monomer for the presented reaction, other alkyl cyanoacrylates can also be used for the same reaction. The reason for choosing ECA is that it is readily available at low cost.

<table border="0" cellpadding="0" cellspacing="0" width="580">
	<tbody>
		<tr height="85">
			<td height="85" style="height:85px;width:143px;">Ethyl cyanoacrylate (ECA) monomer</td>
			<td style="width:113px;">K&#38;R International (Laguna Niguel, CA)</td>
			<td style="width:107px;">I-1605</td>
			<td style="width:219px;">Any pure ECA can be used.</td>
		</tr>
		<tr height="106">
			<td height="106" style="height:106px;width:143px;">Gliadin</td>
			<td style="width:113px;">MGP Ingredients, Inc (Atchison, KS)</td>
			<td style="width:107px;">Gift from the company</td>
			<td style="width:219px;">Gliadin can be purchased from Sigma-Aldrich (cat #: G3375-25G). Instead of gliadin, any commercial&#160; gluten can be used.</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:143px;">HCl</td>
			<td style="width:113px;">Any</td>
			<td style="width:107px;"></td>
			<td style="width:219px;">Any reagent grade chemical can be used.</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:143px;">Acetone</td>
			<td style="width:113px;">Any</td>
			<td style="width:107px;"></td>
			<td style="width:219px;">Any reagent grade chemical can be used.</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:143px;">Methanol</td>
			<td style="width:113px;">Any</td>
			<td style="width:107px;"></td>
			<td style="width:219px;">Any reagent grade chemical can be used.</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:143px;">Ethanol (100%)</td>
			<td style="width:113px;">Any</td>
			<td style="width:107px;"></td>
			<td style="width:219px;">Any reagent grade chemical can be used.</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:143px;">Filter paper</td>
			<td style="width:113px;">Any</td>
			<td style="width:107px;"></td>
			<td style="width:219px;">Any grade filter paper larger than 10 cm can be used.</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:143px;">Cell culture square dish</td>
			<td style="width:113px;">Any</td>
			<td style="width:107px;"></td>
			<td style="width:219px;">Any dish larger than 20 cm x 20 cm can be used.</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:143px;">Coffee grinder</td>
			<td style="width:113px;">Any</td>
			<td style="width:107px;"></td>
			<td style="width:219px;">Any coffee grinder can be used.</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:143px;">Rotary evaporator</td>
			<td style="width:113px;">Any</td>
			<td style="width:107px;"></td>
			<td style="width:219px;">Any rotary evaporator can be used.</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:143px;">Freeze Dryer</td>
			<td style="width:113px;">Any</td>
			<td style="width:107px;"></td>
			<td style="width:219px;">Any freeze dryer that can reach - 70&#176;C can be used.</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:143px;">Centrifuge</td>
			<td style="width:113px;">Any</td>
			<td style="width:107px;"></td>
			<td style="width:219px;">Any centrifuge that can apply 1000 x g can be used.</td>
		</tr>
		<tr height="64">
			<td height="64" style="height:64px;width:143px;">Magnetic stirrer</td>
			<td style="width:113px;">Any</td>
			<td style="width:107px;"></td>
			<td style="width:219px;">Any magnetic stirrer that can turn spin bar to 1000 RPM can be used.</td>
		</tr>
		<tr height="85">
			<td height="85" style="height:85px;width:143px;">Dynamic Light Scattering (DLS)</td>
			<td style="width:113px;">Brookhaven Instruments Corporation</td>
			<td style="width:107px;">NanoBrook Omni Zeta Potential Analyzer</td>
			<td style="width:219px;">DLS from any company can be used.</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:143px;">Scanning Electron Microscope (SEM)</td>
			<td style="width:113px;">Carl Zeiss Inc.</td>
			<td style="width:107px;"></td>
			<td style="width:219px;">Any SEM can be used.</td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:143px;">Dynamic Contact Angle (DCA)</td>
			<td style="width:113px;">Thermo Cahn Instruments</td>
			<td style="width:107px;"></td>
			<td style="width:219px;">Any DCA can be used.</td>
		</tr>
	</tbody>
</table>

a protocol for the production of gliadin-cyanoacrylate nanoparticles for hydrophilic coating

