Name: ligand-mediated nucleation and growth of palladium metal nanoparticles
Uploaded: 2018-06-25T13:00:00
Description: Watch this Scientific Journal Video about Ligand-Mediated Nucleation and Growth of Palladium Metal Nanoparticles at JoVE.com

Работа финансировалась главным образом, Национальный фонд науки (NSF), признается химическое отделение (номер ЧЕ-1507370 премии). Айман м. Карим и Вэньхуэй ли признать частичной финансовой поддержке компанией 3M Non-штатный факультет премии. Это исследование используется ресурсы источника Advanced Фотон (излучение 12-ID-C, пользователь предложение GUP-45774), Департамента энергетики США (DOE) управление науки пользователя объекта действуют для Доу отделение науки Аргоннской национальной лаборатории по контракту № ДЕ AC02-06CH11357. Авторы хотели бы поблагодарить Yubing Лу, кандидат в отделе химического машиностроения в Virginia Tech за его любезное помощь с измерениями лучей. Представленные работы частично был казнен в центре комплексных нанотехнологий, механизма управления науки пользователей работали для Департамента энергетики США (DOE) управление науки. Лос-Аламосской национальной лаборатории, работодатель равных возможностей позитивных действий, были управляется Лос-Аламосской национальной безопасности, ООО, для администрации национальной ядерной безопасности министерства энергетики США по контракту де-AC52-06NA25396.

1. Pd ацетат рекристаллизации
Предупреждение: Этот протокол включает в себя практические операции с высокой температуры посуды и решения. Использование средств индивидуальной защиты, включая термостойкие перчатки и очки. Все операции, связанные с решением обработки должн...

В этом исследовании мы представили мощные методологии для изучения влияния укупорки лигандов для зарождения и роста металлических наночастиц. Мы синтезированных Pd наночастиц в различных растворителях (толуол и пиридина) с помощью Pd ацетат как металла прекурсоров и сверху как лиганд. ?...

Контролируемого синтеза металлических наночастиц имеет большое значение ввиду больших приложений наноструктурированных материалов в катализа, фотоэлектрические, фотоники, датчики и наркотиков доставки1,2,3, 4,5. Для синтеза наночастиц с определенных размеров и распределения размеров, жизненно важно понимать базового механизма для частиц зарождения и роста. Тем не менее получение наночастиц с такими критериями оспорил нано синтез сообщества из-за медленного прогресса в понимании механизмов синтеза и отсутствие надежной кинетических моделей, доступных в литературе. В 1950-х, Ламер предложена модель для зарождения и роста Золи серы, где есть всплеск нуклеации, следуют контролируемой диффузии рост ядер6,7. В этой предлагаемой модели, постулируется, что концентрации мономера увеличивается (за счет сокращения или разложение прекурсоров) и как только уровень выше критической Пересыщение, энергетического барьера для зарождения частиц могут быть преодолены, в результате в всплеск нуклеации (однородной нуклеации). Благодаря предлагаемой всплеск нуклеации, капли концентрации мономера и когда она падает ниже уровня критической Пересыщение нуклеации останавливается. Далее сформированные ядер постулированы расти через распространение мономеров к поверхности наночастиц, хотя без дополнительных нуклеации события происходят. Это приводит к эффективно отделять зарождения и роста во времени и контроль распределения размеров во время процесса роста8. Эта модель была использована для описания формирования различных наночастиц, включая9Ag, Au10, CdSe11и Fe3O412. Однако несколько исследований показано, что классическая зарождения теории (УНТ) невозможно описать формирование наночастицы коллоидных, в частности для металлических наночастиц, где1, наблюдается дублирование зарождения и роста 13,14,,1516,17. В одном из этих исследований Watzky и Финке создан двухступенчатый механизм для формирования Иридиум наночастиц13, в котором медленный непрерывный нуклеации перекрывается с поверхности роста быстро наночастиц (где рост автокаталитических). Медленно нуклеации и быстро автокаталитических роста наблюдались также для различных видов металлических наночастиц, например Pd14,15,18,19,Pt20и Rh21 ,22. Несмотря на последние достижения в разработке зарождения и роста модели1,23,24,25, роль лигандов часто игнорируется в предлагаемых моделей. Тем не менее лиганды показано, влияют на наночастицы размер14,,1526 и морфология19,27 , а также каталитической активности и избирательности28 , 29. Например, Ян и др. 30 управление размер наночастиц Pd, начиная от 9,5 и 15 Нм, меняя концентрацию trioctylphosphine (сверху). В синтезе магнитных наночастиц (Fe3O4), размер заметно сократилось с 11 до 5 Нм при лиганда (octadecylamine) металл прекурсоров соотношение увеличилось с 1 до 60. Интересно, что было показано размер наночастиц Pt быть чувствительным к длину цепочки аминов лигандов (например., n-hexylamine и octadecylamine), где меньших размеров наночастиц могут быть получены с использованием более цепи (т.е., 31octadecylamine).
Размер изменения, вызванные различные концентрации и различных видов лигандами-явное свидетельство для вклада лигандов в кинетике зарождения и роста. К сожалению мало исследований, приходилось роль лигандов и в этих исследованиях, были использованы некоторые предположения часто ради простоты, которые в свою очередь сделать эти модели применимы только для конкретных условий32,33. Говоря более конкретно Ремпель и коллег разработана кинетическая модель для описания формирования квантовых точек (CdSe) присутствии укупорки лигандами. Однако в их исследовании, Связывание лиганда с поверхности наночастиц предполагается на равновесии в любой данный момент времени32. Это предположение может справедливо, когда лиганды находятся в большой избыток. Наша группа недавно разработала новый лиганд ориентированная модель14 , который приходится для связывания укупорки лигандов с прекурсорами (комплекс металла) и поверхности наночастиц как обратимых реакций14. Кроме того наша модель на основе лиганд может использоваться в других системах металлических наночастиц, где синтеза кинетика, кажется, быть затронуты присутствием лигандами.
В текущем исследовании мы используем наш недавно разработанных лиганд-модель на основе для прогнозирования формирования и роста наночастиц Pd в различных растворителях, включая толуола и пиридина. Для нашей модели ввода в situ лучей был использован для получения концентрацию наночастиц и размер распределения во время синтеза. Измерение размера и концентрации частиц, дополняется кинетического моделирования, позволяет нам извлечь более точную информацию о зарождения и роста ставок. Мы также показывают, что наша модель на основе лигандом, который явно приходится Связывание лиганда металл, высоко интеллектуальный и могут быть использованы для разработки синтеза процедуры для получения наночастиц с желаемых размеров.

