This work was supported by WVU Chemical and Biomedical Engineering Department startup funds (M.F.B.). The authors would like to thank Dr. Marcela Redigolo for guidance on grid preparation and image capture of nanoparticles with TEM, Dr. Qiang Wang for support on evaluating XRD and FTIR spectra, Dr. John Zondlo and Hunter Snoderly for programming and integrating the temperature controller into the nanoparticle synthesis protocol, James Hall for his assistance in assembly of the nanoparticle synthesis setup, Alexander Pueschel and Jenna Vito for aiding in quantification of MnO nanoparticle diameters from TEM images, and the WVU Shared Research Facility for use of the TEM, XRD, and FTIR.

The authors have nothing to disclose.

The protocol herein describes a facile, one-pot synthesis of MnO nanoparticles using Mn(II) ACAC, DE, and OA. Mn(II) ACAC is utilized as the starting material to provide a source of Mn2+ for MnO nanoparticle formation. The starting material can be easily substituted to enable production of other metal oxide nanoparticles. For example, when iron(III) ACAC is applied, Fe3O4 nanoparticles can be generated using the same nanoparticle synthesis equipment and protocol described<sup class="xref"...

Metal oxide nanoparticles possess magnetic, electric, and catalytic properties, which have been applied in bioimaging1,2,3, sensor technologies4,5, catalysis6,7,8, energy storage9, and water purification10. Within the biomedical field, iron oxide nanoparticles and manganese oxide (MnO) nanoparticles have proven utility as contrast agents in magnetic resonance imaging (MRI)1,2. Iron oxide nanoparticles produce robust negative contrast on T2* MRI and are powerful enough to visualize single labeled cells in vivo11,12,13; however, the negative MRI signal cannot be modulated and remains &#8220;ON&#8221; throughout the duration of typical experiments. Due to endogenous iron present in the liver, bone marrow, blood and spleen, the negative contrast generated from iron oxide nanoparticles may be difficult to interpret. MnO nanoparticles, on the other hand, are responsive to a drop in pH. MRI signal for MnO nanoparticles can transition from &#8220;OFF&#8221; to &#8220;ON&#8221; once the nanoparticles are internalized inside the low pH endosomes and lysosomes of the target cell such as a cancer cell14,15,16,17,18,19. The positive contrast on T1 MRI produced from the dissolution of MnO to Mn2+ at low pH is unmistakable and can improve cancer detection specificity by only lighting up at the target site within a malignant tumor. Control over nanoparticle size, morphology and composition is crucial to achieve maximum MRI signal from MnO nanoparticles. Herein, we describe how to synthesize and characterize MnO nanoparticles using the thermal decomposition method and note different strategies for fine-tuning nanoparticle properties by altering variables in the synthesis process. This protocol can be easily modified to produce other magnetic nanoparticles such as iron oxide nanoparticles.
MnO nanoparticles have been produced by a variety of techniques including thermal decomposition20,21,22,23,24,25, hydro/solvothermal26,27,28,29, exfoliation30,31,32,33,34, permanganates reduction35,36,37,38, and adsorption-oxidation39,40,41,42. Thermal decomposition is the most commonly used technique which involves dissolving manganese precursors, organic solvents, and stabilizing agents at high temperatures (180 &#8211; 360 &#176;C) under the presence of an inert gaseous atmosphere to form MnO nanoparticles43. Out of all of these techniques, thermal decomposition is the superior method to generate a variety of MnO nanocrystals of pure phase (MnO, Mn3O4 and Mn2O3) with a narrow size distribution. Its versatility is highlighted through the ability to tightly control nanoparticle size, morphology and composition by altering reaction time44,45,46, temperature44,47,48,49, types/ratios of reactants20,45,47,48,50 and inert gas47,48,50 used. The main limitations of this method are the requirement for high temperatures, the oxygen-free atmosphere, and the hydrophobic coating of the synthesized nanoparticles, which requires further modification with polymers, lipids or other ligands to increase solubility for biological applications14,51,52,53.
