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Ermakov YA, Asadchikov VE, Roschin BS, Volkov YO, Khomich DA, Nesterenko AM, Tikhonov AM. Comprehensive Study of the Liquid Expanded-Liquid Condensed Phase Transition in 1,2-Dimyristoyl- sn-glycero-3-phospho-l-serine Monolayers: Surface Pressure, Volta Potential, X-ray Reflectivity, and Molecular Dynamics Modeling. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:12326-12338. [PMID: 31480848 DOI: 10.1021/acs.langmuir.9b01450] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
An integrated approach is applied to reveal fine changes in the surface-normal structure of 1,2-dimyristoyl-sn-glycero-3-phospho-l-serine (DMPS) monolayers at the air-lipid-water interface occurring in a liquid expanded (LE)-liquid condensed (LC) transition. The combination of the Langmuir monolayer technique, X-ray reflectometry, and molecular dynamics (MD) modeling provides new insight into the molecular nature of electrostatic phenomena in different stages of lipid compression. A homemade setup with a laboratory X-ray source (λ = 1.54 Å) offers a nondestructive way to reveal the structural difference between the LE and LC phases of the lipid. The electron density profile in the direction normal to the interface is recovered from the X-ray reflectivity data with the use of both model-independent and model-based approaches. MD simulations of the DMPS monolayer are performed for several areas per lipid using the all-atom force field. Using the conventional theory of capillary waves, a comparison is made between the electron density profiles reconstructed from the X-ray data and those calculated directly from MD modeling, which demonstrates remarkable agreement between the experiment and simulations for all selected lipid densities. This confirms the validity of the simulations and allows an analysis of the contributions of the hydrophobic tails and hydrated polar groups to the electron density profile and to the dipole component of the electric field at the interface. According to the MD data, the dependence of the Volta potential on the area per lipid in the monolayer has a different molecular nature below and above the phase transition. In the LE state of the monolayer, the potential is determined mostly by the oriented water molecules in the polar region of the lipid. In the LE-LC transition, these molecules are displaced to the bulk, and their effect on the Volta potential becomes insignificant compared with the contribution of the hydrophobic tails. The hydrophobic tails are highly ordered in the state of the liquid crystal so that their dipole moments entirely determine the growth of the potential upon compression up to the monolayer collapse.
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Affiliation(s)
- Yu A Ermakov
- Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences , Leninsky pr., 31/4 , Moscow 119071 , Russia
| | - V E Asadchikov
- Shubnikov Institute of Crystallography , Federal Research Center Crystallography and Photonics, Russian Academy of Sciences , Leninsky pr., 59 , Moscow 119333 , Russia
| | - B S Roschin
- Shubnikov Institute of Crystallography , Federal Research Center Crystallography and Photonics, Russian Academy of Sciences , Leninsky pr., 59 , Moscow 119333 , Russia
| | - Yu O Volkov
- Shubnikov Institute of Crystallography , Federal Research Center Crystallography and Photonics, Russian Academy of Sciences , Leninsky pr., 59 , Moscow 119333 , Russia
- Institute of Solid State Physics, Russian Academy of Sciences , Academician Ossipyan str. 2 , Moscow District, Chernogolovka 142432 , Russia
| | - D A Khomich
- Lomonosov Moscow State University , Biology Faculty, Leninskie gory 1/12 , Moscow 119234 , Russia
- Engelhardt Institute of Molecular Biology , Russian Academy of Sciences , Vavilova, 32 , Moscow 119991 , Russia
| | - A M Nesterenko
- Belozersky Institute of Physico-Chemical Biology , Lomonosov Moscow State University ; Leninskie gory 1/40 , Moscow , 119991 , Russia
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry , Russian Academy of Sciences , Miklukho-Maklaya 16/10 , Moscow 117997 , Russia
| | - A M Tikhonov
- Institute of Solid State Physics, Russian Academy of Sciences , Academician Ossipyan str. 2 , Moscow District, Chernogolovka 142432 , Russia
- Kapitza Institute for Physical Problems, Russian Academy of Sciences , ul. Kosygina 2 , Moscow 119334 , Russia
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Cyriac J, Pradeep T, Kang H, Souda R, Cooks RG. Low-Energy Ionic Collisions at Molecular Solids. Chem Rev 2012; 112:5356-411. [DOI: 10.1021/cr200384k] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Jobin Cyriac
- DST Unit of
Nanoscience, Department
of Chemistry, Indian Institute of Technology Madras, Chennai 600 036, India
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United
States
| | - T. Pradeep
- DST Unit of
Nanoscience, Department
of Chemistry, Indian Institute of Technology Madras, Chennai 600 036, India
| | - H. Kang
- Department of Chemistry, Seoul National University, Gwanak-gu, Seoul 151-747,
Republic of Korea
| | - R. Souda
- International
Center for Materials
Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - R. G. Cooks
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United
States
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Morton M, Barron J, Kemper T, Sinnott S, Iordanova N. Modeling reaction pathways of low energy particle deposition on polymer surfaces via first principle calculations. J Phys Chem A 2011; 115:4976-87. [PMID: 21526747 DOI: 10.1021/jp111869t] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The chemical processes that lead to polystyrene surface modification via low energy deposition of C(2)H(+), C(2)F(+), CH(2), CH(2)(+), and H(+) radicals and ions are examined using first principles calculations. Specifically, the reaction mechanisms responsible for products identified in classical molecular dynamics with reactive empirical bond-order potentials are examined using density functional theory. In addition, these calculations consider how the presence of charges on the incident particles changes the result for the CH(2) system through the comparison of barriers, transition states, and final products for CH(2) and CH(2)(+). The structures of the reaction species and energy barriers are determined using the B3LYP hybrid functional. Finally, CCSD/6-31G(d,p) single point energy calculations are carried out to obtain optimized energy barriers. The results indicate that the large variety of reactions occurring on the polystyrene surface are a consequence of complex interactions between the substrate and the deposited particles, which can easily be identified and characterized using advanced computational methodologies, such as first principle calculations.