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			<td height="21" style="height:21px;width:291px;">palladium acetate (Pd(OAc)2)</td>
			<td style="width:203px;">ALDRICH</td>
			<td style="width:119px;">520764</td>
			<td style="width:167px;"></td>
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			<td height="21" style="height:21px;width:291px;">anhydrous acetic acid</td>
			<td style="width:203px;">SIAL</td>
			<td style="width:119px;">338826</td>
			<td></td>
		</tr>
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			<td height="21" style="height:21px;width:291px;">trioctylphosphine</td>
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			<td style="width:119px;">718165</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">pyridine</td>
			<td style="width:203px;">MilliporeSigma</td>
			<td style="width:119px;">PX2012-7</td>
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			<td height="21" style="height:21px;width:291px;">toluene</td>
			<td style="width:203px;">SIAL</td>
			<td style="width:119px;">244511</td>
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			<td height="21" style="height:21px;width:291px;">1-hexanol</td>
			<td style="width:203px;">SIAL</td>
			<td style="width:119px;">471402</td>
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			<td height="21" style="height:21px;width:291px;">N8 Horizon SAXS</td>
			<td style="width:203px;">Bruker</td>
			<td style="width:119px;">A32-X1</td>
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		<tr height="23">
			<td height="23" style="height:23px;width:291px;">glovebox</td>
			<td style="width:203px;">Vaccum Atmospheres Co.</td>
			<td style="width:119px;">109035</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">MR HEI-TEC 115V Hotplate</td>
			<td style="width:203px;">Heidolph</td>
			<td style="width:119px;">5053000000</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">hotplate Monoblock insert</td>
			<td style="width:203px;">Heidolph</td>
			<td style="width:119px;">5058000800</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">heat-On 25-ml insert</td>
			<td style="width:203px;">Heidolph</td>
			<td style="width:119px;">5058006200</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">7 mL vials</td>
			<td style="width:203px;">SUPELCO</td>
			<td style="width:119px;">27518</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">micro stir bar PTFE&#160;</td>
			<td style="width:203px;">VWR</td>
			<td style="width:119px;">58948-353</td>
			<td></td>
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		<tr height="21">
			<td height="21" style="height:21px;width:291px;">egg-Shaped Bars&#160;</td>
			<td style="width:203px;">Fisherbrand&#8482;&#160;</td>
			<td style="width:119px;">14-512-121</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">25 mL round bottom flasks</td>
			<td style="width:203px;">ALDRICH</td>
			<td style="width:119px;">Z167495</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">quartz capillary</td>
			<td style="width:203px;">Hampton Research</td>
			<td style="width:119px;">HR6-148</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">MATLAB R2016b</td>
			<td style="width:203px;">MathWorks</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">Bruker SAXS 1.0v</td>
			<td style="width:203px;">Bruker</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:291px;">Diffrac Measurement Center 4.0v</td>
			<td style="width:203px;">Bruker</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
	</tbody>
</table>