Besides thermal decomposition, the hydro/solvothermal method is the only other technique that can produce a variety of MnO phases including MnO, Mn3O4, and MnO2; all other strategies only form MnO2 products. During hydro/solvothermal synthesis, precursors such as Mn(II) stearate54,55 and Mn(II) acetate27 are heated to between 120-200 &#176;C over several hours to achieve nanoparticles with a narrow size distribution; however, specialized reaction vessels are required and reactions are performed at high pressures. In contrast, the exfoliation strategy involves treatment of a layered or bulk material to promote dissociation into 2D single layers. Its main advantage is in producing MnO2 nanosheets, but the synthesis process is long requiring several days and the resulting size of the sheets is difficult to control. Alternatively, permanganates such as KMnO4 can react with reducing agents such as oleic acid56,57, graphene oxide58 or poly(allylamine hydrochloride)59 to create MnO2 nanoparticles. Use of KMnO4 facilitates nanoparticle formation at room temperature over a few minutes to hours within aqueous conditions43. Unfortunately, the rapid synthesis and nanoparticle growth makes it challenging to finely control resulting nanoparticle size. MnO2 nanoparticles can also be synthesized using adsorption-oxidation whereby Mn2+ ions are adsorbed and oxidized to MnO2 by oxygen under basic conditions. This method will produce small MnO2 nanoparticles with a narrow size distribution at room temperature over several hours in aqueous media; however the requirement for adsorption of Mn2+ ions and alkali conditions limits its widespread application43.
Of the MnO nanoparticle synthesis methods discussed, thermal decomposition is the most versatile to generate different monodisperse pure phase nanocrystals with control over nanoparticle size, shape and composition without requiring specialized synthesis vessels. In this manuscript, we describe how to synthesize MnO nanoparticles by thermal decomposition at 280 &#176;C using manganese(II) acetylacetonate (Mn(II) ACAC) as the source of Mn2+ ions, oleylamine (OA) as the reducing agent and stabilizer, and dibenzyl ether (DE) as the solvent under a nitrogen atmosphere. The glassware and tubing setup for nanoparticle synthesis is explained in detail. One advantage of the technique is the inclusion of a temperature controller, thermocouple probe, and heating mantle to enable precise control over the heating rate, peak temperature, and reaction times at each temperature to fine-tune nanoparticle size and composition. Herein, we show how nanoparticle size can also be manipulated by changing the ratio of OA to DE. Additionally, we demonstrate how to prepare nanoparticle samples and measure nanoparticle size, bulk composition and surface composition using transmission electron microscopy (TEM), x-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR), respectively. Further guidance is included on how to analyze the collected images and spectra from each instrument. To generate uniformly shaped MnO nanoparticles, a stabilizer and adequate nitrogen flow must be present; XRD and TEM results are shown for undesired products formed in the absence of OA and under low nitrogen flow. In the Discussion section, we highlight crucial steps in the protocol, metrics to determine successful nanoparticle synthesis, further variation of the decomposition protocol to modify nanoparticle properties (size, morphology and composition), troubleshooting and limitations of the method, and applications of MnO nanoparticles as contrast agents for biomedical imaging.

