scholarly journals Using UV-Vis. Linear Dichroism to Study the Orientation of Molecular Probes and Biomolecules in Lipidic Membranes

2003 ◽  
Vol 17 (2-3) ◽  
pp. 377-398 ◽  
Author(s):  
M. A. R. B. Castanho ◽  
S. Lopes ◽  
M. Fernandes
Keyword(s):  
Distribution Function ◽  
Polarized Light ◽  
Linear Dichroism ◽  
Molecular Probes ◽  
Model Systems ◽  
Spectroscopic Techniques ◽  
Electronic Transition Moment ◽  
Theoretical Predictions ◽  
Linearly Polarized ◽  
Orientational Distribution

Linear dichroism methodologies are based on the different interaction of molecules with linearly polarized light depending on their orientation. Theoretical predictions are used to conclude on the orientation of selected molecules relative to their neighbours (usually an organized matrix). In the specific case of linear dichroism methodologies applied to data obtained from UV-Vis. spectroscopic techniques, the orientational distribution function of the chromophores' electronic transition moment can be calculated and converted to the molecular axis distribution function. In this paper, the orientation of molecular probes and biomolecules in model systems of biomembranes (lipidic matrixes) is explored and illustrated using common membrane probes (trans-parinaric acid, a cyanine and laurdan) and polyene antibiotics (Amphotericin B and Nystatin). The emphasis is on the technique and methodologies themselves, rather than the scientific impact of the attained distributions. The main addressed items are: (1) How to adapt a common UV-Vis. spectrophotometer and spectrofluorimeter to perform linear dicrhoism experiments?, (2) Sample preparation, and (3) Data analysis (including artefacts corrections).

Synthesis and Fabrication of Aligned Conjugated Polymer Thin Films

2012 ◽  
Vol 706-709 ◽  
pp. 1636-1641 ◽  
Author(s):  
Takashi Hirahara ◽  
Masahiro Yoshizawa-Fujita ◽  
Yuko Takeoka ◽  
Masahiro Rikukawa
Keyword(s):  
Functional Groups ◽  
Thermal Annealing ◽  
Conjugated Polymer ◽  
Polarized Light ◽  
Linear Dichroism ◽  
Side Chains ◽  
Absorption Region ◽  
Linearly Polarized ◽  
Cotton Effects ◽  
External Stimuli

Fluorene-thiophene copolymers having chiral and azobenzene substituents, PAzB4-T, were synthesized by the Pd-catalyzed Suzuki coupling method. We studied the aligning organization of the main chain of PAzB4-T with the activation of the attached functional groups by thermal annealing and photo-annealing processes. Circular dichroism (CD) measurements revealed that the thermally annealed PAzB4-T spin-coated films exhibited bisignate Cotton effects over the absorption regions of the polymer main chains and the azobenzene side chains due to the formation of chiral assemblies. After the photo-annealing process, which means linearly polarized light irradiation accompanied by thermal annealing, the PAzB4-T spin-coated films showed linear dichroism over the absorption region of the main chains, due to the alignment of azobenzene side chains against the electric field of the linearly polarized light. These results suggested that rigid conjugated polymers were successfully aligned by the alignment of functional groups with the external stimuli.

Generation of Circularly Polarized Light of Highly Oriented Poly(P-Phenylene Vinylene)

2000 ◽  
Vol 660 ◽  
Author(s):  
A. Marletta ◽  
D. Gonçalves ◽  
O. N. Oliveira ◽  
R. M. Faria ◽  
F. E. G. Guimarães
Keyword(s):  
Polarized Light ◽  
Linear Dichroism ◽  
Asymmetry Factor ◽  
Phenylene Vinylene ◽  
Lb Films ◽  
Circularly Polarized Light ◽  
Langmuir Blodgett ◽  
Efficient Energy ◽  
Absorption Experiment ◽  
Linearly Polarized

ABSTRACTLangmuir-Blodgett (LB) films of poly(p-phenylene vinylene) (PPV) were prepared using an amphiphilic precursor, where the counterion chloride was partially replaced by a long chain dodecylbenzenesulfonate ion. These LB-PPV films are highly ordered along the dipping direction as demonstrated by linear dichroism experiments using linearly polarized optical absorption and emission. The intensity ratio between emitted light parallel and perpendicular to the dipping direction was ca. 17, which is much higher than the dichroic ratio of 3.6 found in the polarized absorption experiment. These values indicate an efficient energy and/or charge transfer between low conjugated segments (disordered) and highly conjugated (ordered) ones after excitation. In addition, the LB films displayed large circular polarization with an asymmetry factor ge which varies from 0.6 to –0.2 when the sample temperature is increased from 30 to 300 K.