ligand-mediated nucleation and growth of palladium metal nanoparticles

Размер, размер распределения и стабильности коллоидных наночастиц сильно страдают от присутствия укупорки лигандами. Несмотря на ключевой вклад укупорки лигандов во время реакции синтеза их роль в регулировании нуклеации и темпы роста наночастиц коллоидных хорошо не понимается. В этой работе, мы демонстрируем механистический расследование роли trioctylphosphine (сверху) в Pd наночастиц в различных растворителях (толуол и пиридина) с использованием в situ лучей и на основе лигандом кинетического моделирования. Наши результаты различных искусственных условиях показывают перекрытие зарождения и роста наночастиц Pd во время реакции, которая противоречит модель зарождения и роста Ламер типа. Модели приходится кинетика Pd-топ, обязательную силу для обоих, прекурсоров и поверхности частицы, которая необходима для захвата изменения размера, а также концентрация частиц в situ. Кроме того мы показываем прогностической силой нашей модели на основе лигандом путем разработки синтетических условий для получения наночастиц с желаемых размеров. Предлагаемая методология может быть применен к другим системам синтез и таким образом служит эффективной стратегией для прогнозирования синтез коллоидных наночастиц.

Систематически изучить ли укупорки лигандов изменить кинетика зарождения и роста, мы взяли два следующих подходов: (i) Связывание лиганда с металлом не был рассмотрен в кинетической модели, похожей на предыдущих исследований (т.е., нуклеации и автокаталитических р...

Watch this Scientific Journal Video about Ligand-Mediated Nucleation and Growth of Palladium Metal Nanoparticles at JoVE.com

Ligand-Mediated Nucleation and Growth of Palladium Metal Nanoparticles

Лиганд опосредованной зарождения и роста наночастиц металла палладия

Основная цель этой работы заключается в том, для прояснения роли укупорки агентов в регулировании размера палладия наночастиц, объединяя яn situ малоуглового рентгеновского рассеяния (лучей) и на основе лигандом кинетического моделирования.