<table><tbody><tr><td>&lt;strong&gt;Chemicals and Gases&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>Benzyl ether (DE)</td><td>Acros Organics</td><td>AC14840-0010</td><td>Concentration: 99%, 1 L</td></tr><tr><td>Drierite</td><td>W. A. Hammond Drierite Co. LTD</td><td>23001</td><td>Drierite 8 mesh, 1 lb</td></tr><tr><td>Ethanol</td><td>Decon Laboratories&amp;nbsp;</td><td>2701</td><td>200 proof, 4 x 3.7 L</td></tr><tr><td>Hexane</td><td>Macron Fine Chemicals</td><td>5189-08</td><td>Concentration:&amp;nbsp; &amp;ge;98.5%, 4 L</td></tr><tr><td>Hydrochloric acid</td><td>VWR</td><td>BDH3030-2.5LPC</td><td>Concentration: 36.5 - 38.0 % ACS, 2.5 L</td></tr><tr><td>Manganese (II) acetyl acetonate (Mn(II)ACAC)</td><td>Sigma Aldrich</td><td>245763-100G</td><td>100 g</td></tr><tr><td>Nitrogen gas tank</td><td>Airgas</td><td>NI R300</td><td>Research 5.7 grade nitrogen, size 300 cylinder</td></tr><tr><td>Nitrogen regulator</td><td>Airgas</td><td>Y11244D580-AG</td><td>Single stage brass 0-100 psi analytical cylinder regulator CGA-580 with needle outlet</td></tr><tr><td>Oleylamine (OA)</td><td>Sigma Aldrich</td><td>O7805-500G</td><td>Concentration: 70%, technical grade, 500 g</td></tr><tr><td>Silicone oil</td><td>Beantown Chemical</td><td>221590-100G</td><td>100 g</td></tr><tr><td>&lt;strong&gt;Equipment&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>Centrifuge</td><td>Beckman-Coulter</td><td>Avanti J-E</td><td>JA-20 fixed-angle aluminum rotor, 8 x 50 mL, 48,400 x g</td></tr><tr><td>Hemisphere mantle</td><td>Ace Glass Inc.</td><td>12035-17</td><td>115 V, 270 W, 500 mL, temperature up to 450 &lt;sup&gt;&amp;deg;&lt;/sup&gt;C</td></tr><tr><td>Hot plate stirrer</td><td>VWR</td><td>97042-642</td><td>120 V, 1000 W, 8.3 A, ceramic top</td></tr><tr><td>Temperature controller</td><td>Yokogawa Electric Corporation</td><td>UP351</td><td></td></tr><tr><td>Temperature probe</td><td>Omega</td><td>KMQXL-040G-12</td><td>Immersion probe, temperature up to 1335 &amp;deg;C</td></tr><tr><td>Vacuum oven</td><td>Fisher Scientific</td><td>282A</td><td>120 V, 1800 W, temperature up to 280 &lt;sup&gt;&amp;deg;&lt;/sup&gt;C</td></tr><tr><td>Vortex mixer</td><td>Fisher Scientific</td><td>02-215-365</td><td>120 V, 50/60 Hz, 150 W</td></tr><tr><td>Water bath sonicator</td><td>Fisher Scientific</td><td>FS30H</td><td>Ultrasonic power 130 W, 3.7 L tank</td></tr><tr><td>&lt;strong&gt;Tools and Materials&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>Dumont tweezer</td><td>Electron Microscopy Sciences</td><td>72703D</td><td>Style 5/45, Dumoxel, 109 mm, for picking up TEM grids</td></tr><tr><td>Dumont reverse tweezer</td><td>Ted Pella</td><td>5748</td><td>Style N2a, 118 mm, NM-SS, self-closing, holding TEM grids in place for sample preparation</td></tr><tr><td>Mortar and pestle</td><td>Amazon</td><td>BS0007</td><td>BIPEE agate mortar and pestle, 70 X 60 X 15 mm labware</td></tr><tr><td>Nalgene&amp;trade; Oak Ridge