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Dobrynina EA, Zykova VA, Surovtsev NV. In-plane and out-of-plane gigahertz sound velocities of saturated and unsaturated phospholipid bilayers from cryogenic to room temperatures. Chem Phys Lipids 2023; 256:105335. [PMID: 37579988 DOI: 10.1016/j.chemphyslip.2023.105335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 06/23/2023] [Accepted: 08/11/2023] [Indexed: 08/16/2023]
Abstract
Here, we examined the gigahertz sound velocities of hydrated multibilayers of saturated (1,2-dimyristoyl-sn-glycero-3-phosphocholine, DMPC) and unsaturated (1,2-dioleoyl-sn-glycero-3-phosphocholine, DOPC) phospholipids by Brillouin spectroscopy. Out-of-plane and in-plane (lateral) phonons were studied independently of each other. Similar strong temperature dependences of the sound velocities were found for phonons of both types. The sound velocities in the low-temperature limit were two-fold higher than that at physiological temperatures; a significant part of the changes in sound velocity occurs in the solid-like gel phase. The factors that may be involved in the peculiar behavior of sound velocity include changes in the chain conformational state, relaxation susceptibility, changes in the elastic modulus at infinite frequencies, and lateral packing of molecules.
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Affiliation(s)
- E A Dobrynina
- Institute of Automation and Electrometry, Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - V A Zykova
- Institute of Automation and Electrometry, Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - N V Surovtsev
- Institute of Automation and Electrometry, Russian Academy of Sciences, Novosibirsk 630090, Russia.
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Zaytseva YV, Zaytseva IV, Surovtsev NV. Characterization of conformational states of POPC and DPPC d62 in POPC/DPPC d62/cholesterol mixtures using Raman spectroscopy. Chem Phys Lipids 2023; 256:105337. [PMID: 37579987 DOI: 10.1016/j.chemphyslip.2023.105337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 06/27/2023] [Accepted: 08/11/2023] [Indexed: 08/16/2023]
Abstract
Conformational states of phospholipid chains in ternary mixtures of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), deuterated 1,2-dipalmitoyl-d62-sn-glycero-3-phosphocholine (DPPCd62), and cholesterol (Chol) were studied by Raman spectroscopy. Parameters of Raman peaks sensitive to conformational order have been used to determine chain order for mixtures over a wide range of compositions. A ternary diagram of fractions of phospholipid chains in conformationally ordered and disordered states has been constructed. It was found that the addition of POPC and cholesterol increases the fraction of DPPC chains in disordered conformations. The so-called liquid-ordered phase includes DPPC molecules in both ordered and disordered states in comparable proportions. It was found that POPC chains are partially ordered in mixtures with DPPC and cholesterol, in contrast to the case of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC). This maybe the underlying reason why ternary mixtures with POPC have different miscibility behavior compared to DOPC.
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Affiliation(s)
- Yu V Zaytseva
- Institute of Automation and Electrometry, Russian Academy of Sciences, Novosibirsk 630090, Russia.
