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Kong L, Zhang M, Zhang Y, Zhang W, Zhou X, Zhang L, Wang X. Influence of the interfacial molecular structures of quaternary ammonium-type poly(ionic liquid) brushes on their antibacterial properties. Polym Chem 2020. [DOI: 10.1039/d0py01153c] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Alkyl chains of C4 are more active in killing bacteria than C16 due to their orderly extension toward PBS solution.
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Affiliation(s)
- Lingli Kong
- Department of Chemistry
- School of Science
- Zhejiang Sci-Tech University
- Hangzhou 310018
- China
| | - Ming Zhang
- Department of Chemistry
- School of Science
- Zhejiang Sci-Tech University
- Hangzhou 310018
- China
| | - Yan Zhang
- Department of Chemistry
- School of Science
- Zhejiang Sci-Tech University
- Hangzhou 310018
- China
| | - Wei Zhang
- Department of Chemistry
- School of Science
- Zhejiang Sci-Tech University
- Hangzhou 310018
- China
| | - Xianjing Zhou
- Department of Chemistry
- School of Science
- Zhejiang Sci-Tech University
- Hangzhou 310018
- China
| | - Li Zhang
- Department of Chemistry
- School of Science
- Zhejiang Sci-Tech University
- Hangzhou 310018
- China
| | - Xinping Wang
- Department of Chemistry
- School of Science
- Zhejiang Sci-Tech University
- Hangzhou 310018
- China
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2
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Yang P, Homan KT, Li Y, Cruz-Rodríguez O, Tesmer JJG, Chen Z. Effect of Lipid Composition on the Membrane Orientation of the G Protein-Coupled Receptor Kinase 2-Gβ1γ2 Complex. Biochemistry 2016; 55:2841-8. [PMID: 27088923 DOI: 10.1021/acs.biochem.6b00354] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Interactions between proteins and cell membranes are critical for biological processes such as transmembrane signaling, and specific components of the membrane may play roles in helping to organize or mandate particular conformations of both integral and peripheral membrane proteins. One example of a signaling enzyme whose function is dependent on membrane binding and whose activity is affected by specific lipid components is G protein-coupled receptor (GPCR) kinase 2 (GRK2). Efficient GRK2-mediated phosphorylation of activated GPCRs is dependent not only on its recruitment to the membrane by heterotrimeric Gβγ subunits but also on the presence of highly negatively charged lipids, in particular phosphatidylinositol 4',5'-bisphosphate (PIP2). We hypothesized that PIP2 may favor a distinct orientation of the GRK2-Gβγ complex on the membrane that is more optimal for function. In this study, we compared the possible orientations of the GRK2-Gβγ complex and Gβγ alone on model cell membranes prepared with various anionic phospholipids as deduced from sum frequency generation vibrational and attenuated total reflectance Fourier transform infrared spectroscopic methods. Our results indicate that PIP2 affects the membrane orientation of the GRK2-Gβ1γ2 complex but not that of complexes formed with anionic phospholipid binding deficient mutations in the GRK2 pleckstrin homology (PH) domain. Gβ1γ2 exhibits a similar orientation on the lipid bilayer regardless of its lipid composition. The PIP2-induced orientation of the GRK2-Gβ1γ2 complex is therefore most likely caused by specific interactions between PIP2 and the GRK2 PH domain. Thus, PIP2 not only helps recruit GRK2 to the membrane but also "fine tunes" the orientation of the GRK2-Gβγ complex so that it is better positioned to phosphorylate activated GPCRs.
