Name: stable aqueous suspensions of manganese ferrite clusters with tunable nanoscale dimension and composition
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Este trabalho foi generosamente apoiado pela Universidade Brown e pelo Consórcio de Energia Avançada. Agradecemos ao Dr. Qingbo Zhang por seu método sintético estabelecido de MFCs de óxido de ferro.

1. Síntese de MFCs com controle sobre o diâmetro geral dos MFCs e composição ferrita
<ol><li>Lave e seque completamente todos os vidros para serem usados na síntese. A quantidade de água na síntese impacta as dimensões dos MFCs, por isso é crucial garantir que o vidro não tenha água residual nele16,26.<ol>
<li>Para lavar os vidros, enxágue com água e detergente e esfregue com uma escova de frasco para remover os detritos. Enxágue ...

<ol>
	<li>Makridis, A., 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=In+vitro+application+of+Mn-ferrite+nanoparticles+as+novel+magnetic+hyperthermia+agents.">In vitro application of Mn-ferrite nanoparticles as novel magnetic hyperthermia agents.</a> Journal of Materials Chemistry B. 2 (47), 8390-8398 (2014).</li><li>Nelson-Cheeseman, B., Chopdekar, R., Toney, M., Arenholz, E., Suzuki, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interplay+between+magnetism+and+chemical+structure+at+spinel-spinel+interfaces.">Interplay between magnetism and chemical structure at spinel-spinel interfaces.</a> Journal of Applied Physics. 111 (9), 093903 (2012).</li><li>Otero-Lorenzo, R., Fantechi, E., Sangregorio, C., Salgueiri&#241;o, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Solvothermally+driven+Mn+doping+and+clustering+of+iron+oxide+nanoparticles+for+heat+delivery+applications.">Solvothermally driven Mn doping and clustering of iron oxide nanoparticles for heat delivery applications.</a> Chemistry-A European Journal. 22 (19), 6666-6675 (2016).</li><li>Mohapatra, 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=Enhancement+of+magnetic+heating+efficiency+in+size+controlled+MFe+2+O+4+(M=+Mn,+Fe,+Co+and+Ni)+nanoassemblies.">Enhancement of magnetic heating efficiency in size controlled MFe 2 O 4 (M= Mn, Fe, Co and Ni) nanoassemblies.</a> Rsc Advances. 5 (19), 14311-14321 (2015).</li><li>Qi, Y., 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=Carboxylic+silane-exchanged+manganese+ferrite+nanoclusters+with+high+relaxivity+for+magnetic+resonance+imaging.">Carboxylic silane-exchanged manganese ferrite nanoclusters with high relaxivity for magnetic resonance imaging.</a> Journal of Materials Chemistry B. 1 (13), 1846-1851 (2013).</li><li>Anandhi, J. S., Jacob, G. A., Joseyphus, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Factors+affecting+the+heating+efficiency+of+Mn-doped+Fe3O4+nanoparticles.">Factors affecting the heating efficiency of Mn-doped Fe3O4 nanoparticles.</a> Journal of Magnetism and Magnetic Materials. 512, 166992 (2020).</li><li>Del Bianco, L., 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=Mechanism+of+magnetic+heating+in+Mn-doped+magnetite+nanoparticles+and+the+role+of+intertwined+structural+and+magnetic+properties.">Mechanism of magnetic heating in Mn-doped magnetite nanoparticles and the role of intertwined structural and magnetic properties.</a> Nanoscale. 11 (22), 10896-10910 (2019).</li><li>Padmapriya, G., Manikandan, A., Krishnasamy, V., Jaganathan, S. K., Antony, S. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enhanced+catalytic+activity+and+magnetic+properties+of+spinel+Mn+x+Zn+1&#8722;x+Fe+2+O+4+(0.0&#8804;x&#8804;1.0)+nano-photocatalysts+by+microwave+irradiation+route.">Enhanced catalytic activity and magnetic properties of spinel Mn x Zn 1&#8722;x Fe 2 O 4 (0.0&#8804;x&#8804;1.0) nano-photocatalysts by microwave irradiation route.</a> Journal of Superconductivity and Novel Magnetism. 29 (8), 2141-2149 (2016).</li><li>Kim, 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=Continuous+O2-evolving+MnFe2O4+nanoparticle-anchored+mesoporous+silica+nanoparticles+for+efficient+photodynamic+therapy+in+hypoxic+cancer.">Continuous O2-evolving MnFe2O4 nanoparticle-anchored mesoporous silica nanoparticles for efficient photodynamic therapy in hypoxic cancer.</a> Journal of the American Chemical Society. 139 (32), 10992-10995 (2017).</li><li>Silva, L. H., Cruz, F. F., Morales, M. M., Weiss, D. J., Rocco, P. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Magnetic+targeting+as+a+strategy+to+enhance+therapeutic+effects+of+mesenchymal+stromal+cells.">Magnetic targeting as a strategy to enhance therapeutic effects of mesenchymal stromal cells.</a> Stem Cell Research &amp; Therapy. 8 (1), 1-8 (2017).</li><li>Otero-Lorenzo, R., Ramos-Docampo, M. A., Rodriguez-Gonzalez, B., Comesan&#771;a-Hermo, M., Salgueiri&#241;o, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Solvothermal+clustering+of+magnetic+spinel+ferrite+nanocrystals:+a+Raman+perspective.">Solvothermal clustering of magnetic spinel ferrite nanocrystals: a Raman perspective.</a> Chemistry of Materials. 29 (20), 8729-8736 (2017).</li><li>Aghazadeh, M., Karimzadeh, I., Ganjali, M. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=PVP+capped+Mn2++doped+Fe3O4+nanoparticles:+a+novel+preparation+method,+surface+engineering+and+characterization.">PVP capped Mn2+ doped Fe3O4 nanoparticles: a novel preparation method, surface engineering and characterization.</a> Materials Letters. 228, 137-140 (2018).</li><li>Li, Z., 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=Solvothermal+synthesis+of+MnFe+2+O+4+colloidal+nanocrystal+assemblies+and+their+magnetic+and+electrocatalytic+properties.">Solvothermal synthesis of MnFe 2 O 4 colloidal nanocrystal assemblies and their magnetic and electrocatalytic properties.</a> New Journal of Chemistry. 39 (1), 361-368 (2015).</li><li>Guo, P., Zhang, G., Yu, J., Li, H., Zhao, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Controlled+synthesis,+magnetic+and+photocatalytic+properties+of+hollow+spheres+and+colloidal+nanocrystal+clusters+of+manganese+ferrite.">Controlled synthesis, magnetic and photocatalytic properties of hollow spheres and colloidal nanocrystal clusters of manganese ferrite.</a> Colloids and Surfaces A: Physicochemical and Engineering Aspects. 395, 168-174 (2012).</li><li>Pardo, A., 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=Synthesis,+characterization,+and+evaluation+of+superparamagnetic+doped+ferrites+as+potential+therapeutic+nanotools.">Synthesis, characterization, and evaluation of superparamagnetic doped ferrites as potential therapeutic nanotools.</a> Chemistry of Materials. 32 (6), 2220-2231 (2020).</li><li>Xiao, Z., 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=Libraries+of+uniform+magnetic+multicore+nanoparticles+with+tunable+dimensions+for+biomedical+and+photonic+applications.">Libraries of uniform magnetic multicore nanoparticles with tunable dimensions for biomedical and photonic applications.</a> ACS Applied Materials &amp; Interfaces. 12 (37), 41932-41941 (2020).</li><li>Choi, Y. S., Young Yoon, H., Sung Lee, J., Hua Wu, J., Keun 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=Synthesis+and+magnetic+properties+of+size-tunable+Mn+x+Fe3&#8722;x+O4+ferrite+nanoclusters.">Synthesis and magnetic properties of size-tunable Mn x Fe3&#8722;x O4 ferrite nanoclusters.</a> Journal of Applied Physics. 115 (17), (2014).</li><li>Creixell, M., 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=The+effect+of+grafting+method+on+the+colloidal+stability+and+in+vitro+cytotoxicity+of+carboxymethyl+dextran+coated+magnetic+nanoparticles.">The effect of grafting method on the colloidal stability and in vitro cytotoxicity of carboxymethyl dextran coated magnetic nanoparticles.</a> Journal of Materials Chemistry. 20 (39), 8539-8547 (2010).</li><li>Latorre, M., Rinaldi, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Applications+of+magnetic+nanoparticles+in+medicine:+magnetic+fluid+hyperthermia.">Applications of magnetic nanoparticles in medicine: magnetic fluid hyperthermia.</a> Puerto Rico Health Sciences Journal. 28 (3), (2009).</li><li>Yeap, S. P., Lim, J., Ooi, B. S., Ahmad, A. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Agglomeration,+colloidal+stability,+and+magnetic+separation+of+magnetic+nanoparticles:+collective+influences+on+environmental+engineering+applications.">Agglomeration, colloidal stability, and magnetic separation of magnetic nanoparticles: collective influences on environmental engineering applications.</a> Journal of Nanoparticle Research. 19 (11), 1-15 (2017).</li><li>Lee, S. -. Y., Harris, M. 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Preparation of uniform particles by hydrolysis of Fe (III)-chloride,-nitrate, and-perchlorate solutions.</a> Journal of Colloid and Interface Science. 63 (3), 509-524 (1978).</li><li>Weizenecker, J., Gleich, B., Rahmer, J., Dahnke, H., Borgert, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Three-dimensional+real-time+in+vivo+magnetic+particle+imaging.">Three-dimensional real-time in vivo magnetic particle imaging.</a> Physics in Medicine &amp; Biology. 54 (5), 1 (2009).</li><li>Zhu, X., Li, J., Peng, P., Hosseini Nassab, N., Smith, B. 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Este trabalho demonstra uma síntese de poliol modificada de nanocristais de ferrite de manganês agrupados em agregados de nanoescala uniforme29. Nesta síntese, o cloreto de ferro (III) e o cloreto de manganês(II) sofrem uma reação e redução da hidrólise forçada, formando MnxFe3-xO4 molecular. Estas moléculas de ferrite formam nanocristais primários sob a alta temperatura e alta pressão nos reatores, finalmente se reunindo em agregados esfér...

