Name: interfacial molecular-level structures of polymers and biomacromolecules revealed via sum frequency generation vibrational spectroscopy
Uploaded: 2019-08-13T13:30:00
Description: Watch this Scientific Journal Video about Interfacial Molecular-level Structures of Polymers and Biomacromolecules Revealed via Sum Frequency Generation Vibrational Spectroscopy at JoVE.com

This study was supported by the State Key Development Program for Basic Research of China (2017YFA0700500) and the National Natural Science Foundation of China (21574020). The Fundamental Research Funds for the Central Universities, a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD) and the National Demonstration Center for Experimental Biomedical Engineering Education (Southeast University) were also greatly appreciated.

1. SFG experimental
<ol>
	<li>Use a commercial picosecond SFG system (Table of Materials), which provides a fundamental 1064 nm beam with a pulse width of ~20 ps and a frequency of 50 Hz, based on an Nd:YAG laser.</li>
	<li>Convert the fundamental 1064 nm beam into a 532 nm beam and a 355 nm beam by using second and third harmonic modules. Directly guide the 532 nm beam as an input light beam and generate the other input mid-infrared (IR) beam covering the frequency range from 1000 to ...

<ol>
	<li>Shen, Y. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optical+Second+Harmonic+Generation+at+Interfaces.">Optical Second Harmonic Generation at Interfaces.</a> Annual Review of Physical Chemistry. 40, 327-350 (1989).</li><li>Shen, Y. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surface+properties+probed+by+second-harmonic+and+sum-frequency+generation.">Surface properties probed by second-harmonic and sum-frequency generation.</a> Nature. 337, 519-525 (1989).</li><li>Lu, 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=Studying+Polymer+Surfaces+and+Interfaces+with+Sum+Frequency+Generation+Vibrational+Spectroscopy.">Studying Polymer Surfaces and Interfaces with Sum Frequency Generation Vibrational Spectroscopy.</a> Analytical Chemistry. 89 (1), 466-489 (2017).</li><li>Chen, X., Clarke, M. L., Wang, J., Chen, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sum+Frequency+Generation+Vibrational+Spectroscopy+Studies+on+Molecular+Conformation+and+Orientation+of+Biological+Molecules+at+Interfaces.">Sum Frequency Generation Vibrational Spectroscopy Studies on Molecular Conformation and Orientation of Biological Molecules at Interfaces.</a> International Journal of Modern Physics B. 19 (4), 691-713 (2005).</li><li>Eisenthal, K. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Liquid+Interfaces+Probed+by+Second-Harmonic+and+Sum-Frequency+Spectroscopy.">Liquid Interfaces Probed by Second-Harmonic and Sum-Frequency Spectroscopy.</a> Chemical Reviews. 96 (4), 1343-1360 (1996).</li><li>Richmond, G. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molcular+Bonding+and+Interactions+at+Aqueous+Surfaces+as+Probed+by+Vibrational+Sum+Frequency+Spectroscopy.">Molcular Bonding and Interactions at Aqueous Surfaces as Probed by Vibrational Sum Frequency Spectroscopy.</a> Chemical Reviews. 102 (8), 2693-2724 (2002).</li><li>Wang, H., Gan, W., Lu, R., Rao, Y., Wu, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantitative+spectral+and+orientational+analysis+in+surface+sum+frequency+generation+vibrational+spectroscopy(SFG-VS).">Quantitative spectral and orientational analysis in surface sum frequency generation vibrational spectroscopy(SFG-VS).</a> International Reviews in Physical Chemistry. 24 (2), 191-256 (2007).</li><li>Shultz, M. J., Schnitzer, C., Simonelli, D., Baldelli, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sum+frequency+generation+spectroscopy+of+the+aqueous+interface:+Ionic+and+soluble+molecular+solutions.">Sum frequency generation spectroscopy of the aqueous interface: Ionic and soluble molecular solutions.</a> International Reviews in Physical Chemistry. 19 (1), 123-153 (2010).</li><li>Li, 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=Detecting+Surface+Hydration+of+Poly(2-hydroxyethyl+methacrylate)+in+Solution+in+situ.">Detecting Surface Hydration of Poly(2-hydroxyethyl methacrylate) in Solution in situ.</a> Macromolecules. 49, 3116-3125 (2016).</li><li>Li, X., Lu, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evolution+of+Irreversibly+Absorbed+Layer+Promotes+Dewetting+of+Polystyrene+Film+on+Sapphire.">Evolution of Irreversibly Absorbed Layer Promotes Dewetting of Polystyrene Film on Sapphire.</a> Macromolecules. 51, 6653-6660 (2018).