Name: in situ characterization of boehmite particles in water using liquid sem
Uploaded: 2017-09-27T13:00:00
Description: Watch this Scientific Journal Video about In Situ Characterization of Boehmite Particles in Water Using Liquid SEM at JoVE.com

We are grateful to the Pacific Northwest National Laboratory (PNNL) Nuclear Process Science Initiative (NPSI)-Laboratory Directed Research and Development (LDRD) fund for support. Dr. Sayandev Chatterjee provided the synthesized boehmite particles. Instrumental access was provided through a W. R. Wiley Environmental Molecular Sciences Laboratory (EMSL) General User Proposal. EMSL is a national scientific user facility sponsored by the Office of Biological and Environmental Research (BER) at PNNL. PNNL is operated by Battelle for the DOE under Contract DE-AC05-76RL01830.

1. Prepare AlOOH Liquid Sample
NOTE: Do not touch the specimen or anything inside the SEM chamber with bare hands. Powder free gloves should be worn at all times when handling the SALVI device and mounting it onto the SEM stage in order to avoid potential contamination during surface analysis.
<ol>
	<li>Make an AlOOH stock solution (1 mg/mL)
	<ol>
		<li>Dissolve 10 mg of AlOOH powder in 10 mL DI water to make the 1 mg/mL AlOOH stock solution.</li>
		<li>Ultrasonicate the sto...

<ol>
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SEM is a powerful technique in surface characterization of organic and inorganic materials on a nanoscale (nm) level with high resolution1. For example, it is widely used for analyzing the solid and dry samples such as geological materials26 and semiconductor27. However, it has limitations in characterizing the wet and liquid samples due to the incompatibility of liquid within the highly vacuumed environment required for electron microscopy<sup class...

Scanning Electron Microscope (SEM) has been widely applied to investigate a variety of specimens by producing high resolution imaging1. The energy dispersive x-ray spectroscopy (EDX) associated with the SEM enables the determination of elemental composition1. Traditionally, SEM is applied for imaging only dry and solid samples. In the last 30 years, Environmental SEM (ESEM) was developed for analyzing the partial hydrated samples in a vapor environment2,3,4,5. However, ESEM is unable to image the wet, fully fluid samples with desired high resolution6. Wet SEM cells were also developed to image wet specimens using SEM7,8; nevertheless, these cells were developed mainly for biological specimens and backscattered electron imaging, and are more accessible for applications with those designs9,10.
To address the challenges in analyzing various samples in their native liquid environment using SEM, we invented a vacuum compatible microfluidic device, System for Analysis at the Liquid Vacuum Interface (SALVI), to enable high spatial resolution secondary electron (SE) imaging and elemental analysis of liquid samples using the high vacuum mode in SEM. This novel technique includes the following unique features: 1) liquid is directly probed in a small aperture of 1 - 2 &#181;m in diameter; 2) liquid is held within the hole by surface tension; and 3) SALVI is portable and can be adapted to more than one analytical platform11,12,13,14,15,16,17,18.
SALVI consists of a 100 nm thick silicon nitride (SiN) membrane and a 200 &#181;m wide microchannel made of polydimethylsiloxane (PDMS) block. The SiN membrane window is applied to seal the microchannel. The fabrication details and key design considerations were detailed in previous papers and patents11,19,20. Currently, a leading manufacturer and distributor of consumable supply for microscopy has purchased the license to sell SALVI devices commercially for liquid SEM applications21,22.
The applications of SALVI in vacuum-based analytical instruments have been demonstrated using a variety of aqueous solutions and complex liquid mixtures including biofilms, mammalian cells, nanoparticles, and electrode materials12,14,17,20,23,24. However, most of the aforementioned work utilized time-of-flight secondary ion mass spectrometry (ToF-SIMS) as the key analysis tool, thus the application of liquid SEM with SALVI has not been explored fully. In this work, SALVI has been used to study larger non-spherical colloidal particles in liquid using liquid SEM imaging and EDX elemental analysis. The sample consists of AlOOH particles synthesized at our laboratory. Submicrometer-sized boehmite particles are known to exist in high-level radioactive waste at the Hanford site. They are slow to dissolve and may cause rheological problems in waste treatment. Therefore, it is important to have the capability to characterize boehmite particles in liquid25. This technical approach can be used to study boehmite in various physicochemical conditions for improved understanding of these particles and related rheological properties. These particles were utilized to demonstrate step-by-step how to apply SALVI to high vacuum SEM in order to study particles suspended in liquid. Key technical points for SALVI and SEM integration and SEM data acquisition are highlighted within the paper.
The protocol provides demonstration of the liquid sample analysis using SALVI and liquid SEM imaging, for those who are interested in utilizing this novel technique in diverse applications of liquid SEM in the future.

