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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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2
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Raman Microscopy Techniques to Study Lipid Droplet Composition in Cancer Cells. Methods Mol Biol 2022; 2413:193-209. [PMID: 35044667 PMCID: PMC9939018 DOI: 10.1007/978-1-0716-1896-7_20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Raman spectroscopy using feature selection schemes has considerable advantages over gas chromatography for the analysis of fatty acids' composition changes. Here, we introduce an educational methodology to demonstrate the potential of micro-Raman spectroscopy to determine with high accuracy the unsaturation or saturation degrees and composition changes of the fatty acids found in the lipid droplets of the LNCaP prostate cancer cells that were treated with various fatty acids. The methodology uses highly discriminatory wavenumbers among fatty acids present in the sample selected by using the Support Vector Machine algorithm.
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3
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Potcoava MC, Futia GL, Gibson EA, Schlaepfer IR. Lipid profiling using Raman and a modified support vector machine algorithm. JOURNAL OF RAMAN SPECTROSCOPY : JRS 2021; 52:1910-1922. [PMID: 35814195 PMCID: PMC9269992 DOI: 10.1002/jrs.6238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Accepted: 08/03/2021] [Indexed: 06/15/2023]
Abstract
Lipid droplets are dynamic organelles that play important cellular roles. They are composed of a phospholipid membrane and a core of triglycerides and sterol esters. Fatty acids have important roles in phospholipid membrane formation, signaling, and synthesis of triglycerides as energy storage. Better non-invasive tools for profiling and measuring cellular lipids are needed. Here we demonstrate the potential of Raman spectroscopy to determine with high accuracy the composition changes of the fatty acids and cholesterol found in the lipid droplets of prostate cancer cells treated with various fatty acids. The methodology uses a modified least squares fitting (LSF) routine that uses highly discriminatory wavenumbers between the fatty acids present in the sample using a support vector machine algorithm. Using this new LSF routine, Raman micro-spectroscopy can become a better non-invasive tool for profiling and measuring fatty acids and cholesterol for cancer biology.
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Affiliation(s)
- Mariana C. Potcoava
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, Illinois, USA
| | - Gregory L. Futia
- Department of Bioengineering, University of Colorado Denver, Aurora, Colorado, USA
| | - Emily A. Gibson
- Department of Bioengineering, University of Colorado Denver, Aurora, Colorado, USA
| | - Isabel R. Schlaepfer
- Division of Medical Oncology, School of Medicine, University of Colorado Denver, Aurora, Colorado, USA
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4
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Hasan N, Schwieger C, Tee HT, Wurm FR, Busse K, Kressler J. Crystallization of a polyphosphoester at the air-water interface. Eur Polym J 2018. [DOI: 10.1016/j.eurpolymj.2018.03.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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5
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Kotula AP, Walker ARH, Migler KB. Raman analysis of bond conformations in the rotator state and premelting of normal alkanes. SOFT MATTER 2016; 12:5002-5010. [PMID: 27174157 PMCID: PMC4973810 DOI: 10.1039/c6sm00182c] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We perform Raman spectroscopic measurements on normal alkanes (CnH2n+2) to quantify the n dependence of the conformational disorder that occurs below the melt temperature. We employ a three-state spectral analysis method originally developed for semi-crystalline polyethylene that posits crystalline, amorphous, and non-crystalline consecutive trans (NCCT) conformations to extract their respective mass fractions. For the alkanes studied that melt via a rotator phase (21 ≤n≤ 37), we find that conformational disorder can be quantified by the loss of NCCT mass fraction, which systematically decreases with increasing chain length. For those that melt directly via the crystal phase (n≥ 40), we observe NCCT conformational mass fractions that are independent of chain length but whose disordered mass fraction increases with length. These complement prior IR measurements which measure disorder via gauche conformations, but have not been able to measure the mass fraction of this disorder as a function of n. An interesting feature of the three-state analysis when applied to alkanes is that the measured fraction of disordered chain conformations in the rotator phase of (10 to 30)% greatly exceeds the mass fraction of gauche bonds (1 to 7)% as measured from IR; we reconcile this difference through DFT calculations.