tubes</td><td>ThermoFisher Scientific</td><td>3139-0050</td><td>Polypropylene copolymer, 50,000 x g, 50 mL, pack of 10</td></tr><tr><td>Scintillation vials</td><td>Fisher Scientific</td><td>03-337-4</td><td>20 mL vials with white caps, case of 500</td></tr><tr><td>TEM grids</td><td>Ted Pella</td><td>01813-F</td><td>Carbon Type-B, 300 mesh, copper, pack of 50</td></tr><tr><td>&lt;strong&gt;Glassware Setup&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>4-neck round bottom flask</td><td>Chemglass Life Sciences</td><td>CG-1534-01</td><td>24/40 joint, 500 mL, #7 chem thread for thermometers</td></tr><tr><td>6-port vacuum manifold</td><td>Chemglass Life Sciences</td><td>CG-4430-02</td><td>480 nm, 6 ports, 4 mm PTFE stopcocks</td></tr><tr><td>Adapter</td><td>Chemglass Life Sciences</td><td>CG-1014-01</td><td>24/40 inner joint, 90&lt;sup&gt;&amp;deg;&lt;/sup&gt;</td></tr><tr><td>Condenser</td><td>Chemglass Life Sciences</td><td>CG-1216-03</td><td>24/40 joint, 365 mm, 250 mm jacket length</td></tr><tr><td>Drierite 26800 drying column</td><td>Cole-Parmer&amp;nbsp;</td><td>EW-07193-00</td><td>200 L/hr, 90 psi</td></tr><tr><td>Funnel</td><td>Chemglass Life Sciences</td><td>CG-1720-L-02</td><td>24/40 joint, 100 powder funnel, 195 mm OAL</td></tr><tr><td>Interlocked worm gear hose clamp</td><td>Grainger</td><td>16P292</td><td>1/2&quot; wide stainless steel clamp, 3/8&quot; to 7/8&quot; diameter, to secure condenser tubing, 10 pack&amp;nbsp;</td></tr><tr><td>Keck clips</td><td>Kemtech America Inc</td><td>CS002440</td><td>24/40 joint</td></tr><tr><td>Metal claw clamp</td><td>Fisher Scientific</td><td>05-769-7Q</td><td>22cm, three-prong extension clamps</td></tr><tr><td>Metal claw clamp holder</td><td>Fisher Scientific</td><td>05-754Q</td><td>Clamp regular holder</td></tr><tr><td>Mineral oil bubbler</td><td>Kemtech America Inc</td><td>B257040</td><td>185 mm</td></tr><tr><td>Rotovap trap</td><td>Chemglass Life Sciences</td><td>CG-1319-02</td><td>24/40 joints, 100 mL, self washing rotary evaporator</td></tr><tr><td>Rubber stopper</td><td>Chemglass Life Sciences</td><td>CG-3022-98</td><td>24/40 joints, red rubber</td></tr><tr><td>Tubing for air/water&amp;nbsp;</td><td>McMaster-Carr</td><td>6516T21</td><td>Clear Tygon PVC for air/water, B-44-3, 1/4&quot; ID, 1/16&quot; wall, 25 ft</td></tr><tr><td>Tubing for air/water&amp;nbsp;</td><td>McMaster-Carr</td><td>6516T26</td><td>Clear Tygon PVC for air/water, B-44-3, 3/8&quot; ID, 1/16&quot; wall, 25 ft</td></tr><tr><td>Tubing for chemicals</td><td>McMaster-Carr</td><td>5155T34</td><td>Clear Tygon PVC for chemicals, E-3603, 3/8&quot; ID, 1/16&quot; wall, 50 ft</td></tr><tr><td>&lt;strong&gt;Analysis Programs&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>XRD analysis program</td><td>Malvern Panalytical</td><td>N/A</td><td>X&#039;Pert HighScore Plus</td></tr><tr><td>FTIR analysis program</td><td>Varian, Inc.</td><td>N/A</td><td>Varian Resolutions Pro</td></tr></tbody></table>