<table width="2033">
	<tbody>
		<tr height="20">
			<td height="20" style="width:289px;height:20px;">Carbon Coater</td>
			<td style="width:311px;">Cressington</td>
			<td style="width:196px;">208 Carbon</td>
			<td style="width:1237px;">It is accompanied with thickness monitor MTM-10.</td>
		</tr>
		<tr height="20">
			<td height="20" style="width:289px;height:20px;">SEM</td>
			<td style="width:311px;">FEI</td>
			<td>Quanta 3D FEG</td>
			<td style="width:1237px;">It provides highly resolved scanning electron microscopy and elemental analysis.</td>
		</tr>
		<tr height="20">
			<td height="20" style="width:289px;height:20px;">System for Analysis at the Liquid Vacuum Interface (SALVI)</td>
			<td style="width:311px;">Pacific Northwest National Laboratory</td>
			<td>N/A</td>
			<td style="width:1237px;">SALVI is a unique, vacuum compatible microfluidic cell that enables the characterization of the liquid sample using vacuu- based scientific instrument.</td>
		</tr>
		<tr height="20">
			<td height="20" style="width:289px;height:20px;">PEEK Union</td>
			<td style="width:311px;">Valco</td>
			<td>ZU1TPK</td>
			<td>The polyether ether ketone union is used for connecting the inlet and outlet of SALVI</td>
		</tr>
		<tr height="20">
			<td height="20" style="width:289px;height:20px;">Syringe</td>
			<td style="width:311px;">BD</td>
			<td>309659</td>
			<td style="width:1237px;">1 mL</td>
		</tr>
		<tr height="20">
			<td height="20" style="width:289px;height:20px;">Pipette</td>
			<td style="width:311px;">Thermo Fisher Scientific</td>
			<td>21-377-821</td>
			<td style="width:1237px;">Range: 100 to 1,000 mL</td>
		</tr>
		<tr height="20">
			<td height="20" style="width:289px;height:20px;">Pipette Tip 1</td>
			<td style="width:311px;">Neptune</td>
			<td>2112.96.BS</td>
			<td style="width:1237px;">1,000 &#181;L</td>
		</tr>
		<tr height="20">
			<td height="20" style="width:289px;height:20px;">Pipette Tip 2</td>
			<td style="width:311px;">Rainin</td>
			<td>17001865</td>
			<td style="width:1237px;">20 &#181;L</td>
		</tr>
		<tr height="20">
			<td height="20" style="width:289px;height:20px;">Syringe Pump</td>
			<td style="width:311px;">Harvard Apparatus</td>
			<td>70-2213</td>
			<td style="width:1237px;">It is used to inject the liquid sample into the SALVI device.</td>
		</tr>
		<tr height="20">
			<td height="20" style="width:289px;height:20px;">pH meter</td>
			<td style="width:311px;">Fisher Scientific/accumet</td>
			<td>13-636-AP72</td>
			<td style="width:1237px;">It is used for measuring the pH of AlOOH in DI water.</td>
		</tr>
		<tr height="20">
			<td height="20" style="width:289px;height:20px;">Barnstead Ultrapure Water System, UV/UF</td>
			<td style="width:311px;">Thermo Scientific Barnstead</td>
			<td style="width:196px;">Nanopure diamond D11931</td>
			<td style="width:1237px;">It is used for producing DI water.</td>
		</tr>
		<tr height="20">
			<td height="20" style="width:289px;height:20px;">Centrifuge tubes</td>
			<td style="width:311px;">Fisher scientific/Falcon</td>
			<td>15-527-90</td>
			<td style="width:1237px;">15 mL</td>
		</tr>
		<tr height="20">
			<td height="20" style="width:289px;height:20px;">Bransonic ultrasonic cleaner</td>
			<td style="width:311px;">Sigma-Aldrich</td>
			<td>2510</td>
			<td style="width:1237px;">It is used to ultrasonicate the AlOOH liquid sample.</td>
		</tr>
		<tr height="20">
			<td height="20" style="width:289px;height:20px;">Balance</td>
			<td style="width:311px;">Mettler Toledo</td>
			<td>11106015</td>
			<td style="width:1237px;">XS64</td>
		</tr>
		<tr height="20">
			<td height="20" style="width:289px;height:20px;">AlOOH</td>
			<td style="width:311px;">Pacific Northwest National Laboratory</td>
			<td>N/A</td>
			<td style="width:1237px;">It is synthesized by scientists at Pacific Northwest National Laboratory.</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">xT microscope Control</td>
			<td>FEI</td>
			<td>Quanta 3D FEG</td>
			<td>Default microscope control software of SEM Quanta 3D FEG</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">EDAX Genesis software</td>
			<td style="width:311px;">EDAX</td>
			<td>N/A</td>
			<td style="width:1237px;">The software is used for collecting the EDX elemental information of the samples.</td>
		</tr>
		<tr height="21">
			<td height="21" style="width:289px;height:21px;">Teflon tubing</td>
			<td>SUPELCO</td>
			<td>58697-U</td>
			<td style="width:1237px;">It is used for introducing the sample into the microchannel and holding adequate volume of liquid.</td>
		</tr>
	</tbody>
</table>

