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 border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Chemicals and Gases</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&#160;</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:&#160; &#8805;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>Equipment</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 &#176;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 &#176;C</td>
		</tr>
		<tr>
			<td>Vacuum oven</td>
			<td>Fisher Scientific</td>
			<td>282A</td>
			<td>120 V, 1800 W, temperature up to 280 &#176;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>Tools and Materials</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&#8482; 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>Glassware Setup</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&#176;</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&#160;</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&#34; wide stainless steel clamp, 3/8&#34; to 7/8&#34; diameter, to secure condenser tubing, 10 pack&#160;</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&#160;</td>
			<td>McMaster-Carr</td>
			<td>6516T21</td>
			<td>Clear Tygon PVC for air/water, B-44-3, 1/4&#34; ID, 1/16&#34; wall, 25 ft</td>
		</tr>
		<tr>
			<td>Tubing for air/water&#160;</td>
			<td>McMaster-Carr</td>
			<td>6516T26</td>
			<td>Clear Tygon PVC for air/water, B-44-3, 3/8&#34; ID, 1/16&#34; 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&#34; ID, 1/16&#34; wall, 50 ft</td>
		</tr>
		<tr>
			<td>Analysis Programs</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>XRD analysis program</td>
			<td>Malvern Panalytical</td>
			<td>N/A</td>
			<td>X&#39;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

12.8K 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

Synthesis, Assembly, and Characterization of Monolayer Protected Gold Nanoparticle Films for Protein Monolayer Electrochemistry

Colloidal gold nanoparticles protected with alkanethiolate ligands called monolayer protected gold clusters (MPCs) are synthesized and subsequently incorporated into film assemblies that serve as adsorption platforms for protein monolayer electrochemistry (PME). PME is utilized as the model system for studying electrochemical properties of redox proteins by confining them to an adsorption platform at a modified electrode, which also serves as a redox partner for electron transfer (ET) reactions. Studies have shown that gold nanoparticle film assemblies of this nature provide for a more homogeneous protein adsorption environment and promote ET without distance dependence compared to the more traditional systems modified with alkanethiol self-assembled monolayers (SAM).1-3 In this paper, MPCs functionalized with hexanethiolate ligands are synthesized using a modified Brust reaction4 and characterized with ultraviolet visible (UV-Vis) spectroscopy, transmission electron microscopy (TEM), and proton (1H) nuclear magnetic resonance (NMR). MPC films are assembled on SAM modified gold electrode interfaces by using a "dip cycle" method of alternating MPC layers and dithiol linking molecules. Film growth at gold electrode is tracked electrochemically by measuring changes to the double layer charging current of the system. Analogous films assembled on silane modified glass slides allow for optical monitoring of film growth and cross-sectional TEM analysis provides an estimated film thickness. During film assembly, manipulation of the MPC ligand protection as well as the interparticle linkage mechanism allow for networked films, that are readily adaptable, to interface with redox protein having different adsorption mechanism. For example, Pseudomonas aeruginosa azurin (AZ) can be adsorbed hydrophobically to dithiol-linked films of hexanethiolate MPCs and cytochrome c (cyt c) can be immobilized electrostatically at a carboxylic acid modified MPC interfacial layer. In this report, we focus on the film protocol for the AZ system exclusively. Investigations involving the adsorption of proteins on MPC modified synthetic platforms could further the understanding of interactions between biomolecules and man-made materials, and consequently aid the development of biosensor schemes, ET modeling systems, and synthetic biocompatible materials.5-8

Alkanethiolate stabilized gold colloids known as monolayer protected clusters (MPCs) are synthesized, characterized, and assembled into thin films as an adsorption interface for protein monolayer electrochemistry of simple redox protein like Pseudomonas aeruginosa azurin (AZ) and cytochrome c (cyt c).

Colloidal gold nanoparticles protected with alkanethiolate ligands called monolayer protected gold clusters (MPCs) are synthesized and subsequently ...