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Affiliation(s)
- Anthony P Kotula
- Materials Science & Engineering Division, NIST, Gaithersburg, Maryland 20899, USA.
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6
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Zhao M, Beattie RJ, Fearon AM, O'Donnell CP, Downey G. Prediction of naturally-occurring, industrially-induced and total trans fatty acids in butter, dairy spreads and Cheddar cheese using vibrational spectroscopy and multivariate data analysis. Int Dairy J 2015. [DOI: 10.1016/j.idairyj.2015.07.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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7
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Uysal RS, Boyaci IH, Genis HE, Tamer U. Determination of butter adulteration with margarine using Raman spectroscopy. Food Chem 2013; 141:4397-403. [DOI: 10.1016/j.foodchem.2013.06.061] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Revised: 06/11/2013] [Accepted: 06/13/2013] [Indexed: 11/25/2022]
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8
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Üçüncüoğlu D, İlaslan K, Boyacı İH, Özay DS. Rapid detection of fat adulteration in bakery products using Raman and near-infrared spectroscopies. Eur Food Res Technol 2013. [DOI: 10.1007/s00217-013-2030-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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9
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Sagitova EA, Donfack P, Prokhorov KA, Nikolaeva GY, Gerasin VA, Merekalova ND, Materny A, Antipov EM, Pashinin PP. Symmetric C–C Stretching Mode Splitting versus CH2-Chain Conformation Order in Sodium Montmorillonite Modified by Cetyltrimethylammonium Bromide. J Phys Chem B 2011; 116:221-31. [PMID: 22136532 DOI: 10.1021/jp208036c] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Elena A. Sagitova
- A.M. Prokhorov General Physics Institute of Russian Academy of Sciences, Moscow, Russia
- Physics Department, Center of Functional Materials and Nanomolecular Science, Jacobs University, Bremen, Germany
| | - Patrice Donfack
- Physics Department, Center of Functional Materials and Nanomolecular Science, Jacobs University, Bremen, Germany
| | - Kirill A. Prokhorov
- A.M. Prokhorov General Physics Institute of Russian Academy of Sciences, Moscow, Russia
| | | | - Viktor A. Gerasin
- A.V. Topchiev Institute of Petrochemical Synthesis of Russian Academy of Sciences, Moscow, Russia
| | - Nadezhda D. Merekalova
- A.V. Topchiev Institute of Petrochemical Synthesis of Russian Academy of Sciences, Moscow, Russia
| | - Arnulf Materny
- Physics Department, Center of Functional Materials and Nanomolecular Science, Jacobs University, Bremen, Germany
| | - Evgeny M. Antipov
- A.V. Topchiev Institute of Petrochemical Synthesis of Russian Academy of Sciences, Moscow, Russia
| | - Pavel P. Pashinin
- A.M. Prokhorov General Physics Institute of Russian Academy of Sciences, Moscow, Russia
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10
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Ahmed S, Nikolov Z, Wunder SL. Effect of Curvature on Nanoparticle Supported Lipid Bilayers Investigated by Raman Spectroscopy. J Phys Chem B 2011; 115:13181-90. [DOI: 10.1021/jp205999p] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Selver Ahmed
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Zhorro Nikolov
- College of Engineering, Drexel University, Philadelphia, Pennsylvania 19104, United States
| | - Stephanie L. Wunder
- Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, United States
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11
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Giarola M, Rossi B, Mosconi E, Fontanella M, Marzola P, Scambi I, Sbarbati A, Mariotto G. Fast and minimally invasive determination of the unsaturation index of white fat depots by micro-Raman spectroscopy. Lipids 2011; 46:659-67. [PMID: 21574019 DOI: 10.1007/s11745-011-3567-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2010] [Accepted: 04/19/2011] [Indexed: 11/26/2022]
Abstract
In the last 20 years increasing interest has been devoted to the investigation of white adipose tissue (WAT) because hypo- or hyperfunction of WAT is involved in the pathogenesis of obesity and other pathologies. The investigation and discrimination of different characteristics in adipose tissues by means of spectroscopic techniques appears as a topic of current interest, also in view of possible medical-technological applications. The aim of this work was to establish micro-Raman spectroscopy as a tool for the characterization of mammals fat tissue. After preliminary tests aimed at defining a suitable sample preparation protocol, Raman spectra of WAT specimens excised from mice of different ages were recorded in the energy range 750-3,350 cm⁻¹. Quantitative values of the unsaturation index were obtained through the calibration with HR-NMR spectra of lipid extracts. Raman spectroscopy detected a sharp increase in the unsaturation index between 22 and 30 days of age in close correspondence with the weaning of mice (21 days). The present results show that Raman spectroscopy is an inexpensive, fast and robust technique to analyze the unsaturation index of mammals fat tissues that could be routinely used in bioptic samples.