A inclusão de manganês como dopant em uma rede de óxido de ferro pode, sob as condições adequadas, aumentar a magnetização do material em campos de alta aplicação em comparação com óxidos de ferro puros. Como resultado, as nanopartículas de manganês ferrite (MnxFe3-xO4) são nanomateriais magnéticos altamente desejáveis devido à sua alta magnetização de saturação, forte resposta a campos externos e baixa citotoxicidade1,2,3,4,5. Tanto os nanocristais de domínio único quanto os agrupamentos desses nanocristais, denominados partículas multidomainas, têm sido investigados em diversas aplicações biomédicas, incluindo entrega de medicamentos, hipertermia magnética para tratamento do câncer e ressonância magnética (RM)6,7,8. Por exemplo, o grupo Hyeon em 2017 usou nanopartículas de ferrite de manganês de domínio único como um catalisador fenton para induzir a hipóxia do câncer e explorou o T2contrast do material para rastreamento de ressonância magnética9. É surpreendente à luz desses e outros estudos positivos de materiais ferritais que há poucas demonstrações in vivo em comparação com nanomateriais de óxido de ferro puro (Fe3O4), e nenhuma aplicação relatada em humanos9,10.
Um imenso desafio enfrentado na tradução das características dos nanomateriais ferrite para a clínica é a geração de aglomerados uniformes, não agregadores e nanoescala11,12,13,14. Embora as abordagens sintéticas convencionais para os nanocristais monodomínios sejam bem desenvolvidas, os aglomerados multidomain do tipo de interesse neste trabalho não são facilmente produzidos de forma uniforme e controlada15,16. Além disso, a composição ferrita geralmente não é estequiométrica e não apenas está relacionada à concentração inicial dos precursores e isso pode obscurecer ainda mais a caracterização sistemática estrutura-função desses materiais9,12,13,17. Aqui, abordamos essas questões demonstrando uma abordagem sintética que produz controle independente sobre a dimensão do cluster e a composição de nanomateriais de ferrite de manganês.
Este trabalho também fornece um meio de superar a pobre estabilidade coloidal dos nanomateriais ferrite18,19,20. As nanopartículas magnéticas são geralmente propensas à agregação devido à forte atração de partículas de partículas; ferrites sofrem mais com esse problema à medida que sua magnetização líquida maior amplifica a agregação de partículas. Em meios biológicos relevantes, esses materiais produzem grandes agregados suficientes que os materiais coletam rapidamente, limitando assim suas rotas de exposição a animais ou pessoas20,21,22. Hilt et al. encontraram outra consequência da agregação de partículas-partículas em seu estudo de aquecimento magnetotémico e degradação de corante23. Em concentrações de partículas ligeiramente maiores, ou aumento do tempo de exposição ao campo, a eficácia dos materiais foi reduzida à medida que os materiais agregados ao longo do tempo e as áreas de superfície de partículas ativas diminuíram. Essas e outras aplicações se beneficiariam de superfícies de cluster projetadas para fornecer barreiras estéricas que impediam interações partículas-partícula24,25.
Aqui relatamos uma abordagem sintética para sintetizar os aglomerados de ferrite de manganês (MFCs) com dimensões e composição controláveis. Essas partículas de multidomaina consistem em um conjunto de nanocristais de ferrite de manganês primários que são agregados duramente; a associação próxima dos nanocristais primários melhora suas propriedades magnéticas e fornece um tamanho total de cluster, 50-300 nm, bem combinado com as dimensões ideais para uma nanomedicina. Alterando a quantidade de água e o precursor do cloreto de manganês, podemos controlar independentemente o diâmetro e a composição globais. O método utiliza reações hidrotérmicas simples e eficientes de um pote que permitem experimentação frequente e otimização de materiais. Esses MFCs podem ser facilmente purificados em uma solução concentrada de produtos, que é ainda modificada por polímeros sulfoados que transmitem estabilidade coloidal. Sua sintonia, uniformidade e estabilidade de fase de solução são características de grande valor nas aplicações de nanomateriais em engenharia biomédica e ambiental.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>0.1 Micron Vaccum Filtration Filter</td>
			<td>Thermo Fisher Scientific</td>
			<td>NC9902431</td>
			<td>for filtration of aggregated clusters after synthesis and surface coating to achieve a uniform solution</td>
		</tr>
		<tr>
			<td>2-Acrylamido-2-methylpropane sulfonic acid (AMPS, 99%)</td>
			<td>Sigma-Aldrich</td>
			<td>282731-250G</td>
			<td>reagent used in copolymer to surface coat nanoclusters and functionalize them for biological media</td>
		</tr>
		<tr>
			<td>2,2&#8242;-Azobis(2-methylpropionitrile) (AIBN)</td>
			<td>Sigma-Aldrich</td>
			<td>441090-100G</td>
			<td>reagent used in copolymer making as the free ridical generator</td>
		</tr>
		<tr>
			<td>4-Morpholineethanesulfonic acid, 2-(N-Morpholino)ethanesulfonic acid (MES)</td>
			<td>Sigma-Aldrich</td>
			<td>M3671-250G</td>
			<td>acidic buffer used to stabilize nanocluster surface coating process</td>
		</tr>
		<tr>
			<td>Acrylic acid</td>
			<td>Sigma-Aldrich</td>
			<td>147230-100G</td>
			<td>reagent used in copolymer to surface coat nanoclusters and functionalize them for biological media; anhydrous, contains 200 ppm MEHQ as inhibitor, 99%</td>
		</tr>
		<tr>
			<td>Analytical Balance</td>
			<td>Avantor</td>
			<td>VWR-205AC</td>
			<td>used to weigh out solid chemical reagents for use in synthesis and dilution</td>
		</tr>
		<tr>
			<td>Digital Sonifier and Probe</td>