manganese oxide nanoparticle synthesis by thermal decomposition of manganese(ii) acetylacetonate

For biomedical applications, metal oxide nanoparticles such as iron oxide and manganese oxide (MnO), have been used as biosensors and contrast agents in magnetic resonance imaging (MRI). While iron oxide nanoparticles provide constant negative contrast on MRI over typical experimental timeframes, MnO generates switchable positive contrast on MRI through dissolution of MnO to Mn2+ at low pH within cell endosomes to &#8216;turn ON&#8217; MRI contrast. This protocol describes a one-pot synthesis of MnO nanoparticles formed by thermal decomposition of manganese(II) acetylacetonate in oleylamine and dibenzyl ether. Although running the synthesis of MnO nanoparticles is simple, the initial experimental setup can be difficult to reproduce if detailed instructions are not provided. Thus, the glassware and tubing assembly is first thoroughly described to allow other investigators to easily reproduce the setup. The synthesis method incorporates a temperature controller to achieve automated and precise manipulation of the desired temperature profile, which will impact resulting nanoparticle size and chemistry. The thermal decomposition protocol can be readily adapted to generate other metal oxide nanoparticles (e.g., iron oxide) and to include alternative organic solvents and stabilizers (e.g., oleic acid). In addition, the ratio of organic solvent to stabilizer can be changed to further impact nanoparticle properties, which is shown herein. Synthesized MnO nanoparticles are characterized for morphology, size, bulk composition, and surface composition through transmission electron microscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy, respectively. The MnO nanoparticles synthesized by this method will be hydrophobic and must be further manipulated through ligand exchange, polymeric encapsulation, or lipid capping to incorporate hydrophilic groups for interaction with biological fluids and tissues.

To confirm successful synthesis, MnO nanoparticles should be assayed for size and morphology (TEM), bulk composition (XRD), and surface composition (FTIR). Figure 2 shows representative TEM images of MnO nanoparticles synthesized using decreasing ratios of oleylamine (OA, the stabilizer) to dibenzyl ether (DE, the organic solvent): 60:0, 50:10, 40:20, 30:30, 20:40, 10:50. Ideal TEM images consist of individual nanoparticles (shown as dark rounded octagons in Figure 2</st...

Watch this Scientific Journal Video about Manganese Oxide Nanoparticle Synthesis by Thermal Decomposition of ManganeseII Acetylacetonate at JoVE.com

Manganese Oxide Nanoparticle Synthesis by Thermal Decomposition of ManganeseII Acetylacetonate

This protocol details a facile, one-pot synthesis of manganese oxide (MnO) nanoparticles by thermal decomposition of manganese(II) acetylacetonate in the presence of oleylamine and dibenzyl ether. MnO nanoparticles have been utilized in diverse applications including magnetic resonance imaging, biosensing, catalysis, batteries, and waste water treatment.

Manganese Oxide Nanoparticle Synthesis by Thermal Decomposition of Manganese(II) Acetylacetonate

For biomedical applications, metal oxide nanoparticles such as iron oxide and manganese oxide (MnO), have been used as biosensors and contrast agents in ...

manganese-oxide-nanoparticle-synthesis-thermal-decomposition

Research

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Bioengineering

12.9K Views.  West Virginia University. This protocol details a facile, one-pot synthesis of manganese oxide (MnO) nanoparticles by thermal decomposition of manganese(II) acetylacetonate in the presence of oleylamine and dibenzyl ether. MnO nanoparticles have been utilized in diverse applications including magnetic resonance imaging, biosensing, catalysis, batteries, and waste water treatment.

Video: Manganese Oxide Nanoparticle Synthesis by Thermal Decomposition of ManganeseII Acetylacetonate

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.

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

Chemistry

Nanothermite with Meringue-like Morphology: From Loose Powder to Ultra-porous Objects