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Affiliation(s)
- M Giarola
- Dipartimento di Informatica, Università di Verona, Verona, Italy
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12
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Sagitova EA, Donfack P, Prokhorov KA, Nikolaeva GY, Gerasin VA, Merekalova ND, Materny A, Antipov EM, Pashinin PP. Raman Spectroscopic Characterization of the Interlayer Structure of Na+-Montmorillonite Clay Modified by Ditetradecyl Dimethyl Ammonium Bromide. J Phys Chem B 2009; 113:7482-90. [PMID: 19413282 DOI: 10.1021/jp810050h] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Elena A. Sagitova
- A.M. Prokhorov General Physics Institute of RAS, A.V. Topchiev Institute of Petrochemical Synthesis of RAS, Moscow, Russia, School of Engineering and Science, Jacobs University, Bremen, Germany
| | - Patrice Donfack
- A.M. Prokhorov General Physics Institute of RAS, A.V. Topchiev Institute of Petrochemical Synthesis of RAS, Moscow, Russia, School of Engineering and Science, Jacobs University, Bremen, Germany
| | - Kirill A. Prokhorov
- A.M. Prokhorov General Physics Institute of RAS, A.V. Topchiev Institute of Petrochemical Synthesis of RAS, Moscow, Russia, School of Engineering and Science, Jacobs University, Bremen, Germany
| | - Goulnara Yu. Nikolaeva
- A.M. Prokhorov General Physics Institute of RAS, A.V. Topchiev Institute of Petrochemical Synthesis of RAS, Moscow, Russia, School of Engineering and Science, Jacobs University, Bremen, Germany
| | - Viktor A. Gerasin
- A.M. Prokhorov General Physics Institute of RAS, A.V. Topchiev Institute of Petrochemical Synthesis of RAS, Moscow, Russia, School of Engineering and Science, Jacobs University, Bremen, Germany
| | - Nadezhda D. Merekalova
- A.M. Prokhorov General Physics Institute of RAS, A.V. Topchiev Institute of Petrochemical Synthesis of RAS, Moscow, Russia, School of Engineering and Science, Jacobs University, Bremen, Germany
| | - Arnulf Materny
- A.M. Prokhorov General Physics Institute of RAS, A.V. Topchiev Institute of Petrochemical Synthesis of RAS, Moscow, Russia, School of Engineering and Science, Jacobs University, Bremen, Germany
| | - Evgeny M. Antipov
- A.M. Prokhorov General Physics Institute of RAS, A.V. Topchiev Institute of Petrochemical Synthesis of RAS, Moscow, Russia, School of Engineering and Science, Jacobs University, Bremen, Germany
| | - Pavel P. Pashinin
- A.M. Prokhorov General Physics Institute of RAS, A.V. Topchiev Institute of Petrochemical Synthesis of RAS, Moscow, Russia, School of Engineering and Science, Jacobs University, Bremen, Germany
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13
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Guerrini L, Izquierdo-Lorenzo I, Garcia-Ramos JV, Domingo C, Sanchez-Cortes S. Self-assembly of α,ω-aliphatic diamines on Ag nanoparticles as an effective localized surface plasmon nanosensor based in interparticle hot spots. Phys Chem Chem Phys 2009; 11:7363-71. [DOI: 10.1039/b904631c] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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14
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Kavitha G, Narayana C. Raman Spectroscopic Investigations of Pressure-Induced Phase Transitions in n-Hexane. J Phys Chem B 2007; 111:14130-5. [DOI: 10.1021/jp075188o] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- G. Kavitha
- Light Scattering Laboratory, Chemistry and Physics of Material Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560 064, India
| | - Chandrabhas Narayana
- Light Scattering Laboratory, Chemistry and Physics of Material Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560 064, India
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15