			<td>Branson</td>
			<td>B450</td>
			<td>used to sonicate nanocluster solution during surface coating to break up aggregates</td>
		</tr>
		<tr>
			<td>Dopamine hydrochloride</td>
			<td>Sigma-Aldrich</td>
			<td>H8502-25G</td>
			<td>used in surface coating for ligand exchange reaction</td>
		</tr>
		<tr>
			<td>Ethylene glycol (anhydrous, 99.8%)</td>
			<td>Sigma-Aldrich</td>
			<td>324558-2L</td>
			<td>reagent used as solvent in hydrothermal synthesis of nanoclusters</td>
		</tr>
		<tr>
			<td>Glass Vials (20mL)</td>
			<td>Premium Vials</td>
			<td>B1015</td>
			<td>container for nanocluster solution during washing and surface coating as well as polymer solutions</td>
		</tr>
		<tr>
			<td>Graduated Beaker (100mL)</td>
			<td>Corning</td>
			<td>1000-100</td>
			<td>container for mixing of solid and liquid reagents during hydrothermal synthesis (to be transferred into autoclave reactor before oven)</td>
		</tr>
		<tr>
			<td>Handheld Magnet</td>
			<td>MSC Industrial Supply, Inc.</td>
			<td>92673904</td>
			<td>1/2&#34; Long x 1/2&#34; Wide x 1/8&#34; High, 5 Poles, Rectangular Neodymium Magnet low strength magnet used to precipitate nanoclusters from solution (field strength is increased with steel wool when needed)</td>
		</tr>
		<tr>
			<td>Hydrochloric acid (ACS grade, 37%)</td>
			<td>Fisher Scientific</td>
			<td>7647-01-0</td>
			<td>for removing leftover nanocluster debris and cleaning autoclave reactors for next use</td>
		</tr>
		<tr>
			<td>Hydrothermal Autoclave Reactor</td>
			<td>Toption</td>
			<td>TOPT-HP500</td>
			<td>container for finished reagent mixture to withstand high temperature and pressure created by the oven in hydrothermal synthesis</td>
		</tr>
		<tr>
			<td>Iron(III) Chloride Hexahydrate (FeCl3&#183;6H2O, ACS reagent, 97%)</td>
			<td>ACS</td>
			<td>236489-500G</td>
			<td>reagent used in synthesis of nanoclusters as source of iron (III) that becomes iron (II) in finished nanocluster product (keep dry and weigh out quickly to avoid water contamination)</td>
		</tr>
		<tr>
			<td>Labware Washer Brushes</td>
			<td>Fisher Scientific</td>
			<td>13-641-708</td>
			<td>used to wash and clean glassware before synthesis</td>
		</tr>
		<tr>
			<td>Magnetic Stir Plate</td>
			<td>Thermo Fisher Scientific</td>
			<td>50093538</td>
			<td>for mixing of solid and liquid reagents during hydrothermal synthesis</td>
		</tr>
		<tr>
			<td>Manganese chloride tetrahydrate (MnCl2&#183;4H2O, 99.0%, crystals, ACS)</td>
			<td>Sigma-Aldrich</td>
			<td>1375127-2G</td>
			<td>reagent used in synthesis of nanoclusters as source of manganese</td>
		</tr>
		<tr>
			<td>Micropipette (100-1000&#956;L)</td>
			<td>Thermo Fisher Scientific</td>
			<td>FF-1000</td>
			<td>for transferring liquid reagents such as water and manganese chloride</td>
		</tr>
		<tr>
			<td>N-(3-Dimethylaminopropyl)-N&#8242;-ethylcarbodiimide hydrochloride (EDC)</td>
			<td>Sigma-Aldrich</td>
			<td>25952-53-8</td>
			<td>used in surface coating to assist in ligand exchange of copolymer (keep bulk chemical in freezer and diluted solution in refrigerator)</td>
		</tr>
		<tr>
			<td>N,N-Dimethylformamide (DMF)</td>
			<td>Sigma-Aldrich</td>
			<td>227056-2L</td>
			<td>reagent used in copolymer making as the solvent</td>
		</tr>
		<tr>
			<td>Polyacrylic acid sodium salt (PAA, Mw~6,000)</td>
			<td>PolyScience Inc.</td>
			<td>06567-250</td>
			<td>reagent used in hydrothermal synthesis to initially coat the nanoclusters (eventually replaced in surface coating step)</td>
		</tr>
		<tr>
			<td>Poly(ethylene glycol) methyl ether acrylate</td>
			<td>Sigma-Aldrich</td>
			<td>454990-250ML</td>
			<td>reagent used in copolymer to surface coat nanoclusters and functionalize them for biological media; average Mn 480, contains 100 ppm BHT as inhibitor, 100 ppm MEHQ as inhibitor</td>
		</tr>
		<tr>
			<td>Reagents Acetone, 4L, ACS Reagent</td>
			<td>Cole-Parmer</td>
			<td>UX-78920-66</td>
			<td>used as solvent to precipitate nanoclusters during washing</td>
		</tr>
		<tr>
			<td>Single Channel Pipette, Adjustable 1-10 mL</td>
			<td>Eppendorf</td>
			<td>3123000080</td>
			<td>for transferring ethylene glycol and other liquids</td>
		</tr>
		<tr>
			<td>Steel Wool</td>
			<td>Lowe&#39;s</td>
			<td>788470</td>
			<td>used to increase the magnetic field strength in the vial to aid in precipitation of nanoclusters for washing and surface coating</td>
		</tr>
		<tr>
			<td>Stirring Bar</td>
			<td>Thomas Scientific</td>
			<td>8608S92</td>
			<td>for mixing of solid and liquid reagents during hydrothermal synthesis</td>
		</tr>
		<tr>
			<td>Table Clamp</td>
			<td>Grainger</td>
			<td>29YW53</td>
			<td>for tight sealing of autoclave reactor to withstand high pressure of oven during hyrothermal synthesis</td>
		</tr>
		<tr>
			<td>Urea (ACS reagent, 99.0%)</td>
			<td>Sigma-Aldrich</td>
			<td>U5128-500G</td>
			<td>reagent used in hydrothermal synthesis to create a basic solution</td>
		</tr>
		<tr>
			<td>Vaccum Filtration Bottle Tops</td>
			<td>Thermo Fisher Scientific</td>
			<td>596-3320</td>
			<td>for filtration of aggregated clusters after synthesis and surface coating to achieve a uniform solution</td>
		</tr>
		<tr>
			<td>Vacuum Controller V-850</td>
			<td>Buchi</td>
			<td>BU-V850</td>
			<td>for filtration of aggregated clusters after synthesis and surface coating to achieve a uniform solution</td>
		</tr>
		<tr>
			<td>Vacuum Oven</td>
			<td>Fisher Scientific</td>
			<td>13-262-51</td>
			<td>used to create high temperature and pressure needed for nanocluster formation in hydrothermal synthesis</td>
		</tr>
	</tbody>
</table>

