Name: Interfacial Molecular-level Structures of Polymers and Biomacromolecules Revealed via Sum Frequency Generation Vibrational Spectroscopy (Video) | JoVE Journal
Uploaded: 2019-08-13T13:30:00.000+00:00
Duration: 9 min 43 s
Description: Learn sum frequency generation vibrational spectroscopy to study interfacial molecular structures of polymers and biomacromolecules. This noninvasive optical technique reveals chain conformational order with submonolayer sensitivity.

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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.

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<li>Lu, X., Clarke, M. L., Li, D., Wang, X., Chen, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((A+Sum+Frequency+Generation+Vibrational+Study+of+the+Interference+Effect+in+Poly%28n-butyl+methacrylate%29+Thin+Films+Sandwiched+between+Silica+and+Water%5BTitle%5D)+AND+%22Journal+of+Physical+Chemistry+C%22%5BJournal%5D)">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>
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<li>Li, B., Lu, X., Ma, Y., Han, X., Chen, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Method+to+Probe+Glass+Transition+Temperatures+of+Polymer+Thin+Films%5BTitle%5D)+AND+%22ACS+Macro+Letters%22%5BJournal%5D)">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/pubmed?term=((Interchain+Overlap+Affects+Formation+of+Silk+Fibroin+Secondary+Structure+on+Hydrophobic+Polystyrene+Surface+Detected+via+Achiral%2FChiral+Sum+Frequency+Generation%5BTitle%5D)+AND+%22Langmuir%22%5BJournal%5D)">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/pubmed?term=((Calcium-dependent+hydrolysis+of+supported+planar+lipids+was+triggered+by+honey+bee+venom+phospholipase+A2+with+the+right+orientation+at+the+interface%5BTitle%5D)+AND+%22Physical+Chemistry+Chemical+Physics%22%5BJournal%5D)">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/pubmed?term=((Sum+Frequency+Generation+Vibrational+Spectroscopy+Studies+on+Protein+Adsorption%5BTitle%5D)+AND+%22Journal+of+Physical+Chemistry+B%22%5BJournal%5D)">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/pubmed?term=((Detection+of+Amide+I+Signals+of+Interfacial+Proteins+in+Situ+Using+SFG%5BTitle%5D)+AND+%22Journal+of+American+Chemical+Society%22%5BJournal%5D)">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/pubmed?term=((Probing+the+Spontaneous+Membrane+Insertion+of+a+Tall-Anchored+Membrane+Protein+by+Sum+Frequency+Generation+Spectroscopy%5BTitle%5D)+AND+%22Journal+of+American+Chemistry+Society%22%5BJournal%5D)">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/pubmed?term=((Calcium+Ions+Affect+Water+Molecular+Structures+Surrounding+an+Oligonucleotide+Duplex+as+Revealed+by+Sum+Frequency+Generation+Vibrational+Spectroscopy%5BTitle%5D)+AND+%22Langmuir%22%5BJournal%5D)">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/pubmed?term=((Sum-frequency+generation+spectroscopy+of+DNA+monolayers%5BTitle%5D)+AND+%22Biosensors+%26+Bioelectronics%22%5BJournal%5D)">Sum-frequency generation spectroscopy of DNA monolayers.</a> Biosensors & 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/pubmed?term=((Metal+Cation-induced+Deformation+of+DNA+Self-Assembled+Monolayers+on+Silicon%3A+Vibrational+Sum+Frequency+Generation+Spectroscopy%5BTitle%5D)+AND+%22Journal+of+American+Chemistry+Society%22%5BJournal%5D)">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/pubmed?term=((Sum-frequency-generation+spectroscopy+of+DNA+films+in+air+and+aqueous+environments%5BTitle%5D)+AND+%22Biointerphases%22%5BJournal%5D)">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/pubmed?term=((DNA+on+Stage%3A+Showcasing+Oligonucleotides+at+Surfaces+and+Interfaces+with+Second+Harmonic+and+Vibrational+Sum+Frequency+Generation%5BTitle%5D)+AND+%22Journal+of+Physical+Chemistry+Letters%22%5BJournal%5D)">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/pubmed?term=((The+thermal+reorganization+of+DNA+immobilized+at+the+silica%2Fbuffer+interface%3A+a+vibrational+sum+frequency+generation+investigation%5BTitle%5D)+AND+%22Physical+Chemistry+Chemical+Physics%22%5BJournal%5D)">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/pubmed?term=((Interference+Effects+in+Sum+Frequency+Spectra+from+Monolayers+on+Composite+Dielectric%2FMetal+Substrates%5BTitle%5D)+AND+%22Journal+of+Physical+Chemistry+B%22%5BJournal%5D)">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/pubmed?term=((Interference+effects+in+the+sum+frequency+generation+spectra+of+thin+organic+films.+I.+Theoretical+modeling+and+simulation%5BTitle%5D)+AND+%22Journal+of+Chemical+Physics%22%5BJournal%5D)">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/pubmed?term=((Interference+Effects+in+Sum+Frequency+Vibrational+Spectra+of+Thin+Polymer+Films%3A+An+Experimental+and+Modeling+Investigation%5BTitle%5D)+AND+%22Journal+of+Physical+Chemistry+B%22%5BJournal%5D)">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/pubmed?term=((Interfacial+Fresnel+Coefficients+and+Molecular+Structures+of+Model+Cell+Membranes%3A+From+a+Lipid+Monolayer+to+a+Lipid+Bilayer%5BTitle%5D)+AND+%22Journal+of+Physical+Chemistry+C%22%5BJournal%5D)">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/pubmed?term=((Interfacial+Water+at+Polyurethane-Sapphire+Interface%5BTitle%5D)+AND+%22Langmuir%22%5BJournal%5D)">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/pubmed?term=((Molecular+Structure+of+Polystyrene+at+Air%2FPolymer+and+Solid%2FPolymer+Interfaces%5BTitle%5D)+AND+%22Physical+Review+Letters%22%5BJournal%5D)">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/pubmed?term=((Biological+Macromolecules+at+Interfaces+Probed+by+Chiral+Vibrational+Sum+Frequency+Generation+Spectroscopy%5BTitle%5D)+AND+%22Chemical+Reviews%22%5BJournal%5D)">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/pubmed?term=((Sum-Frequency+Vibrational+Spectroscopy+on+Chiral+Liquids%3A+A+Novel+Technique+to+Probe+Molecular+Chirality%5BTitle%5D)+AND+%22Physical+Review+Letters%22%5BJournal%5D)">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/pubmed?term=((Materials+fabrication+from+Bombyx+mori+silk+fibroin%5BTitle%5D)+AND+%22Nature+Protocols%22%5BJournal%5D)">Materials fabrication from Bombyx mori silk fibroin.</a> Nature Protocols. 6, 1612-1631 (2011).</li>
</ol>

