Name: in situ characterization of hydrated proteins in water by salvi and tof-sims
Uploaded: 2016-02-15T15:00:00
Description: Watch this Scientific Journal Video about In Situ Characterization of Hydrated Proteins in Water by SALVI and ToF-SIMS at JoVE.com

We are grateful to the Pacific Northwest National Laboratory (PNNL) Chemical Imaging Initiative-Laboratory Directed Research and Development (CII-LDRD) and Materials Synthesis and Simulation across Scales (MS3) Initiative LDRD fund for support. Instrumental access was provided through a W. R. Wiley Environmental Molecular Sciences Laboratory (EMSL) Science Themed Proposal. EMSL is a national scientific user facility sponsored by the Office of Biological and Environmental Research (BER) at PNNL. The authors thank Mr. Xiao Sui, Mr. Yuanzhao Ding, and Ms. Juan Yao for proof reading the manuscript and providing useful feedback. PNNL is operated by Battelle for the DOE under Contract DE-AC05-76RL01830.

1. Cleaning and Sterilization of the SALVI Microchannel
<ol>
	<li>Sterilization of the Microchannel in SALVI
	<ol>
		<li>Draw 2 ml of 70% ethanol aqueous solution into a syringe, connect the syringe with the inlet end of SALVI, and slowly inject 1 ml of the liquid in 10 min. Remove the syringe at the end of injection. Next, connect the inlet and outlet of SALVI using a polyetheretherketone (PEEK) union. Alternately, use a syringe pump to conduct the same procedure. For example, set the flow speed at 100 &#956;l/min.</l...

<ol>
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Cell Biol. 7 (11), 861-866 (2006).</li><li>Zhang, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mapping+hydration+dynamics+around+a+protein+surface.">Mapping hydration dynamics around a protein surface.</a> Proc. Natl. Acad. Sci. U. S. A. 104 (47), 18461-18466 (2007).</li><li>Xia, N., May, C. J., McArthur, S. L., Castner, D. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Time-of-flight+secondary+ion+mass+spectrometry+analysis+of+conformational+changes+in+adsorbed+protein+films.">Time-of-flight secondary ion mass spectrometry analysis of conformational changes in adsorbed protein films.</a> Langmuir. 18 (10), 4090-4097 (2002).</li><li>Gray, J. 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J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Probing+aqueous+surfaces+by+ToF-SIMS.">Probing aqueous surfaces by ToF-SIMS.</a> LC GC N. Am. (Oct), 34-38 (2011).</li><li>Yu, X. -. Y., Yang, L., Cowin, J., Iedema, M., Zhu, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Systems+and+methods+for+analyzing+liquids+under+vacuum.">Systems and methods for analyzing liquids under vacuum.</a> US patent. , (2013).</li><li>Yu, X. -. Y., Liu, B., Yang, L., Zhu, Z., Marshall, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microfluidic+electrochemical+device+and+process+for+chemical+imaging+and+electrochemical+analysis+at+the+electrode-liquid+interface+in+situ.">Microfluidic electrochemical device and process for chemical imaging and electrochemical analysis at the electrode-liquid interface in situ.</a> US patent. , (2014).</li><li>Yang, L., Zhu, Z., Yu, X. -. Y., Thevuthasan, S., Cowin, J. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Performance+of+a+microfluidic+device+for+in+situ+ToF-SIMS+analysis+of+selected+organic+molecules+at+aqueous+surfaces.">Performance of a microfluidic device for in situ ToF-SIMS analysis of selected organic molecules at aqueous surfaces.</a> Anal. 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Interface Anal. 46 (4), 224-228 (2014).</li><li>Hua, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+situ+molecular+imaging+of+hydrated+biofilm+in+a+microfluidic+reactor+by+ToF-SIMS.">In situ molecular imaging of hydrated biofilm in a microfluidic reactor by ToF-SIMS.</a> Analyst. 139 (7), 1609-1613 (2014).</li><li>Hua, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Two-dimensional+and+three-dimensional+dynamic+imaging+of+live+biofilms+in+a+microchannel+by+time-of-flight+secondary+ion+mass+spectrometry.">Two-dimensional and three-dimensional dynamic imaging of live biofilms in a microchannel by time-of-flight secondary ion mass spectrometry.</a> Biomicrofluidics. 9 (3), 031101 (2015).</li><li>Liu, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+situ+chemical+probing+of+the+electrode-electrolyte+interface+by+ToF-SIMS.">In situ chemical probing of the electrode-electrolyte interface by ToF-SIMS.</a> Lab Chip. 14 (5), 855-859 (2014).</li><li>Pankov, R., Yamada, K. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fibronectin+at+a+glance.">Fibronectin at a glance.</a> J. Cell Sci. 115 (20), 3861-3863 (2002).</li><li>Pierschbacher, M. D., Hayman, E. G., Ruoslahti, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Location+of+the+cell-attachment+site+in+fibronectin+with+monoclonal+antibodies+and+proteolytic+fragments+of+the+molecule.">Location of the cell-attachment site in fibronectin with monoclonal antibodies and proteolytic fragments of the molecule.</a> Cell. 26 (2), 259-267 (1981).</li><li>Engvall, E., Ruoslahti, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Binding+of+soluble+form+of+fibroblast+surface+protein,+fibronectin,+to+collagen.">Binding of soluble form of fibroblast surface protein, fibronectin, to collagen.</a> Int. J. Cancer. 20 (1), 1-5 (1977).</li><li>Green, F. M., Gilmore, I. S., Seah, M. 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A. 31 (5), 050819 (2013).</li><li>Muramoto, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=ToF-SIMS+Analysis+of+Adsorbed+Proteins:+Principal+Component+Analysis+of+the+Primary+Ion+Species+Effect+on+the+Protein+Fragmentation+Patterns.">ToF-SIMS Analysis of Adsorbed Proteins: Principal Component Analysis of the Primary Ion Species Effect on the Protein Fragmentation Patterns.</a> J. Phys. Chem. C. 115 (49), 24247-24255 (2011).</li><li>Br&#252;ning, C., Hellweg, S., Dambach, S., Lipinsky, D., Arlinghaus, H. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improving+the+interpretation+of+ToF-SIMS+measurements+on+adsorbed+proteins+using+PCA.">Improving the interpretation of ToF-SIMS measurements on adsorbed proteins using PCA.</a> Surf. 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SALVI is a microfluidic interface that allows dynamic liquid surface and liquid-solid interface analysis by vacuum based instruments, such as ToF-SIMS and scanning electron microscopy (SEM). Due to the usage of small apertures to expose liquid directly in vacuum, SALVI is suitable for many finely focused spectroscopy and imaging techniques without any modifications;22 the portability and versatility of microfluidics make it a true multimodal imaging platform. Distinct features and significance of SALVI compare...