</li><li>Lu, X., Spanninga, S. A., Kristalyn, C. B., Chen, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surface+Orientation+of+Phenyl+Groups+in+Poly(sodium+4-styrenesulfonate)+and+in+Poly(sodium+4-styrenesulfonate):+Poly(3,4-ethylenedioxythiophene)+Mixture+Examined+by+Sum+Frequency+Generation+Vibrational+Spectroscopy.">Surface Orientation of Phenyl Groups in Poly(sodium 4-styrenesulfonate) and in Poly(sodium 4-styrenesulfonate): Poly(3,4-ethylenedioxythiophene) Mixture Examined by Sum Frequency Generation Vibrational Spectroscopy.</a> Langmuir. 26 (17), 14231-14235 (2010).</li><li>Lu, X., Clarke, M. L., Li, D., Wang, X., Chen, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Sum+Frequency+Generation+Vibrational+Study+of+the+Interference+Effect+in+Poly(n-butyl+methacrylate)+Thin+Films+Sandwiched+between+Silica+and+Water.">A Sum Frequency Generation Vibrational Study of the Interference Effect in Poly(n-butyl methacrylate) Thin Films Sandwiched between Silica and Water.</a> Journal of Physical Chemistry C. 115, 13759-13767 (2011).</li><li>Lu, 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=Directly+Probing+Molecular+Ordering+at+the+Buried+Polymer/Metal+Interface+2:+Using+P-Polarized+Input+Beams.">Directly Probing Molecular Ordering at the Buried Polymer/Metal Interface 2: Using P-Polarized Input Beams.</a> Macromolecules. 45, 6087-6094 (2012).</li><li>Lu, X., Myers, J. N., Chen, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+Ordering+of+Phenyl+Groups+at+the+Buried+Polystyrene/Metal+Interface.">Molecular Ordering of Phenyl Groups at the Buried Polystyrene/Metal Interface.</a> Langmuir. 30, 9418-9422 (2014).</li><li>Li, B., Lu, X., Ma, Y., Han, X., Chen, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Method+to+Probe+Glass+Transition+Temperatures+of+Polymer+Thin+Films.">Method to Probe Glass Transition Temperatures of Polymer Thin Films.</a> ACS Macro Letters. 4, 548-551 (2015).</li><li>Li, X., Deng, G., Ma, L., Lu, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interchain+Overlap+Affects+Formation+of+Silk+Fibroin+Secondary+Structure+on+Hydrophobic+Polystyrene+Surface+Detected+via+Achiral/Chiral+Sum+Frequency+Generation.">Interchain Overlap Affects Formation of Silk Fibroin Secondary Structure on Hydrophobic Polystyrene Surface Detected via Achiral/Chiral Sum Frequency Generation.</a> Langmuir. 34, 9453-9459 (2018).</li><li>Kai, S., Li, X., Li, B., Han, X., Lu, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Calcium-dependent+hydrolysis+of+supported+planar+lipids+was+triggered+by+honey+bee+venom+phospholipase+A2+with+the+right+orientation+at+the+interface.">Calcium-dependent hydrolysis of supported planar lipids was triggered by honey bee venom phospholipase A2 with the right orientation at the interface.</a> Physical Chemistry Chemical Physics. 20, 63-67 (2018).</li><li>Wang, J., Buck, S., Chen, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sum+Frequency+Generation+Vibrational+Spectroscopy+Studies+on+Protein+Adsorption.">Sum Frequency Generation Vibrational Spectroscopy Studies on Protein Adsorption.</a> Journal of Physical Chemistry B. 106, 11666-11672 (2002).</li><li>Wang, J., 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=Detection+of+Amide+I+Signals+of+Interfacial+Proteins+in+Situ+Using+SFG.">Detection of Amide I Signals of Interfacial Proteins in Situ Using SFG.</a> Journal of American Chemical Society. 125, 9914-9915 (2003).</li><li>Nguyen, K. T., 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=Probing+the+Spontaneous+Membrane+Insertion+of+a+Tall-Anchored+Membrane+Protein+by+Sum+Frequency+Generation+Spectroscopy.">Probing the Spontaneous Membrane Insertion of a Tall-Anchored Membrane Protein by Sum Frequency Generation Spectroscopy.</a> Journal of American Chemistry Society. 132, 15112-15115 (2010).</li><li>Li, X., Ma, L., Lu, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Calcium+Ions+Affect+Water+Molecular+Structures+Surrounding+an+Oligonucleotide+Duplex+as+Revealed+by+Sum+Frequency+Generation+Vibrational+Spectroscopy.">Calcium Ions Affect Water Molecular Structures Surrounding an Oligonucleotide Duplex as Revealed by Sum Frequency Generation Vibrational Spectroscopy.</a> Langmuir. , (2018).</li><li>Sartenaer, Y., 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=Sum-frequency+generation+spectroscopy+of+DNA+monolayers.">Sum-frequency generation spectroscopy of DNA monolayers.</a> Biosensors &amp; Bioelectronics. 22, 2179-2183 (2007).