| | - I V Zaytseva
- Institute of Automation and Electrometry, Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - N V Surovtsev
- Institute of Automation and Electrometry, Russian Academy of Sciences, Novosibirsk 630090, Russia
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Krzyzanowski N, Porcar L, Perez-Salas U. A Small-Angle Neutron Scattering, Calorimetry and Densitometry Study to Detect Phase Boundaries and Nanoscale Domain Structure in a Binary Lipid Mixture. MEMBRANES 2023; 13:323. [PMID: 36984710 PMCID: PMC10051979 DOI: 10.3390/membranes13030323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 03/06/2023] [Accepted: 03/07/2023] [Indexed: 06/18/2023]
Abstract
Techniques that can probe nanometer length scales, such as small-angle neutron scattering (SANS), have become increasingly popular to detect phase separation in membranes. But to extract the phase composition and domain structure from the SANS traces, complementary information is needed. Here, we present a SANS, calorimetry and densitometry study of a mixture of two saturated lipids that exhibits solidus-liquidus phase coexistence: 1,2-dipalmitoyl-d62-sn-glycero-3-phosphocholine (dDPPC, tail-deuterated DPPC) and 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC). With calorimetry, we investigated the phase diagram for this system and found that the boundary traces for both multilamellar vesicles (MLVs) as well as 50 nm unilamellar vesicles overlap. Because the solidus boundary was mostly inaccessible by calorimetry, we investigated it by both SANS and molecular volume measurements for a 1:1 dDPPC:DLPC lipid mixture. From the temperature behavior of the molecular volume for the 1:1 dDPPC:DLPC mixture, as well as the individual molecular volume of each lipid species, we inferred that the liquidus phase consists of only fluid-state lipids while the solidus phase consists of lipids that are in gel-like states. Using this solidus-liquidus phase model, the SANS data were analyzed with an unrestricted shape model analysis software: MONSA. The resulting fits show irregular domains with dendrite-like features as those previously observed on giant unilamellar vesicles (GUVs). The surface pair correlation function describes a characteristic domain size for the minority phase that decreases with temperature, a behavior found to be consistent with a concomitant decrease in membrane mismatch between the liquidus and solidus phases.
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Affiliation(s)
- Natalie Krzyzanowski
- Department of Physics, University of Illinois at Chicago, Chicago, IL 60608, USA
| | - Lionel Porcar
- Large Scale Structures Group, Institut Laue-Langevin, CEDEX 9, 38042 Grenoble, France
| | - Ursula Perez-Salas
- Department of Physics, University of Illinois at Chicago, Chicago, IL 60608, USA
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Zaytseva YV, Zaytseva IV, Surovtsev NV. Conformational state diagram of DOPC/DPPC d62/cholesterol mixtures. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:183869. [PMID: 35063400 DOI: 10.1016/j.bbamem.2022.183869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 01/09/2022] [Accepted: 01/12/2022] [Indexed: 06/14/2023]
Abstract
Raman spectra of aqueous suspensions of vesicles composed of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), deuterated 1,2-dipalmitoyl-d62-sn-glycero-3-phosphocholine (DPPCd62), and cholesterol (Chol) were studied at room temperature to determine the conformational states of the phospholipid hydrocarbon chains. Deuteration of DPPCd62 allowed us to characterize the conformational states of DOPC and DPPCd62 independently. The parameters of Raman peaks, which are sensitive to the conformational order, were studied in a wide range of compositions. It was found that the DOPC molecules are conformationally disordered for all compositions. The conformational state of the DPPCd62 molecules changes with composition. Their conformational state is influenced by cholesterol-induced partial disordering and DOPC solvation, transforming the DPPC molecules into the disordered state. The conformational state diagram from the Raman experiment was compared with outcomes from the differential scanning calorimetry (DSC) experiment. The Raman spectra also revealed that the DPPC molecules coexist in the disordered and all-trans ordered states for the DOPC/DPPCd62/Chol mixtures except for the pure liquid-disordered phase.
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Affiliation(s)
- Yu V Zaytseva
- Institute of Automation and Electrometry, Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - I V Zaytseva
- Institute of Automation and Electrometry, Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - N V Surovtsev
- Institute of Automation and Electrometry, Russian Academy of Sciences, Novosibirsk 630090, Russia.