Hydration is crucial to the structure,1 conformation,2 and biological activity3 of proteins. Proteins without water molecules surrounding them would not have viable biological activities. Specifically, water molecules interact with the surface and internal structure of proteins, and different hydration states of proteins make such interactions distinct.4 The interaction of proteins with solid surfaces is a fundamental phenomenon with implications in nanotechnology, biomaterials and tissue engineering processes. Studies have long indicated that conformational changes may occur as a protein encounters a surface. ToF-SIMS has been envisioned as the technique that has the potential to study the protein-solid interface.5-7 It is important to understand the hydration of proteins on solid surfaces, which potentially provides a fundamental understanding of the mechanism of their structure, conformation, and biological activity.
However, major surface analytical techniques are mostly vacuum-based and direct applications for volatile liquid studies are difficult due to the rapid evaporation of volatile liquid under the vacuum environment. We developed a vacuum compatible microfluidic interface, System for Analysis at the Liquid Vacuum Interface (SALVI), to enable direct observations of liquid surfaces and liquid-solid interactions using time-of-flight secondary ion mass spectrometry (ToF-SIMS).8-11 The unique aspects include the following: 1) the detection window is an aperture of 2-3 &#956;m in diameter allowing direct imaging of the liquid surface, 2) surface tension is used to hold the liquid within the aperture, and 3) SALVI is portable among multiple analytical platforms.11,12
SALVI is composed of a silicon nitride (SiN) membrane as the detection area and a microchannel made of polydimethylsiloxane (PDMS). It is fabricated in the clean room, and the fabrication and key design factors have been detailed in previous papers and patents.8-12 The applications of ToF-SIMS as an analytical tool were demonstrated using a variety of aqueous solutions and complex liquid mixtures, some of which contained nanoparticles.13-17 Specifically, SALVI liquid ToF-SIMS allows dynamic probing of the liquid-solid interface of live biological systems (i.e., biofilms), single cells, and solid-electrolyte interface, opening new opportunities for in situ condensed phase studies including liquids using ToF-SIMS. However, the current design does not permit gas-liquid interactions yet. This is a direction for future development. SALVI has been used to study the hydrated protein film in this work for the first time.
Fibronectin is a commonly used protein dimer, consisting of two nearly identical monomers linked by a pair of disulfide bonds,18 which is well-known for its ability to bind cells.19,20 It was chosen as a model system to illustrate that the hydrated protein film could be dynamically probed using the SALVI liquid ToF-SIMS approach. The protein solution was introduced into the microchannel. After incubating for 12 hr, a hydrated protein film formed on the back side of the SiN membrane. Deionized (DI) water was used to rinse off the channel after protein introduction. Information was collected from hydrated fibronectin protein molecules in the SALVI microchannel using dynamic ToF-SIMS. DI water was also studied as a control to compare with results obtained from hydrated fibronectin thin film. Distinct differences were observed between the hydrated protein film and DI water. This work demonstrates that protein adsorption on surface in the liquid environment can be studied using the novel SALVI and liquid ToF-SIMS approach. The video protocol is intended to provide technical guidance for people who are interested in utilizing this new analytical tool for diverse applications of SALVI with ToF-SIMS and reduce unnecessary mistakes in liquid handling as well as ToF-SIMS data acquisition and analysis.

