scholarly journals Laurdan and Di-4-ANEPPDHQ probe different properties of the membrane

2016 ◽  
Author(s):  
Mariana Amaro ◽  
Francesco Reina ◽  
Martin Hof ◽  
Christian Eggeling ◽  
Erdinc Sezgin
Keyword(s):  
Cell Biology ◽  
Lipid Membrane ◽  
Chemical Properties ◽  
Emission Spectra ◽  
Spectral Shift ◽  
Membrane Lipid ◽  
Time Resolved ◽  
Lipid Packing ◽  
Physico Chemical ◽  
Polarity Sensitive

AbstractLipid packing is a crucial feature of cellular membranes. Quantitative analysis of membrane lipid packing can be achieved using polarity sensitive probes whose emission spectrum depends on the lipid packing. However, detailed insight into the exact mechanism that causes the spectral shift is essential to interpret the data correctly. Here, we analysed frequently used polarity sensitive probes, Laurdan and di-4-ANEPPDHQ, to test whether the underlying physical mechanisms of their spectral shift is the same, thus whether they report on the same physico-chemical properties of the cell membrane. Their steady-state spectra as well as time-resolved emission spectra in solvents and model membranes showed that they probe different properties of the lipid membrane. Our findings are important for the application of these dyes in cell biology.

scholarly journals Dynamic solvatochromism in solvent mixtures

2001 ◽  
Vol 73 (3) ◽  
pp. 405-409 ◽  
Author(s):  
Diana E. Wetzler ◽  
Carlos Chesta ◽  
Roberto Fernández-Prini ◽  
Pedro F. Aramendía
Keyword(s):  
Excited State ◽  
Ground State ◽  
Emission Spectroscopy ◽  
Characteristic Time ◽  
Polar Solvent ◽  
Emission Spectra ◽  
Spectral Shift ◽  
Solvent Mixtures ◽  
Time Resolved ◽  
Different Temperatures

Solvatochromism and thermochromism of 4-aminophthalimide and 4-amino-N-methylphthalimide were studied by absorption and steady-state and time-resolved emission spectroscopy in solvent mixtures of toluene­ethanol and toluene­acetonitrile at different temperatures. Emission spectra shift to the red upon addition of a polar solvent (PS) to toluene. Solvent mixtures show a much greater thermochromic shift to the blue in emission than the neat solvents. This is explained by the decrease in temperature of the exothermic association of the polar solvent to the excited state. Emission spectra are time dependent in solvent mixtures in the ns timescale. The time evolution of this emission is interpreted on the basis of the different solvation of the ground state and the emitting excited state. Stern­Volmer plots are obtained for the dependence of the spectral-shift characteristic time with [PS].

scholarly journals Fluorescence and Physico-Chemical Properties of Hydrogenated Detonation Nanodiamonds

2020 ◽  
Vol 6 (1) ◽  
pp. 7 ◽  
Author(s):  
Giannis Thalassinos ◽  
Alastair Stacey ◽  
Nikolai Dontschuk ◽  
Billy J. Murdoch ◽  
Edwin Mayes ◽  
...  
Keyword(s):  
Chemical Properties ◽  
Detonation Nanodiamonds ◽  
Fluorescence Properties ◽  
Spectroscopy Analysis ◽  
Time Resolved ◽  
Colloidal Properties ◽  
Physico Chemical ◽  
First Time ◽  
Electron Energy Loss ◽  
Surface Chemistries

Hydrogenated detonation nanodiamonds are of great interest for emerging applications in areas from biology and medicine to lubrication. Here, we compare the two main hydrogenation techniques—annealing in hydrogen and plasma-assisted hydrogenation—for the creation of detonation nanodiamonds with a hydrogen terminated surface from the same starting material. Synchrotron-based soft X-ray spectroscopy, infrared absorption spectroscopy, and electron energy loss spectroscopy were employed to quantify diamond and non-diamond carbon contents and determine the surface chemistries of all samples. Dynamic light scattering was used to study the particles’ colloidal properties in water. For the first time, steady-state and time-resolved fluorescence spectroscopy analysis at temperatures from room temperature down to 10 K was performed to investigate the particles’ fluorescence properties. Our results show that both hydrogenation techniques produce hydrogenated detonation nanodiamonds with overall similar physico-chemical and fluorescence properties.