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

The advantage of this SAXS technique is that it can obtain the time evolution of particle size distribution and the actual concentration of particles at the same time. Extracting the kinetic rates from SAXS is crucial for understanding the effects of capping ligands on the nucleation growth mechanism of colloidal metal non-particles. Chemically accurate kinetic models enable predictive synthesis of palladium nanoparticles of specific sizes.Similar methods can be used for other metal and metal oxides, minimizing trial and error testing of synthetic conditions. First add 40 milliliters of glacial acetic acid to a 50 milliliter three neck round bottom flask containing 0.75 grams of palladium acetate and a stir bar. Equip the flask with a condenser, stopper the other necks and fix the flask in a heating insert on a stirring hot plate.Slowly open the condenser water valve and allow the water to flow through the condenser. Stir the solution at 300 rpm at room temperature until no more palladium acetate dissolves. Which usually takes 10 to 15 minutes.Then, set the hotplate to 100 degrees celsius. Continue stirring the mixture at 100 degrees celsius until the palladium acetate has dissolved completely which usually takes about 30 minutes. During this time, preheat two 20 milliliter glass vials, vacuum filtration glassware and filter paper in a drying oven at 90 degrees celsius.Heat about 80 milliliters of water in a 250 milliliter beaker to 80 to 90 degrees celsius. Preheat another hotplate to 100 degrees celsius. Once the palladium acetate has dissolved, quickly assemble the filtration components and fix the filter flask on the preheated hotplate.Remove the glass vials from the oven. Connect a vacuum pump to the filter flask, start the vacuum pump, and quickly filter the palladium acetate solution under vacuum. Quickly transfer the filtrate to the two preheated 20 milliliter vials.Cap the vials with polypropylene caps with PTFE silicone septa. Seal the vials with plastic paraffin film and immerse them in the hot water in the beaker. Cover the beaker with aluminum foil and place the beaker on the hotplate used for the filter flask.Set the hotplate temperature to 80 degrees celsius. Decrease the temperature by 20 degrees celsius every hour to cool the solutions to room temperature. Then turn off the hotplate and leave the beaker undisturbed overnight to allow crystallization.The next day, remove the acetic acid from the vials leaving the palladium acetate trimer crystals in the vial. Wash the crystals three times with two milliliter portions of hexane. Wrap the vials in aluminum foil to exclude light and dry the crystals under a flow of nitrogen gas at room temperature overnight.Store the crystals under an inert atmosphere. To begin the synthesis procedure, degas about five milliliters each of one hexanol and pyridine by bubbling nitrogen gas through each solvent at about 10 milliliters per minute for 30 minutes. Then, weigh 0.112 grams of recrystallized palladium acetate into a seven milliliter vial.Cap the vial with a polypropylene cap with a PTFE silicone septum. Insert a needle through the septum as a vent and purge the vial atmosphere with nitrogen gas for five minutes. Transfer the solvents and the vial of palladium acetate into a nitrogen filled glove box and add 2.5 milliliters of pyridine to the palladium acetate.Seal the vial with plastic paraffin film remove the vial from the glove box and sonicate the vial for 40 minutes to dissolve the palladium acetate. Begin preheating a hotplate with a vial heating insert to 125 degrees celsius so that the solution will reach 100 degrees celsius. Once the palladium acetate has dissolved, return the vial to the glove box.Transfer one milliliter of this 20 millimolar palladium acetate solution to a seven milliliter vial equipped with a micro stir bar. Add 8.9 microliters of trioctylphosphine to the solution and shake the vial for 30 seconds by hand. Add one milliliter of one hexanol to the reaction mixture seal the vial, and remove the reaction mixture from the glove box.Flow nitrogen gas above the solution level at a low flow rate to maintain an inert atmosphere in the vial at a slight positive pressure. Place the vial in the hotplate insert and begin stirring the reaction mixture at 300 rpm. Allow the reaction to proceed for the desired duration.Then remove the vial from the insert and allow the mixture to cool to room temperature. Initialize the SAXS software and click on the command window in the measurement software. Set the voltage and current to 50 kilovolts and 1000 micro amperes respectively.Load a one to one by volume mixture of pyridine and one hexanol into a quarts capillary and seal the capillary. Fix the capillary to the capillary holder parallel to the X direction, which is perpendicular to the beam. Mount the holder in the instrument chamber and close the chamber.Start the vacuum pump and wait for the chamber pressure to stabilize at less than 0.3 millibars. Fix the X axis within the capillary sample range. Then drag the Y axis slider to move the capillary close to the beam.Select scan type Y fill in the start and stop positions, and set the increment to 0.05 millimeters. Start the scan across the Y axis. Once the scan has finished, identify the middle position across the capillary at which the X ray path length through the liquid sample is at a maximum.Which is the measurement position. In the wizard, set the capillary to the measurement position and select transmission of sample to measure the sample transmission using glassy carbon as the reference standard. Apply the new settings and move the glassy carbon into the beam path to take a 10 second measurement of the sample with and without glassy carbon in the beam path.Still scan and save the 2D scattering graph. Then, set up the wizard to take a 1800 second measurement of the solvent background alone. Then set up the wizard to measure glassy carbon only.Move the capillary out of the xray path by setting it to a different position. Place the glassy carbon in the path and take a 10 second measurement of glassy carbon alone. Save the wizard and run the wizard program to take the measurements specified in the text protocol.When finished, vent the instrument chamber and mount a sealed capillary containing the palladium nanoparticle suspension in the instrument. After that, repeat the same procedure with an empty capillary and with a capillary filled with water for later use in calibrating the scattering intensity to an absolute scale. The absolute scaling of SAXS intensity by using water or another standard sample allows the extraction of the actual particle concentration of the solution which is directly related to the nucleation events in the synthesis reaction.When the synthesis of palladium nanoparticles in toluene was modeled without accounting for ligand metal binding, the model did not reflect the time evolution of the concentration of nano particles or of the concentration of palladium atoms. When association and dissociation of the capping ligands was incorporated into the model, the model closely followed the experimental data indicating that the capping ligands affected the nucleation and growth kinetics of palladium nano particles. Estimation of the rate kinetics indicated that nucleation was slow and growth was fast which agrees with previous studies.The binding of ligands to the nano particle surface reduced the concentration of active sites expanding the time window for nucleation. The model also accurately captured the nucleation and growth kinetics of palladium nano particles in pyridine despite the significant difference in kinetics between the toluene and pyridine systems. Further, the model accurately predicted nano particle sizes in pyridine from different precursor concentrations using the estimated rate constants.We first had the idea for this method when we found that despite the significant contribution of capping ligands in altering the size colloidal nano particle, their exact role in controlling nano particle nucleation growth is poorly understood. Our SAXS and kinetic modeling methodology can pave the way to design synthetic procedures to obtain colloidal nano particles with the desired sizes for potential applications in catalysis and drug delivery.