in situ characterization of boehmite particles in water using liquid sem

In situ imaging and elemental analysis of boehmite (AlOOH) particles in water is realized using the System for Analysis at the Liquid Vacuum Interface (SALVI) and Scanning Electron Microscopy (SEM). This paper describes the method and key steps in integrating the vacuum compatible SAVLI to SEM and obtaining secondary electron (SE) images of particles in liquid in high vacuum. Energy dispersive x-ray spectroscopy (EDX) is used to obtain elemental analysis of particles in liquid and control samples including deionized (DI) water only and an empty channel as well. Synthesized boehmite (AlOOH) particles suspended in liquid are used as a model in the liquid SEM illustration. The results demonstrate that the particles can be imaged in the SE mode with good resolution (i.e., 400 nm). The AlOOH EDX spectrum shows significant signal from the aluminum (Al) when compared with the DI water and the empty channel control. In situ liquid SEM is a powerful technique to study particles in liquid with many exciting applications. This procedure aims to provide technical know-how in order to conduct liquid SEM imaging and EDX analysis using SALVI and to reduce potential pitfalls when using this approach.

The representative results are presented to show how the particles are imaged and analyzed using in situ liquid SEM imaging coupled with EDX. The results include SE images and EDX spectra. The SE images were obtained at 100,000X and 200,000X magnification levels in Figure 1. Figure 1a depicts the SE image of the AlOOH, Figure 1b DI water, and Figure 1c the hole ...

Watch this Scientific Journal Video about In Situ Characterization of Boehmite Particles in Water Using Liquid SEM at JoVE.com

In Situ Characterization of Boehmite Particles in Water Using Liquid SEM

We present a procedure for real-time imaging and elemental composition analysis of boehmite particles in deionized water by in situ liquid Scanning Electron Microscopy.

In Situ Characterization of Boehmite Particles in Water Using Liquid SEM

In situ imaging and elemental analysis of boehmite (AlOOH) particles in water is realized using the System for Analysis at the Liquid Vacuum Interface ...