The goal of the protocol described in this article is to prepare aluminothermic compositions (nanothermites) in the form of porous, monolithic objects. Nanothermites are combustible materials made up of inorganic fuel and an oxidizer. In nanothermite foams, aluminum is the fuel and aluminum phosphate and tungsten trioxide are the oxidizing moieties. The highest flame propagation velocities (FPVs) in nanothermites are observed in loose powders and FPVs are strongly decreased by pelletizing nanothermite powders. From a physical standpoint, nanothermite loose powders are metastable systems. Their properties can be altered by unintentional compaction induced by shocks or vibrations or by the segregation of particles over time by settling phenomena, which originates from the density differences of their components. Moving from a powder to an object is the challenge that must be overcome to integrate nanothermites in pyrotechnic systems. Nanothermite objects must have both a high open porosity and good mechanical strength. Nanothermite foams meet both of these criteria, and they are prepared by dispersing a nano-sized aluminothermic mixture (Al/WO3) in orthophosphoric acid. The reaction of aluminum with the acid solution gives the AlPO4 &#34;cement&#34; in which Al and WO3 nanoparticles are embedded. In nanothermite foams, aluminum phosphate plays the dual role of binder and oxidizer. This method can be used with tungsten trioxide, which is not altered by the preparation process. It could probably be extended to some oxides, which are commonly used for the preparation of high performance nanothermites. The WO3-based nanothermite foams described in this article are particularly insensitive to impact and friction, which makes them far safer to handle than loose Al/WO3 powder. The fast combustion of these materials has interesting applications in pyrotechnic igniters. Their use in detonators as primers would require the incorporation of a secondary explosive in their composition.

This manuscript describes the synthesis of combustible aluminophosphate matrices by the reaction of orthophosphoric acid (H3PO4) with aluminum nanopowder. When this reaction is carried out with excess aluminum in the presence of tungsten trioxide nanopowder, it leads to a solid, porous nanothermite foam.

The goal of the protocol described in this article is to prepare aluminothermic compositions (nanothermites) in the form of porous, monolithic objects. ...

Chemical Precipitation Method for the Synthesis of Nb2O5 Modified Bulk Nickel Catalysts with High Specific Surface Area

We demonstrate a method for the synthesis of NixNb1-xO catalysts with sponge-like and fold-like nanostructures. By varying the Nb:Ni ratio, a series of NixNb1-xO nanoparticles with different atomic compositions (x = 0.03, 0.08, 0.15, and 0.20) have been prepared by chemical precipitation. These NixNb1-xO catalysts are characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy. The study revealed the sponge-like and fold-like appearance of Ni0.97Nb0.03O and Ni0.92Nb0.08O on the NiO surface, and the larger surface area of these NixNb1-xO catalysts, compared with the bulk NiO. Maximum surface area of 173 m2/g can be obtained for Ni0.92Nb0.08O catalysts. In addition, the catalytic hydroconversion of lignin-derived compounds using the synthesized Ni0.92Nb0.08O catalysts have been investigated.

Chemical Precipitation Method for the Synthesis of Nb2O5 Modified Bulk Nickel Catalysts with High Specific Surface Area

A protocol for the synthesis of sponge-like and fold-like Ni1-xNbxO nanoparticles by chemical precipitation is presented.

We demonstrate a method for the synthesis of NixNb1-xO catalysts with sponge-like and fold-like nanostructures. By varying the Nb:Ni ratio, a series of ...

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.

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

Microwave-driven Synthesis of Iron Oxide Nanoparticles for Fast Detection of Atherosclerosis

A fast and reproducible microwave-driven protocol has been developed for the synthesis of neridronate-functionalized nanoparticles. Starting from the synthesis of hydrophobic nanoparticles, our method is based on an adaptation from thermal decomposition method to microwave driven synthesis. The new methodology produces a decrease in the reaction times in comparison with traditional procedures. Moreover, the use of the microwave technology increases the reproducibility of the reactions, something important from the point of view of clinical applications. The novelty of this iron oxide nanoparticle is the attachment of Neridronate. The use of this molecule leads a bisphosphonate moiety towards the outside of the nanoparticle that provides Ca2+ binding properties in vitro and selective accumulation in vivo in the atheroma plaque. The protocol allows the synthesis and plaque detection in about 3 hr since the initial synthesis from organic precursors. Their accumulation in the atherosclerotic area in less than 1 hr provides a contrast agent particularly suitable for clinical applications.

Microwave technology enables extremely fast synthesis of iron oxide nanoparticles for atherosclerosis plaque characterization. The use of an aminobisphosphonate in the external side of the nanoparticle provides a fast accumulation in the atherosclerotic area.