</li><li>Asanuma, H., Noguchi, H., Uosaki, K., Yu, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Metal+Cation-induced+Deformation+of+DNA+Self-Assembled+Monolayers+on+Silicon:+Vibrational+Sum+Frequency+Generation+Spectroscopy.">Metal Cation-induced Deformation of DNA Self-Assembled Monolayers on Silicon: Vibrational Sum Frequency Generation Spectroscopy.</a> Journal of American Chemistry Society. 130, 8016-8022 (2008).</li><li>Howell, C., Schmidt, R., Kurz, V., Koelsch, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sum-frequency-generation+spectroscopy+of+DNA+films+in+air+and+aqueous+environments.">Sum-frequency-generation spectroscopy of DNA films in air and aqueous environments.</a> Biointerphases. 3 (3), FC47 (2008).</li><li>Walter, S. R., Geiger, F. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=DNA+on+Stage:+Showcasing+Oligonucleotides+at+Surfaces+and+Interfaces+with+Second+Harmonic+and+Vibrational+Sum+Frequency+Generation.">DNA on Stage: Showcasing Oligonucleotides at Surfaces and Interfaces with Second Harmonic and Vibrational Sum Frequency Generation.</a> Journal of Physical Chemistry Letters. 1, 9-15 (2010).</li><li>Li, Z., Weeraman, C., Azam, M. S., Osman, E., Gibbs-Davis, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+thermal+reorganization+of+DNA+immobilized+at+the+silica/buffer+interface:+a+vibrational+sum+frequency+generation+investigation.">The thermal reorganization of DNA immobilized at the silica/buffer interface: a vibrational sum frequency generation investigation.</a> Physical Chemistry Chemical Physics. 17, 12452-12457 (2015).</li><li>Lambert, A. G., Neivandt, D. J., Briggs, A. M., Usadi, E. W., Davies, P. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interference+Effects+in+Sum+Frequency+Spectra+from+Monolayers+on+Composite+Dielectric/Metal+Substrates.">Interference Effects in Sum Frequency Spectra from Monolayers on Composite Dielectric/Metal Substrates.</a> Journal of Physical Chemistry B. 106, 5461-5469 (2002).</li><li>Tong, Y., 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=Interference+effects+in+the+sum+frequency+generation+spectra+of+thin+organic+films.+I.+Theoretical+modeling+and+simulation.">Interference effects in the sum frequency generation spectra of thin organic films. I. Theoretical modeling and simulation.</a> Journal of Chemical Physics. 133, 034704 (2010).</li><li>McGall, S. J., Davies, P. B., Neivandt, D. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interference+Effects+in+Sum+Frequency+Vibrational+Spectra+of+Thin+Polymer+Films:+An+Experimental+and+Modeling+Investigation.">Interference Effects in Sum Frequency Vibrational Spectra of Thin Polymer Films: An Experimental and Modeling Investigation.</a> Journal of Physical Chemistry B. 108, 16030-16039 (2004).</li><li>Li, 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=Interfacial+Fresnel+Coefficients+and+Molecular+Structures+of+Model+Cell+Membranes:+From+a+Lipid+Monolayer+to+a+Lipid+Bilayer.">Interfacial Fresnel Coefficients and Molecular Structures of Model Cell Membranes: From a Lipid Monolayer to a Lipid Bilayer.</a> Journal of Physical Chemistry C. 118, 28631-28639 (2014).</li><li>Zhou, J., Anim-Danso, E., Zhang, Y., Zhou, Y., Dhinojwala, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interfacial+Water+at+Polyurethane-Sapphire+Interface.">Interfacial Water at Polyurethane-Sapphire Interface.</a> Langmuir. 31 (45), 12401-12407 (2015).</li><li>Gautam, K. 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=Molecular+Structure+of+Polystyrene+at+Air/Polymer+and+Solid/Polymer+Interfaces.">Molecular Structure of Polystyrene at Air/Polymer and Solid/Polymer Interfaces.</a> Physical Review Letters. 85 (18), 3854-3857 (2000).</li><li>Yan, E. Y., Fu, L., Wang, Z., Liu, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biological+Macromolecules+at+Interfaces+Probed+by+Chiral+Vibrational+Sum+Frequency+Generation+Spectroscopy.">Biological Macromolecules at Interfaces Probed by Chiral Vibrational Sum Frequency Generation Spectroscopy.</a> Chemical Reviews. 114, 8471-8498 (2014).</li><li>Belkin, M. A., Kulakov, T. A., Ernst, K. H., Yan, L., Shen, Y. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sum-Frequency+Vibrational+Spectroscopy+on+Chiral+Liquids:+A+Novel+Technique+to+Probe+Molecular+Chirality.">Sum-Frequency Vibrational Spectroscopy on Chiral Liquids: A Novel Technique to Probe Molecular Chirality.</a> Physical Review Letters. 85, 4474 (2000).</li><li>Rockwood, D. N., 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=Materials+fabrication+from+Bombyx+mori+silk+fibroin.">Materials fabrication from Bombyx mori silk fibroin.</a> Nature Protocols. 6, 1612-1631 (2011).</li></ol>