Combinatorial Synthesis of and High-throughput Protein Release from Polymer Film and Nanoparticle Libraries

Polyanhydrides are a class of biomaterials with excellent biocompatibility and drug delivery capabilities. While they have been studied extensively with conventional one-sample-at-a-time synthesis techniques, a more recent high-throughput approach has been developed enabling the synthesis and testing of large libraries of polyanhydrides1. This will facilitate more efficient optimization and design process of these biomaterials for drug and vaccine delivery applications. The method in this work describes the combinatorial synthesis of biodegradable polyanhydride film and nanoparticle libraries and the high-throughput detection of protein release from these libraries. In this robotically operated method (Figure 1), linear actuators and syringe pumps are controlled by LabVIEW, which enables a hands-free automated protocol, eliminating user error. Furthermore, this method enables the rapid fabrication of micro-scale polymer libraries, reducing the batch size while resulting in the creation of multivariant polymer systems. This combinatorial approach to polymer synthesis facilitates the synthesis of up to 15 different polymers in an equivalent amount of time it would take to synthesize one polymer conventionally. In addition, the combinatorial polymer library can be fabricated into blank or protein-loaded geometries including films or nanoparticles upon dissolution of the polymer library in a solvent and precipitation into a non-solvent (for nanoparticles) or by vacuum drying (for films). Upon loading a fluorochrome-conjugated protein into the polymer libraries, protein release kinetics can be assessed at high-throughput using a fluorescence-based detection method (Figures 2 and 3) as described previously1. This combinatorial platform has been validated with conventional methods2 and the polyanhydride film and nanoparticle libraries have been characterized with 1H NMR and FTIR. The libraries have been screened for protein release kinetics, stability and antigenicity; in vitro cellular toxicity, cytokine production, surface marker expression, adhesion, proliferation and differentiation; and in vivo biodistribution and mucoadhesion1-11. The combinatorial method developed herein enables high-throughput polymer synthesis and fabrication of protein-loaded nanoparticle and film libraries, which can, in turn, be screened in vitro and in vivo for optimization of biomaterial performance.

This method describes the combinatorial synthesis of biodegradable polyanhydride film and nanoparticle libraries and the high-throughput detection of protein release from these libraries.

Polyanhydrides are a class of biomaterials with excellent biocompatibility and drug delivery capabilities. While they have been studied extensively with ...

Evaluation of Polymeric Gene Delivery Nanoparticles by Nanoparticle Tracking Analysis and High-throughput Flow Cytometry

Non-viral gene delivery using polymeric nanoparticles has emerged as an attractive approach for gene therapy to treat genetic diseases1 and as a technology for regenerative medicine2. Unlike viruses, which have significant safety issues, polymeric nanoparticles can be designed to be non-toxic, non-immunogenic, non-mutagenic, easier to synthesize, chemically versatile, capable of carrying larger nucleic acid cargo and biodegradable and/or environmentally responsive. Cationic polymers self-assemble with negatively charged DNA via electrostatic interaction to form complexes on the order of 100 nm that are commonly termed polymeric nanoparticles. Examples of biomaterials used to form nanoscale polycationic gene delivery nanoparticles include polylysine, polyphosphoesters, poly(amidoamines)s and polyethylenimine (PEI), which is a non-degradable off-the-shelf cationic polymer commonly used for nucleic acid delivery1,3 . Poly(beta-amino ester)s (PBAEs) are a newer class of cationic polymers4 that are hydrolytically degradable5,6 and have been shown to be effective at gene delivery to hard-to-transfect cell types such as human retinal endothelial cells (HRECs)7, mouse mammary epithelial cells8, human brain cancer cells9 and macrovascular (human umbilical vein, HUVECs) endothelial cells10.
A new protocol to characterize polymeric nanoparticles utilizing nanoparticle tracking analysis (NTA) is described. In this approach, both the particle size distribution and the distribution of the number of plasmids per particle are obtained11. In addition, a high-throughput 96-well plate transfection assay for rapid screening of the transfection efficacy of polymeric nanoparticles is presented. In this protocol, poly(beta-amino ester)s (PBAEs) are used as model polymers and human retinal endothelial cells (HRECs) are used as model human cells. This protocol can be easily adapted to evaluate any polymeric nanoparticle and any cell type of interest in a multi-well plate format.

A protocol for nanoparticle tracking analysis (NTA) and high-throughput flow cytometry to evaluate polymeric gene delivery nanoparticles is described. NTA is utilized to characterize the nanoparticle particle size distribution and the plasmid per particle distribution. High-throughput flow cytometry enables quantitative transfection efficacy evaluation for a library of gene delivery biomaterials.

Non-viral gene delivery using polymeric nanoparticles has emerged as an attractive approach for gene therapy to treat genetic diseases1 and as a ...