We have nothing to disclose.

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><tbody><tr><td>1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC)&amp;nbsp;</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>&amp;ge;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>&amp;ge;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&amp;amp;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&#039;-CGAAGGCTTCCAGCT-3&#039;</td></tr><tr><td>Single strand of oligonucleotide</td><td>Nanjing Genscript Biotechnology Co., Ltd.</td><td>H04936</td><td>&amp;nbsp;3&amp;cent;-end modified by cholesterol-triethylene glycol(Chol-TEG) (5&amp;cent;-GCTTCCGAAGGTCGA-3&amp;cent;)</td></tr><tr><td>Sodium carbonate anhydrous</td><td>Sinopharm Chemical Reagent Co., Ltd</td><td>10019260</td><td>&amp;ge;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&amp;nbsp;</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

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. 
Figure 5 shows the buried interfacial PHEMA structure after water intrusion with a ~150 nm PHEMA hydrogel film and <strong class=...

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 ...

interfacial-molecular-level-structures-polymers-biomacromolecules

Research

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Covalent attachment of probe molecules to atomic force microscopy (AFM) cantilever tips is an essential technique for the investigation of their physical properties. This allows us to determine the stretching force, desorption force and length of polymers via AFM-based single molecule force spectroscopy with high reproducibility.

Covalent Attachment of Single Molecules for AFM-based Force Spectroscopy

This protocol describes the application of atomic force microscopy and nanoscale infrared spectroscopy to evaluate the performance of photothermal nanoscale infrared spectroscopy in the characterization of three-dimensional multi-polymeric samples.

Advances in Nanoscale Infrared Spectroscopy to Explore Multiphase Polymeric Systems

A multimodal, rapid hyperspectral imaging framework was developed to obtain broadband vibrational sum-frequency generation (VSFG) images, along with brightfield, second harmonic generation (SHG) imaging modalities. Due to the infrared frequency being resonant with molecular vibrations, microscopic structural and mesoscopic morphology knowledge is revealed of symmetry-allowed samples.

Multimodal Nonlinear Hyperspectral Chemical Imaging Using Line-Scanning Vibrational Sum-Frequency Generation Microscopy

Here, we present the protocol to study the local flexibility and dynamics of biomolecules using time-resolved fluorescence anisotropy at the single-molecule level in confocal microscopy mode.

Time-Resolved Fluorescence Anisotropy from Single Molecules for Characterizing Local Flexibility in Biomolecules

This protocol provides detailed instructions and examples for sample preparation, data acquisition, and data analysis to characterize synthetic polymers with varying dispersity and end-groups using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

MALDI-ToF MS Method for the Characterization of Synthetic Polymers with Varying Dispersity and End Groups

Learn sum frequency generation vibrational spectroscopy to study interfacial molecular structures of polymers and biomacromolecules. This noninvasive optical technique reveals chain conformational order with submonolayer sensitivity.

Interfacial Molecular-level Structures of Polymers and Biomacromolecules Revealed via Sum Frequency Generation Vibrational Spectroscopy (Video) | JoVE Journal

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

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