1
|
Zhang S, Fu N, Cui W, Peng S, Srivatsan N, Chen Z. Probing the Saltwater Immersion Effect on Buried Interfacial Structures between a Sealant and Adhesion Promoter at the Molecular Level. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024. [PMID: 39150881 DOI: 10.1021/acs.langmuir.4c01449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/18/2024]
Abstract
In this research, we used sum frequency generation vibrational spectroscopy to investigate the buried interface of a thiol-epoxy model aerospace sealant in contact with a silane-based adhesion promoter (6111) following exposures to 3% saltwater at elevated temperatures and elevated temperatures alone. The results suggest that the saltwater caused a change at the interface between the adhesion promoter and sealant, while an elevated temperature of 60 °C itself did not affect the interfacial structure noticeably. Model hydrolyzed and nonhydrolyzed silanes were also used in the study to compare with the adhesion promoter 6111 to understand the interfacial behavior of main silane components in 6111 as well as their potential role in adhesion. The amino silane in 6111 likely segregates more at the sealant/adhesion promoter interface and interacts with the sealant compared to the vinyl silane. The results imply that the saltwater immersion process led to the disordering of the adhesion promoter/sealant interface (caused by interfacial structural randomization), which could potentially have implications for adhesion.
Collapse
Affiliation(s)
- Shuqing Zhang
- Department of Macromolecular Science and Engineering, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Na Fu
- PPG Aerospace, 2890 W. Empire Ave, Burbank, California 91504, United States
| | - Weibin Cui
- PPG Aerospace, 2890 W. Empire Ave, Burbank, California 91504, United States
| | - Shane Peng
- PPG Aerospace, 2890 W. Empire Ave, Burbank, California 91504, United States
| | | | - Zhan Chen
- Department of Macromolecular Science and Engineering, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
- Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| |
Collapse
|
2
|
Navakauskas E, Niaura G, Strazdaite S. Effect of deuteration on a phosphatidylcholine lipid monolayer structure: New insights from vibrational sum-frequency generation spectroscopy. Colloids Surf B Biointerfaces 2022; 220:112866. [PMID: 36174490 DOI: 10.1016/j.colsurfb.2022.112866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 09/07/2022] [Accepted: 09/19/2022] [Indexed: 10/14/2022]
Abstract
We used vibrational sum-frequency generation (VSFG) spectroscopy to elucidate the possible effect of various levels of isotopic substitution (H/D) on the properties of the DPPC monolayer by probing DPPC/D2O interface. We found that deuteration of the choline group has a great impact on monolayer properties, while monolayers with deuterated alkyl chains do not exhibit any differences under our experimental conditions. In addition, deuteration of the choline group strongly affected the hydration of the phosphate group. We showed by probing symmetric stretching vibration of phosphate group that denser packing only slightly reduced the hydration of DPPC-d13 and DPPC-d75 monolayers. Moreover, addition of calcium ions, which generally cause a marked dehydration of the lipid monolayer, had no effect on lipid monolayers with deuterated choline group. We proposed that one way to explain this experimental finding could be deuteration induced changes in the structure of lipid's choline group, resulting in a well-hydrated but Ca2+ ion blocking structure. These results have important implications for various spectroscopic techniques, which commonly use deuteration of phospholipids to circumvent overlapping between vibrational bands.
Collapse
Affiliation(s)
- Edvinas Navakauskas
- Department of Organic Chemistry, Center for Physical Sciences and Technology (FTMC), Saulėtekis ave. 3, LT-10257 Vilnius, Lithuania
| | - Gediminas Niaura
- Department of Organic Chemistry, Center for Physical Sciences and Technology (FTMC), Saulėtekis ave. 3, LT-10257 Vilnius, Lithuania.