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Zaytseva YV, Surovtsev NV. Raman scattering in protonated and deuterated 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC): Indicators of conformational and lateral orders. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2022; 267:120583. [PMID: 34782267 DOI: 10.1016/j.saa.2021.120583] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2021] [Revised: 11/01/2021] [Accepted: 11/02/2021] [Indexed: 06/13/2023]
Abstract
The use of deuterocarbons is an effective method in the Raman spectroscopy of multicomponent lipid materials and biological samples. Here, Raman spectra of hydrated multilamellar vesicles of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), its deuterated analog 1,2-dipalmitoyl-d62-sn-glycero-3-phosphocholine (DPPCd62), and DPPC-DPPCd62 mixtures were studied in a wide temperature range to specify the Raman indicators of conformational and lateral orders. The temperature dependence of the 985 cm-1 line in the deuterated phospholipid unequivocally indicates that this line corresponds to the CC stretching vibrations of deuterated hydrocarbon chains in the all-trans conformation. It was also concluded that the ratio of Raman intensities at the maximum of the peak of the symmetric CD2 stretching and at a maximum near 2168 cm-1 reflects the conformational order of the hydrocarbon chain and can be used for an evaluation of the fraction of the all-trans sequences. The frequency of the symmetric CD2 stretching peak is sensitive to the phase state (gel or fluid) but has a low sensitivity to the partial conformational disordering within the gel phase. The Raman study of DPPC-DPPCd62 mixtures reveals that the lateral order contributes to the ratio of intensities of the antisymmetric and symmetric CH2 stretching peaks as a prefactor enhancing the effect of conformational ordering.
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Affiliation(s)
- Yu V Zaytseva
- Institute of Automation and Electrometry, Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - N V Surovtsev
- Institute of Automation and Electrometry, Russian Academy of Sciences, Novosibirsk 630090, Russia.
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Ly TQ, Yang F, Baldelli S. In situ quantitative study of the phase transition in surfactant adsorption layers at the silica-water interface using total internal reflection Raman spectroscopy. Phys Chem Chem Phys 2021; 23:21701-21713. [PMID: 34581333 DOI: 10.1039/d1cp02645c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Dimethyldodecylamine N-oxide (DDAO), a unique type of surfactant, shows high surface activity with two distinct energy states at the buried hydrophilic silica/aqueous solution interface studied by total internal reflection (TIR) Raman spectroscopy combined with ratiometric and kinetic analysis. Different from other types of surfactant, i.e., ionic and nonionic, the adsorption of DDAO demonstrates a specific critical surface aggregation concentration (csac) at 0.15 mM gives a complete surface coverage of 6.6 ± 0.3 μmol m-2, much lower than the bulk critical micellization concentration (cmc) at the same conditions (csac ≈ 0.072 cmc). A phase transition of adsorbed layers from liquid crystalline as the intermediate state to the disordered liquid phase is spectroscopically and energetically analyzed. The adsorption of DDAO on silica surfaces is described quantitatively in a potential energy curve.
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Affiliation(s)
- Thong Q Ly
- Department of Chemistry, University of Houston, Houston, Texas 77204-5003, USA.
| | - Fangyuan Yang
- Department of Chemistry, University of Houston, Houston, Texas 77204-5003, USA.
| | - Steven Baldelli
- Department of Chemistry, University of Houston, Houston, Texas 77204-5003, USA.
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Tuning the phase transition temperature of hybrid Span60-L64 thermoresponsive niosomes: Insights from fluorescence and Raman spectroscopy. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.117110] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Continuous gradient temperature Raman spectroscopy of 1-stearoyl- 2-docosahexaenoyl, 1-stearoyl- 2-arachidonoyl, and 1,2-stearoyl phosphocholines. Chem Phys Lipids 2021; 239:105116. [PMID: 34271000 DOI: 10.1016/j.chemphyslip.2021.105116] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 07/08/2021] [Accepted: 07/09/2021] [Indexed: 11/23/2022]
Abstract
Mixed chain phospholipids containing a saturated fatty acid at sn1 and a polyunsaturated fatty acid in sn2 are common in the specialized biological membranes prevalent in neural, retinal and organ tissues. Particularly important are mixed lipids containing palmitic or stearic acid and arachidonic or docosahexaenoic acid. Gradient temperature Raman spectroscopy (GTRS) applies the temperature gradients utilized in differential scanning calorimetry to Raman spectroscopy, providing a straightforward technique to identify molecular rearrangements and phase transitions. Herein we utilize GTRS for 1-18:0, 2-20:4n-6 PC; 1-18:0 2-22:6n-3 PC; and 1-18:0, 2-18:0 PC from -80 to 50 °C temperatures. 20 Mb three-dimensional data arrays with 0.2 °C increments and first/second derivatives allowed detailed vibrational mode assignment and analysis. Samples were analyzed neat and with molecular hydration. Previously reported phase transitions for hydrated 18:0-20:4PC and 18:0-22:6PC and numerous spectral differences resulting from hydration and the double bond structure were clearly observed. Molecular models showed that the addition of minimal water molecules results in significant structural differences compared to the neat molecules; 18:0-22:6PC is strikingly compact with water when viewed from the hydrophilic end. This precise Raman data cannot be observed in typically utilized fully hydrated vesicle samples, however the improved GTRS will allow for more precise analysis in fully hydrated vesicles because the underlying modes in the unavoidably broadened spectra can be identified.