A fast and reproducible microwave-driven protocol has been developed for the synthesis of neridronate-functionalized nanoparticles. Starting from the ...

Synthesis of Metal Nanoparticles Supported on Carbon Nanotube with Doped Co and N Atoms and its Catalytic Applications in Hydrogen Production

A method for facile synthesis of nanostructured catalysts supported on carbon nanotubes with atomically dispersed cobalt and nitrogen dopant is presented herein. The novel strategy is based on a facile one-pot pyrolysis treatment of cobalt (II) acetylacetonate and nitrogen-rich organic precursors under Ar atmosphere at 800 &#176;C, resulting in the formation of Co- and N- co-doped carbon nanotube with earthworm-like morphology. The obtained catalyst was found to have a high density of defect sites, as confirmed by Raman spectroscopy. Here, cobalt (II) nanoparticles were stabilized on the atomically dispersed cobalt- and nitrogen-doped carbon nanotubes. The catalyst was confirmed to be effective in the catalytic hydrolysis of ammonia borane, in which the turnover frequency was 5.87 mol H2&#183;molCo-1&#183;min-1, and the specific hydrogen generation rate was determined to be 2447 mL H2&#183;gCo-1&#183;min-1. A synergistic function between the Co nanoparticle and the doped carbon nanotubes was proposed for the first time in the catalytic hydrolysis of ammonia borane reaction under a mild condition. The resulting hydrogen production with its high energy density and minimal refueling time could be suitable for future development as energy sources for mobile and stationary applications such as road trucks and forklifts in transport and logistics.

Here, we present a protocol to synthesize Co nanoparticles supported on carbon nanotubes with Co- and N- dopants for hydrogen productions.

A method for facile synthesis of nanostructured catalysts supported on carbon nanotubes with atomically dispersed cobalt and nitrogen dopant is presented ...

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

Manganese ferrite clusters (MFCs) are spherical assemblies of tens to hundreds of primary nanocrystals whose magnetic properties are valuable in diverse applications. Here we describe how to form these materials in a hydrothermal process that permits the independent control of product cluster size (from 30 to 120 nm) and manganese content of the resulting material. Parameters such as the total amount of water added to the alcoholic reaction media and the ratio of manganese to iron precursor are important factors in achieving multiple types of MFC nanoscale products. A fast purification method uses magnetic separation to recover the materials making production of grams of magnetic nanomaterials quite efficient. We overcome the challenge of magnetic nanomaterial aggregation by applying highly charged sulfonate polymers to the surface of these nanomaterials yielding colloidally stable MFCs that remain non-aggregating even in highly saline environments. These non-aggregating, uniform, and tunable materials are excellent prospective materials for biomedical and environmental applications.

We report a one-pot hydrothermal synthesis of manganese ferrite clusters (MFCs) that offers independent control over material dimension and composition. Magnetic separation allows rapid purification while surface functionalization using sulfonated polymers ensures the materials are non-aggregating in biologically relevant medium. The resulting products are well positioned for biomedical applications.

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

Metal Oxide Heterojunction for Photocatalytic Activities

There is a significant global demand for improvements in synthesis techniques and their optimal characteristics, especially for industrial-scale applications. Sol-gel-based solution combustion synthesis (SG-SCS) is a simple method to produce ordered porous materials. In this regard, Pearson&#39;s hard and soft acids and bases theory assists in selecting host-dopant reactivity to form a proper heterojunction.
The formation of a heterojunction also changes the essential properties of the materials, improving photocatalysis via charge transfer or synergistic activities. A calcination temperature of 500 &#176;C is ideal for this process based on the results of the stability assessment via a differential thermogravimetry ratio analysis (DTG).
The nanoscale dimensions of the nanoparticles (NPs) and nanocomposites (NCs) generated were validated using X-ray diffraction and high-resolution transmission electron microscopy (HRTEM). Furthermore, the scanning electron microscopy micrographs and BET analyses confirmed the porosity nature of the materials. HRTEM, X-ray photoelectron spectroscopy, and energy-dispersive X-ray investigations established the materials composition. The study found that NCs degraded the acid orange 8 (AO8) color more efficiently than bare ZnO.