<table border="0" cellpadding="0" cellspacing="0" width="1170">
	<tbody>
		<tr height="20">
			<td height="20" style="height:20px;width:389px;">ToF-SIMS</td>
			<td style="width:260px;">IONTOF</td>
			<td style="width:121px;">TOF.SIMS 5</td>
			<td style="width:400px;">Resolution: &#62; 10,000 m/&#916;m for mass resolution; &#62; 4,000 m/&#916;m for high spatial resolution&#160;</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:389px;">System for Analysis at the Liquid Vacuum Interface (SALVI)</td>
			<td style="width:260px;">Pacific Northwest National Laboratory</td>
			<td style="width:121px;">N/A</td>
			<td style="width:400px;">SALVI is a unique, self-contained, portable analytical tool that, for the first time, enables vacuum-based scientific instruments such as time-of-flight secondary ion mass spectrometry (ToF-SIMS) to analyze liquid surfaces in their natural state at the molecular level.</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:389px;">PEEK Union</td>
			<td style="width:260px;">Valco</td>
			<td style="width:121px;">ZU1TPK</td>
			<td>for connecting the inlet and outlet of SALVI</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:389px;">5 Axes Sample Stage</td>
			<td style="width:260px;">IONTOF</td>
			<td style="width:121px;">N/A</td>
			<td>Stage is self-made for mounting SALVI in ToF-SIMS</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:389px;">Barnstead Nanopure Water Purification System</td>
			<td style="width:260px;">Thermo Fisher Scientific</td>
			<td style="width:121px;">D11921</td>
			<td>ROpure LP Reverse Osmosis filtration module (D2716)</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:389px;">Syringe</td>
			<td style="width:260px;">BD</td>
			<td style="width:121px;">309659</td>
			<td style="width:400px;">1 mL</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:389px;">Pipette</td>
			<td style="width:260px;">Thermo Fisher Scientific</td>
			<td style="width:121px;">21-377-821</td>
			<td>Range: 100 to 1000 mL</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:389px;">Pipette Tip</td>
			<td style="width:260px;">Neptune</td>
			<td style="width:121px;">2112.96.BS</td>
			<td>1000 &#181;L</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:389px;">Centrifuge Tube</td>
			<td style="width:260px;">Corning</td>
			<td style="width:121px;">430791</td>
			<td>15 mL</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:389px;">Fibronectin</td>
			<td style="width:260px;">Sigma-Aldrich</td>
			<td style="width:121px;">F1141</td>
			<td>1 mg/mL</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:389px;">Ethanol</td>
			<td style="width:260px;">Thermo Fisher Scientific</td>
			<td style="width:121px;">S25310A</td>
			<td>95% Denatured</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:389px;">Gibco PBS</td>
			<td style="width:260px;">Thermo Fisher Scientific</td>
			<td style="width:121px;">10010-023</td>
			<td>pH 7.4</td>
		</tr>
	</tbody>
</table>

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.

A couple of representative results are presented to demonstrate the advantages of the proposed protocol. By using the SALVI microfluidic interface, the primary ion beam (Bi3+) can directly bombard on the hydrated fibronectin film in DI water. Thus the molecular chemical mapping of the liquid surface can be successfully acquired.
Figure 1a and 1b show the positive ToF-SIMS m...

Watch this Scientific Journal Video about In Situ Characterization of Hydrated Proteins in Water by SALVI and ToF-SIMS at JoVE.com

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.

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 ...

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Photoelectron Imaging of Anions Illustrated by 310 Nm Detachment of F&#8722;

Photoelectron Imaging of Anions Illustrated by 310 Nm Detachment of FÃƒÆ’Ã‚Â¢Ãƒâ€¹Ã¢â‚¬Â '

Anion photoelectron imaging is a very efficient method for the study of energy states of bound negative ions, neutral species and interactions of unbound ...