| | - Simona Strazdaite
- Department of Organic Chemistry, Center for Physical Sciences and Technology (FTMC), Saulėtekis ave. 3, LT-10257 Vilnius, Lithuania
| |
Collapse
|
3
|
Li Y, Feng R, Liu M, Guo Y, Zhang Z. Mechanism by Which Cholesterol Induces Sphingomyelin Conformational Changes at an Air/Water Interface. J Phys Chem B 2022; 126:5481-5489. [PMID: 35839485 DOI: 10.1021/acs.jpcb.2c03127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This work investigates the interactions in cholesterol and sphingomyelin monolayers at the molecular level by high-resolution broadband sum frequency generation vibrational spectroscopy (HR-BB-SFG-VS). The SFG spectra of natural egg sphingomyelin (ESM) as a function of cholesterol concentration are obtained at an air/water interface under different polarization combinations. The analysis of the spectra shows that cholesterol can induce sphingomyelin conformational changes at an air/water interface. The mechanism is proposed. When cholesterol is inserted into the ESM monolayer, the inherent intramolecular hydrogen bonds between the phosphate moiety and 3OH in the sphingosine backbones are destroyed. During this process, the sphingosine backbones become more ordered, while the conformation of the N-linked long acid chain remains unaltered. The OH of the cholesterol head group can bind to the -PO-2 of the ESM molecule, and the orientation of the -PO-2 in the head groups changes to be more parallel to the interface.
Collapse
Affiliation(s)
- Yiyi Li
- Beijing National Laboratory for Molecular Sciences, Laboratory of Molecular Reaction Dynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Rongjuan Feng
- Beijing National Laboratory for Molecular Sciences, Laboratory of Molecular Reaction Dynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Minghua Liu
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Colloid, Interface and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yuan Guo
- Beijing National Laboratory for Molecular Sciences, Laboratory of Molecular Reaction Dynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhen Zhang
- Beijing National Laboratory for Molecular Sciences, Laboratory of Molecular Reaction Dynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| |
Collapse
|
4
|
Wang H, Hu XH, Wang HF. Temporal and Chirp Effects of Laser Pulses on the Spectral Lineshape in Sum-Frequency Generation Vibrational Spectroscopy. J Chem Phys 2022; 156:204706. [DOI: 10.1063/5.0088506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Assignment and interpretation of the sum-frequency generation vibrational spectra (SFG-VS) depend on the ability to measure and understand the factors affecting the SFG-VS spectral lineshape accurately and reliably. In the past, the formulation of the polarization selection rules for SFG-VS and the development of the sub-wavenumber high-resolution broadband SFG-VS (HR-BB-SFG-VS) have provided solutions for many of these needs. However, despite these advantages, HR-BB-SFG-VS has not been widely adopted. The majority of SFG measurements so far still relies on the picosecond scanning SFG-VS (ps-SFG-VS) or the conventional broadband SFG-VS (BB-SFG-VS) with the spectral resolution around (mostly above) 10 cm-1, which also results in less ideal spectral lineshape in the SFG spectra due to the temporal and chirp effects of the laser pulses used in experiment. In this report, the temporal and the chirp effects of laser pulses with different profiles in the SFG experiment on the measured SFG-VS spectral lineshape are examined through spectral simulation. In addition, the experimental data of a classical model system, i.e., OTS (octadecyltrichlorosilane) monolayer on glass, obtained from the ps-SFG-VS, the BB-SFG-VS, and the HR-BB-SFG-VS measurements, are directly compared and examined. These results show that temporal and chirp effects are often significant in the conventional BB-SFG-VS, resulting lineshape distortions and peak position shifts besides spectral broadening. Such temporal and chirp effects are less significant in the ps scanning SFG-VS. For the HR-BB-SFG-VS, spectral broadening, and temporal and chirp effects are insignificant, making HR-BB-SFG-VS the choice for accurate and reliable measurement and analysis of SFG-VS spectra.