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Synthesis and Characterization of Functionalized Metal-organic Frameworks

Metal-organic frameworks have attracted extraordinary amounts of research attention, as they are attractive candidates for numerous industrial and technological applications. Their signature property is their ultrahigh porosity, which however imparts a series of challenges when it comes to both constructing them and working with them. Securing desired MOF chemical and physical functionality by linker/node assembly into a highly porous framework of choice can pose difficulties, as less porous and more thermodynamically stable congeners (e.g., other crystalline polymorphs, catenated analogues) are often preferentially obtained by conventional synthesis methods. Once the desired product is obtained, its characterization often requires specialized techniques that address complications potentially arising from, for example, guest-molecule loss or preferential orientation of microcrystallites. Finally, accessing the large voids inside the MOFs for use in applications that involve gases can be problematic, as frameworks may be subject to collapse during removal of solvent molecules (remnants of solvothermal synthesis). In this paper, we describe synthesis and characterization methods routinely utilized in our lab either to solve or circumvent these issues. The methods include solvent-assisted linker exchange, powder X-ray diffraction in capillaries, and materials activation (cavity evacuation) by supercritical CO2 drying. Finally, we provide a protocol for determining a suitable pressure region for applying the Brunauer-Emmett-Teller analysis to nitrogen isotherms, so as to estimate surface area of MOFs with good accuracy.

Synthesis, activation, and characterization of intentionally designed metal-organic framework materials is challenging, especially when building blocks are incompatible or unwanted polymorphs are thermodynamically favored over desired forms. We describe how applications of solvent-assisted linker exchange, powder X-ray diffraction in capillaries and activation via supercritical CO2 drying, can address some of these challenges.

Синтеза и характеристики функционализированным Металл-органические каркасы

Metal-organic frameworks have attracted extraordinary amounts of research attention, as they are attractive candidates for numerous industrial and ...

Using Polystyrene-block-poly(acrylic acid)-coated Metal Nanoparticles as Monomers for Their Homo- and Co-polymerization

We present a template-free method for &#8220;polymerizing&#8221; nanoparticles into long chains without side branches. A variety of nanoparticles are encapsulated in polystyrene-block-poly(acrylic acid) (PSPAA) shells and then used as monomers for their self-assembly. Spherical PSPAA micelles upon acid treatment are known to assemble into cylindrical micelles. Exploiting this tendency, the core-shell nanoparticles are induced to aggregate, coalesce, and then transform into long chains. When more than one type of nanoparticles are used, random and block &#8220;copolymers&#8221; of nanoparticles can be obtained. Detailed procedures are reported for the PSPAA encapsulation of nanoparticles, homo- and co-polymerization of the core-shell nanoparticles, separation and purification of the resulting nanoparticle chains. Transformations of single-line chains into double- and triple-line chains are also presented. The synergy between the polymer shell and the embedded nanoparticles leads to an unusual chain-growth polymerization mode, giving long nanoparticle chains that are distinct from the products of the traditional step-growth aggregation process.

Using Polystyrene-block-polyacrylic acid-coated Metal Nanoparticles as Monomers for Their Homo- and Co-polymerization

We report protocols for &#8220;polymerizing&#8221; various types of polymer-encapsulated metal nanoparticles into long chains of &#8220;homo-&#8220; and &#8220;co-polymers&#8221;.

Использование Polystyrene-<em&gt; Блок</em&gt; Поли (акриловая кислота) -покрытие металлических наночастиц в качестве мономеров для их гомо- и полимеризации

We present a template-free method for &#8220;polymerizing&#8221; nanoparticles into long chains without side branches. A variety of nanoparticles are ...