To investigate the structural information from a molecular level, SFG has its inherent advantages (i.e., monolayer or sub-monolayer sensitivity and interfacial selectivity), which can be applied to study various interfaces, such as the solid/solid, solid/liquid, solid/gas, liquid/gas, liquid/liquid interfaces. Although the equipment maintenance and the optical alignment are still time-consuming, the payoff is significant in that the detailed molecular-level information at the surfaces and interfaces can be obtained.
...

Development of sum frequency generation (SFG) vibrational spectroscopy can be dated back to the work done by Shen et al. thirty years ago1,2. The uniqueness of the interfacial selectivity and sub-monolayer sensitivity makes SFG vibrational spectroscopy appreciated by a large number of researchers in the fields of physics, chemistry, biology, and materials science, etc3,4,5. Currently, a broad range of scientific issues related to surfaces and interfaces are being investigated using SFG, especially for complex interfaces with respect to polymers and biomacromolecules, such as the chain structures and structural relaxation at the buried polymer interfaces, the protein secondary structures, and the interfacial water structures9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26.
For polymer surfaces and interfaces, thin-film samples are generally prepared by spin-coating to obtain the desired surfaces or interfaces. The problem arises due to the signal interference from the two interfaces of the as-prepared films, which leads to inconvenience for analyzing the collected SFG spectra27,28,29. In most cases, the vibrational signal only from one single interface, either film/substrate or film/the other medium, is desirable. Actually, the solution to this problem is quite easy, namely, to experimentally maximize the light fields at the desirable interface and minimize the light fields at the other interface. Hence, the Fresnel coefficients or the local field coefficients need to be calculated via the thin film model and to be validated with respect to the experimental results3,9,10,11,12,13,14,15,30.
With the above background in mind, some polymer and biological interfaces could be investigated in order to understand fundamental science from the molecular level. In the following, taking three interfacial issues as examples: probing poly(2-hydroxyethyl methacrylate) (PHEMA) surface and buried interface with substrate9, formation of silk fibroin (SF) secondary structures on the polystyrene (PS) surface and water structures surrounding model short-chain oligonucleotide duplex16,21, we will show how the SFG vibrational spectroscopy helps to reveal the interfacial molecular-level structures in connection to the underlying science.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC)&#160;</td>