stable aqueous suspensions of manganese ferrite clusters with tunable nanoscale dimension and composition

Os aglomerados de ferrite de manganês (MFCs) são conjuntos esféricos de dezenas a centenas de nanocristais primários cujas propriedades magnéticas são valiosas em diversas aplicações. Aqui descrevemos como formar esses materiais em um processo hidrotérmico que permite o controle independente do tamanho do cluster do produto (de 30 a 120 nm) e o teor de manganês do material resultante. Parâmetros como a quantidade total de água adicionada à mídia de reação alcoólica e a razão entre manganês e precursor de ferro são fatores importantes para alcançar múltiplos tipos de produtos nanoescala MFC. Um método de purificação rápida usa a separação magnética para recuperar os materiais que fazem a produção de gramas de nanomateriais magnéticos bastante eficiente. Superamos o desafio da agregação de nanomateriais magnéticos aplicando polímeros sulfonatos altamente carregados à superfície desses nanomateriais que produzem MFCs coloidalmente estáveis que permanecem não agregando mesmo em ambientes altamente salinos. Esses materiais não agregadores, uniformes e incompará-los são excelentes materiais prospectivos para aplicações biomédicas e ambientais.

Após o tratamento hidrotérmico, a mistura de reação se transforma em uma dispersão negra viscosa como pode ser visto na Figura 1. O que resulta após a purificação é uma solução MFC altamente concentrada que se comporta como um ferrofluido. O fluido no frasco responde em segundos quando colocado perto de um ímã portátil (<0,5 T), formando uma massa negra macroscópica que pode ser movida à medida que o ímã é colocado em diferentes locais.
Esta sí...

Watch this Scientific Journal Video about Stable Aqueous Suspensions of Manganese Ferrite Clusters with Tunable Nanoscale Dimension and Composition at JoVE.com

Stable Aqueous Suspensions of Manganese Ferrite Clusters with Tunable Nanoscale Dimension and Composition

Relatamos uma síntese hidrotérmica de um pote de aglomerados de ferrita de manganês (MFCs) que oferece controle independente sobre a dimensão e a composição do material. A separação magnética permite a purificação rápida enquanto a funcionalização da superfície usando polímeros sulfoados garante que os materiais não sejam agregados em meio biologicamente relevante. Os produtos resultantes estão bem posicionados para aplicações biomédicas.