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Affiliation(s)
- Pei Yang
- Department of Chemistry, University of Michigan , 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Kristoff T Homan
- Departments of Pharmacology and Biological Chemistry, Life Sciences Institute, University of Michigan , Ann Arbor, Michigan 48109, United States
| | - Yaoxin Li
- Department of Chemistry, University of Michigan , 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Osvaldo Cruz-Rodríguez
- Departments of Pharmacology and Biological Chemistry, Life Sciences Institute, University of Michigan , Ann Arbor, Michigan 48109, United States.,Ph.D. Program in Chemical Biology, University of Michigan , Ann Arbor, Michigan 48109, United States
| | - John J G Tesmer
- Departments of Pharmacology and Biological Chemistry, Life Sciences Institute, University of Michigan , Ann Arbor, Michigan 48109, United States
| | - Zhan Chen
- Department of Chemistry, University of Michigan , 930 North University Avenue, Ann Arbor, Michigan 48109, United States
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3
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Leng C, Buss HG, Segalman RA, Chen Z. Surface Structure and Hydration of Sequence-Specific Amphiphilic Polypeptoids for Antifouling/Fouling Release Applications. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:9306-11. [PMID: 26245923 DOI: 10.1021/acs.langmuir.5b01440] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Amphiphilic polypeptoids can be designed with specific sequences of hydrophilic and hydrophobic units, which determine their surface properties for antifouling/fouling release purposes. Although the sequence-dependent surface structures of polypeptoids have been extensively investigated, e.g., with X-ray spectroscopy, their molecular structures under the aqueous conditions relevant to marine fouling have not been studied. In this work, we applied sum frequency generation (SFG) vibrational spectroscopy to study the surface structures and hydration of a series of amphiphilic polypeptoid coatings with different sequences in air and water. SFG spectra, in agreement with X-ray spectroscopy studies, revealed that the surface coverage of the hydrophilic N-(2-methoxyethyl)glycine (Nme) units in air is affected by both the number and position of the hydrophobic N-(heptafluorobutyl)glycine (NF) units in the peptoid chain and is negatively correlated with the surface concentration of the fluorine element. Our ability to probe the SFG signals of water molecules at the peptoid surface provides new information on the hydrated film properties. From these SFG signals and the time evolution of water contact angles on the polymers, we see that the hydrated film properties are also dependent upon the peptoid sequence. This work indicates that the surface presence of the Nme groups and the ability of the polymers to order and strongly hydrogen bond with interfacial water molecules determine their antifouling properties, whereas the surface restructuring rate upon contact with water affects their fouling release behaviors.
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Affiliation(s)
- Chuan Leng
- Department of Chemistry, University of Michigan , Ann Arbor, Michigan 48109, United States
| | - Hilda G Buss
- Department of Chemical Engineering, University of California , Berkeley, California 94720, United States
| | - Rachel A Segalman
- Departments of Materials and Chemical Engineering, University of California , Santa Barbara, California 93106, United States
| | - Zhan Chen
- Department of Chemistry, University of Michigan , Ann Arbor, Michigan 48109, United States
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Yang W, Tian K, Ye S. Interaction between Potassium Phosphate Buffer Solution and Modeling Cell Membrane Investigated by Sum Frequency Generation Vibrational Spectroscopy. CHINESE J CHEM PHYS 2015. [DOI: 10.1063/1674-0068/28/cjcp1504070] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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5
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Leng C, Hung HC, Sun S, Wang D, Li Y, Jiang S, Chen Z. Probing the Surface Hydration of Nonfouling Zwitterionic and PEG Materials in Contact with Proteins. ACS APPLIED MATERIALS & INTERFACES 2015; 7:16881-8. [PMID: 26159055 DOI: 10.1021/acsami.5b05627] [Citation(s) in RCA: 183] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Zwitterionic polymers and poly(ethylene glycol) (PEG) have been reported as promising nonfouling materials, and strong surface hydration has been proposed as a significant contributor to the nonfouling mechanism. Better understanding of the similarity and difference between these two types of materials in terms of hydration and protein interaction will benefit the design of new and effective nonfouling materials. In this study, sum frequency generation (SFG) vibrational spectroscopy was applied for in situ and real-time assessment of the surface hydration of the sulfobetaine methacrylate (SBMA) and oligo(ethylene glycol) methacrylate (OEGMA) polymer brushes, denoted as pSBMA and pOEGMA, in contact with proteins. Whereas a majority of strongly hydrogen-bonded water was observed at both pSBMA and pOEGMA surfaces, upon contact with proteins, the surface hydration of pSBMA remained unaffected, but the water ordering at the pOEGMA surface was disturbed. The effects of free sulfobetaine, free PEG chains with two different molecular weights, and PEG coated gold nanoparticles on the surface hydration of proteins were investigated. The results indicated that free sulfobetaine could strengthen the protein hydration layer, but free PEG chains greatly disrupt the protein hydration layer and likely directly interact with the protein molecules. In contrast to free PEG, the PEG chains anchored on the nanoparticles behave similarly to the pOEGMA surface and could induce strong hydrogen bonding of the water molecules at the protein surfaces.