The overall goal of this in situ liquid scanning electron microscopy imaging procedure is to provide technical knowhow for efficient imaging and analysis of particles in liquids in conventional high-vacuum SEM using a vacuum-compatible microfluidic module. This method can help answer key questions in the microscopy and microanalysis field such as how to characterize evolving particle size and morphology responding to the environmental changes. The main advantage of this technique is that we can directly visualize polydispersed particles in liquid without drying or freezing the sample in high-vacuum mode and also without resorting to environmental SEM.The implication of this technique extend toward the efficient analysis or the various liquid material and the biological samples using SEM because many of them only function or exist in liquid. Visual demonstration of this method is critical as simple mounting and in situ imaging steps are difficult to learn because they are different from regular solid samples. Begin this procedure with carbon coating of the system for analysis at the liquid vacuum interface, or SALVI device, as described in the tech's protocol.Mounting the microfluidic device on the SEM stage is quite critical for the success of in situ liquid SEM analysis. Make sure the device is properly grounded and is secured to minimize the charging effect before the experiment. To mount the SALVI device onto the SEM stage, first open the SEM specimen chamber door carefully once venting has completed.Select the SEM specimen holder. Fix the holder onto the center of the stage using the appropriate bolt and hex wrench. Place two strips of double sided carbon tape on the specimen holder.Then stick the SALVI device onto the carbon tape placed on the holder with the silicon nitride membrane side facing up. Securely immobilize the SALVI onto the specimen holder using an additional two strips of single sided copper tape to bind the SALVI PDMS block to the SEM specimen holder. In addition use the copper tapes to connect the silicon nitride frame and the metal specimen holder.Make sure that the tape does not completely cover the silicon nitride membrane. To pump down the specimen chamber, close the specimen chamber door, select the high vacuum mode on the SEM software GUI under the beam control page, click the pump button on the beam control page to start vacuuming. Apply pressure by hand to the chamber door until the desired vacuum is established.Next make apertures in the silicon nitride membrane using focused ion beam, or FIB, as described in the tech's protocol. Following the procedure, turn off both the electron beam and ion beam to vent the chamber by clicking beam on when the corresponding beam imaging area is activated. Click vent on the beam control page to vent the specimen chamber.Carefully open the SEM chamber door after it is fully vented leaving the SALVI device as it is on the stage. Draw one milliliter of deionized water into a sterile syringe and connect the syringe with the inlet of the microfluidic device using a polytetrafluoroethylene tubing adapter fitting. Slowly inject the liquid for three to five minutes.Repeat this process three times using one milliliter of 10 micrograms per milliliter aluminum oxyhydroxide to ensure the concentration of the sample is not diluted by the preloaded deionized water. After the injection, remove the syringe. Connect the inlet and outlet of SALVI using polyether ether ketone union.Dry any liquid outside the SALVI with lab wipes. If there are any bubbles within the tubing or microchannel, redo the sample injection until no bubbles are seen within the tubing. To take images using the ETD and secondary electron mode, first close the specimen chamber door.After establishing the desired vacuum on the chamber door as before, activate the electron beam imaging area by clicking the pause icon on the toolbar. Turn on the electron beam by clicking the beam on button on the beam control page. Select the ETD and the secondary electron mode for imaging from the detector's drop-down menu.In selecting the optimal conditions it is really important to be able to attain high-quality images. In this work, we will show you a set of conditions suitable for a secondary electron imaging of the light elements like aluminum silicon. When analyzing other elements like iron and nickel, operation conditions should be modified to optimize the secondary electron imaging.Set the accelerating voltage to eight kiloelectron-volts and the beam current to approximately 0.47 nanoamps from the corresponding list boxes displayed on the GUI toolbar at the electron beam imaging area. Set the working distance as seven millimeters by typing seven into the text box of the coordinate Z on the navigation page when the actual distance is selected. Magnify the feature to 1, 000 X and twist the contrast, brightness, coarse and fine knobs on the manual user interface to optimize the image of the particle feature.Center the first hole in the live image of the electron beam imaging area by twisting the X and Y shift knobs on the manual user interface board, enlarge the images with particles to magnification 200, 000 X by twisting the magnification knob on the manual user interface board. Select the screen resolution to 1, 024 by 884 from the list box on the tool bar. Then set the scan rate as 30 microseconds from the list box on the tool bar.Press the F4 key to take the snapshot of the current image shown in the electron beam imaging area. Press the control and S keys to save the image as a TIF file to the desired location with the defined file name including an incremental number. Zoom out by twisting the magnification knob to locate the next adjacent hole.Repeat these operations to image the aluminum oxyhydroxide particles in the rest of the holes. To conduct elemental analysis using energy-dispersive x-ray spectroscopy, or EDX, insert the energy-dispersive spectroscopy detectors into the chamber. Select the ETD on the microscope control monitor.Then select the secondary electron mode for viewing the sample on the electron beam imaging area and set the parameters as before. Enlarge the aluminum oxyhydroxide particles in each hole with a magnification of 200, 000 X by twisting the magnification knob on the manual user interface board. Next open the associated EDAC software.Click start recording new spectra in the user interface to collect the EDX spectrum. Select peak ID to choose the probable elements of the spectrum. Then type in the observed elements into the element field.Click add to apply the element to the spectrum. Click on file and then click save as. Save the spectral data in CSV format using the desired file name for plotting using a graphing software.After finishing the imaging and spectrum recording for each of the holes, turn off the electron beam by clicking the beam on button on the beam control page when the electron beam imaging area is on. Vent the SEM chamber by clicking vent on the same page. Carefully take the sample off the stage by removing all the tapes after the chamber door is open.Repeat the procedure to conduct the control experiments using deionized water and an empty microchannel. Finally plot the EDX spectrum as described in the tech's protocol. Using the SALVI microfluidic interface, the electron beam can directly bombard the small, micrometer sized aperture with liquid underneath.Boehmite particles in deionized water were compared with the deionized water control and empty channel control in their secondary electron images. This provides direct evidence of particle secondary electron imaging of Boehmite particles in the liquid. Visualization of the particle in deionized water within the one micrometer hole demonstrates the feasibility to observe particles in liquid in situ.In the Boehmite sample, a strong aluminum peak is observed. In contrast, only a strong oxygen peak is observed in the deionized sample indicating the observation of water. In the empty channel, residual of the gallium-focused ion beam is seen.The oxygen peak is quite small because there is not any water inside. Once mastered this technique can be done in a couple of hours if it is performed properly. Generally individuals new to this method will struggle because it is difficult to directly visualize liquids in high-vacuum SEM.After watching this video, you should have a good understanding of how to characterize particles in liquid using in situ liquid SEM with SALVI. While attempting this procedure it is really important to remember that the microreactor should be free of leaks before mounting to the SEM stage. Following this procedure, other methods like TOF-SIMS or NMR can be performed in order to answer additional questions like molecular composition and fluidic field mapping.After its development, this technique paved the way for researchers in the field of material sciences, chemical engineering and nuclear engineering to explore particle size and morphological changes in a caustic liquid environment. Don't forget that when working with surface analysis using SEM, gloves and goggles should be worn when performing this procedure.

