Molecular dynamics study of structure and vibrational spectra at zwitterionoic lipid/aqueous KCl, NaCl, and CaCl2 solution interfaces

Ishiyama, Tatsuya; Shirai, Shinnosuke; Okumura, Tomoaki; Morita, Akihiro

doi:10.1063/1.5006543

Cited by 18 publications

(16 citation statements)

References 79 publications

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“…MD trajectories indicate that Ca 2þ primarily binds to the carboxylates. These results are consistent with previous literature (19,22,32,33) but are surprising in the context of the IR results. Previous FTIR results show minimal changes to the carboxylate peaks and large changes to the phosphate and ester peaks (25).…”

Section: Ca 2d Primarily Binds Carboxylatessupporting

confidence: 93%

“…Different studies produce contradictory interpretations regarding the binding site of Ca 2þ . In FTIR studies, for example, Ca 2þ binding seems to mostly impact the ester and phosphate groups (7,24,25) of PS, whereas MD indicates phosphates and carboxylates are involved (19,22,32,33), and some studies show binding modes involving the esters (19,23,30). The location of bound Ca 2þ likely depends on the concentration of Ca 2þ , which explains some of this discrepancy (19,21,23).…”

Section: Structural and Dynamic Effects Of Calcium Ionsmentioning

confidence: 99%

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Physiological Calcium Concentrations Slow Dynamics at the Lipid-Water Interface

Valentine

Cárdenas

Elber

et al. 2018

Biophysical Journal

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Phospholipids can interact strongly with ions at physiological concentrations, and these interactions can alter membrane properties. Here, we describe the effects of calcium ions on the dynamics in phospholipid membranes. We used a combination of time-resolved ultrafast two-dimensional infrared spectroscopy and molecular dynamics simulations. We found that millimolar Ca 2þ concentrations lead to slower fluctuations in the local environment at the lipid-water interface of membranes with phosphatidylserine. The effect was only observed in bilayers containing anionic phosphatidylserine; membranes composed of only zwitterionic phosphatidylcholine did not experience a slowdown. Local water dynamics were measured using the ester groups as label-free probes and were found to be up to 50% slower with 2.5 mM Ca 2þ . Molecular dynamics simulations show that Ca 2þ primarily binds to the carboxylate group of phosphatidylserines. These findings have implications for apoptotic and diseased cells in which phosphatidylserine is exposed to extracellular calcium and for the biophysical effects of divalent cations on lipid bilayers.

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Section: Ca 2d Primarily Binds Carboxylatessupporting

confidence: 93%

Section: Structural and Dynamic Effects Of Calcium Ionsmentioning

confidence: 99%

Physiological Calcium Concentrations Slow Dynamics at the Lipid-Water Interface

Valentine

Cárdenas

Elber

et al. 2018

Biophysical Journal

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“…The dependence of second harmonic signal intensity on surface potential and surface charges are well established and is attributed to the bulk χ (3) effect. [56][57][58][59][60][61] This third-order contribution was first reported at the silica/water interface using the second harmonic spectroscopy by Eisenthal et al 56 We note that the χ (3) is likely contributing to SHG signal and due to the applied electric field.…”

Section: Second Harmonic Intensity and Nonlinearsupporting

confidence: 61%

Pushing and Pulling on OH-and H3O+ with Electric Fields Across Water’s Surface

Ray

Limaye²,

Saha³

et al. 2021

Preprint

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We use second harmonic generation spectroscopy, molecular dynamics simulation, and theoretical modeling to study the response of the neat liquid water-air interface to changes in the potential of an external electrode positioned above the liquid. We observe a parabolic dependence of second harmonic intensity on applied potential, indicating that water’s net interfacial dipole responds linearly. We also observe a minimum intensity when the potential is tuned to a specific positive value. Interpreting this minimum based on the macroscopic electrostatic potential profile yields misleading physical conclusions because it neglects the internal bias exerted on molecular orientations by the excess surface concentrations of OH- or H3O+. We thus find that water’s net interfacial dipole orientation is primarily responsive to the effects of these ionic species rather than the external electric field.

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“…This is also true for the glycerol solution surface spectra. Yet, more recently, there is convincing evidence that alignment in the z direction of surface and subsurface water (and bulk, χ (3) effect) from the EDL contributes to the low frequency 3200 cm –1 band for low concentration salt solutions in general. − …”

Section: Resultsmentioning

confidence: 99%

Iron(III) Speciation Observed at Aqueous and Glycerol Surfaces: Vibrational Sum Frequency and X-ray

Husek

Biswas

et al. 2019

J. Am. Chem. Soc.

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Aqueous solutions of FeCl3 have been widely studied to shed light on a number of processes from dissolution, mineralization, biology, electrocatalysis, corrosion, to microbial biomineralization. Yet there are little to no molecular level studies of the air–liquid FeCl3 interface. Here, both aqueous and glycerol FeCl3 solution surfaces are investigated with polarized vibrational sum frequency generation (SFG) spectroscopy. We also present the first ever extreme ultraviolet reflection–absorption (XUV-RA) spectroscopy measurements of solvated ions and complexes at a solution interface, and observe with both X-ray photoelectron spectroscopy (XPS) and XUV-RA the existence of Fe(III) at the surface and in the near surface regions of glycerol FeCl3 solutions, where glycerol is used as a high vacuum compatible proxy for water. XPS showed Cl– and Fe(III) species with significant Fe(III) interfacial enrichment. In aqueous solutions, an electrical double layer (EDL) of Cl– and Fe(III) species at 0.5 m FeCl3 concentration is observed as evidenced from an enhancement of molecular ordering of water dipoles, consistent with the observed behavior at the glycerol surface. At higher concentrations in water, the EDL appears to be substantially repressed, indicative of further Fe(III) complex enrichment and dominance of a centrosymmetric Fe(III) species that is surface active. In addition, a significant vibrational red-shift of the dangling OH from the water molecules that straddle the air–water interface reveals that the second solvation shell of the surface active Fe(III) complex permeates the topmost layer of the aqueous interface.

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Molecular dynamics study of structure and vibrational spectra at zwitterionoic lipid/aqueous KCl, NaCl, and CaCl2 solution interfaces

Cited by 18 publications

References 79 publications

Physiological Calcium Concentrations Slow Dynamics at the Lipid-Water Interface

Physiological Calcium Concentrations Slow Dynamics at the Lipid-Water Interface

Pushing and Pulling on OH-and H3O+ with Electric Fields Across Water’s Surface

Iron(III) Speciation Observed at Aqueous and Glycerol Surfaces: Vibrational Sum Frequency and X-ray

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