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Affiliation(s)
- Michelle Morton
- Department of Chemistry, Georgia Southwestern State University, Americus, Georgia 31709, United States
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Choukourov A, Biederman H, Slavinska D, Hanley L, Grinevich A, Boldyryeva H, Mackova A. Mechanistic Studies of Plasma Polymerization of Allylamine. J Phys Chem B 2005; 109:23086-95. [PMID: 16854007 DOI: 10.1021/jp0535691] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Plasma polymerization of allylamine is performed both in continuous wave and pulsed mode. Chemical derivatization is applied to determine primary and secondary amine concentration. Primary amines are efficiently formed, but secondary amines are more abundant. A polymerization mechanism is proposed to account for the difference in amine content obtained from comparison between continuous wave and pulsed mode plasma polymerization. The AFM measurements performed on ultrathin (1-10 nm) plasma polymers confirm the continuity of films and that the film growth on silicon occurs via a layer-by-layer mechanism because no islandlike structures were detected.
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Affiliation(s)
- Andrei Choukourov
- Charles University, Faculty of Mathematics and Physics, Department of Macromolecular Physics, V. Holesovickach 2, 18000 Prague, Czech Republic.
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Crot CA, Wu C, Schlossman ML, Trainor TP, Eng PJ, Hanley L. Determining the conformation of an adsorbed Br-PEG-peptide by long period X-ray standing wave fluorescence. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2005; 21:7899-906. [PMID: 16089398 PMCID: PMC2583370 DOI: 10.1021/la0505115] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Long-period X-ray standing wave fluorescence (XSW) and X-ray reflectivity techniques are employed to probe the conformation of a Br-poly(ethylene glycol) (PEG)-peptide adsorbate at the hydrated interface of a polystyrene substrate. The Br atom on this Br-PEG-peptide construct serves as a marker atom allowing determination by XSW of its position and distribution with respect to the adsorption surface with angstrom resolution. Adsorption occurs on native or ion-beam-modified polystyrene films that are spin-coated onto a Si substrate and display either nonpolar or polar surfaces, respectively. A compact, oriented monolayer of Br-PEG-peptide can be formed with the peptide end adsorbed onto the polar surface and the PEG end terminating with the Br tag extending into the aqueous phase. The 108-141 A distance of the Br atom from the polystyrene surface in this oriented monolayer is similar to the estimated approximately 150 A length of the extended Br-PEG-peptide. This Br-polystyrene distance depends on adsorption time and surface properties prior to adsorption. Incomplete multilayers form on the polar surface after sufficient adsorption time elapses. By contrast, adsorption onto the nonpolar surface is submonolayer, patchy, and highly disordered with an isotropic Br distribution. Overall, this combination of X-ray surface scattering techniques with a novel sample preparation strategy has several advantages as a real space probe of adsorbed or covalently bound biomolecules at the liquid-solid interface.
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Affiliation(s)
- Carrie A. Crot
- Department of Chemistry, University of Illinois at Chicago, Chicago, IL 60607-7061
| | - Chunping Wu
- Department of Chemistry, University of Illinois at Chicago, Chicago, IL 60607-7061
| | - Mark L. Schlossman
- Department of Chemistry, University of Illinois at Chicago, Chicago, IL 60607-7061
- Department of Physics, University of Illinois at Chicago, Chicago, IL 60607
| | - Thomas P. Trainor
- Department of Chemistry and Biochemistry, University of Alaska Fairbanks, Fairbanks, AK 99775
| | - Peter J. Eng
- Center for Advanced Radiation Sources, The University of Chicago, Chicago, IL 60603
| | - Luke Hanley
- Department of Chemistry, University of Illinois at Chicago, Chicago, IL 60607-7061
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