in-situ-characterization-boehmite-particles-water-using-liquid

Research

JoVE Journal

Chemistry

Untargeted Metabolomics from Biological Sources Using Ultraperformance Liquid Chromatography-High Resolution Mass Spectrometry (UPLC-HRMS)

Here we present a workflow to analyze the metabolic profiles for biological samples of interest including; cells, serum, or tissue. The sample is first separated into polar and non-polar fractions by a liquid-liquid phase extraction, and partially purified to facilitate downstream analysis. Both aqueous (polar metabolites) and organic (non-polar metabolites) phases of the initial extraction are processed to survey a broad range of metabolites. Metabolites are separated by different liquid chromatography methods based upon their partition properties. In this method, we present microflow ultra-performance (UP)LC methods, but the protocol is scalable to higher flows and lower pressures. Introduction into the mass spectrometer can be through either general or compound optimized source conditions. Detection of a broad range of ions is carried out in full scan mode in both positive and negative mode over a broad m/z range using high resolution on a recently calibrated instrument. Label-free differential analysis is carried out on bioinformatics platforms. Applications of this approach include metabolic pathway screening, biomarker discovery, and drug development.

Untargeted Metabolomics from Biological Sources Using Ultraperformance Liquid Chromatography-High Resolution Mass Spectrometry UPLC-HRMS

Untargeted metabolomics provides a hypothesis generating snapshot of a metabolic profile. This protocol will demonstrate the extraction and analysis of metabolites from cells, serum, or tissue. A range of metabolites are surveyed using liquid-liquid phase extraction, microflow ultraperformance liquid chromatography/high-resolution mass spectrometry (UPLC-HRMS) coupled to differential analysis software.

Here we present a workflow to analyze the metabolic profiles for biological samples of interest including; cells, serum, or tissue. The sample is first ...

Assessment of Boron Doped Diamond Electrode Quality and Application to In Situ Modification of Local pH by Water Electrolysis

Boron doped diamond (BDD) electrodes have shown considerable promise as an electrode material where many of their reported properties such as extended solvent window, low background currents, corrosion resistance, etc., arise from the catalytically inert nature of the surface. However, if during the growth process, non-diamond-carbon (NDC) becomes incorporated into the electrode matrix, the electrochemical properties will change as the surface becomes more catalytically active. As such it is important that the electrochemist is aware of the quality and resulting key electrochemical properties of the BDD electrode prior to use. This paper describes a series of characterization steps, including Raman microscopy, capacitance, solvent window and redox electrochemistry, to ascertain whether the BDD electrode contains negligible NDC i.e. negligible sp2 carbon. One application is highlighted which takes advantage of the catalytically inert and corrosion resistant nature of an NDC-free surface i.e. stable and quantifiable local proton and hydroxide production due to water electrolysis at a BDD electrode. An approach to measuring the local pH change induced by water electrolysis using iridium oxide coated BDD electrodes is also described in detail.

Assessment of Boron Doped Diamond Electrode Quality and Application to In Situ Modification of Local pH by Water Electrolysis

A protocol is described for the characterization of the key electrochemical parameters of a boron doped diamond (BDD) electrode and subsequent application for in situ pH generation experiments.

Boron doped diamond (BDD) electrodes have shown considerable promise as an electrode material where many of their reported properties such as extended ...

