Name: stable aqueous suspensions of manganese ferrite clusters with tunable nanoscale dimension and composition
Uploaded: 2022-02-05T15:00:00
Description: Watch this Scientific Journal Video about Stable Aqueous Suspensions of Manganese Ferrite Clusters with Tunable Nanoscale Dimension and Composition at JoVE.com

这项工作得到了布朗大学和先进能源联盟的慷慨支持。我们非常感谢张青波博士建立的氧化铁MFC合成方法。

1. 控制中间商联总直径和铁氧体组成的中间商联苯合成
<ol><li>清洗并彻底干燥所有用于合成的玻璃器皿。合成中的水量会影响MFC的尺寸，因此确保玻璃器皿中没有残留水至关重要16，26。<ol>
<li>要清洗玻璃器皿，请用水和洗涤剂冲洗，并用烧瓶刷擦洗以清除碎屑。彻底冲洗以除去所有洗涤剂，然后用去离子水冲洗完毕。</li>
		<li>要干燥玻璃...

<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. 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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. 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T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surface+modification+of+magnetic+nanoparticles+capped+by+oleic+acids:+Characterization+and+colloidal+stability+in+polar+solvents.">Surface modification of magnetic nanoparticles capped by oleic acids: Characterization and colloidal stability in polar solvents.</a> Journal of Colloid and Interface Science. 293 (2), 401-408 (2006).</li><li>Yeap, S. P., Ahmad, A. L., Ooi, B. S., Lim, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrosteric+stabilization+and+its+role+in+cooperative+magnetophoresis+of+colloidal+magnetic+nanoparticles.">Electrosteric stabilization and its role in cooperative magnetophoresis of colloidal magnetic nanoparticles.</a> Langmuir. 28 (42), 14878-14891 (2012).</li><li>Wydra, R. J., Oliver, C. E., Anderson, K. W., Dziubla, T. 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这项工作证明了锰铁氧体纳米晶体的改性多元醇合成，这些纳米晶体聚集在一起形成均匀的纳米级聚集体29。在该合成中，氯化铁（III）和氯化锰（II）进行强制水解反应和还原，形成分子MnxFe3-xO4。这些铁氧体分子在反应器中的高温和高压下形成初级纳米晶体，最终组装成球形聚集体，这里称为磁铁矿铁氧体簇（MFC）。没有足够的反应时间或足够...