Specific Futures of Optical Anisotropy in Terbium Iron and Terbium Gallium Garnets

2014 ◽  
Vol 605 ◽  
pp. 553-556
Author(s):  
Natalia Tsidaeva ◽  
Viktorija Abaeva ◽  
Anatoly Turiev ◽  
Elena Enaldieva ◽  
Tengiz Butkhuzi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Energy Levels ◽  
Strong Dependence ◽  
Polarized Light ◽  
Magnetization Vector ◽  
Linear Dichroism ◽  
Linear Birefringence ◽  
Optical Channels ◽  
Linearly Polarized ◽  
Magnetic Linear Dichroism

We reported magnetooptical properties of Tb3+in single crystals of Tb3Fe5O12and Tb3Ga5O12for ion occupying sites of D2symmetry in the garnets structure. It is shown that in the employed Voigt geometry the magnetic linear birefringence and the dichroism reach values 10-4, and have a strong dependence on the wavelength and a strong anisotropy. The absorption spectra were obtained at temperatures of 30K, 100K using magnetic field up to 25 kOe applied parallel and perpendiculare to the electric vector E linearly polarized light on the7F67F0and7F67F1optical transitions region. The aim of this research was revealing of a role of contributions of exchange interaction and a crystal field in splitting of energy levels of the basic condition7F6ion Tb3+multiplet in Tb ferrite-garnet by studying of character of spectra magnetic linear dichroism (MLD) paramagnetic and ferrimagnetic crystals placed in an external magnetic field. More over, the assumption about nonreciprocity of magnetic linear birefringence (MLB) spectra and dichroism with the change of the relative orientation of the magnetization vector I and the light wave vector has been experimentally confirmed. This effect may use as a base for the design of the different transducers, for example, magnetooptical optical channels commutator.

NQR in Dipolar and Quadrupolar Glasses

1990 ◽  
Vol 45 (3-4) ◽  
pp. 313-322 ◽  
Author(s):  
R. Blinc
Keyword(s):  
Distribution Function ◽  
Order Parameter ◽  
Polarization Distribution ◽  
Quadrupole Resonance ◽  
Theoretical Predictions ◽  
Temperature Dependences ◽  
Orientational Distribution ◽  
Local Polarization ◽  
Nuclear Quadrupole ◽  
Orientational Distribution Function

Abstract It is shown that nuclear quadrupole resonance and quadrupole perturbed magnetic resonance represent a powerful technique to determine the local polarization distribution and its second moment, the Edwards-Anderson order parameter, in proton and deuteron glasses. For quadrupolar glasses the local orientational distribution function can be determined from the inhomogeneous NMR or NQR lineshape, thus allowing for a measurement of the quadrupolar Edwards-Anderson order parameter. The comparison of the temperature dependences of the thus obtained order parameters with theoretical predictions then allows for a discrimination between the different possible models of the glassy transition.

Anisotropy of the Linear Magnetic Birefridence of Europium Iron Garnet

2014 ◽  
Vol 605 ◽  
pp. 548-552
Author(s):  
Natalia Tsidaeva ◽  
Viktorija Abaeva ◽  
Anatoly Turiev ◽  
Elena Enaldieva ◽  
Tengiz Butkhuzi ◽  
...  
Keyword(s):  
Single Crystal ◽  
Polarized Light ◽  
Magnetization Vector ◽  
Linear Dichroism ◽  
Linear Birefringence ◽  
Optical Channels ◽  
Iron Garnets ◽  
Linearly Polarized ◽  
Magnetic Linear Dichroism ◽  
Iron Garnet

The results of investigation of magnetic linear birefringence (MLB) and magnetic linear dichroism (MLD) of Eu3Fe5O12(EuIG) iron garnet on7F07F6optical transitions upon variation of the directions of the magnetization vector I relative to the electric vector E linearly polarized light that propagates through single crystal iron garnets are presented. The measurements were made on Eu3Fe5O12single-crystal samples in the form of plates 100 μm thick cut in the (110) and (100) plane at the temperatures T = 82 and in a magnetic field H= 25 kOe. The absorption spectra of the linearly polarized light were studied. It is shown that MLB and dichroism in the region of the7F07F6absorption band reach values 10-3. First experimentally discovered nonreciprocity of MLB spectra and dichroism with the change of the relative orientation of the magnetization vector I and the light wave vector. This effect may use as a base for the design of the different transducers, for example, magnetooptical optical channels commutator.