Synthesis and Exfoliation of Discotic Zirconium Phosphates to Obtain Colloidal Liquid Crystals

Due to their abundance in natural clay and potential applications in advanced materials, discotic nanoparticles are of interest to scientists and engineers. Growth of such anisotropic nanocrystals through a simple chemical method is a challenging task. In this study, we fabricate discotic nanodisks of zirconium phosphate [Zr(HPO4)2&#183;H2O] as a model material using hydrothermal, reflux and microwave-assisted methods. Growth of crystals is controlled by duration time, temperature, and concentration of reacting species. The novelty of the adopted methods is that discotic crystals of size ranging from hundred nanometers to few micrometers can be obtained while keeping the polydispersity well within control. The layered discotic crystals are converted to monolayers by exfoliation with tetra-(n)-butyl ammonium hydroxide [(C4H9)4NOH, TBAOH]. Exfoliated disks show isotropic and nematic liquid crystal phases. Size and polydispersity of disk suspensions is highly important in deciding their phase behavior.

A two dimensional model material of discotic zirconium phosphate was developed. The inorganic crystal with lamellar structure was synthesized by hydrothermal, reflux, and microwave-assisted methods. On exfoliation with organic molecules, layered crystals can be converted to monolayers, and nematic liquid crystal phase was formed at sufficient concentration of monolayers.

Due to their abundance in natural clay and potential applications in advanced materials, discotic nanoparticles are of interest to scientists and ...

Radiolabeling and Quantification of Cellular Levels of Phosphoinositides by High Performance Liquid Chromatography-coupled Flow Scintillation

Phosphoinositides (PtdInsPs) are essential signaling lipids responsible for recruiting specific effectors and conferring organelles with molecular identity and function. Each of the seven PtdInsPs varies in their distribution and abundance, which are tightly regulated by specific kinases and phosphatases. The abundance of PtdInsPs can change abruptly in response to various signaling events or disturbance of the regulatory machinery. To understand how these events lead to changes in the amount of PtdInsPs and their resulting impact, it is important to quantify PtdInsP levels before and after a signaling event or between control and abnormal conditions. However, due to their low abundance and similarity, quantifying the relative amounts of each PtdInsP can be challenging. This article describes a method for quantifying PtdInsP levels by metabolically labeling cells with 3H-myo-inositol, which is incorporated into PtdInsPs. Phospholipids are then precipitated and deacylated. The resulting soluble 3H-glycero-inositides are further extracted, separated by high-performance liquid chromatography (HPLC), and detected by flow scintillation. The labeling and processing of yeast samples is described in detail, as well as the instrumental setup for the HPLC and flow scintillator. Despite losing structural information regarding acyl chain content, this method is sensitive and can be optimized to concurrently quantify all seven PtdInsPs in cells.

Phosphoinositides are signaling lipids whose relative abundance rapidly changes in response to various stimuli. This article describes a method to measure the abundance of phosphoinositides by metabolically labeling cells with 3H-myo-inositol, followed by extraction and deacylation. Extracted glycero-inositides are then separated by high-performance liquid chromatography and quantified by flow scintillation.

Phosphoinositides (PtdInsPs) are essential signaling lipids responsible for recruiting specific effectors and conferring organelles with molecular ...

In Situ Characterization of Hydrated Proteins in Water by SALVI and ToF-SIMS

This work demonstrates in situ characterization of protein biomolecules in the aqueous solution using the System for Analysis at the Liquid Vacuum Interface (SALVI) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The fibronectin protein film was immobilized on the silicon nitride (SiN) membrane that forms the SALVI detection area. During ToF-SIMS analysis, three modes of analysis were conducted including high spatial resolution mass spectrometry, two-dimensional (2D) imaging, and depth profiling. Mass spectra were acquired in both positive and negative modes. Deionized water was also analyzed as a reference sample. Our results show that the fibronectin film in water has more distinct and stronger water cluster peaks compared to water alone. Characteristic peaks of amino acid fragments are also observable in the hydrated protein ToF-SIMS spectra. These results illustrate that protein molecule adsorption on a surface can be studied dynamically using SALVI and ToF-SIMS in the liquid environment for the first time.

In Situ Characterization of Hydrated Proteins in Water by SALVI and ToF-SIMS

This work presents a protocol for liquid handling and sample introduction to a microchannel for in situ time-of-flight secondary ion mass spectrometry analysis of protein biomolecules in an aqueous solution.

This work demonstrates in situ characterization of protein biomolecules in the aqueous solution using the System for Analysis at the Liquid Vacuum ...