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Kavitha G, Narayana C. Pressure-Induced Structural Transition in n-Pentane: A Raman Study. J Phys Chem B 2007; 111:7003-8. [PMID: 17542630 DOI: 10.1021/jp068285a] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Pressure-induced Raman spectroscopy studies on n-pentane have been carried out up to 17 GPa at ambient temperature. n-Pentane undergoes a liquid-solid transition around 3.0 GPa and a solid-solid transition around 12.3 GPa. The intensity ratio of the Raman modes related to all-trans conformation (1130 cm-1 and 2850 cm-1) to that of gauche conformation (1090 cm-1 and 2922 cm-1) suggests an increase in the gauche population conformers above 12.3 GPa. This is accompanied with broadening of Raman modes above 12.3 GPa. The high-pressure phase of n-pentane above 12.3 GPa is a disordered phase where the carbon chains are kinked. The pressure-induced order-disorder phase transition is different from the behavior of higher hydrocarbon like n-heptane.
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Affiliation(s)
- G Kavitha
- Light Scattering Laboratory, Chemistry and Physics of Material Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560 064, India
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16
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Mohanambe L, Vasudevan S. Aromatic Molecules in Restricted Geometries: Pyrene Excimer Formation in an Anchored Bilayer. J Phys Chem B 2006; 110:14345-54. [PMID: 16854141 DOI: 10.1021/jp061695e] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The galleries of an anionic clay, Mg-Al Layered Double Hydroxide (Mg-Al LDH) have been functionalized by intercalating the anionic surfactant do-decyl sulfate. Within the galleries, the alkyl chains of the surfactant adopt a bilayer structure with the sulfate headgroup anchored to the inorganic sheet. Pyrene molecules have been solubilized in the anchored bilayer by partitioning from polar solvents. The presence of pyrene molecules induces conformational disorder in the alkyl chains of the bilayer and more importantly inhibits the rotational disordering motion of the sulfate headgroup. Pyrene fluorescence indicates formation of excimers whose intensity increases with concentration of solubilized pyrene indicating that they are mobile. Pyrene solubilized in the anchored bilayer exhibits unusual phenomena; on evacuation the excimer band disappear but reappears on releasing vacuum. It is shown that this behavior arises due to the loss of water of hydration of the headgroup on evacuation and as a consequence the pyrene moves into the less polar interior of the bilayer where it is immobile and can no longer diffuse and form excimers. The motion of pyrene into the interior of the bilayer creates free space near the surfactant chain termini, which manifests in the disappearance of the methyl-rocking mode of the ordered (-tt) end-chain conformer in the Raman spectra.
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Affiliation(s)
- L Mohanambe
- Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560012, India
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17
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Abstract
High-pressure Raman scattering studies at ambient temperature are performed on n-heptane. We observe a liquid-solid transition around 1.5 GPa from the changes in the Raman spectra. This has been reported in earlier works. With increasing pressure, we observe large changes in the Raman modes and the spectra show a distinct change around 7.5 GPa. This marks the solid-solid transition at 7.5 GPa observed in n-heptane for the first time. As predicted in theoretical work, we observe dampening of methyl rotation in n-heptane below 7.5 GPa. With increase in pressure above 7.5 GPa we observe a definitive conversion of gauche to trans conformation in the solid phase. Upon release of pressure we do not observe any hysteresis, which suggests that the solid-solid transition takes place with no volume change or is a second-order transition. In this paper we propose this transition to be an orientational order-disorder transition driven by the dampening of the rotation of the methyl group.