Identification of Metal Oxide Nanoparticles in Histological Samples by Enhanced Darkfield Microscopy and Hyperspectral Mapping

Nanomaterials are increasingly prevalent throughout industry, manufacturing, and biomedical research. The need for tools and techniques that aid in the identification, localization, and characterization of nanoscale materials in biological samples is on the rise. Currently available methods, such as electron microscopy, tend to be resource-intensive, making their use prohibitive for much of the research community. Enhanced darkfield microscopy complemented with a hyperspectral imaging system may provide a solution to this bottleneck by enabling rapid and less expensive characterization of nanoparticles in histological samples. This method allows for high-contrast nanoscale imaging as well as nanomaterial identification. For this technique, histological tissue samples are prepared as they would be for light-based microscopy. First, positive control samples are analyzed to generate the reference spectra that will enable the detection of a material of interest in the sample. Negative controls without the material of interest are also analyzed in order to improve specificity (reduce false positives). Samples can then be imaged and analyzed using methods and software for hyperspectral microscopy or matched against these reference spectra in order to provide maps of the location of materials of interest in a sample. The technique is particularly well-suited for materials with highly unique reflectance spectra, such as noble metals, but is also applicable to other materials, such as semi-metallic oxides. This technique provides information that is difficult to acquire from histological samples without the use of electron microscopy techniques, which may provide higher sensitivity and resolution, but are vastly more resource-intensive and time-consuming than light microscopy.

Enhanced darkfield microscopy and hyperspectral imaging with spectral mapping enable screening, localization, and identification of nanoscale materials in histological samples with improved speed and accuracy over traditional methods. The goal of this paper is to provide methods for darkfield imaging and hyperspectral mapping of metal oxide nanoparticles in histological samples.

Nanomaterials are increasingly prevalent throughout industry, manufacturing, and biomedical research. The need for tools and techniques that aid in the ...

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 Gold Nanoparticle Integrated Photo-responsive Liposomes and Measurement of Their Microbubble Cavitation upon Pulse Laser Excitation

Photo-responsive nanoparticles (NPs) have received considerable attention because of their potential in providing spatial, temporal, and dosage control over the drug release. However, most of the relevant technologies are still in the development process and are unprocurable by clinics. Here, we describe a facile fabrication of these photo-responsive NPs with commercially available gold NPs and thermo-responsive liposomes. Calcein is used as a model drug to evaluate the encapsulation efficiency and the release kinetic profile upon heat/light stimulation. Finally, we show that this photo-triggered release is due to the membrane disruption caused by microbubble cavitation, which can be measured with hydrophone.

This protocol describes a simple preparation method for gold nanoparticle integrated photo-responsive liposomes with the commercially available materials. It also shows how to measure the microbubble cavitation process of the synthesized liposomes upon the treatment of pulsed laser.

Photo-responsive nanoparticles (NPs) have received considerable attention because of their potential in providing spatial, temporal, and dosage control ...

An Integrated System to Remotely Trigger Intracellular Signal Transduction by Upconversion Nanoparticle-mediated Kinase Photoactivation

Upconversion nanoparticle (UCNP)-mediated photoactivation is a new approach to remotely control bioeffectors with much less phototoxicity and with deeper tissue penetration. However, the existing instrumentation on the market is not readily compatible with upconversion application. Therefore, modifying the commercially available instrument is essential for this research. In this paper, we first illustrate the modifications of a conventional fluorimeter and fluorescence microscope to make them compatible for photon upconversion experiments. We then describe the synthesis of a near-infrared (NIR)-triggered caged protein kinase A catalytic subunit (PKA) immobilized on a UCNP complex. Parameters for microinjection and NIR photoactivation procedures are also reported. After the caged PKA-UCNP is microinjected into REF52 fibroblast cells, the NIR irradiation, which is significantly superior to conventional UV irradiation, efficiently triggers the PKA signal transduction pathway in living cells. In addition, positive and negative control experiments confirm that the PKA-induced pathway leading to the disintegration of stress fibers is specifically triggered by NIR irradiation. Thus, the use of protein-modified UCNP provides an innovative approach to remotely control light-modulated cellular experiments, in which direct exposure to UV light must be avoided.

In this protocol, caged protein kinase A (PKA), a cellular signal transduction bioeffector, was immobilized on a nanoparticle surface, microinjected into the cytosol, and activated by the upconverted UV light from near-infrared (NIR) irradiation, inducing downstream stress fiber disintegration in the cytosol.

Upconversion nanoparticle (UCNP)-mediated photoactivation is a new approach to remotely control bioeffectors with much less phototoxicity and with deeper ...