This article presents a protocol for the production of protein-based nanoparticles that changes the hydrophobic surface to hydrophilic by a simple spray coating. These nanoparticles are produced by the polymerization reaction of alkyl cyanoacrylate on the surface of cereal protein (gliadin) molecules. Alkyl cyanoacrylate is a monomer that instantly polymerizes at RT when it is applied to the surface of materials. Its polymerization reaction is initiated by the trace amounts of weakly basic or nucleophilic species on the surface, including moisture. Once polymerized, the polymerized alkyl cyanoacrylates show a strong affinity with the object materials because nitrile groups are in the backbone of poly (alkyl cyanoacrylate). Proteins also work as initiator for this polymerization because they contain amine groups that can initiate the polymerization of cyanoacrylate. If aggregated protein is used as an initiator, protein aggregate is surrounded by the hydrophobic poly(alkyl cyanoacrylate) chains after the polymerization reaction of alkyl cyanoacrylate. By controlling the experimental condition, particles in the nanometer range are produced. The produced nanoparticles readily adsorb to the surface of most materials including glass, metals, plastics, wood, leather, and fabrics. When the surface of a material is sprayed with the produced nanoparticle suspension and rinsed with water, the micellar structure of nanoparticle changes its conformation, and the hydrophilic proteins are exposed to the air. As a result, the nanoparticle-coated surface changes to hydrophilic.

Nanoparticles can be prepared in various reaction conditions. Gliadin forms aggregate in broad range of ethanol content5. However, the size of aggregates needs to be as small as possible because an additional layer (i.e., polymerized ECA) will be added to this aggregate and this process will make the final size larger. If the final size of particle is too large, the particle will be unstable and will easily be precipitated. Therefore, 68% aqueous ethanol was chosen as ...

Watch this Scientific Journal Video about A Protocol for the Production of Gliadin-cyanoacrylate Nanoparticles for Hydrophilic Coating at JoVE.com

A Protocol for the Production of Gliadin-cyanoacrylate Nanoparticles for Hydrophilic Coating

This article presents a protocol for the production of protein-based nanoparticles that changes the hydrophobic surface to hydrophilic. The produced nanoparticle is an assembly of gliadin-cyanoacrylate diblock copolymers. Spray coating with the produced nanoparticle changes the surface of target material to a hydrophilic surface.

This article presents a protocol for the production of protein-based nanoparticles that changes the hydrophobic surface to hydrophilic by a simple spray ...

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6.8K Views.  USDA/ARS/NCAUR. This article presents a protocol for the production of protein-based nanoparticles that changes the hydrophobic surface to hydrophilic. The produced nanoparticle is an assembly of gliadin-cyanoacrylate diblock copolymers. Spray coating with the produced nanoparticle changes the surface of target material to a hydrophilic surface.

Video: A Protocol for the Production of Gliadin-cyanoacrylate Nanoparticles for Hydrophilic Coating

Production of Disulfide-stabilized Transmembrane Peptide Complexes for Structural Studies

Physical interactions among the lipid-embedded alpha-helical domains of membrane proteins play a crucial role in folding and assembly of membrane protein complexes and in dynamic processes such as transmembrane (TM) signaling and regulation of cell-surface protein levels. Understanding the structural features driving the association of particular sequences requires sophisticated biophysical and biochemical analyses of TM peptide complexes. However, the extreme hydrophobicity of TM domains makes them very difficult to manipulate using standard peptide chemistry techniques, and production of suitable study material often proves prohibitively challenging. Identifying conditions under which peptides can adopt stable helical conformations and form complexes spontaneously adds a further level of difficulty. Here we present a procedure for the production of homo- or hetero-dimeric TM peptide complexes from materials that are expressed in E. coli, thus allowing incorporation of stable isotope labels for nuclear magnetic resonance (NMR) or non-natural amino acids for other applications relatively inexpensively. The key innovation in this method is that TM complexes are produced and purified as covalently associated (disulfide-crosslinked) assemblies that can form stable, stoichiometric and homogeneous structures when reconstituted into detergent, lipid or other membrane-mimetic materials. We also present carefully optimized procedures for expression and purification that are equally applicable whether producing single TM domains or crosslinked complexes and provide advice for adapting these methods to new TM sequences.

Biophysical and biochemical studies of interactions among membrane-embedded protein domains face many technical challenges, the first of which is obtaining appropriate study material. This article describes a protocol for producing and purifying disulfide-stabilized transmembrane peptide complexes that are suitable for structural analysis by solution nuclear magnetic resonance (NMR) and other analytical applications.

Physical  interactions among the lipid-embedded alpha-helical domains of membrane  proteins play a crucial role in folding and assembly of membrane ...