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Raman spectroscopy and DSC assay of the phase coexistence in binary DMPC/cholesterol multilamellar vesicles. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1863:183514. [PMID: 33232709 DOI: 10.1016/j.bbamem.2020.183514] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 11/16/2020] [Accepted: 11/18/2020] [Indexed: 01/06/2023]
Abstract
The phospholipid/cholesterol binary model systems are an example of simple models whose structure has caused controversy and genuine interest over many decades. The cornerstone underlying the description of such models is the answer to the question of whether these membranes are separated into coexisting phases or domains. Here, we apply label-free Raman spectroscopy and differential scanning calorimetry (DSC) to verify the phase coexistence in 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC)/cholesterol binary model. Raman spectra demonstrate the peculiarity at 30% molar fraction of cholesterol. Above this concentration, Raman data demonstrate similar characteristics at T = 291, 298, 303 K. At lower molar fractions, at 303 K, we found the agreement of Raman spectra with the predictions of the lever rule of cholesterol. Taken together, low cooperativity of the transition at 30 mol% and the fulfillment of the lever rule suggest the existence of nanoclusters composed of approximately 4 DMPC and 2 cholesterol molecules. At 298 K, the compliance of the lever rule was found in the range from 0 to 20 mol% of cholesterol. At 291 K, the addition of 5% cholesterol leads to the abrupt change of Raman spectra parameters and their continuous evolution with the further increase of cholesterol molar fraction. It seems that cholesterol plays a twofold role in binary mixtures; it reduces the intermolecular cooperativity and forms clusters whose size and DMPC-to-cholesterol ratio depend on cholesterol concentration and temperature.
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Zykova VA, Adichtchev SV, Surovtsev NV. Effect of the Hydrocarbon Chain Disorder in Phosphatidylcholine Bilayers on Gigahertz Sound Velocity. J Phys Chem B 2020; 124:9079-9085. [PMID: 32970434 DOI: 10.1021/acs.jpcb.0c06043] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Suspensions of multilamellar vesicles of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and hydrated and dehydrated aligned multilamellar samples of DMPC were studied by Brillouin spectroscopy in the temperature range from 90 to 333 K. The sound velocity of the longitudinal acoustic wave was evaluated from the Brillouin spectra. It was found that phase transition, hydration state, and planar or vesicular form of bilayers affect the gigahertz sound velocity. Usually, the temperature dependence of the sound velocity is weak in solid substances. Amazingly, the sound velocity of hydrated DMPC samples showed significant temperature-induced changes of up to 1.8 times, even within the solid-like gel phase. We explained this effect by temperature-induced excitations of the disordered conformational states of the hydrocarbon chains as well as anharmonic effects. In addition, the relevance of the gigahertz sound velocity to the description of subterahertz Raman features was demonstrated.
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Affiliation(s)
- V A Zykova
- Institute of Automation and Electrometry, Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - S V Adichtchev
- Institute of Automation and Electrometry, Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - N V Surovtsev
- Institute of Automation and Electrometry, Russian Academy of Sciences, Novosibirsk 630090, Russia
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