Suspensões aquosas estáveis de aglomerados de ferrite de manganês com dimensão e composição de nanoescala tunable

Manganese ferrite clusters (MFCs) are spherical assemblies of tens to hundreds of primary nanocrystals whose magnetic properties are valuable in diverse ...

Neste vídeo, apresentamos a síntese.de nano aglomerados de ferrite de manganês super paramagnéticos. Relatamos uma síntese hidrotérmica de um pote de aglomerados de ferrite de manganês ou MFCs que oferece controle independente sobre a dimensão nanocristal primário e cluster, bem como a razão ferro-manganês. A separação magnética permite a rápida purificação da amostra enquanto a funcionalização do serviço usando um polímero sulfoado garante que os materiais não sejam agregados, mesmo em soluções aquosas biologicamente relevantes.Os produtos resultantes estão bem posicionados para aplicações em biotecnologia e medicina. Lave e seque completamente todos os vidros para serem usados na síntese. A quantidade de água na síntese impacta as dimensões dos MFCs.Por isso, é crucial garantir que o vidro não tenha água residual. Para lavar os vidros, enxágue com água e detergente e esfregue com uma escova DE ESF para remover os detritos. Enxágue bem para remover todo o detergente e finalize com a lavagem de água desionizada.Enxágüe os reatores forrados de polifenóis com ácido clorídrico de 37% para remover quaisquer detritos do uso anterior. Para isso, coloque os reatores e suas tampas em um grande béquer e encha com ácido clorídrico até que os reatores estejam completamente submersos. Deixe isso descansar por 30 minutos antes de derramar o ácido clorídrico.Enxágue continuamente o béquer com os reatores com água por um a dois minutos, em seguida, coloque os reatores no forno para secar. Use uma pipeta automática para transferir 20 mililitros de glico de etileno em um béquer de 50 mililitros com uma barra de agitação magnética. Despere a quantidade necessária de cloreto de ferro para alcançar uma concentração final de 1,3 milimililar e adicione-o ao béquer.Coloque o béquer em uma placa de agitação e ligue-o a 480 RPM para começar a agitação contínua do béquer. Pesar 250 miligramas de ácido poliacrílico e adicioná-lo ao béquer. Após a adição do PAA, a solução se torna opaca e ligeiramente mais clara na cor.Pesar 1,2 gramas de Ureia e adicioná-lo ao béquer. Usando uma pipeta, adicione 0,7 milimônio cloreto de manganês ao béquer. Por fim, usando a pipeta, adicione a quantidade necessária de água ultra pura ao béquer.Deixe a solução mexer por trinta minutos e observe a mudança de cor. Ele vai apresentar como uma cor laranja escura translúcida. Transfira a mistura de reação para o reator PPL.Note que após a solução ter se agitado, alguns sólidos podem ter se acumulado nas laterais do béquer. Use um ímã para arrastar a barra de agitação ao redor das paredes do béquer para garantir que quaisquer sólidos que tenham se acumulado nas laterais sejam dispersos na solução de reação. Uma vez que a solução esteja mista e pronta, transfira-a para o reator forrado PPL de 50 mililitros.Use um grampo e uma alavanca para selar o reator na autoclave de aço inoxidável o mais firmemente possível. Fixar o vaso do reator em uma superfície estável e usando uma haste, inseri-la na tampa como alavanca, empurre o reator para selar. Observe que o reator selado não deve ser capaz de ser aberto manualmente.Isso é crucial, pois o ambiente de alta pressão do forno requer uma vedação apertada no reator. Coloque um reator em um forno por 20 horas a 215 graus Celsius. Depois que a reação hidrotérmica for feita, remova o reator do forno e deixe esfriar até a temperatura ambiente.A pressão do forno permitirá que o reator seja aberto manualmente. Observe que, neste ponto, o reator conterá o produto MFC dispersado em glicol de etileno com outras impurezas, como polímero não redigido. E será uma solução negra opaca.O produto isolado nas etapas seguintes. Coloque 200 miligramas de lã de aço em um frasco de vidro. Encha o frasco de vidro no meio do caminho com a mistura de reação do reator.Encha o resto do frasco com acetona e agite bem. Observe que a lã de aço aumenta a força do campo magnético no frasco e ajudará a separação magnética dos nano aglomerados da solução. Coloque o frasco em um ímã para que a coleta magnética ocorra.O resultado será uma solução translúcida com precipitação na parte inferior. Despeje a solução sobrenante enquanto os MFCs são magneticamente presos pela lã de aço, segurando o ímã até o fundo do frasco enquanto derramam. O glicol de etileno será removido principalmente nesta etapa.Comece a lavar com a baixa proporção de acetona para água e aumente a proporção em lavagens subsequentes até ficar pura. Faça isso de três a quatro vezes. Retire o frasco do ímã e encha-o com água.Agite bem para dissolver os MFCs. Agora o produto estará totalmente disperso na água. Repita as duas etapas anteriores várias vezes até que a solução aquosa dos MFCs não produz bolhas quando abalada.O resultado será um ferrofluido escuro opaco que responderá fortemente aos ímãs. Para manter nossos clusters estáveis, modificamos-os com um co-polímero, PAA-co-AMPS-co-PEG, que fornece repulsão estérica e eletrostática. O grupo sulfonato das unidades AMPS fornecerá estabilização de carga, enquanto a unidade PEG dificultará estericamente a agregação interglomerada.No geral, os clusters modificados permanecerão estáveis mesmo em vários tipos de condições adversas. Combine 10 mililitros de nanopartículas purificadas em um frasco de 20 mililitros, com 10 mililitros de solução de dopamina Nitra saturada. Espere por cinco minutos.Lave os MFCs revestidos de dopamina Nitra usando separação magnética. Despeje o supernatante amarelo pálido. Adicione água e agite vigorosamente.Em seguida, despeje água usando o ímã para reter o produto. Repita esta lavagem várias vezes, deixando a coleção marrom escura no frasco. Misture um mililitro de solução EDC, um mililitro de buffer MES e três mililitros de solução de polímero.Mexa levemente girando a mistura e deixe descansar por aproximadamente cinco minutos. Deve ser uma solução clara e incolor quando totalmente combinada. Adicione essa mistura à coleção MFC e coloque o frasco em um banho de gelo.Abaixe o sonicator da sonda na solução e ligue-a. Após um tratamento de sônica de cinco minutos, adicione cerca de cinco mililitros de água ultra pura ao frasco enquanto o sonicator ainda está funcionando. Continue monitorando a embarcação para garantir que nenhum produto derrame.Mantenha o gelo na mistura de água gelada, pois parte do gelo inicial derreterá devido à intensidade e calor da sônica. Deixe a mistura sonicar por mais 25 minutos por um total de 30 minutos. Coloque o frasco em cima de um ímã para separar os MFCs e despeje a solução sobrenatante.Lave os MFCs modificados com água desionizada várias vezes. Encha o frasco com os MFCs com água ultra pura. Pipeta este fluido em um sistema de filtragem de vácuo com um filtro de membrana de sulfato de poliether de 0,1 mícrons para remover quaisquer MFCs irreversivelmente agregados.Certifique-se de lavar as paredes do funil para minimizar qualquer perda do produto. Filtro de vácuo a solução. Repita este processo duas a três vezes.O resultado será uma solução aquosa purificada de MFCs mono dispersos. MFCs isolados quando o método de separação magnética tem maior mono dispersidade do que aqueles separados com ultracentrifugação, como mostrado aqui. Aqui, vemos imagens TEM de nano aglomerados purificados, em ordem de aumentar o diâmetro médio do cluster.Denotada como DC.A quantidade de água adicionada na mistura de reação inicial determina o diâmetro dos nano aglomerados. Adicionar mais água na reação resulta em nano aglomerados com diâmetros menores, enquanto menos água aumenta seus diâmetros. Desta forma, o experimentador tem controle sobre o tamanho do produto nano cluster.Aqui vemos imagens TEM de nano aglomerados, a fim de aumentar a relação manganês para molar de ferro. A razão entre manganês e precursores de ferro na mistura de reação inicial determina a razão molar dos metais no produto do cluster. O aumento da relação manganês/ferro na síntese aumentará essa proporção nos clusters, e vice-versa.Em contraste, as imagens TEM a seguir retratam amostras com morfologias irregulares. Como mostrado na imagem esquerda, o aglomerado fora de forma derramado foi produzido com a exclusão de qualquer água adicional. Isso dificulta a montagem dinâmica dos nano cristais primários que ainda não formaram clusters.A amostra na imagem à direita teve tempo de reação insuficiente, o que não foi suficiente para o crescimento primário de nano cristal e o amadurecimento do cluster. Esses resultados ruins demonstram que uma quantidade adequada do reagente, bem como o tempo de reação, é necessária para alcançar resultados consistentemente bem sucedidos. Aqui, colocamos uma amostra dos clusters codificados paa originais no buffer PBS à esquerda.À direita, fazemos o mesmo com uma quantidade equivalente dos clusters codificados PAA co-AMPS-co-PEG modificados. Observe a agregação rápida dos clusters codificados paa, enquanto os clusters modificados permanecem estáveis por um longo tempo. Isso sugere a melhora da estabilidade coloidal como resultado da codificação do copolímero.Em conclusão, nossa síntese permite a produção rápida e eficiente de aglomerados de ferrite de manganês. A síntese cria a dimensão e a composição do cluster independentemente tunable, simplesmente controlando a adição de água e manganês à relação precursora do ferro. Podemos facilmente modificar este método para alcançar diferentes, mas previsíveis nanomateriais magnéticos.Além disso, as técnicas de funcionalização magnética e de funcionalização de serviços alcançam alta dispersão mono e forte estabilidade nos meios biológicos, respectivamente. Nosso método permite maior acessibilidade na produção de clusters e aplicação generalizada em uma variedade de campos.