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Affiliation(s)
- G Kavitha
- Chemistry and Physics of Material Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bangalore 560 064, India
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18
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Beattie JR, Bell SEJ, Borgaard C, Fearon A, Moss BW. Prediction of adipose tissue composition using raman spectroscopy: Average properties and individual fatty acids. Lipids 2006; 41:287-94. [PMID: 16711604 DOI: 10.1007/s11745-006-5099-1] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Raman spectroscopy has been used for the first time to predict the FA composition of unextracted adipose tissue of pork, beef, lamb, and chicken. It was found that the bulk unsaturation parameters could be predicted successfully [R2 = 0.97, root mean square error of prediction (RMSEP) = 4.6% of 4 sigma], with cis unsaturation, which accounted for the majority of the unsaturation, giving similar correlations. The combined abundance of all measured PUFA (> or = 2 double bonds per chain) was also well predicted with R2 = 0.97 and RMSEP = 4.0% of 4 sigma. Trans unsaturation was not as well modeled (R2 = 0.52, RMSEP = 18% of 4 sigma); this reduced prediction ability can be attributed to the low levels of trans FA found in adipose tissue (0.035 times the cis unsaturation level). For the individual FA, the average partial least squares (PLS) regression coefficient of the 18 most abundant FA (relative abundances ranging from 0.1 to 38.6% of the total FA content) was R2 = 0.73; the average RMSEP = 11.9% of 4 sigma. Regression coefficients and prediction errors for the five most abundant FA were all better than the average value (in some cases as low as RMSEP = 4.7% of 4 sigma). Cross-correlation between the abundances of the minor FA and more abundant acids could be determined by principal component analysis methods, and the resulting groups of correlated compounds were also well-predicted using PLS. The accuracy of the prediction of individual FA was at least as good as other spectroscopic methods, and the extremely straightforward sampling method meant that very rapid analysis of samples at ambient temperature was easily achieved. This work shows that Raman profiling of hundreds of samples per day is easily achievable with an automated sampling system.
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Affiliation(s)
- J Renwick Beattie
- School of Chemistry, Queen's University, Belfast BT9 5AG, Northern Ireland
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Beattie JR, Bell SEJ, Moss BW. A critical evaluation of Raman spectroscopy for the analysis of lipids: fatty acid methyl esters. Lipids 2005; 39:407-19. [PMID: 15506235 DOI: 10.1007/s11745-004-1245-z] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The work presented here is aimed at determining the potential and limitations of Raman spectroscopy for fat analysis by carrying out a systematic investigation of C4-C24 FAME. These provide a simple, well-characterized set of compounds in which the effect of making incremental changes can be studied over a wide range of chain lengths and degrees of unsaturation. The effect of temperature on the spectra was investigated over much larger ranges than would normally be encountered in real analytical measurements. It was found that for liquid FAME the best internal standard band was the carbonyl stretching vibration v(C=O), whose position is affected by changes in sample chain length and physical state; in the samples studied here, it was found to lie between 1729 and 1748 cm(-1). Further, molar unsaturation could be correlated with the ratio of the nu(C=O) to either nu(C=C) or delta(H-C=) with R2 > 0.995. Chain length was correlated with the delta(CH2)tw/v(C=O) ratio, (where "tw" indicates twisting) but separate plots for odd- and even-numbered carbon chains were necessary to obtain R2 > 0.99 for liquid samples. Combining the odd- and even-numbered carbon chain data in a single plot reduced the correlation to R2 = 0.94-0.96, depending on the band ratios used. For molal unsaturation the band ratio that correlated linearly with unsaturation (R2 > 0.99) was nu(C=C)/delta(CH2)sc (where "sc" indicates scissoring). Other band ratios show much more complex behavior with changes in chemical and physical structure. This complex behavior results from the fact that the bands do not arise from simple vibrations of small, discrete regions of the molecules but are due to complex motions of large sections of the FAME so that making incremental changes in structure does not necessarily lead to simple incremental changes in spectra.