Sequencing of Plant Wall Heteroxylans Using Enzymic, Chemical (Methylation) and Physical (Mass Spectrometry, Nuclear Magnetic Resonance) Techniques

This protocol describes the specific techniques used for the characterization of reducing end (RE) and internal region glycosyl sequence(s) of heteroxylans. De-starched wheat endosperm cell walls were isolated as an alcohol-insoluble residue (AIR)1 and sequentially extracted with water (W-sol Fr) and 1 M KOH containing 1% NaBH4 (KOH-sol Fr) as described by Ratnayake et al. (2014)2. Two different approaches (see summary in Figure 1) are adopted. In the first, intact W-sol AXs are treated with 2AB to tag the original RE backbone chain sugar residue and then treated with an endoxylanase to generate a mixture of 2AB-labelled RE and internal region reducing oligosaccharides, respectively. In a second approach, the KOH-sol Fr is hydrolyzed with endoxylanase to first generate a mixture of oligosaccharides which are subsequently labelled with 2AB. The enzymically released ((un)tagged) oligosaccharides from both W- and KOH-sol Frs are then methylated and the detailed structural analysis of both the native and methylated oligosaccharides is performed using a combination of MALDI-TOF-MS, RP-HPLC-ESI-QTOF-MS and ESI-MSn. Endoxylanase digested KOH-sol AXs are also characterized by nuclear magnetic resonance (NMR) that also provides information on the anomeric configuration. These techniques can be applied to other classes of polysaccharides using the appropriate endo-hydrolases.

Sequencing of Plant Wall Heteroxylans Using Enzymic, Chemical Methylation and Physical Mass Spectrometry, Nuclear Magnetic Resonance Techniques

This protocol describes the specific techniques used for the structural characterization of reducing end (RE) and internal region glycosyl sequence(s) of heteroxylans by tagging the RE with 2 aminobenzamide prior to enzymatic (endoxylanase) hydrolysis and then analysis of the resultant oligosaccharides using mass spectrometry (MS) and nuclear magnetic resonance (NMR).

This protocol describes the specific techniques used for the characterization of reducing end (RE) and internal region glycosyl sequence(s) of ...

In Situ Characterization of Shewanella oneidensis MR1 Biofilms by SALVI and ToF-SIMS

Bacterial biofilms are surface-associated communities that are vastly studied to understand their self-produced extracellular polymeric substances (EPS) and their roles in environmental microbiology. This study outlines a method to cultivate biofilm attachment to the System for Analysis at the Liquid Vacuum Interface (SALVI) and achieve in situ chemical mapping of a living biofilm by time-of-flight secondary ion mass spectrometry (ToF-SIMS). This is done through the culturing of bacteria both outside and within the SALVI channel with our specialized setup, as well as through optical imaging techniques to detect the biofilm presence and thickness before ToF-SIMS analysis. Our results show the characteristic peaks of the Shewanella biofilm in its natural hydrated state, highlighting upon its localized water cluster environment, as well as EPS fragments, which are drastically different from the same biofilm's dehydrated state. These results demonstrate the breakthrough capability of SALVI that allows for in situ biofilm imaging with a vacuum-based chemical imaging instrument.

In Situ Characterization of Shewanella oneidensis MR1 Biofilms by SALVI and ToF-SIMS

This article presents a method for growing a biofilm for in situ time-of-flight secondary ion mass spectrometry for chemical mapping in its hydrated state, enabled by a microfluidic reactor, System for Analysis at the liquid Vacuum Interface. The Shewanella oneidensis MR-1 with green fluorescence protein was used as a model.

Bacterial biofilms are surface-associated communities that are vastly studied to understand their self-produced extracellular polymeric substances (EPS) ...

Using Graphene Liquid Cell Transmission Electron Microscopy to Study in Situ Nanocrystal Etching

Graphene liquid cell electron microscopy provides the ability to observe nanoscale chemical transformations and dynamics as the reactions are occurring in liquid environments. This manuscript describes the process for making graphene liquid cells through the example of graphene liquid cell transmission electron microscopy (TEM) experiments of gold nanocrystal etching. The protocol for making graphene liquid cells involves coating gold, holey-carbon TEM grids with chemical vapor deposition graphene and then using those graphene-coated grids to encapsulate liquid between two graphene surfaces. These pockets of liquid, with the nanomaterial of interest, are imaged in the electron microscope to see the dynamics of the nanoscale process, in this case the oxidative etching of gold nanorods. By controlling the electron beam dose rate, which modulates the etching species in the liquid cell, the underlying mechanisms of how atoms are removed from nanocrystals to form different facets and shapes can be better understood. Graphene liquid cell TEM has the advantages of high spatial resolution, compatibility with traditional TEM holders, and low start-up costs for research groups. Current limitations include delicate sample preparation, lack of flow capability, and reliance on electron beam-generated radiolysis products to induce reactions. With further development and control, graphene liquid cell may become a ubiquitous technique in nanomaterials and biology, and is already being used to study mechanisms governing growth, etching, and self-assembly processes of nanomaterials in liquid on the single particle level.