Thin-layer Chromatographic (TLC) Separations and Bioassays of Plant Extracts to Identify Antimicrobial Compounds

A common screen for plant antimicrobial compounds consists of separating plant extracts by paper or thin-layer chromatography (PC or TLC), exposing the chromatograms to microbial suspensions (e.g. fungi or bacteria in broth or agar), allowing time for the microbes to grow in a humid environment, and visualizing zones with no microbial growth.&#160;The effectiveness of this screening method, known as bioautography, depends on both the quality of the chromatographic separation and the care taken with microbial culture conditions.&#160;This paper describes standard protocols for TLC and contact bioautography&#160;with a novel application to amino acid-fermenting bacteria. The extract is separated on flexible (aluminum-backed) silica TLC plates, and bands are visualized under ultraviolet (UV) light.&#160;Zones are cut out and incubated face down onto agar inoculated with the test microorganism.&#160;Inhibitory bands are visualized by staining the agar plates with tetrazolium red.&#160;The method is applied to the separation of red clover (Trifolium pratense cv. Kenland) phenolic compounds and their screening for activity against Clostridium sticklandii, a hyper ammonia-producing bacterium (HAB) that is native to the bovine rumen.&#160;The TLC methods apply to many types of plant extracts&#160;and other bacterial species (aerobic or anaerobic), as well as fungi, can be used as test organisms if culture conditions are modified to fit the growth requirements of the species.

Thin-layer Chromatographic TLC Separations and Bioassays of Plant Extracts to Identify Antimicrobial Compounds

Methods are described for thin-layer chromatographic (TLC) separation of plant extracts and contact bioautography to identify antibacterial metabolites. The methods are applied to the screening of red clover phenolic compounds inhibiting hyper&#160;ammonia-producing bacteria (HAB) native to the bovine rumen.

A common screen for plant antimicrobial compounds consists of separating plant extracts by paper or thin-layer chromatography (PC or TLC), exposing the ...

A Simple Method for the Size Controlled Synthesis of Stable Oligomeric Clusters of Gold Nanoparticles under Ambient Conditions

Reducing dilute aqueous HAuCl4 with sodium thiocyanate (NaSCN) under alkaline conditions produces 2 to 3 nm diameter nanoparticles. Stable grape-like oligomeric clusters of these yellow nanoparticles of narrow size distribution are synthesized under ambient conditions via two methods. The delay-time method controls the number of subunits in the oligoclusters by varying the time between the addition of HAuCl4 to alkaline solution and the subsequent addition of reducing agent, NaSCN. The yellow oligoclusters produced range in size from ~3 to ~25 nm. This size range can be further extended by an add-on method utilizing hydroxylated gold chloride (Na+[Au(OH4-x)Clx]-) to auto-catalytically increase the number of subunits in the as-synthesized oligocluster nanoparticles, providing a total range of 3 nm to 70 nm. The crude oligocluster preparations display narrow size distributions and do not require further fractionation for most purposes. The oligoclusters formed can be concentrated &#62;300 fold without aggregation and the crude reaction mixtures remain stable for weeks without further processing. Because these oligomeric clusters can be concentrated before derivatization they allow expensive derivatizing agents to be used economically. In addition, we present two models by which predictions of particle size can be made with great accuracy.

We describe a simple method for producing highly stable oligomeric clusters of gold nanoparticles via the reduction of chloroauric acid (HAuCl4) with sodium thiocyanate (NaSCN). The oligoclusters have a narrow size distribution and can be produced with a wide range of sizes and surface coats.

Reducing dilute aqueous HAuCl4 with sodium thiocyanate (NaSCN) under alkaline conditions produces 2 to 3 nm diameter nanoparticles. Stable grape-like ...

Protocol for the Synthesis of Ortho-trifluoromethoxylated Aniline Derivatives

Molecules bearing trifluoromethoxy (OCF3) group often show desired pharmacological and biological properties. However, facile synthesis of trifluoromethoxylated aromatic compounds remains a formidable challenge in organic synthesis. Conventional approaches often suffer from poor substrate scope, or require use of highly toxic, difficult-to-handle, and/or thermally labile reagents. Herein, we report a user-friendly protocol for the synthesis of methyl 4-acetamido-3-(trifluoromethoxy)benzoate using 1-trifluoromethyl-1,2-benziodoxol-3(1H)-one (Togni reagent II). Treating methyl 4-(N-hydroxyacetamido)benzoate (1a) with Togni reagent II in the presence of a catalytic amount of cesium carbonate (Cs2CO3) in chloroform at RT afforded methyl 4-(N-(trifluoromethoxy)acetamido)benzoate (2a). This intermediate was then converted to the final product methyl 4-acetamido-3-(trifluoromethoxy)benzoate (3a) in nitromethane at 120 &#176;C. This procedure is general and can be applied to the synthesis of a broad spectrum of ortho-trifluoromethoxylated aniline derivatives, which could serve as useful synthetic building blocks for the discovery and development of new pharmaceuticals, agrochemicals, and functional materials.