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Affiliation(s)
- Chuan Leng
- †Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Hsiang-Chieh Hung
- ‡Department of Chemical Engineering, University of Washington, Seattle, Washington 98195, United States
| | - Shuwen Sun
- †Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Dayang Wang
- §Ian Wark Research Institute, University of South Australia, Mawson Lakes, SA 5095, Australia
| | - Yuting Li
- ‡Department of Chemical Engineering, University of Washington, Seattle, Washington 98195, United States
| | - Shaoyi Jiang
- ‡Department of Chemical Engineering, University of Washington, Seattle, Washington 98195, United States
| | - Zhan Chen
- †Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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Lis D, Backus EHG, Hunger J, Parekh SH, Bonn M. Liquid flow along a solid surface reversibly alters interfacial chemistry. Science 2014; 344:1138-42. [DOI: 10.1126/science.1253793] [Citation(s) in RCA: 152] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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7
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Optical Sum Frequency Generation Spectra of Water Molecules on a Polycarbonate Film Exposed to O 2 Plasma. E-JOURNAL OF SURFACE SCIENCE AND NANOTECHNOLOGY 2014. [DOI: 10.1380/ejssnt.2014.414] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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8
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Hankett JM, Collin WR, Chen Z. Molecular Structural Changes of Plasticized PVC after UV Light Exposure. J Phys Chem B 2013; 117:16336-44. [DOI: 10.1021/jp409254y] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Jeanne M. Hankett
- Department
of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - William R. Collin
- Department
of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Zhan Chen
- Department
of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
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Yang P, Glukhova A, Tesmer JJG, Chen Z. Membrane orientation and binding determinants of G protein-coupled receptor kinase 5 as assessed by combined vibrational spectroscopic studies. PLoS One 2013; 8:e82072. [PMID: 24278472 PMCID: PMC3838385 DOI: 10.1371/journal.pone.0082072] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2013] [Accepted: 10/20/2013] [Indexed: 11/18/2022] Open
Abstract
G-protein coupled receptors (GPCRs) are integral membrane proteins involved in a wide variety of biological processes in eukaryotic cells, and are targeted by a large fraction of marketed drugs. GPCR kinases (GRKs) play important roles in feedback regulation of GPCRs, such as of β-adrenergic receptors in the heart, where GRK2 and GRK5 are the major isoforms expressed. Membrane targeting is essential for GRK function in cells. Whereas GRK2 is recruited to the membrane by heterotrimeric Gβγ subunits, the mechanism of membrane binding by GRK5 is not fully understood. It has been proposed that GRK5 is constitutively associated with membranes through elements located at its N-terminus, its C-terminus, or both. The membrane orientation of GRK5 is also a matter of speculation. In this work, we combined sum frequency generation (SFG) vibrational spectroscopy and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) to help determine the membrane orientation of GRK5 and a C-terminally truncated mutant (GRK51-531) on membrane lipid bilayers. It was found that GRK5 and GRK51-531 adopt a similar orientation on model cell membranes in the presence of PIP2 that is similar to that predicted for GRK2 in prior studies. Mutation of the N-terminal membrane binding site of GRK5 did not eliminate membrane binding, but prevented observation of this discrete orientation. The C-terminus of GRK5 does not have substantial impact on either membrane binding or orientation in this model system. Thus, the C-terminus of GRK5 may drive membrane binding in cells via interactions with other proteins at the plasma membrane or bind in an unstructured manner to negatively charged membranes.