			<td>Avanti Polar Lipids, Inc.</td>
			<td>850355P-1g</td>
			<td></td>
		</tr>
		<tr>
			<td>Anhydrous ethanol</td>
			<td>Sinopharm Chemical Reagent Co., Ltd</td>
			<td>100092680</td>
			<td>&#8805;99.7%</td>
		</tr>
		<tr>
			<td>CaF2 prism</td>
			<td>Chengdu YaSi Optoelectronics Co., Ltd.</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Calcium chloride anhydrous</td>
			<td>Sinopharm Chemical Reagent Co., Ltd</td>
			<td>10005817</td>
			<td>&#8805;96.0%</td>
		</tr>
		<tr>
			<td>deuterated DPPC (d-DPPC)</td>
			<td>Avanti Polar Lipids, Inc.</td>
			<td>860345P-100mg</td>
			<td></td>
		</tr>
		<tr>
			<td>Electromagnetic oven</td>
			<td>Zhejiang Supor Co., Ltd</td>
			<td>C21-SDHCB37</td>
			<td></td>
		</tr>
		<tr>
			<td>Langmuir-Blodgett (LB) trough</td>
			<td>KSV NIMA Co., Ltd.</td>
			<td>KN 2003</td>
			<td></td>
		</tr>
		<tr>
			<td>Lithium bromide anhydrous</td>
			<td>Sinopharm Chemical Reagent Co., Ltd</td>
			<td>20056926</td>
			<td></td>
		</tr>
		<tr>
			<td>Milli-Q synthesis system</td>
			<td>Millipore</td>
			<td></td>
			<td>Ultrapure water</td>
		</tr>
		<tr>
			<td>Plasma cleaner</td>
			<td>Chengdu Mingheng Science&#38;Technology Co., Ltd</td>
			<td>PDC-MG</td>
			<td>Oxygen plasma cleaning</td>
		</tr>
		<tr>
			<td>Poly(2-hydroxyethyl methacrylate) (PHEMA)</td>
			<td>Sigma-Aldrich Co., LLC.</td>
			<td>192066 MSDS</td>
			<td>Mw = 300 000</td>
		</tr>
		<tr>
			<td>Polystyrene</td>
			<td>Sigma-Aldrich Co., LLC.</td>
			<td>330345 MSDS</td>
			<td>Mw = 48 kDa and Mn = 47 kDa</td>
		</tr>
		<tr>
			<td>Silk cocoons</td>
			<td></td>
			<td></td>
			<td>From Bombyx mori</td>
		</tr>
		<tr>
			<td>Single complementary strand of oligonucleotide</td>
			<td>Nanjing Genscript Biotechnology Co., Ltd.</td>
			<td>H03596</td>
			<td>5&#39;-CGAAGGCTTCCAGCT-3&#39;</td>
		</tr>
		<tr>
			<td>Single strand of oligonucleotide</td>
			<td>Nanjing Genscript Biotechnology Co., Ltd.</td>
			<td>H04936</td>
			<td>&#160;3&#162;-end modified by cholesterol-triethylene glycol(Chol-TEG) (5&#162;-GCTTCCGAAGGTCGA-3&#162;)</td>
		</tr>
		<tr>
			<td>Sodium carbonate anhydrous</td>
			<td>Sinopharm Chemical Reagent Co., Ltd</td>
			<td>10019260</td>
			<td>&#8805;99.8%</td>
		</tr>
		<tr>
			<td>Spin-coater</td>
			<td>Institute of Microelectronics of the Chinese Academy of Sciences</td>
			<td>KW-4A</td>
			<td>For the prepartion of ploymer films&#160;</td>
		</tr>
		<tr>
			<td>Step profiler</td>
			<td>Veeco</td>
			<td>DEKTAK 150</td>
			<td>For the measurement of film thickness</td>
		</tr>
		<tr>
			<td>Sum frequency generation (SFG) vibrational spectroscopy system</td>
			<td>EKSPLA</td>
			<td></td>
			<td>A commercial picosecond SFG system</td>
		</tr>
	</tbody>
</table>