Protocol for the Synthesis of Ortho-trifluoromethoxylated Aniline Derivatives

An operationally simple procedure for the synthesis of ortho-trifluoromethoxylated aniline derivatives via a two-step sequence of O-trifluoromethylation of N-aryl-N-hydroxyacetamide followed by thermally induced intramolecular OCF3-migration is reported.

Molecules bearing trifluoromethoxy (OCF3) group often show desired pharmacological and biological properties. However, facile synthesis of ...

A Simple and Efficient Protocol for the Catalytic Insertion Polymerization of Functional Norbornenes

Norbornene can be polymerized by a variety of mechanisms, including insertion polymerization whereby the double bond is polymerized and the bicyclic nature of the monomer is conserved. The resulting polymer, polynorbornene, has a very high glass transition temperature, Tg, and interesting optical and electrical properties. However, the polymerization of functional norbornenes by this mechanism is complicated by the fact that the endo substituted norbornene monomer has, in general, a very low reactivity. Furthermore, the separation of the endo substituted monomer from the exo monomer is a tedious task. Here, we present a simple protocol for the polymerization of substituted norbornenes (endo:exo ca. 80:20) bearing either a carboxylic acid or a pendant double bond. The process does not require that both isomers be separated, and proceeds with low catalyst loadings (0.01 to 0.02 mol%). The polymer bearing pendant double bonds can be further transformed in high yield, to afford a polymer bearing pendant epoxy groups. These simple procedures can be applied to prepare polynorbornenes with a variety of functional groups, such as esters, alcohols, imides, double bonds, carboxylic acids, bromo-alkyls, aldehydes and anhydrides.

We describe the catalytic insertion polymerization of 5-norbornene-2-carboxylic acid and 5-vinyl-2-norbornene to form functional polymers with a very high glass transition temperature.

Norbornene can be polymerized by a variety of mechanisms, including insertion polymerization whereby the double bond is polymerized and the bicyclic ...

A Protocol for Safe Lithiation Reactions Using Organolithium Reagents

Organolithium reagents are powerful tools in the synthetic chemist&#39;s toolbox. However, the extreme pyrophoric nature of the most reactive reagents warrants proper technique, thorough training, and proper personal protective equipment. To aid in the training of researchers using organolithium reagents, a thorough, step-by-step protocol for the safe and effective use of tert-butyllithium on an inert gas line or within a glovebox is described. As a model reaction, preparation of lithium tert-butyl amide by the reaction of tert-butyl amine with one equivalent of tert-butyl lithium is presented.

The safe and proper use of organolithium reagents is described.

Organolithium reagents are powerful tools in the synthetic chemist&#39;s toolbox. However, the extreme pyrophoric nature of the most reactive reagents ...

An Optimized Protocol for the Efficient Radiolabeling of Gold Nanoparticles by Using a 125I-labeled Azide Prosthetic Group

Here, we demonstrate a detailed protocol for the radiosynthesis of a 125I-labeled azide prosthetic group and its application to the efficient radiolabeling of DBCO-group-functionalized gold nanoparticles using a copper-free click reaction. Radioiodination of the stannylated precursor (2) was carried out by using [125I]NaI and chloramine T as an oxidant at room temperature for 15 min. After HPLC purification of the crude product, the purified 125I-labeled azide (1) was obtained with high radiochemical yield (75 &plusmn; 10%, n = 8) and excellent radiochemical purity (&gt;99%). For the synthesis of radiolabeled 13-nm-sized gold nanoparticles, the DBCO-functionalized gold nanoparticles (3) were prepared by using a thiolated polyethylene glycol polymer. A copper-free click reaction between 1 and 3 gave the 125I-labeled gold nanoparticles (4) with more than 95% of radiochemical yield as determined by radio-thin-layer chromatography (radio-TLC). These results clearly indicate that the present radiolabeling method using a strain-promoted copper-free click reaction will be useful for the efficient and convenient radiolabeling of DBCO-group-containing nanomaterials.

An Optimized Protocol for the Efficient Radiolabeling of Gold Nanoparticles by Using a 125I-labeled Azide Prosthetic Group

A detailed procedure for the synthesis of a 125I-labeled azide and the radiolabeling of dibenzocyclooctyne (DBCO)-group-conjugated, 13-nm-sized gold nanoparticles using a copper-free click reaction is described.

Here, we demonstrate a detailed protocol for the radiosynthesis of a 125I-labeled azide prosthetic group and its application to the efficient ...