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Affiliation(s)
- J Renwick Beattie
- School of Chemistry, Queen's University, Belfast BT9 5AG, Northern Ireland
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20
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Beattie R, Bell SEJ, Borgaard C, Fearon AM, Moss BW. Multivariate prediction of clarified butter composition using raman spectroscopy. Lipids 2004; 39:897-906. [PMID: 15669766 DOI: 10.1007/s11745-004-1312-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Raman spectroscopy has been used to predict the abundance of the FA in clarified butterfat that was obtained from dairy cows fed a range of levels of rapeseed oil in their diet. Partial least squares regression of the Raman spectra against FA compositions obtained by GC showed good prediction for the five major (abundance >5%) FA with R2 = 0.74-0.92 and a root mean SE of prediction (RMSEP) that was 5-7% of the mean. In general, the prediction accuracy fell with decreasing abundance in the sample, but the RMSEP was <10% for all but one of the 10 FA present at levels >1.25%. The Raman method has the best prediction ability for unsaturated FA (R2 = 0.85-0.92), and in particular trans unsaturated FA (best-predicted FA was 18:1 t delta9). This enhancement was attributed to the isolation of the unsaturated modes from the saturated modes and the significantly higher spectral response of unsaturated bonds compared with saturated bonds. Raman spectra of the melted butter samples could also be used to predict bulk parameters calculated from standard analyzes, such as iodine value (R2 = 0.80) and solid fat content at low temperature (R2 = 0.87). For solid fat contents determined at higher temperatures, the prediction ability was significantly reduced (R2 = 0.42), and this decrease in performance was attributed to the smaller range of values in solid fat content at the higher temperatures. Finally, although the prediction errors for the abundances of each of the FA in a given sample are much larger with Raman than with full GC analysis, the accuracy is acceptably high for quality control applications. This, combined with the fact that Raman spectra can be obtained with no sample preparation and with 60-s data collection times, means that high-throughput, on-line Raman analysis of butter samples should be possible.
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Affiliation(s)
- Renwick Beattie
- School of Chemistry, Queen's University, Belfast BT9 5AG, Northern Ireland
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21
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Venkatatraman NV, S.Vasudevan*. Cholesterol Binding to the Alkyl Chains of an Intercalated Surfactant Bilayer. J Phys Chem B 2003. [DOI: 10.1021/jp034672y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- N. V. Venkatatraman
- Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore-566012, India
| | - S.Vasudevan*
- Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore-566012, India
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22
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Venkataraman NV, Vasudevan S. Solubilization of Phenol in an Intercalated Surfactant Bilayer. J Phys Chem B 2003. [DOI: 10.1021/jp027124d] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- N. V. Venkataraman
- Department of Inorganic and Physical Chemistry,Indian Institute of Science, Bangalore 560012, India
| | - S. Vasudevan
- Department of Inorganic and Physical Chemistry,Indian Institute of Science, Bangalore 560012, India
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Snyder RG, Tu K, Klein ML, Mendelssohn R, Strauss HL, Sun W. Acyl Chain Conformation and Packing in Dipalmitoylphosphatidylcholine Bilayers from MD Simulation and IR Spectroscopy. J Phys Chem B 2002. [DOI: 10.1021/jp012145d] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Robert G. Snyder
- Department of Chemistry, University of California, Berkeley, California 94720-1460, Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, and Department of Chemistry, Newark College of Arts and Science, Rutgers University, Newark, New Jersey 07102
| | - Kechuan Tu
- Department of Chemistry, University of California, Berkeley, California 94720-1460, Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, and Department of Chemistry, Newark College of Arts and Science, Rutgers University, Newark, New Jersey 07102
| | - Michael L. Klein
- Department of Chemistry, University of California, Berkeley, California 94720-1460, Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, and Department of Chemistry, Newark College of Arts and Science, Rutgers University, Newark, New Jersey 07102
| | - Richard Mendelssohn
- Department of Chemistry, University of California, Berkeley, California 94720-1460, Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, and Department of Chemistry, Newark College of Arts and Science, Rutgers University, Newark, New Jersey 07102
| | - Herbert L. Strauss