与纯氧化铁相比，在适当的条件下，在氧化铁晶格中加入锰作为掺杂剂可以增加材料在高外加磁场下的磁化。因此，锰铁氧体（MnxFe3-xO4）纳米颗粒由于其高饱和磁化，对外部磁场的强烈响应和低细胞毒性而成为非常理想的磁性纳米材料1，2，3，4，5。单域纳米晶体以及这些纳米晶体的簇（称为多域粒子）已在各种生物医学应用中进行了研究，包括药物递送，用于癌症治疗的磁热疗和磁共振成像（MRI）6，7，8。例如，Hyeon小组在2017年使用单结构域锰铁氧体纳米颗粒作为Fenton催化剂来诱导癌症缺氧，并利用该材料的T2contrast进行MRI跟踪9。令人惊讶的是，鉴于这些和其他对铁氧体材料的积极研究，与纯氧化铁（Fe3O4）纳米材料相比，几乎没有体内演示，也没有报道在人类中的应用9，10。
将铁氧体纳米材料的特征转化为临床时面临的一个巨大挑战是产生均匀的、非聚集的纳米级簇11、12、13、14。虽然传统的单域纳米晶体合成方法已经发展良好，但这项工作中感兴趣的多域簇不容易以统一和受控的方式生产15，16。此外，铁氧体组成通常是非化学计量的，并且不仅仅与前驱体的起始浓度相关，这可能进一步模糊这些材料的系统结构功能表征9，12，13，17。在这里，我们通过展示一种合成方法来解决这些问题，该方法可以对锰铁氧体纳米材料的簇尺寸和组成进行独立控制。
这项工作也为克服铁氧体纳米材料的胶体稳定性差提供了一种手段18，19，20。磁性纳米颗粒通常由于强烈的颗粒 - 颗粒吸引力而容易聚集;铁氧体受这个问题的影响更大，因为它们较大的净磁化放大了粒子聚集。在相关的生物介质中，这些材料产生足够大的聚集体，使材料迅速收集，从而限制了它们与动物或人的接触途径20，21，22。Hilt等人在研究磁热加热和染料降解时发现了颗粒- 颗粒聚集的另一个后果23。在颗粒浓度略高或暴露于场中的时间增加时，随着材料随着时间的推移而聚集并且活性颗粒表面积减小，材料的有效性降低。这些应用和其他应用将受益于簇表面，这些表面旨在提供空间位阻，排除粒子 - 粒子相互作用24，25。
在这里，我们报告了一种合成方法，用于合成具有可控尺寸和成分的锰铁氧体簇（MFC）。这些多域颗粒由硬聚集的初级锰铁氧体纳米晶体的组装组成;初级纳米晶体的紧密结合增强了它们的磁性，并提供了50-300 nm的整体簇尺寸，与纳米医学的最佳尺寸很好地匹配。通过改变水和氯化锰前体的量，我们可以独立控制整体直径和成分。该方法利用简单有效的一锅水热反应，允许频繁的实验和材料优化。这些MFC可以很容易地纯化成浓缩的产品溶液，通过赋予胶体稳定性的磺化聚合物进一步修饰。它们的可调性、均匀性和溶液相稳定性都是纳米材料在生物医学和环境工程中的应用具有重要价值的特点。

<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

锰铁氧体簇（MFC）是数十至数百个初级纳米晶体的球形组件，其磁性在各种应用中都很有价值。在这里，我们描述了如何在水热工艺中形成这些材料，该过程允许独立控制产品簇尺寸（从30到120nm）和所得材料的锰含量。酒精反应介质中加入的水总量和锰与铁前驱体的比例等参数是实现多种类型的MFC纳米级产品的重要因素。快速纯化方法使用磁分离来回收材料，使磁性纳米材料的克数生产非常有效。我们克服了磁性纳米材料聚集的挑战，将高电荷的磺酸盐聚合物应用于这些纳米材料的表面，产生胶体稳定的MFC，即使在高盐度环境中也保持非聚集性。这些非聚集、均匀和可调的材料是生物医学和环境应用的优秀前瞻性材料。

水热处理后，反应混合物变成粘稠的黑色分散体，如图 1所示。纯化后的结果是高度浓缩的MFC溶液，其行为类似于铁磁流体。当放置在手持式磁铁（<0.5 T）附近时，小瓶中的液体在几秒钟内就会做出反应，形成宏观的黑色团块，当磁铁放置在不同的位置时，可以四处移动。
该合成产生的产物的尺寸和铁氧体组成取决于反应混合物中加入的水量和锰与铁前...

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

我们报告了锰铁氧体簇（MFC）的一锅水热合成，可对材料尺寸和成分进行独立控制。磁分离允许快速纯化，而使用磺化聚合物的表面功能化可确保材料在生物相关介质中不聚集。由此产生的产品非常适合生物医学应用。