Reverse Microemulsion-mediated Synthesis of Monometallic and Bimetallic Early Transition Metal Carbide and Nitride Nanoparticles

A reverse microemulsion is used to encapsulate monometallic or bimetallic early transition metal oxide nanoparticles in microporous silica shells. The silica-encapsulated metal oxide nanoparticles are then carburized in a methane/hydrogen atmosphere at temperatures over 800 &#176;C to form silica-encapsulated early transition metal carbide nanoparticles. During the carburization process, the silica shells prevent the sintering of adjacent carbide nanoparticles while also preventing the deposition of excess surface carbon. Alternatively, the silica-encapsulated metal oxide nanoparticles can be nitridized in an ammonia atmosphere at temperatures over 800 &#176;C to form silica-encapsulated early transition metal nitride nanoparticles. By adjusting the reverse microemulsion parameters, the thickness of the silica shells, and the carburization/nitridation conditions, the transition metal carbide or nitride nanoparticles can be tuned to various sizes, compositions, and crystal phases. After carburization or nitridation, the silica shells are then removed using either a room-temperature aqueous ammonium bifluoride solution or a 0.1 to 0.5 M NaOH solution at 40-60 &#176;C. While the silica shells are dissolving, a high surface area support, such as carbon black, can be added to these solutions to obtain supported early transition metal carbide or nitride nanoparticles. If no high surface area support is added, then the nanoparticles can be stored as a nanodispersion or centrifuged to obtain a nanopowder.

A &#8220;removable ceramic coating method&#8221; is presented in visual format for the synthesis of non-sintered and metal-terminated monometallic and bimetallic early transition metal carbide and nitride nanoparticles with tunable sizes and crystal structures.

Обратный Микроэмульсия-опосредованной Синтез монометаллических и биметаллические начале переходного металла карбида и нитрида наночастиц

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

Generation of Zerovalent Metal Core Nanoparticles Using n-(2-aminoethyl)-3-aminosilanetriol

In this work, a facile one-pot reaction for the formation of metal nanoparticles in a water solution through the use of n-(2-aminoethyl)-3-aminosilanetriol is presented. This compound can be used to effectively reduce and complex metal salts into metal core nanoparticles coated with the compound. By controlling the concentrations of salt and silane one is able to control reaction rates, particle size, and nanoparticle coating. The effects of these changes were characterized through transmission electron microscopy (TEM), UV-Vis spectrometry (UV-Vis), Nuclear Magnetic Resonance spectroscopy (NMR) and Fourier Transform Infrared spectroscopy (FTIR). A unique aspect to this reaction is that usually silanes hydrolyze and cross-link in water; however, in this system the silane is water-soluble and stable. It is known that silicon and amino moieties can form complexes with metal salts. The silicon is known to extend its coordination sphere to form penta- or hexa-coordinated species. Furthermore, the silanol group can undergo hydrolysis to form a Si-O-Si silica network, thereby transforming the metal nanoparticles into a functionalized nanocomposites.

Generation of Zerovalent Metal Core Nanoparticles Using n-2-aminoethyl-3-aminosilanetriol

A novel method for metal core nanoparticle synthesis using a water stable silanol is described.

Генерация нулевой валентностью металлический сердечник наночастиц с использованием N- (2-аминоэтил) -3-aminosilanetriol

In this work, a facile one-pot reaction for the formation of metal nanoparticles in a water solution through the use of ...

Photochemical Oxidative Growth of Iridium Oxide Nanoparticles on CdSe@CdS Nanorods

We demonstrate a procedure for the photochemical oxidative growth of iridium oxide catalysts on the surface of seeded cadmium selenide-cadmium sulfide (CdSe@CdS) nanorod photocatalysts. Seeded rods are grown using a colloidal hot-injection method and then moved to an aqueous medium by ligand exchange. CdSe@CdS nanorods, an iridium precursor and other salts are mixed and illuminated. The deposition process is initiated by absorption of photons by the semiconductor particle, which results with formation of charge carriers that are used to promote redox reactions. To insure photochemical oxidative growth we used an electron scavenger. The photogenerated holes oxidize the iridium precursor, apparently in a mediated oxidative pathway. This results in the growth of high quality crystalline iridium oxide particles, ranging from 0.5 nm to about 3 nm, along the surface of the rod. Iridium oxide grown on CdSe@CdS heterostructures was studied by a variety of characterization methods, in order to evaluate its characteristics and quality. We explored means for control over particle size, crystallinity, deposition location on the CdS rod, and composition. Illumination time and excitation wavelength were found to be key parameters for such control. The influence of different growth conditions and the characterization of these heterostructures are described alongside a detailed description of their synthesis. Of significance is the fact that the addition of iridium oxide afforded the rods astounding photochemical stability under prolonged illumination in pure water (alleviating the requirement for hole scavengers).

A protocol for the photochemical oxidative growth of small crystalline iridium oxide nanoparticles on the surface of CdSe@CdS seeded rod nanoparticles is presented.

Фотохимические Окислительный Рост Iridium наночастиц оксида на CdSe @ CdS наностержней

We demonstrate a procedure for the photochemical oxidative growth of iridium oxide catalysts on the surface of seeded cadmium selenide-cadmium sulfide ...