The development of a heterojunction boosts the photocatalytic activities of solution combustion synthesis, which is a time-/energy-efficient process. Advanced analytical characterization techniques were used in this protocol to evaluate the materials&#39; characteristics, and nanocomposites demonstrated improved acid orange-8 dye degradation.

There is a significant global demand for improvements in synthesis techniques and their optimal characteristics, especially for industrial-scale ...

Microwave Synthesis and Characterization of Nickel Hydroxide Nanosheets

Effect of Microwave Synthesis Conditions on the Structure of Nickel Hydroxide Nanosheets

A protocol for rapid, microwave-assisted hydrothermal synthesis of nickel hydroxide nanosheets under mildly acidic conditions is presented, and the effect of reaction temperature and time on the material&#39;s structure is examined. All reaction conditions studied result in aggregates of layered &#945;-Ni(OH)2 nanosheets. The reaction temperature and time strongly influence the structure of the material and product yield. Synthesizing &#945;-Ni(OH)2 at higher temperatures increases the reaction yield, lowers the interlayer spacing, increases crystalline domain size, shifts the frequencies of interlayer anion vibrational modes, and lowers the pore diameter. Longer reaction times increase reaction yields and result in similar crystalline domain sizes. Monitoring the reaction pressure in situ shows that higher pressures are obtained at higher reaction temperatures. This microwave-assisted synthesis route provides a rapid, high-throughput, scalable process that can be applied to the synthesis and production of a variety of transition metal hydroxides used for numerous energy storage, catalysis, sensor, and other applications.

Author Spotlight: A Rapid, Microwave-Assisted Hydrothermal Synthesis Of Nickel Hydroxide Nanosheets 

Nickel hydroxide nanosheets are synthesized by a microwave-assisted hydrothermal reaction. This protocol demonstrates that the reaction temperature and time used for microwave synthesis affects the reaction yield, crystal structure, and local coordination environment.

A protocol for rapid, microwave-assisted hydrothermal synthesis of nickel hydroxide nanosheets under mildly acidic conditions is presented, and the effect ...

Using Magnetometry to Monitor Cellular Incorporation and Subsequent Biodegradation of Chemically Synthetized Iron Oxide Nanoparticles

Magnetic nanoparticles, made of iron oxide, present a peculiar interest for a wide range of biomedical applications for which they are often internalized in cells and then left within. One challenge is to assess their fate in the intracellular environment with reliable and precise methodologies. Herein, we introduce the use of the vibrating sample magnetometer (VSM) to precisely quantify the integrity of magnetic nanoparticles within cells by measuring their magnetic moment. Stem cells are first labeled with two types of magnetic nanoparticles; the nanoparticles have the same core produced via a fast and efficient microwave-based nonaqueous sol gel synthesis and differ in their coating: the commonly used citric acid molecule is compared to polyacrylic acid. The formation of 3D cell-spheroids is then achieved via centrifugation and the magnetic moment of these spheroids is measured at different times with the VSM. The obtained moment is a direct fingerprint of the nanoparticles&#8217; integrity, with decreasing values indicative of a nanoparticle degradation. For both nanoparticles, the magnetic moment decreases over culture time revealing their biodegradation. A protective effect of the polyacrylic acid coating is also shown, when compared to citric acid.

Iron oxide nanoparticles are synthesized via a nonaqueous sol gel procedure and coated with anionic short molecules or polymer. The use of magnetometry for monitoring the incorporation and biotransformations of magnetic nanoparticles inside human stem cells is demonstrated using a vibrating sample magnetometer (VSM).

Magnetic nanoparticles, made of iron oxide, present a peculiar interest for a wide range of biomedical applications for which they are often internalized ...

Manganese Oxide Nanoparticle Synthesis by Thermal Decomposition of Manganese(II) Acetylacetonate

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