stable-aqueous-suspensions-manganese-ferrite-clusters-with-tunable

Research

JoVE Journal

Chemistry

Template Directed Synthesis of Plasmonic Gold Nanotubes with Tunable IR Absorbance

A nearly parallel array of pores can be produced by anodizing aluminum foils in acidic environments1, 2. Applications of anodic aluminum oxide (AAO) membranes have been under development since the 1990's and have become a common method to template the synthesis of high aspect ratio nanostructures, mostly by electrochemical growth or pore-wetting. Recently, these membranes have become commercially available in a wide range of pore sizes and densities, leading to an extensive library of functional nanostructures being synthesized from AAO membranes. These include composite nanorods, nanowires and nanotubes made of metals, inorganic materials or polymers 3-10. Nanoporous membranes have been used to synthesize nanoparticle and nanotube arrays that perform well as refractive index sensors, plasmonic biosensors, or surface enhanced Raman spectroscopy (SERS) substrates 11-16, as well as a wide range of other fields such as photo-thermal heating 17, permselective transport 18, 19, catalysis 20, microfluidics 21, and electrochemical sensing 22, 23. Here, we report a novel procedure to prepare gold nanotubes in AAO membranes. Hollow nanostructures have potential application in plasmonic and SERS sensing, and we anticipate these gold nanotubes will allow for high sensitivity and strong plasmon signals, arising from decreased material dampening 15.

Solution-suspendable gold nanotubes with controlled dimensions can be synthesized by electrochemical deposition in porous anodic aluminum oxide (AAO) membranes using a hydrophobic polymer core. Gold nanotubes and nanotube arrays hold promise for applications in plasmonic biosensing, surface-enhanced Raman spectroscopy, photo-thermal heating, ionic and molecular transport, microfluidics, catalysis and electrochemical sensing.

Dirigido modelo de síntese de nanotubos de Ouro plasmônicos com Absorbância IR Tunable

A nearly parallel array of pores can be produced by anodizing aluminum foils in acidic environments1, 2. Applications of anodic aluminum oxide (AAO) ...

Química

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.