具有可调纳米尺度尺寸和成分的锰铁氧体簇的稳定水悬浮液

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

在本视频中，我们介绍了超顺磁性锰铁氧体纳米团簇的合成。我们报告了锰铁氧体簇或MFC的一锅水热合成，可以独立控制初级纳米晶体和团簇尺寸，以及铁与锰的比例。磁分离允许快速纯化样品，而使用磺化聚合物的服务功能化确保材料不聚集，即使在生物相关的水溶液中也是如此。由此产生的产品非常适合生物技术和医学应用。清洗并彻底干燥所有用于合成的玻璃器皿。合成中的水量会影响MFCs的尺寸。因此，确保玻璃器皿中没有残留的水至关重要。要清洗玻璃器皿，请用水和洗涤剂冲洗，并用FLAS刷子擦洗以清除碎屑。彻底冲洗以除去所有洗涤剂，然后用去离子水冲洗干净。用37%盐酸冲洗多酚衬里反应器，以除去以前使用中的任何碎屑。为此，将反应器及其盖子放在一个大烧杯中，并充满盐酸，直到反应器完全淹没。让它静置30分钟，然后倒出盐酸。用水连续用反应器冲洗烧杯一到两分钟，然后将反应器放入烤箱中晾干。使用自动移液器将20毫升乙二糖转移到带有磁性搅拌棒的50毫升烧杯中。称出所需量的氯化铁以达到1.3毫摩尔的最终浓度，并将其加入烧杯中。将烧杯放在搅拌盘上，以480 RPM的速度打开，开始连续搅拌烧杯。称取250毫克聚丙烯酸，并将其添加到烧杯中。加入PAA后，溶液变得不透明，颜色略浅。称取1.2克尿素，然后将其添加到烧杯中。使用移液器，将0.7毫摩尔氯化锰加入烧杯中。最后，使用移液器，向烧杯中加入所需量的超纯水。让溶液搅拌三十分钟，注意颜色变化。它将呈现为半透明的深橙色。将反应混合物转移到PPL反应器中。请注意，在溶液搅拌后，一些固体可能积聚在烧杯的侧面。使用磁铁将搅拌棒拖到烧杯壁周围，以确保积聚在侧面的任何固体分散到反应溶液中。一旦溶液混合并准备就绪，将其转移到50毫升PPL衬里反应器中。使用夹具和杠杆将反应器尽可能紧密地密封在不锈钢高压灭菌器中。将反应器容器夹在稳定的表面上，并使用棒将其作为杠杆插入盖子中，推动反应器密封。请注意，密封的反应器不应能够用手打开。这一点至关重要，因为烘箱的高压环境要求在反应器上密封。将反应器放入215摄氏度的烤箱中20小时。水热反应完成后，将反应器从烘箱中取出，使其冷却至室温。烤箱的压力将使反应器能够用手打开。请注意，此时，反应器中将含有分散在乙二醇中的MFC产物及其它杂质，例如未反应的聚合物。并且会是不透明的黑色溶液。在以下步骤中隔离了产品。将200毫克钢丝绒放入玻璃瓶中。用来自反应器的反应混合物中途填充玻璃小瓶。用丙酮填充小瓶的其余部分并摇匀。请注意，钢丝球增加了小瓶中的磁场强度，并有助于从溶液中磁性分离纳米团簇。将小瓶放在磁铁上以进行磁性收集。结果将是底部有沉淀物的半透明溶液。倾倒上清液，而MFC通过在浇注时将磁铁固定在小瓶底部来磁性捕获钢丝球。乙二醇大多会在这一步中被除去。开始用低丙酮与水的比例洗涤，并在随后的洗涤中增加该比例，直到纯净。这样做三到四次。从磁铁上取下小瓶并装满水。摇匀以溶解MFC。现在产品将完全分散在水中。重复前两个步骤几次，直到MFC的水溶液在摇动时不产生气泡。结果将是一个暗的不透明铁磁流体，它将对磁铁产生强烈的反应。为了保持我们的簇稳定，我们使用共聚物PAA-co-AMPS-co-PEG对其进行修饰，该共聚物提供空间位阻和静电排斥。AMPS单元的磺酸盐基团将提供电荷稳定，而PEG单元将空间阻挡簇间聚集。总体而言，即使在各种恶劣条件下，修改后的集群也将保持稳定。将10毫升纯化的纳米颗粒与20毫升的小瓶中与10毫升饱和的Nitra多巴胺溶液混合。等待五分钟。使用磁分离洗涤Nitra多巴胺包被的MFC。倒出淡黄色的上清液。加水，用力摇晃。然后使用磁铁倒出水以保留产品。重复此洗涤几次，将深棕色集合留在小瓶中。混合一毫升EDC溶液，一毫升MES缓冲液和三毫升聚合物溶液。旋转混合物轻轻搅拌，静置约五分钟。当完全结合时，它应该是一个透明和无色的溶液。将此混合物添加到MFC集合中，并将小瓶放入冰浴中。将探头超声仪放入溶液中，然后将其打开。经过五分钟的超声处理后，在超声仪仍在运行时向小瓶中加入大约五毫升的超纯水。继续监测容器，确保没有产品溢出。将冰保持在冰水混合物中，因为由于超声处理的强度和热量，一些初始冰会融化。让混合物再超声处理25分钟，总共30分钟。