Orientational Behaviour of some Novel Fluoro-Substituted Liquid Crystals as Studied by Optical Spectroscopy Methods

2011 ◽  
Vol 66 (3-4) ◽  
pp. 251-258 ◽  
Author(s):  
Anna Modlínska ◽  
Danuta Bauman ◽  
Jan Jadżyn ◽  
Roman Dąbrowski
Keyword(s):  
Liquid Crystals ◽  
Optical Spectroscopy ◽  
Orientational Order ◽  
Polarized Light ◽  
Emission Spectra ◽  
Dielectric Anisotropy ◽  
Dichroic Dye ◽  
Linearly Polarized ◽  
Orientational Distribution ◽  
Orientational Distribution Function

The long-range orientational order of eight newly synthesized fluoro-substituted liquid crystals, two with a positive dielectric anisotropy and six with a negative dielectric anisotropy, was studied by means of the optical spectroscopy methods: electronic absorption and fluorescence. The liquid crystals were doped with small amount of the fluorescent dichroic dye. The absorption and emission spectra of linearly polarized light were recorded as a function of temperature in the whole range of the mesophase. The results obtained allow to determine the order parameters〈P2 and〈P4〉as well as the orientational distribution function. An importance of the molecular structure of the liquid crystal on the orientational order was ascertained and discussed.

scholarly journals Recognition of Bio-Structural Anisotropy by Polarization Resolved Imaging

Electronics ◽  
2022 ◽  
Vol 11 (2) ◽  
pp. 255
Author(s):  
Eugenio Fazio ◽  
Sidra Batool ◽  
Mehwish Nisar ◽  
Massimo Alonzo ◽  
Fabrizio Frezza
Keyword(s):  
Simple Technique ◽  
Fibre Orientation ◽  
Polarized Light ◽  
Linear Dichroism ◽  
Structural Anisotropy ◽  
Linearly Polarized ◽  
Material Texture ◽  
Industrial Environments

In this paper, we develop a simple technique to identify material texture from far, by using polarization-resolved imaging. Such a technique can be easily implemented into industrial environments, where fast and cheap sensors are required. The technique has been applied to both isotropic references (Teflon bar) and anisotropic samples (wood). By studying the radiance of the samples illuminated by linearly polarized light, different and specific behaviours are identified for both isotropic and anisotropic samples, in terms of multipolar emission and linear dichroism, from which fibre orientation can be resolved.

Differential polarization imaging of sickled cells

1988 ◽  
Vol 46 ◽  
pp. 62-63
Author(s):  
Marcos F. Maestre
Keyword(s):  
Optical Properties ◽  
Theoretical Approach ◽  
Polarized Light ◽  
Polarization Microscopy ◽  
Spectroscopic Techniques ◽  
Polarization Imaging ◽  
Circularly Polarized Light ◽  
Circularly Polarized ◽  
Microscopic Scale ◽  
Chiral Structures

Recently we have developed a form of polarization microscopy that forms images using optical properties that have previously been limited to macroscopic samples. This has given us a new window into the distribution of structure on a microscopic scale. We have coined the name differential polarization microscopy to identify the images obtained that are due to certain polarization dependent effects. Differential polarization microscopy has its origins in various spectroscopic techniques that have been used to study longer range structures in solution as well as solids. The differential scattering of circularly polarized light has been shown to be dependent on the long range chiral order, both theoretically and experimentally. The same theoretical approach was used to show that images due to differential scattering of circularly polarized light will give images dependent on chiral structures. With large helices (greater than the wavelength of light) the pitch and radius of the helix could be measured directly from these images.

scholarly journals Quantitative linear dichroism imaging of molecular processes in living cells made simple by open software tools

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Alexey Bondar ◽  
Olga Rybakova ◽  
Josef Melcr ◽  
Jan Dohnálek ◽  
Petro Khoroshyy ◽  
...  
Keyword(s):  
Biological Systems ◽  
Linear Dichroism ◽  
Quantitative Information ◽  
Living Cells ◽  
Software Tools ◽  
Model Systems ◽  
Membrane Properties ◽  
Polarization Microscopy ◽  
Molecular Processes ◽  
Wide Range

AbstractFluorescence-detected linear dichroism microscopy allows observing various molecular processes in living cells, as well as obtaining quantitative information on orientation of fluorescent molecules associated with cellular features. Such information can provide insights into protein structure, aid in development of genetically encoded probes, and allow determinations of lipid membrane properties. However, quantitating and interpreting linear dichroism in biological systems has been laborious and unreliable. Here we present a set of open source ImageJ-based software tools that allow fast and easy linear dichroism visualization and quantitation, as well as extraction of quantitative information on molecular orientations, even in living systems. The tools were tested on model synthetic lipid vesicles and applied to a variety of biological systems, including observations of conformational changes during G-protein signaling in living cells, using fluorescent proteins. Our results show that our tools and model systems are applicable to a wide range of molecules and polarization-resolved microscopy techniques, and represent a significant step towards making polarization microscopy a mainstream tool of biological imaging.

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