interfacial molecular-level structures of polymers and biomacromolecules revealed via sum frequency generation vibrational spectroscopy

As a second-order nonlinear optical spectroscopy, sum frequency generation (SFG) vibrational spectroscopy has widely been used in investigating various surfaces and interfaces. This non-invasive optical technique can provide the local molecular-level information with monolayer or submonolayer sensitivity. We here are providing experimental methodology on how to selectively detect the buried interface for both macromolecules and biomacromolecules. With this in mind, interfacial secondary structures of silk fibroin and water structures around model short-chain oligonucleotide duplex are discussed. The former shows a chain-chain overlap or spatial confinement effect and the latter shows a protection function against the Ca2+ ions resulting from the chiral spine superstructure of water.

In the Fresnel coefficient part of Protocol Section, we have shown that, theoretically, it is feasible to selectively detect only one single interface at one time. Here, experimentally, we confirmed that this methodology is basically correct, as shown in Figure 5 and Figure 6.&#160;
Figure 5 shows the buried interfacial PHEMA structure after water intrusion with a ~150 nm PHEMA hydrogel film and <strong c...

Watch this Scientific Journal Video about Interfacial Molecular-level Structures of Polymers and Biomacromolecules Revealed via Sum Frequency Generation Vibrational Spectroscopy at JoVE.com

Interfacial Molecular-level Structures of Polymers and Biomacromolecules Revealed via Sum Frequency Generation Vibrational Spectroscopy

Being comprehensively utilized, sum frequency generation (SFG) vibrational spectroscopy can help to reveal chain conformational order and secondary structural change happening at polymer and biomacromolecule interfaces.

As a second-order nonlinear optical spectroscopy, sum frequency generation (SFG) vibrational spectroscopy has widely been used in investigating various ...

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Biochemistry

Fabricating a UV-Vis and Raman Spectroscopy Immunoassay Platform

Immunoassays are used to detect proteins based on the presence of associated antibodies. Because of their extensive use in research and clinical settings, ...

Force Spectroscopy of Single Protein Molecules Using an Atomic Force Microscope

The determination of the folding process of proteins from their amino acid sequence to their native 3D structure is an important problem in biology. ...

A11-positive &#946;-amyloid Oligomer Preparation and Assessment Using Dot Blotting Analysis

A11-positive ÃƒÆ’Ã…Â½Ãƒâ€šÃ‚Â²-amyloid Oligomer Preparation and Assessment Using Dot Blotting Analysis

&#946;-amyloid (A&#946;) is a hydrophobic peptide with an intrinsic tendency to self-assemble into aggregates. Among various aggregates, A&#946; oligomer ...

Covalent Immobilization of Proteins for the Single Molecule Force Spectroscopy

In recent years, atomic force microscopy (AFM) based single molecule force spectroscopy (SMFS) extended our understanding of molecular properties and ...

Measuring Interactions of Globular and Filamentous Proteins by Nuclear Magnetic Resonance Spectroscopy (NMR) and Microscale Thermophoresis (MST)

Measuring Interactions of Globular and Filamentous Proteins by Nuclear Magnetic Resonance Spectroscopy NMR and Microscale Thermophoresis MST

Filamentous proteins such as vimentin provide organization within cells by providing a structural scaffold with sites that bind proteins containing plakin ...

A Fluorescence Fluctuation Spectroscopy Assay of Protein-Protein Interactions at Cell-Cell Contacts

A variety of biological processes involves cell-cell interactions, typically mediated by proteins that interact at the interface between neighboring ...

Looking Outwards: Isolation of Cyanobacterial Released Carbohydrate Polymers and Proteins

Cyanobacteria can actively secrete a wide range of biomolecules into the extracellular environment, such as heteropolysaccharides and proteins. The ...

Characterization at the Molecular Level using Robust Biochemical Approaches of a New Kinase Protein

Extensive whole genome sequencing has identified many Open Reading Frames (ORFs) providing many potential proteins. These proteins may have important ...

OaAEP1-Mediated Enzymatic Synthesis and Immobilization of Polymerized Protein for Single-Molecule Force Spectroscopy

Chemical and bio-conjugation techniques have been developed rapidly in recent years and allow the building of protein polymers. However, a controlled ...

Characterization of Amyloid Structures in Aging C. Elegans Using Fluorescence Lifetime Imaging

Characterization of Amyloid Structures in Aging C. Elegans Using Fluorescence Lifetime Imaging

Amyloid fibrils are associated with a number of neurodegenerative diseases such as Huntington&#39;s, Parkinson&#39;s, or Alzheimer&#39;s disease. These ...