Using Graphene Liquid Cell Transmission Electron Microscopy to Study in Situ Nanocrystal Etching

Graphene liquid cell electron microscopy can be used to observe nanocrystal dynamics in a liquid environment with greater spatial resolution than other liquid cell electron microscopy techniques. Etching premade nanocrystals and following their shape using graphene liquid cell Transmission Electron Microscopy can yield important mechanistic information about nanoparticle transformations.

Graphene liquid cell electron microscopy provides the ability to observe nanoscale chemical transformations and dynamics as the reactions are occurring in ...

Preparation of Graphene-Supported Microwell Liquid Cells for In Situ Transmission Electron Microscopy

The fabrication and preparation of graphene-supported microwell liquid cells (GSMLCs) for in situ electron microscopy is presented in a stepwise protocol. The versatility of the GSMLCs is demonstrated in the context of a study about etching and growth dynamics of gold nanostructures from a HAuCl4 precursor solution. GSMLCs combine the advantages of conventional silicon- and graphene-based liquid cells by offering reproducible well depths together with facile cell manufacturing and handling of the specimen under investigation. The GSMLCs are fabricated on a single silicon substrate which drastically reduces the complexity of the manufacturing process compared to two-wafer-based liquid cell designs. Here, no bonding or alignment process steps are required. Furthermore, the enclosed liquid volume can be tailored to the respective experimental requirements by simply adjusting the thickness of a silicon nitride layer. This enables a significant reduction of window bulging in the electron microscope vacuum. Finally, a state-of-the-art quantitative evaluation of single particle tracking and dendrite formation in liquid cell experiments using only open source software is presented.

Preparation of Graphene-Supported Microwell Liquid Cells for In Situ Transmission Electron Microscopy

A protocol for preparation of graphene-supported microwell liquid cells for in situ electron microscopy of gold nanocrystals from HAuCl4 precursor solution is presented. Furthermore, an analysis routine is presented to quantify observed etching and growth dynamics.

The fabrication and preparation of graphene-supported microwell liquid cells (GSMLCs) for in situ electron microscopy is presented in a stepwise protocol. ...

In situ FTIR Spectroscopy as a Tool for Investigation of Gas/Solid Interaction: Water-Enhanced CO2 Adsorption in UiO-66 Metal-Organic Framework

In situ infrared spectroscopy is an inexpensive, highly sensitive, and selective valuable tool to investigate the interaction of polycrystalline solids with adsorbates. Vibrational spectra provide information on the chemical nature of adsorbed species and their structure. Thus, they are very useful for obtaining molecular level understanding of surface species. The IR spectrum of the sample itself gives some direct information about the material. General conclusions can be drawn concerning hydroxyl groups, some stable surface species and impurities. However, the spectrum of the sample is &#34;blind&#34; with respect to the presence of coordinatively unsaturated ions and gives rather poor information about the acidity of surface hydroxyls, species decisive for the adsorption and catalytic properties of the materials. Furthermore, no discrimination between bulk and surface species can be made. These problems are solved by the use of probe molecules, substances that interact specifically with the surface; the alteration of some spectral features of these molecules as a result of adsorption provides valuable information about the nature, properties, location, concentration, etc., of the surface sites.
The experimental protocol for in-situ IR studies of gas/sample interaction includes preparation of a sample pellet, activation of the material, initial spectral characterization through the analysis of the background spectra, characterization by probe molecules, and study of the interaction with a particular set of gas mixtures. In this paper we investigate a zirconium terephthalate metal organic framework, Zr6O4(OH)4(BDC)6 (BDC = benzene-1,4-dicarboxylate), namely UiO-66 (UiO refers to University of Oslo). The acid sites of the UiO-66 sample are determined by using CO and CD3CN as molecular probes. Furthermore, we have demonstrated that CO2 is adsorbed on basic sites exposed on dehydroxylated UiO-66. Introduction of water to the system produces hydroxyl groups acting as additional CO2 adsorption sites. As a result, CO2 adsorption capacity of the sample is strongly enhanced.

In situ FTIR Spectroscopy as a Tool for Investigation of Gas/Solid Interaction: Water-Enhanced CO2 Adsorption in UiO-66 Metal-Organic Framework

The use of FTIR spectroscopy for investigation of the surface properties of polycrystalline solids is described. Preparation of sample pellets, activation procedures, characterization with probe molecules and model studies of CO2 adsorption are discussed.

In situ infrared spectroscopy is an inexpensive, highly sensitive, and selective valuable tool to investigate the interaction of polycrystalline solids ...