In Situ Detection and Single Cell Quantification of Metal Oxide Nanoparticles Using Nuclear Microprobe Analysis

Micro-analytical techniques based on chemical element imaging enable the localization and quantification of chemical composition at the cellular level. They offer new possibilities for the characterization of living systems and are particularly appropriate for detecting, localizing and quantifying the presence of metal oxide nanoparticles both in biological specimens and the environment. Indeed, these techniques all meet relevant requirements in terms of (i) sensitivity (from 1 up to 10 &#181;g.g-1 of dry mass), (ii) micrometer range spatial resolution, and (iii) multi-element detection. Given these characteristics, microbeam chemical element imaging can powerfully complement routine imaging techniques such as optical and fluorescence microscopy. This protocol describes how to perform a nuclear microprobe analysis on cultured cells (U2OS) exposed to titanium dioxide nanoparticles. Cells must grow on and be exposed directly in a specially designed sample holder used on the optical microscope and in the nuclear microprobe analysis stages. Plunge-freeze cryogenic fixation of the samples preserves both the cellular organization and the chemical element distribution. Simultaneous nuclear microprobe analysis (scanning transmission ion microscopy, Rutherford backscattering spectrometry and particle induced X-ray emission) performed on the sample provides information about the cellular density, the local distribution of the chemical elements, as well as the cellular content of nanoparticles. There is a growing need for such analytical tools within biology, especially in the emerging context of Nanotoxicology and Nanomedicine for which our comprehension of the interactions between nanoparticles and biological samples must be deepened. In particular, as nuclear microprobe analysis does not require nanoparticles to be labelled, nanoparticle abundances are quantifiable down to the individual cell level in a cell population, independently of their surface state.

In Situ Detection and Single Cell Quantification of Metal Oxide Nanoparticles Using Nuclear Microprobe Analysis

We describe a procedure for the detection of chemical elements present in situ in human cells as well as their in vitro quantification. The method is well-suited to any cell type and is particularly useful for quantitative chemical analyses in single cells following in vitro metal oxide nanoparticles exposure.

На месте Выявление и количественная оценка одноклеточного наночастиц оксидов металлов, с использованием ядерных рентгенофлуоресцентного анализа

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

Molten-Salt Synthesis of Complex Metal Oxide Nanoparticles

The development of feasible synthesis methods is critical for the successful exploration of novel properties and potential applications of nanomaterials. Here, we introduce the molten-salt synthesis (MSS) method for making metal oxide nanomaterials. Advantages over other methods include its simplicity, greenness, reliability, scalability, and generalizability. Using pyrochlore lanthanum hafnium oxide (La2Hf2O7) as a representative, we describe the MSS protocol for the successful synthesis of complex metal oxide nanoparticles (NPs). Furthermore, this method has the unique ability to produce NPs with different material features by changing various synthesis parameters such as pH, temperature, duration, and post-annealing. By fine-tuning these parameters, we are able to synthesize highly uniform, non-agglomerated, and highly crystalline NPs. As a specific example, we vary the particle size of the La2Hf2O7&#160;NPs by changing the concentration of the ammonium hydroxide solution used in the MSS process, which allows us to further explore the effect of particle size on various properties. It is expected that the MSS method will become a more popular synthesis method for nanomaterials and more widely employed in the nanoscience and nanotechnology community in the upcoming years.

Here, we demonstrate a unique, relatively low-temperature, molten-salt synthesis method for preparing uniform complex metal oxide lanthanum hafnate nanoparticles.

Расплавленной соли синтеза наночастиц сложных оксидов металлов

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

Synthesis and Characterization of Amphiphilic Gold Nanoparticles

Gold nanoparticles covered with a mixture of 1-octanethiol (OT) and 11-mercapto-1-undecane sulfonic acid (MUS) have been extensively studied because of their interactions with cell membranes, lipid bilayers, and viruses. The hydrophilic ligands make these particles colloidally stable in aqueous solutions and the combination with hydrophobic ligands creates an amphiphilic particle that can be loaded with hydrophobic drugs, fuse with the lipid membranes, and resist nonspecific protein adsorption. Many of these properties depend on nanoparticle size and the composition of the ligand shell. It is, therefore, crucial to have a reproducible synthetic method and reliable characterization techniques that allow the determination of nanoparticle properties and the ligand shell composition. Here, a one-phase chemical reduction, followed by a thorough purification to synthesize these nanoparticles with diameters below 5 nm, is presented. The ratio between the two ligands on the surface of the nanoparticle can be tuned through their stoichiometric ratio used during synthesis. We demonstrate how various routine techniques, such as transmission electron microscopy (TEM), nuclear magnetic resonance (NMR), thermogravimetric analysis (TGA), and ultraviolet-visible (UV-Vis) spectrometry, are combined to comprehensively characterize the physicochemical parameters of the nanoparticles.