- Department of Chemistry, University of California, Berkeley, California 94720-1460, Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, and Department of Chemistry, Newark College of Arts and Science, Rutgers University, Newark, New Jersey 07102
| | - Wenjun Sun
- Department of Chemistry, University of California, Berkeley, California 94720-1460, Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, and Department of Chemistry, Newark College of Arts and Science, Rutgers University, Newark, New Jersey 07102
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24
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Lefevre T, Picquart M. Thermotropic aspects of multilamellar organisation of mono-unsaturated phospholipid OPPC. Chem Phys Lipids 1998. [DOI: 10.1016/s0009-3084(98)00007-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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25
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Cirák J, Horváth L. Effect of lateral chain-chain spacing on the Raman spectrum of dipalmitoyl phosphatidylcholine bilayers. Chem Phys Lipids 1988. [DOI: 10.1016/0009-3084(88)90007-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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26
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Needham D, Evans E. Structure and mechanical properties of giant lipid (DMPC) vesicle bilayers from 20 degrees C below to 10 degrees C above the liquid crystal-crystalline phase transition at 24 degrees C. Biochemistry 1988; 27:8261-9. [PMID: 3233209 DOI: 10.1021/bi00421a041] [Citation(s) in RCA: 235] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
We have used micromechanical tests to measure the thermoelastic properties of the liquid and gel phases of dimyristoylphosphatidylcholine (DMPC). We have found that the rippled P beta' phase is only formed when a vesicle is cooled to temperatures below the main acyl chain crystallization transition, Tc, under zero or very low membrane tension. We also found that the P beta' surface ripple or superlattice can be pulled flat under high membrane tension into a planar structure. For a ripple structure formed by acyl chains perpendicular to the projected plane, the projected area change that results from a flattening process is a direct measure of the molecular crystal angle. As such, the crystal angle was found to increase from about 24 degrees just below Tc to about 33 degrees below the pretransition. It was also observed that the P beta' superlattice did not form when annealed L beta' phase vesicles were heated from 5 degrees C to Tc; likewise, ripples did not form when the membrane was held under large tension during freezing from the L alpha phase. Each of these three procedures could be used to create a metastable planar structure which we have termed L*beta' since it is lamellar and plane-crystalline with acyl chains tilted to the bilayer plane. However, we show that this structure is not as condensed as the L beta' phase below 10 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- D Needham
- Department of Pathology, University of British Columbia, Vancouver, Canada
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27
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Teixeira-Dias J, de Carvalho L, da Costa A, Lampreia IM, Barbosa EF. Conformational studies by Raman spectroscopy and statistical analysis of gauche interactions in n-butylamine. ACTA ACUST UNITED AC 1986. [DOI: 10.1016/0584-8539(86)80139-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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28
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Rooney MW, Yachnin S, Kucuk O, Lis LJ, Kauffman JW. Oxygenated cholesterols synergistically immobilize acyl chains and enhance protein helical structure in human erythrocyte membranes. BIOCHIMICA ET BIOPHYSICA ACTA 1985; 820:33-9. [PMID: 4052416 DOI: 10.1016/0005-2736(85)90212-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Fourier transform infrared spectroscopy revealed that insertion of 20 alpha-hydroxycholesterol into human erythrocyte membranes (10% of total membrane sterol) immobilized the lipid acyl chains to a degree equivalent to enriching total membrane cholesterol by 50% (Rooney, M.W., Lange, Y. and Kauffman, J.W. (1984) J. Biol. Chem. 259, 8281-8285). Raman spectroscopy showed that the amount of acyl chain rotamers was not significantly altered by the presence of 20 alpha-hydroxycholesterol, indicating that acyl chain immobilization was limited to an inhibition of lateral motion. The presence of 20 alpha-hydroxycholesterol may synergistically enhance the acyl-chain-immobilizing behavior of membrane cholesterol. In addition, protein helical structure was not altered by 20 alpha-hydroxycholesterol. The insertion of 7 alpha-hydroxycholesterol into erythrocyte membranes resulted in an increase in protein helical structure which was comparable to that observed for erythrocyte membranes enriched with pure cholesterol by 50%. However, both acyl chain mobility and conformation were unchanged. These results suggest a synergistic behavior between oxysterols and cholesterol in modifying erythrocyte membrane packing.