Um método simples para o tamanho Síntese controlada de estáveis ​​Oligoméricas Clusters de nanopartículas em condições ambientais

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

Construction and Systematical Symmetric Studies of a Series of Supramolecular Clusters with Binary or Ternary Ammonium Triphenylacetates

Functions of clusters in nano or sub-nano scale significantly depend on not only kinds of their components but also arrangements, or symmetry, of their components. Therefore, the arrangements in the clusters have been precisely characterized, especially for metal complexes. Contrary to this, characterizations of molecular arrangements in supramolecular clusters composed of organic molecules are limited to a few cases. This is because construction of the supramolecular clusters, especially obtaining a series of the supramolecular clusters, is difficult due to low stability of non-covalent bonds compare to covalent bonds. From this viewpoint, utilization of organic salts is one of the most useful strategies. A series of the supramolecules could be constructed by combinations of a specific organic molecule with various counter ions. Especially, primary ammonium carboxylates are suitable as typical examples of supramolecules because various kinds of carboxylic acids and primary amines are commercially available, and it is easy to change their combinations. Previously, it was demonstrated that primary ammonium triphenylacetates using various kinds of primary amines specifically construct supramolecular clusters, which are composed of four ammoniums and four triphenylacetates assembled by charge-assisted hydrogen bonds, in crystals obtained from non-polar solvents. This study demonstrates an application of the specific construction of the supramolecular clusters as a strategy to conduct systematical symmetric study for clarification of correlations between molecular arrangements in supramolecules and kinds and numbers of their components. In the same way with binary salts composed of triphenylacetates and one kind of primary ammoniums, ternary organic salts composed of triphenylacetates and two kinds of ammoniums construct the supramolecular clusters, affording a series of the supramolecular clusters with various kinds and numbers of the components.

This article describes construction of a series of hydrogen-bonding supramolecular clusters in crystals using primary ammonium triphenylacetates, which are recrystallized from non-polar solvents. This selective construction of the supramolecular clusters leads to effective systematical symmetric studies about a correlation between the supramolecular clusters and their components.

Construção e sistemática simétricas Estudos de uma série de Supramoleculares Clusters com binários ou ternários Triphenylacetates Amônio

Functions of clusters in nano or sub-nano scale significantly depend on not only kinds of their components but also arrangements, or symmetry, of their ...

A Simple, Low-cost, and Robust System to Measure the Volume of Hydrogen Evolved by Chemical Reactions with Aqueous Solutions

There is a growing research interest in the development of portable systems which can deliver hydrogen on-demand to proton exchange membrane (PEM) hydrogen fuel cells. Researchers seeking to develop such systems require a method of measuring the generated hydrogen. Herein, we describe a simple, low-cost, and robust method to measure the hydrogen generated from the reaction of solids with aqueous solutions. The reactions are conducted in a conventional one-necked round-bottomed flask placed in a temperature controlled water bath. The hydrogen generated from the reaction in the flask is channeled through tubing into a water-filled inverted measuring cylinder. The water displaced from the measuring cylinder by the incoming gas is diverted into a beaker on a balance. The balance is connected to a computer, and the change in the mass reading of the balance over time is recorded using data collection and spreadsheet software programs. The data can then be approximately corrected for water vapor using the method described herein, and parameters such as the total hydrogen yield, the hydrogen generation rate, and the induction period can also be deduced. The size of the measuring cylinder and the resolution of the balance can be changed to adapt the setup to different hydrogen volumes and flow rates.

The study of methods to generate on-demand hydrogen for fuel cells continues to grow in importance. However, systems to measure hydrogen evolution from the reaction of chemicals with water can be complicated and expensive. This article details a simple, low-cost, and robust method to measure the evolution of hydrogen gas.

Um simples, de baixo custo e sistema robusto para medir o volume de hidrogênio desprendido por reacções químicas com soluções aquosas

There is a growing research interest in the development of portable systems which can deliver hydrogen on-demand to proton exchange membrane (PEM) ...

Determining the Chemical Composition of Corrosion Inhibitor/Metal Interfaces with XPS: Minimizing Post Immersion Oxidation

An approach for acquiring more reliable X-ray photoelectron spectroscopy data from corrosion inhibitor/metal interfaces is described. More specifically, the focus is on metallic substrates immersed in acidic solutions containing organic corrosion inhibitors, as these systems can be particularly sensitive to oxidation following removal from solution. To minimize the likelihood of such degradation, samples are removed from solution within a glove box purged with inert gas, either N2 or Ar. The glove box is directly attached to the load-lock of the ultra-high vacuum X-ray photoelectron spectroscopy instrument, avoiding any exposure to the ambient laboratory atmosphere, and thus reducing the possibility of post immersion substrate oxidation. On this basis, one can be more certain that the X-ray photoelectron spectroscopy features observed are likely to be representative of the in situ submerged scenario, e.g. the oxidation state of the metal is not modified.

A protocol to avoid the oxidation of metallic substrates during sample transfer from an inhibited acidic solution to an X-ray photoelectron spectrometer is presented.

Determinar a composição química do inibidor de corrosão / Metal Interfaces com XPS: Minimizando Pós Immersion Oxidação

An approach for acquiring more reliable X-ray photoelectron spectroscopy data from corrosion inhibitor/metal interfaces is described. More specifically, ...

Preparation of Polyoxometalate-based Photo-responsive Membranes for the Photo-activation of Manganese Oxide Catalysts

This paper presents a method to prepare charge-transfer chromophores using polyoxotungstate (PW12O403-), transition metal ions (Ce3+ or Co2+), and organic polymers, with the aim of photo-activating oxygen-evolving manganese oxide catalysts, which are important components in artificial photosynthesis. The cross-linking technique was applied to obtain a self-standing membrane with a high PW12O403- content. Incorporation and structure retention of PW12O403- within the polymer matrix were confirmed by FT-IR and micro-Raman spectroscopy, and optical characteristics were investigated by UV-Vis spectroscopy, which revealed successful construction of the metal-to-metal charge transfer (MMCT) unit. After deposition of MnOx oxygen evolving catalysts, photocurrent measurements under visible light irradiation verified the sequential charge transfer, Mn &#8594; MMCT unit &#8594; electrode, and&#160;the photocurrent intensity was consistent with the redox potential of the donor metal (Ce or Co). This method provides a new strategy for preparing integrated systems involving catalysts and photon-absorption parts for use with photo-functional materials.

Here, we present a protocol to prepare charge transfer chromophores based on a polyoxometalate/polymer composite membrane.

Preparação de membranas de foto-sensível com base em germânio para a foto-ativação de catalisadores de óxido de manganês

This paper presents a method to prepare charge-transfer chromophores using polyoxotungstate (PW12O403-), transition metal ions (Ce3+ or Co2+), and organic ...