Collapse
|
5
|
Sofińska K, Lupa D, Chachaj-Brekiesz A, Czaja M, Kobierski J, Seweryn S, Skirlińska-Nosek K, Szymonski M, Wilkosz N, Wnętrzak A, Lipiec E. Revealing local molecular distribution, orientation, phase separation, and formation of domains in artificial lipid layers: Towards comprehensive characterization of biological membranes. Adv Colloid Interface Sci 2022; 301:102614. [PMID: 35190313 DOI: 10.1016/j.cis.2022.102614] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 01/28/2022] [Accepted: 02/01/2022] [Indexed: 01/01/2023]
Abstract
Lipids, together with molecules such as DNA and proteins, are one of the most relevant systems responsible for the existence of life. Selected lipids are able to assembly into various organized structures, such as lipid membranes. The unique properties of lipid membranes determine their complex functions, not only to separate biological environments, but also to participate in regulatory functions, absorption of nutrients, cell-cell communication, endocytosis, cell signaling, and many others. Despite numerous scientific efforts, still little is known about the reason underlying the variability within lipid membranes, and its biochemical significance. In this review, we discuss the structural complexity of lipid membranes, as well as the importance to simplify studied systems in order to understand phenomena occurring in natural, complex membranes. Such systems require a model interface to be analyzed. Therefore, here we focused on analytical studies of artificial systems at various interfaces. The molecular structure of lipid membranes, specifically the nanometric thickens of molecular bilayer, limits in a major extent the choice of highly sensitive methods suitable to study such structures. Therefore, we focused on methods that combine high sensitivity, and/or chemical selectivity, and/or nanometric spatial resolution, such as atomic force microscopy, nanospectroscopy (tip-enhanced Raman spectroscopy, infrared nanospectroscopy), phase modulation infrared reflection-absorption spectroscopy, sum-frequency generation spectroscopy. We summarized experimental and theoretical approaches providing information about molecular structure and composition, lipid spatial distribution (phase separation), organization (domain shape, molecular orientation) of lipid membranes, and real-time visualization of the influence of various molecules (proteins, drugs) on their integrity. An integral part of this review discusses the latest achievements in the field of lipid layer-based biosensors.
Collapse
|
6
|
Hu XH, Fu L, Hou J, Zhang YN, Zhang Z, Wang HF. N-H Chirality in Folded Peptide LK 7β Is Governed by the C α-H Chirality. J Phys Chem Lett 2020; 11:1282-1290. [PMID: 31977221 DOI: 10.1021/acs.jpclett.9b03470] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Recent chiral sum-frequency generation vibrational spectroscopy (SFG-VS) measurements revealed that two N-H stretching modes in the 3100-3500 cm-1 range in folded peptide LK7β exhibit chiral characteristics. Here, we report the first phase-resolved subwavenumber high-resolution broadband SFG-VS (HR-BB-SFG-VS) measurement of the folded peptide LK7β. The results show that this chiral N-H band consists of four, instead of two, distinctive peaks, and they are with two groups of opposite spectral phases. Moreover, the phases of these N-H peaks completely flip from the l-LK7β to the d-LK7β peptide, suggesting that the chirality of the N-H in the folded peptide LK7β is completely governed by the chirality of the Cα-H of the amino acids. This discovery provides a clue on why proteins in nature are composed of the α-amino acids rather than β- or γ-amino acids and may help us understand how life works.
Collapse
Affiliation(s)
- Xiao-Hua Hu
- Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials , Fudan University , 220 Handan Road , Shanghai 200433 , China
| | - Li Fu
- William R. Wiley Environmental Molecular Sciences Laboratory , Pacific Northwest National Laboratory , Richland , Washington 99352 , United States
| | - Jian Hou
- Beijing National Laboratory for Molecular Sciences , Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190 , China
| | - Yue-Ning Zhang
- Beijing National Laboratory for Molecular Sciences , Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190 , China
| | - Zhen Zhang
- Beijing National Laboratory for Molecular Sciences , Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190 , China
| | - Hong-Fei Wang
- Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials , Fudan University , 220 Handan Road , Shanghai 200433 , China
- School of Science , Westlake University , 18 Shilongshan Road , Hangzhou 310024 , China
| |
Collapse
|
7
|
High-resolution and high-repetition-rate vibrational sum-frequency generation spectroscopy of one- and two-component phosphatidylcholine monolayers. Anal Bioanal Chem 2019; 411:4861-4871. [DOI: 10.1007/s00216-019-01690-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2018] [Revised: 01/21/2019] [Accepted: 02/13/2019] [Indexed: 01/23/2023]
|