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29
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Casal HL, Mantsch HH, Cameron DG. A vibrational spectroscopic study of the ice-melting-induced transition of 1,2-dibehenoyl-sn-glycero-3-phosphocholine. Chem Phys Lipids 1984. [DOI: 10.1016/0009-3084(84)90034-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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30
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Thomas GJ, Prescott B, Day LA. Structure similarity, difference and variability in the filamentous viruses fd, If1, IKe, Pf1 and Xf. Investigation by laser Raman spectroscopy. J Mol Biol 1983; 165:321-56. [PMID: 6405045 DOI: 10.1016/s0022-2836(83)80260-5] [Citation(s) in RCA: 116] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The filamentous bacteriophages fd, If1, IKe, Pf1, Xf and Pf3 in aqueous solutions of low, moderate and high ionic strength have been investigated as a function of temperature by laser Raman difference spectroscopy. By analogy with Raman spectra of model compounds and viruses of known structure, the data reveal the following structural features: the predominant secondary structure of the coat protein subunit in each virus is the alpha-helix, but the amount of alpha-helix differs from one virus to another, ranging from an estimated high of 100% in Pf1 to a low of approximately 50% in Xf. The molecular environment and intermolecular interactions of tyrosine, tryptophan and phenylalanine residues differ among the different viruses, as do the conformations of aliphatic amino acid side-chains. The foregoing features of coat protein structure are highly sensitive to changes in Na+ concentration, temperature or both. The backbones of A-DNA and B-DNA structures do not occur in any of the viruses, and unusual DNA structures are indicated for all six viruses. The alpha-helical protein subunits of Pf1, like those of Pf3 and Xf, can undergo reversible transitions to beta-sheet structures while retaining their association with DNA; yet fd, IKe and If1 do not undergo such transitions. Raman intensity changes with ionic strength or temperature suggest that transgauche rotations of aliphatic amino acid side-chains and stacking of aromatic side-chains are important structural variables in each virus.
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31
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Wilkinson DA, Nagle JF. Specific heats of lipid dispersions in single phase regions. BIOCHIMICA ET BIOPHYSICA ACTA 1982; 688:107-15. [PMID: 7093266 DOI: 10.1016/0005-2736(82)90584-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Differential scanning calorimetry has been used for the first time to measure the specific heat, Cp, as a function of temperature in the single phase regions above and below the main phase transition temperature, Tm, for dispersions of saturated phosphatidylcholines and phosphatidylethanolamines. Within error limits Cp, when expressed per gram, does not vary in any systematic way with chain length or headgroup. Its temperature dependence in both single phase regions qualitatively resembles that of n-alkanes. Contributions to Cp from intrachain vibrations and interchain van der Waals' interactions have been calculated and account for nearly all the measured Cp at temperatures above Tm. However, these contributions do not yield the observed temperature dependence below Tm. It is conjectured that such a temperature dependence arises from the unhindering of chain vibrations as the lipids undergo thermal expansion, and the result of a preliminary calculation which supports this conjecture is presented.
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