Amphiphilic gold nanoparticles can be used in many biological applications. A protocol to synthesize gold nanoparticles coated by a binary mixture of ligands and a detailed characterization of these particles is presented.

Синтез и характеристика амфифилических золотых наночастиц

Gold nanoparticles covered with a mixture of 1-octanethiol (OT) and 11-mercapto-1-undecane sulfonic acid (MUS) have been extensively studied because of ...

Synthesis Method for Cellulose Nanofiber Biotemplated Palladium Composite Aerogels

Here, a method to synthesize cellulose nanofiber biotemplated palladium composite aerogels is presented. Noble metal aerogel synthesis methods often result in fragile aerogels with poor shape control. The use of carboxymethylated cellulose nanofibers (CNFs) to form a covalently bonded hydrogel allows for the reduction of metal ions such as palladium on the CNFs with control over both nanostructure and macroscopic aerogel monolith shape after supercritical drying. Crosslinking the carboxymethylated cellulose nanofibers is achieved using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) in the presence of ethylenediamine. The CNF hydrogels maintain their shape throughout synthesis steps including covalent crosslinking, equilibration with precursor ions, metal reduction with high concentration reducing agent, rinsing in water, ethanol solvent exchange, and CO2 supercritical drying. Varying the precursor palladium ion concentration allows for control over the metal content in the final aerogel composite through a direct ion chemical reduction rather than relying on the relatively slow coalescence of pre-formed nanoparticles used in other sol-gel techniques. With diffusion as the basis to introduce and remove chemical species into and out of the hydrogel, this method is suitable for smaller bulk geometries and thin films. Characterization of the cellulose nanofiber-palladium composite aerogels with scanning electron microscopy, X-ray diffractometry, thermal gravimetric analysis, nitrogen gas adsorption, electrochemical impedance spectroscopy, and cyclic voltammetry indicates a high surface area, metallized palladium porous structure.

A synthesis method for cellulose nanofiber biotemplated palladium composite aerogels is presented.The resulting composite aerogel materials offer potential for catalysis, sensing, and hydrogen gas storage applications.

Метод синтеза целлюлозы Нанофибр биошаблонированных палладий композитных аэрогелей

Here, a method to synthesize cellulose nanofiber biotemplated palladium composite aerogels is presented. Noble metal aerogel synthesis methods often ...

Ion Mobility-Mass Spectrometry Techniques for Determining the Structure and Mechanisms of Metal Ion Recognition and Redox Activity of Metal Binding Oligopeptides

Electrospray ionization (ESI) can transfer an aqueous-phase peptide or peptide complex to the gas-phase while conserving its mass, overall charge, metal-binding interactions, and conformational shape. Coupling ESI with ion mobility-mass spectrometry (IM-MS) provides an instrumental technique that allows for simultaneous measurement of a peptide&#8217;s mass-to-charge (m/z) and collision cross section (CCS) that relate to its stoichiometry, protonation state, and conformational shape. The overall charge of a peptide complex is controlled by the protonation of 1) the peptide&#8217;s acidic and basic sites and 2) the oxidation state of the metal ion(s). Therefore, the overall charge state of a complex is a function of the pH of the solution that affects the peptides metal ion binding affinity. For ESI-IM-MS analyses, peptide and metal ions solutions are prepared from aqueous-only solutions, with the pH adjusted with dilute aqueous acetic acid or ammonium hydroxide. This allows for pH dependence and metal ion selectivity to be determined for a specific peptide. Furthermore, the m/z and CCS of a peptide complex can be used with B3LYP/LanL2DZ molecular modeling to discern binding sites of the metal ion coordination and tertiary structure of the complex. The results show how ESI-IM-MS can characterize the selective chelating performance of a set of alternative methanobactin peptides and compare them to the copper-binding peptide methanobactin.

Ion mobility-mass spectrometry and molecular modeling techniques can characterize the selective metal chelating performance of designed metal-binding peptides and the copper-binding peptide methanobactin. Developing new classes of metal chelating peptides will help lead to therapeutics for diseases associated with metal ion misbalance.

Ионная мобильность-массовая спектрометрия Методы для определения структуры и механизмов распознавания ионов металла и Redox деятельности металлических связывая олигопептиды