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Affiliation(s)
- Pei Yang
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Alisa Glukhova
- Departments of Pharmacology and Biological Chemistry, Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, United States of America
- Program in Chemical Biology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - John J. G. Tesmer
- Departments of Pharmacology and Biological Chemistry, Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail: (ZC); (JJGT)
| | - Zhan Chen
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail: (ZC); (JJGT)
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Leng C, Gibney KA, Liu Y, Tew GN, Chen Z. In Situ Probing the Surface Restructuring of Antibiofouling Amphiphilic Polybetaines in Water. ACS Macro Lett 2013; 2:1011-1015. [PMID: 35581870 DOI: 10.1021/mz400503z] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Antibiofouling materials have a wide range of applications in biomedical devices and marine coatings. Due to the amphiphilic nature of proteins and organisms, amphiphilic materials have been designed to resist their unspecific adsorption. Surface restructuring behavior of amphiphilic materials in water is believed to play a key role in the antibiofouling mechanisms. In this work, the surface structures of several amphiphilic polybetaine coatings in water have been probed in situ using sum frequency generation (SFG) vibrational spectroscopy. These are novel polybetaines constructed from functionalized polynorbornenes. The polybetaines with oligo(ethylene glycol) (OEG), octyl (C8), or fluorinated (F13) side chains exhibit different surface restructuring behaviors upon contacting water due to their different surface hydrophobicity. The OEG and C8 chains were present and ordered at the water interface, while the F13 chain withdrew from water. The hydrophilic betaine group extended into the water and formed hydrogen bonds with water molecules. The surface restructuring of these materials detected using SFG can be well correlated to their antibiofouling performance, providing an understanding of their antibiofouling mechanisms.
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Affiliation(s)
- Chuan Leng
- Department
of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Katherine A. Gibney
- Department
of Polymer Science and Engineering, Conte Research Center, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Yuwei Liu
- Department
of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Gregory N. Tew
- Department
of Polymer Science and Engineering, Conte Research Center, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Zhan Chen
- Department
of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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Dewan S, Yeganeh MS, Borguet E. Experimental Correlation Between Interfacial Water Structure and Mineral Reactivity. J Phys Chem Lett 2013; 4:1977-82. [PMID: 26283137 DOI: 10.1021/jz4007417] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
We present an experimental demonstration of the effect of solvent structure on the interfacial reactivity of the silica/water interface using in situ vibrational Sum-frequency Generation (vSFG) spectroscopy. The response of the molecular arrangement of the interfacial solvent to the presence of cations is pH dependent with the highest sensitivity at neutral pH, relevant to geochemical and biological environments. The pH-dependent changes in vSFG spectra are in excellent correlation with the enhancement of quartz dissolution in salt water, which was hypothesized by Dove et al. to be due to changes of the interfacial solvent structure at the silica surface. vSFG provides mechanistic insights into silica dissolution and sheds light on the role of ions in altering interfacial solvent ordering, which has implications in fields ranging from protein-water interactions to oil recovery.
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Affiliation(s)
- Shalaka Dewan
- †Department of Chemistry, Temple University, 1901 North 13th Street, Philadelphia, Pennsylvania 19122, United States
| | - Mohsen S Yeganeh
- ‡ExxonMobil Research and Engineering Company, 1545 Route 22 East, Annandale, New Jersey 08801, United States
| | - Eric Borguet
- †Department of Chemistry, Temple University, 1901 North 13th Street, Philadelphia, Pennsylvania 19122, United States
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Leng C, Liu Y, Jenkins C, Meredith H, Wilker JJ, Chen Z. Interfacial structure of a DOPA-inspired adhesive polymer studied by sum frequency generation vibrational spectroscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:6659-64. [PMID: 23663073 DOI: 10.1021/la4008729] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Marine mussels deposit adhesive proteins containing 3,4-dihydroxyphenylalanine (DOPA) to attach themselves to different surfaces. Isolating such proteins from biological sources for adhesion purposes tends to be challenging. Recently, a simplified synthetic adhesive polymer, poly[(3,4-dihydroxystyrene)-co-styrene] (PDHSS), was developed to mimic DOPA-containing proteins. The pendant catechol group in this polymer provides cross-linking and adhesion much like mussel proteins do. In this work, sum frequency generation (SFG) vibrational spectroscopy was applied to reveal the structures of this DOPA-inspired polymer at air, water, and polymer interfaces. SFG spectroscopy results showed that when underwater, the catechol rings and the quinone rings were ordered, ready to adhere to surfaces. At the hydrophobic polystyrene interface, benzene π-π stacking is likely the adhesive force, whereas at the hydrophilic poly(allylamine) interface, primary amines may form hydrogen bonds with catechol or react with quinones for adhesion.