Exfoliation and Analysis of Large-area, Air-Sensitive Two-Dimensional Materials

We describe methods for producing and analyzing large, thin flakes of air-sensitive two-dimensional materials. Thin flakes of layered or van der Waals crystals are produced using mechanical exfoliation, in which layers are peeled off a bulk crystal using adhesive tape. This method produces high-quality flakes, but they are often small and can be hard to find, particularly for materials with relatively high cleavage energies such as black phosphorus. By heating the substrate and the tape, two-dimensional material adhesion to the substrate is promoted, and the flake yield can be increased by up to a factor of ten. After exfoliation, it is necessary to image or otherwise analyze these flakes but some two-dimensional materials are sensitive to oxygen or water and will degrade when exposed air. We have designed and tested a hermetic transfer cell to temporarily maintain the inert environment of a glovebox so that air-sensitive flakes can be imaged and analyzed with minimal degradation. The compact design of the transfer cell is such that optical analysis of sensitive materials can be performed outside of a glovebox without specialized equipment or modifications to existing equipment.

A method for exfoliating large thin flakes of air sensitive two-dimensional materials and safely transporting them for analysis outside of a glovebox is presented.

Esfoliação e análise da grande-área, bidimensionais materiais sensíveis ao ar

We describe methods for producing and analyzing large, thin flakes of air-sensitive two-dimensional materials. Thin flakes of layered or van der Waals ...

Synthesis of In37P20(O2CR)51 Clusters and Their Conversion to InP Quantum Dots

This text presents a method for the synthesis of In37P20(O2C14H27)51 clusters and their conversion to indium phosphide quantum dots. The In37P20(O2CR)51 clusters have been observed as intermediates in the synthesis of InP quantum dots from molecular precursors (In(O2CR)3, HO2CR, and P(SiMe3)3) and may be isolated as a pure reagent for subsequent study and use as a single-source precursor. These clusters readily convert to crystalline and relatively monodisperse samples of quasi-spherical InP quantum dots when subjected to thermolysis conditions in the absence of additional precursors above 200 &#176;C. The optical properties, morphology, and structure of both the clusters and quantum dots are confirmed using UV-Vis spectroscopy, photoluminescence spectroscopy, transmission electron microscopy, and powder X-ray diffraction. The molecular symmetry of the clusters is additionally confirmed by solution-phase 31P NMR spectroscopy. This protocol demonstrates the preparation and isolation of atomically-precise InP clusters, and their reliable and scalable conversion to InP QDs.

Synthesis of In37P20O2CR51 Clusters and Their Conversion to InP Quantum Dots

A protocol for the synthesis of In37P20(O2C14H27)51 clusters and their conversion to indium phosphide quantum dots is presented.

Síntese de37P20(O2CR)51 clusters e sua conversão para pontos Quantum INP

This text presents a method for the synthesis of In37P20(O2C14H27)51 clusters and their conversion to indium phosphide quantum dots. The In37P20(O2CR)51 ...

Computation of Atmospheric Concentrations of Molecular Clusters from ab initio Thermochemistry

The computational study of the formation and growth of atmospheric aerosols requires an accurate Gibbs free energy surface, which can be obtained from gas phase electronic structure and vibrational frequency calculations. These quantities are valid for those atmospheric clusters whose geometries correspond to a minimum on their potential energy surfaces. The Gibbs free energy of the minimum energy structure can be used to predict atmospheric concentrations of the cluster under a variety of conditions such as temperature and pressure. We present a computationally inexpensive procedure built on a genetic algorithm-based configurational sampling followed by a series of increasingly accurate screening calculations. The procedure starts by generating and evolving the geometries of a large set of configurations using semi-empirical models then refines the resulting unique structures at a series of high-level ab initio levels of theory. Finally, thermodynamic corrections are computed for the resulting set of minimum-energy structures and used to compute the Gibbs free energies of formation, equilibrium constants, and atmospheric concentrations. We present the application of this procedure to the study of hydrated glycine clusters under ambient conditions.

Computation of Atmospheric Concentrations of Molecular Clusters from ab initio Thermochemistry

The atmospheric concentrations of weakly bound molecular clusters can be computed from the thermochemical properties of low energy structures found through a multi-step configurational sampling methodology utilizing a genetic algorithm and semi-empirical and ab initio quantum chemistry.

Computação de Concentrações Atmosféricas de Aglomerados Moleculares a partir de ab initio Termoquímica

The computational study of the formation and growth of atmospheric aerosols requires an accurate Gibbs free energy surface, which can be obtained from gas ...

Preparation of Expanded Chitin Foams and their Use in the Removal of Aqueous Copper

Chitin is an underexploited, naturally abundant, mechanically robust, and chemically resistant biopolymer. These qualities are desirable in an adsorbent, but chitin lacks the necessary specific surface area, and its modification involves specialized techniques and equipment. Herein is described a novel chemical procedure for expanding chitin flakes, derived from shrimp shell waste, into foams with higher surface area. The process relies on the evolution of H2 gas from the reaction of water with NaH trapped in a chitin gel. The preparation method requires no specialized equipment. Powder X-ray diffraction and N2-physisorption indicate that the crystallite size decreases from 6.6 nm to 4.4 nm and the specific surface area increases from 12.6 &#177; 2.1 m2/g to 73.9 &#177; 0.2 m2/g. However, infrared spectroscopy and thermogravimetric analysis indicate that the process does not change the chemical identity of the chitin. The specific Cu adsorption capacity of the expanded chitin increases in proportion to specific surface area from 13.8 &#177; 2.9 mg/g to 73.1 &#177; 2.0 mg/g. However, the Cu adsorption capacity as a surface density remains relatively constant at an average of 10.1 &#177; 0.8 atom/nm2, which again suggests no change in the chemical identity of the chitin. This method offers the means to transform chitin into a higher surface area material without sacrificing its desirable properties. Although the chitin foam is described here as an adsorbent, it can be envisioned as a catalyst support, thermal insulator, and structural material.

This study describes a method to expand chitin into a foam by chemical techniques that require no specialized equipment.

Preparação de espumas de cebolinha expandidas e seu uso na remoção de cobre aquoso

Chitin is an underexploited, naturally abundant, mechanically robust, and chemically resistant biopolymer. These qualities are desirable in an adsorbent, ...