Retroductal Nanoparticle Injection to the Murine Submandibular Gland

Two common goals of salivary gland therapeutics are prevention and cure of tissue dysfunction following either autoimmune or radiation injury. By locally delivering bioactive compounds to the salivary glands, greater tissue concentrations can be safely achieved versus systemic administration. Furthermore, off target tissue effects from extra-glandular accumulation of material can be dramatically reduced. In this regard, retroductal injection is a widely used method for investigating both salivary gland biology and pathophysiology. Retroductal administration of growth factors, primary cells, adenoviral vectors, and small molecule drugs has been shown to support gland function in the setting of injury. We have previously shown the efficacy of a retroductally injected nanoparticle-siRNA strategy to maintain gland function following irradiation. Here, a highly effective and reproducible method to administer nanomaterials to the murine submandibular gland through Wharton's duct is detailed (Figure 1). We describe accessing the oral cavity and outline the steps necessary to cannulate Wharton's duct, with further observations serving as quality checks throughout the procedure.

Local drug delivery to the submandibular glands is of interest in understanding salivary gland biology and for the development of novel therapeutics. We present an updated and detailed retroductal injection protocol, designed to improve delivery accuracy and experimental reproducibility. The application presented herein is the delivery of polymeric nanoparticles.

Two common goals of salivary gland therapeutics are prevention and cure of tissue dysfunction following either autoimmune or radiation injury. By locally ...

Fabrication of Gradient Nanopattern by Thermal Nanoimprinting Technique and Screening of the Response of Human Endothelial Colony-forming Cells

Nanotopography can be found in various extracellular matrices (ECMs) around the body and is known to have important regulatory actions upon cellular reactions. However, it is difficult to determine the relation between the size of a nanostructure and the responses of cells owing to the lack of proper screening tools. Here, we show the development of reproducible and cost-effective gradient nanopattern plates for the manipulation of cellular responses. Using anodic aluminum oxide (AAO) as a master mold, gradient nanopattern plates with nanopillars of increasing diameter ranges [120-200&#8239;nm (GP 120/200), 200-280&#8239;nm (GP 200/280), and 280-360&#8239;nm (GP 280/360)] were fabricated by a thermal imprinting technique. These gradient nanopattern plates were designed to mimic the various sizes of nanotopography in the ECM and were used to screen the responses of human endothelial colony-forming cells (hECFCs). In this protocol, we describe the step-by-step procedure of fabricating gradient nanopattern plates for cell engineering, techniques of cultivating hECFCs from human peripheral blood, and culturing hECFCs on nanopattern plates.

Here, we present a protocol for the fabrication of gradient nanopattern plates via thermal nanoimprinting and the method of screening responses of human endothelial progenitor cells to the nanostructures. By using the described technology, it is possible to produce a scaffold that can manipulate cell behavior by physical stimuli.

Nanotopography can be found in various extracellular matrices (ECMs) around the body and is known to have important regulatory actions upon cellular ...

Catalytic Scavenging of Plant Reactive Oxygen Species In Vivo by Anionic Cerium Oxide Nanoparticles

Reactive oxygen species (ROS) accumulation is a hallmark of plant abiotic stress response. ROS play&#160;a dual role in plants by acting as signaling molecules at low levels and damaging molecules at high levels. Accumulation of ROS in stressed plants can damage metabolites, enzymes, lipids, and DNA, causing a reduction of plant growth and yield. The ability of cerium oxide nanoparticles (nanoceria) to catalytically scavenge ROS in vivo provides a unique tool to understand and bioengineer plant abiotic stress tolerance. Here, we present a protocol to synthesize and characterize poly (acrylic) acid coated nanoceria (PNC), interface the nanoparticles with plants via leaf lamina infiltration, and monitor their distribution and ROS scavenging in vivo using confocal microscopy. Current molecular tools for manipulating ROS accumulation in plants are limited to model species and require laborious transformation methods. This protocol for in vivo ROS scavenging has the potential to be applied to wild type plants with broad leaves and leaf structure like Arabidopsis thaliana.

Catalytic Scavenging of Plant Reactive Oxygen Species In Vivo by Anionic Cerium Oxide Nanoparticles

Here, we present a protocol for the synthesis and characterization of cerium oxide nanoparticles (nanoceria) for ROS (reactive oxygen species) scavenging in vivo, nanoceria imaging in plant tissues by confocal microscopy, and in vivo monitoring of nanoceria ROS scavenging by confocal microscopy.

Reactive oxygen species (ROS) accumulation is a hallmark of plant abiotic stress response. ROS play&#160;a dual role in plants by acting as signaling ...