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Affiliation(s)
- Chuan Leng
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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Yang P, Boughton A, Homan KT, Tesmer JJG, Chen Z. Membrane orientation of Gα(i)β(1)γ(2) and Gβ(1)γ(2) determined via combined vibrational spectroscopic studies. J Am Chem Soc 2013; 135:5044-51. [PMID: 23461393 DOI: 10.1021/ja3116026] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The manner in which the heterotrimeric G protein complexes Gβ1γ2 and Gαiβ1γ2 interact with membranes is likely related to their biological function. We combined complementary measurements from sum frequency generation (SFG) vibrational and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy to determine the possible membrane orientations of Gβ1γ2 and the Gαiβ1γ2 heterotrimer more precisely than could be achieved using SFG alone. The most likely orientations of Gβ1γ2 and the Gαiβ1γ2 heterotrimer were both determined to fall within a similar narrow range of twist and tilt angles, suggesting that Gβ1γ2 may bind to Gαi without a significant change in orientation. This "basal" orientation seems to depend primarily on the geranylgeranylated C-terminus of Gγ2 along with basic residues at the N-terminus of Gαi, and suggests that activated G protein-coupled receptors (GPCRs) must reorient G protein heterotrimers at lipid bilayers to catalyze nucleotide exchange. The innovative methodologies developed in this paper can be widely applied to study the membrane orientation of other proteins in situ.
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Affiliation(s)
- Pei Yang
- Department of Chemistry, University of Michiga n, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
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Yang P, Wu FG, Chen Z. Dependence of Alamethicin Membrane Orientation on the Solution Concentration. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2013; 117:3358-3365. [PMID: 23565299 PMCID: PMC3613978 DOI: 10.1021/jp3099522] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Alamethicin has been extensively studied as an antimicrobial peptide and is widely used as a simple model for ion channel proteins. It has been shown that the antimicrobial activity of peptides is related to their membrane orientation. In this study, we determined the relationship between the solution concentration of alamethicin and its membrane orientation in lipid bilayers using sum frequency generation (SFG) vibrational spectroscopy. Our SFG results indicated that the alamethicin molecules more or less lay down on the surface of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) lipid bilayers at a low peptide concentration of 0.84 μM; the α-helix segment tilts at about 88°, and 310-helix segment tilts at about 58° versus the surface normal. However, when the peptide concentration was increased to 15.6 μM, we observed that alamethicin molecules further inserted into the lipid bilayers: the α-helical component changes its orientation to make a 37° tilt from the lipid bilayer normal, and the 310-helical component tilts at about 50° versus the surface normal. This is in agreement with the barrel-stave mode for the alamethicin-cell membrane interaction as reported previously. Additionally, we have also studied membrane orientation of alamethicin as a function of peptide concentration with SFG. Our results showed that the membrane orientation of the alamethicin α-helical component changed substantially with the increase of the alamethicin concentration, while the membrane orientation of the 310-helical component remained more or less the same.
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Affiliation(s)
| | | | - Zhan Chen
- To whom correspondence should be addressed. Fax: 734-647-4865.