The MPLEx Protocol for Multi-omic Analyses of Soil Samples

Mass spectrometry (MS)-based integrated metaproteomic, metabolomic, and lipidomic (multi-omic) studies are transforming our ability to understand and characterize microbial communities in environmental and biological systems. These measurements are even enabling enhanced analyses of complex soil microbial communities, which are the most complex microbial systems known to date. Multi-omic analyses, however, do have sample preparation challenges, since separate extractions are typically needed for each omic study, thereby greatly amplifying the preparation time and amount of sample required. To address this limitation, a 3-in-1 method for the simultaneous extraction of metabolites, proteins, and lipids (MPLEx) from the same soil sample was created by adapting a solvent-based approach. This MPLEx protocol has proven to be both simple and robust for many sample types, even when utilized for limited quantities of complex soil samples. The MPLEx method also greatly enabled the rapid multi-omic measurements needed to gain a better understanding of the members of each microbial community, while evaluating the changes taking place upon biological and environmental perturbations.

A protocol is presented for simultaneously extracting metabolites, proteins, and lipids from a single soil sample, allowing reduced sample preparation times and enabling multi-omic mass spectrometry analyses of samples with limited quantities.

Mass spectrometry (MS)-based integrated metaproteomic, metabolomic, and lipidomic (multi-omic) studies are transforming our ability to understand and ...

Automation of a Positron-emission Tomography (PET) Radiotracer Synthesis Protocol for Clinical Production

The development of new positron-emission tomography (PET) tracers is enabling researchers and clinicians to image an increasingly wide array of biological targets and processes. However, the increasing number of different tracers creates challenges for their production at radiopharmacies. While historically it has been practical to dedicate a custom-configured radiosynthesizer and hot cell for the repeated production of each individual tracer, it is becoming necessary to change this workflow. Recent commercial radiosynthesizers based on disposable cassettes/kits for each tracer simplify the production of multiple tracers with one set of equipment by eliminating the need for custom tracer-specific modifications. Furthermore, some of these radiosynthesizers enable the operator to develop and optimize their own synthesis protocols in addition to purchasing commercially-available kits. In this protocol, we describe the general procedure for how the manual synthesis of a new PET tracer can be automated on one of these radiosynthesizers and validated for the production of clinical-grade tracers. As an example, we use the ELIXYS radiosynthesizer, a flexible cassette-based radiochemistry tool that can support both PET tracer development efforts, as well as routine clinical probe manufacturing on the same system, to produce [18F]Clofarabine ([18F]CFA), a PET tracer to measure in vivo deoxycytidine kinase (dCK) enzyme activity. Translating a manual synthesis involves breaking down the synthetic protocol into basic radiochemistry processes that are then translated into intuitive chemistry &#34;unit operations&#34; supported by the synthesizer software. These operations can then rapidly be converted into an automated synthesis program by assembling them using the drag-and-drop interface. After basic testing, the synthesis and purification procedure may require optimization to achieve the desired yield and purity. Once the desired performance is achieved, a validation of the synthesis is carried out to determine its suitability for the production of the radiotracer for clinical use.

Automation of a Positron-emission Tomography PET Radiotracer Synthesis Protocol for Clinical Production

Positron-emission tomography (PET) imaging sites that are involved in multiple early clinical research trials need robust and versatile radiotracer manufacturing capabilities. Using the radiotracer [18F]Clofarabine as an example, we illustrate how to automate the synthesis of a radiotracer using a flexible, cassette-based radiosynthesizer and validate the synthesis for clinical use.

The development of new positron-emission tomography (PET) tracers is enabling researchers and clinicians to image an increasingly wide array of biological ...

Gene-therapy Inspired Polycation Coating for Protection of DNA Origami Nanostructures

DNA origami nanostructures hold an immense potential to be used for biological and medical applications. However, low-salt conditions and nucleases in physiological fluids induce denaturation and degradation of self-assembled DNA nanostructures. In non-viral gene delivery, enzymatic degradation of DNA is overcome by the encapsulation of the negatively charged DNA in a cationic shell. Herein, inspired by gene delivery advancements, a simple, one-step and robust methodology is presented for the stabilization of DNA origami nanostructures by coating them with chitosan and linear polyethyleneimine. The polycation coating efficiently protects DNA origami nanostructures in Mg-depleted and nuclease-rich media. This method also preserves the full addressability of enzyme- and aptamer-based functionalization of DNA nanostructures.

Here, a protocol for the protection of DNA origami nanostructures in Mg-depleted and nuclease-rich media using natural cationic polysaccharide chitosan and synthetic linear polyethyleneimine (LPEI) coatings is presented.

DNA origami nanostructures hold an immense potential to be used for biological and medical applications. However, low-salt conditions and nucleases in ...