将小瓶放在磁铁顶部以分离MFC并倒出上清液。用去离子水清洗改良的MFC几次。用超纯水填充MFC的小瓶。用0.1微米聚醚硫酸盐膜过滤器将这种液体移入真空过滤系统中，以去除任何不可逆聚集的MFC。确保冲洗漏斗壁，以尽量减少产品损失。真空过滤溶液。重复此过程两到三次。结果将是单分散式MFC的纯化水溶液，当磁选方法分离时，分离的MFC比用超速离心分离的MFC具有更高的单分散性，如图所示。在这里，我们看到纯化纳米簇的TEM图像，按平均簇直径增加的顺序排列。在初始反应混合物中添加的水量决定了纳米团簇的直径。在反应中添加更多的水会导致纳米团簇具有较小的直径，而更少的水会增加其直径。通过这种方式，实验者可以控制纳米团簇产物的大小。在这里，我们看到纳米簇的TEM图像，按增加锰与铁摩尔比的顺序排列。初始反应混合物中锰与铁前体的比例决定了团簇产物中金属的摩尔比。增加合成中的锰与铁的比例将增加簇中的这一比率，反之亦然。相比之下，以下TEM图像描绘了具有不规则形态的样品。如左图所示，在排除任何额外水的情况下，产生了不合时宜的溢出簇。这阻碍了尚未形成簇的初级纳米晶体的动态组装。右图中的样品反应时间不足，不足以进行初级纳米晶体生长和团簇成熟。这些不良结果表明，要获得持续成功的结果，需要适量的反应物以及反应时间。在这里，我们将原始 PAA 编码集群的示例放在左侧的 PBS 缓冲区中。在右侧，我们对等量的修改后的 PAA co-AMPS-co-PEG 编码集群执行相同的操作。请注意 PAA 编码集群的快速聚合，而修改后的集群在很长一段时间内保持稳定。这表明由于共聚物编码而提高了胶体稳定性。总之，我们的合成可以快速有效地生产锰铁氧体簇。该合成通过简单地控制水和锰与铁前体的添加比例来产生独立可调的簇尺寸和组成。我们可以很容易地修改这种方法，以获得不同但可预测的磁性纳米材料。此外，磁选和功能化技术分别在生物介质中实现了高单分散性和强稳定性。我们的方法允许在集群生产中实现更大的可访问性，并在各个领域得到广泛应用。

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.

的模板导演电浆黄金纳米管的合成与可调谐红外吸收

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

科研

化学

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.

根据环境条件的金纳米粒子的稳定低聚簇的大小控制合成的一种简便方法

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.

建筑和超分子集群与二元或三元铵Triphenylacetates一系列的体制性对称研究

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.

一种简单，低成本和强大的系统来测量氢气与水溶液化学反应放出的音量

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.

确定缓蚀剂/金属界面的化学成分与XPS：最小化后浸入氧化

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.

氧化锰催化剂光活化 Polyoxometalate 基光响应膜的制备

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.

大面积空气敏感二维材料的去角质与分析

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.

37p20 (o2cr)51聚类中的合成及其转化为 inp 量子点

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.

来自甲流热化学分子簇的大气浓度计算

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.

准备扩大的奇廷泡沫及其用于去除水中的铜

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