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Tian K, Li H, Ye S. Methanol Perturbing Modeling Cell Membranes Investigated using Linear and Nonlinear Vibrational Spectroscopy. CHINESE J CHEM PHYS 2013. [DOI: 10.1063/1674-0068/26/01/27-34] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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16
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Koelsch P, Muglali M, Rohwerder M, Erbe A. Third-order effects in resonant sum-frequency-generation signals at electrified metal/liquid interfaces. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. B, OPTICAL PHYSICS 2013; 30:10.1364/JOSAB.30.000219. [PMID: 24235781 PMCID: PMC3825253 DOI: 10.1364/josab.30.000219] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Vibrational sum-frequency-generation (SFG) spectroscopy experiments at electrified interfaces involve incident laser radiation at frequencies in the IR and near-IR/visible regions as well as a static electric field on the surface. Here we show that mixing the three fields present on the surface can result in third-order effects in resonant SFG signals. This was achieved for closed packed self-assembled monolayers (SAMs) with molecular groups of high optical nonlinearity and surface potentials similar to those typically applied in cyclic voltammograms. Broadband SFG spectroscopy was applied to study a hydrophobic well-ordered araliphatic SAM on a Au(111) surface using a thin-layer analysis cell for spectro-electrochemical investigations in a 100 mM NaOH electrolyte solution. Resonant contributions were experimentally separated from non-resonant contributions of the Au substrate and theoretically analyzed using a fitting function including third-order terms. The resulting ratio of third-order to second-order susceptibilities was estimated to be [Formula: see text](10-10) m/V.
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Affiliation(s)
- Patrick Koelsch
- National ESCA and Surface Analysis Center for Biomedical Problems, Department of Bioengineering, University of Washington, Box 35170, Seattle, Washington 98195-1750, USA
| | - Mutlu Muglali
- Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Str. 1, 40237 Düsseldorf, Germany
| | - Michael Rohwerder
- Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Str. 1, 40237 Düsseldorf, Germany
| | - Andreas Erbe
- Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Str. 1, 40237 Düsseldorf, Germany
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Hankett JM, Liu Y, Zhang X, Zhang C, Chen Z. Molecular level studies of polymer behaviors at the water interface using sum frequency generation vibrational spectroscopy. ACTA ACUST UNITED AC 2012. [DOI: 10.1002/polb.23221] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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18
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Li H, Ye S, Wei F, Ma S, Luo Y. In situ molecular-level insights into the interfacial structure changes of membrane-associated prion protein fragment [118-135] investigated by sum frequency generation vibrational spectroscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:16979-16988. [PMID: 23116165 DOI: 10.1021/la302655p] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Protein aggregation is associated with many "protein deposition diseases". A precise molecular detail of the conformational transitions of such a membrane-associated protein structure is critical to understand the disease mechanism and develop effective treatments. One potential model peptide for studying the mechanism of protein deposition diseases is prion protein fragment [118-135] (PrP118-135), which shares homology with the C-terminal domain of the Alzheimer's β-amyloid peptide. In this study, sum frequency generation vibrational spectroscopy (SFG-VS) has been applied to characterize interactions between PrP118-135 and 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (POPG) lipid bilayer in situ. The conformation change and orientation of PrP118-135 in lipid bilayers have been determined using SFG spectra with different polarization combinations. It is found that low-concentration PrP118-135 predominantly adopts α-helical structure but with tiny β-sheet structure. With the PrP118-135 concentration increasing, the molecular number ratio of parallel β-sheet structure increases and reaches about 44% at a concentration of 0.10 mg/mL, indicating the formation of abnormally folded scrapie isoforms. The α-helical structure inserts into the lipid bilayer with a tilt angle of ~32° versus the surface normal, while the β-sheet structure lies down on the lipid bilayer with the tilt and twist angle both of 90°. The 3300 cm(-1) N-H stretching signal in psp spectra arises from α-helical structure at low PrP concentration and from the β-sheet structure at high PrP concentration. Results from this study will provide an in-depth insight into the early events in the aggregation of PrP in cell membrane.
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Affiliation(s)
- Hongchun Li
- Hefei National Laboratory for Physical Sciences at Microscale, and Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui, People's Republic of China 230026
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