Probing Ethanol-Induced Phospholipid Phase Transitions by the Polarity Sensitive Fluorescence Probes Prodan and Patman

2002 ◽  
Vol 216 (3) ◽  
Author(s):  
R. Hutterer ◽  
M. Hof
Keyword(s):  
Phase Transition ◽  
Emission Spectra ◽  
Fluorescence Probes ◽  
Lipid Phase ◽  
Time Resolved ◽  
Pronounced Increase ◽  
Spectral Shifts ◽  
Gel Phase ◽  
Polarity Sensitive ◽  
Specific Lipid

The emission behaviour of the two polarity sensitive probes Prodan and Patman in phospholipid vesicles was studied as a function of the concentration of ethanol. Comparing the spectral shifts in both the symmetric lipid 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) showing a phase transition from a normal to a fully interdigitated gel phase and the strongly asymmetric lipid 1-stearoyl-2-lauroyl-sn-glycero-3-phosphatidylcholine (C(18):C(12)-PC) favouring a mixed interdigitated gel phase we show that the huge red shifts of Prodan in presence of higher ethanol concentrations cannot be easily attributed to a specific lipid phase transition. Rather, probe relocation and a pronounced increase in solvent relaxation (SR) as monitored by time-resolved emission spectra (TRES) in presence of ethanol contribute to the large shifts observable in both lipid systems in case of Prodan. While Patman exhibits a red shift caused by increased SR due to the ethanol induced formation of a fully interdigitated phase in DPPC, hardly any shift occurs in C(18):C(12)-PC, which is supposed not to undergo an ethanol-induced phase transition.

scholarly journals Confinement Effect of Micro- and Mesoporous Materials on the Spectroscopy and Dynamics of a Stilbene Derivative Dye

2019 ◽  
Vol 20 (6) ◽  
pp. 1316
Author(s):  
Maria di Nunzio ◽  
Ganchimeg Perenlei ◽  
Abderrazzak Douhal
Keyword(s):  
Chemical Properties ◽  
Emission Spectra ◽  
Guest Molecules ◽  
Time Resolved ◽  
Preferential Formation ◽  
J Aggregates ◽  
Confined Media ◽  
A Charge ◽  
Electron Transfer Processes ◽  
Hybrid Complexes

Micro- and mesoporous silica-based materials are a class of porous supports that can encapsulate different guest molecules. The formation of these hybrid complexes can be associated with significant alteration of the physico-chemical properties of the guests. Here, we report on a photodynamical study of a push–pull molecule, trans-4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM), entrapped within faujasite-type zeolites (HY, NaX, and NaY) and MCM-41 in dichloromethane suspensions. The complex formation gives rise to caged monomers and H- and J-aggregates. Steady-state experiments show that the nanoconfinement provokes net blue shifts of both the absorption and emission spectra, which arise from preferential formation of H-aggregates concomitant with a distortion and/or protonation of the DCM structure. The photodynamics of the hybrid complexes are investigated by nano- to picosecond time-resolved emission experiments. The obtained fluorescence lifetimes are 65–99 ps and 350–400 ps for H- and J-aggregates, respectively, while those of monomers are 2.46–3.87 ns. Evidences for the presence of a charge-transfer (CT) process in trapped DCM molecules (monomers and/or aggregates) are observed. The obtained results are of interest in the interpretation of electron-transfer processes, twisting motions of analogues push–pull systems in confined media and understanding photocatalytic mechanisms using this type of host materials.

scholarly journals Physico-chemical properties of β-diketone phosphorus-containing dendrimers

2017 ◽  
Vol 5 (2) ◽  
pp. 128-135 ◽  
Author(s):  
Viktoriia Starova ◽  
Mykhailo Ianchuk ◽  
Olga Zaporozhets ◽  
Anne-Marie Caminade
Keyword(s):  
Surface Tension ◽  
Chemical Properties ◽  
Emission Spectra ◽  
Red Shift ◽  
Fluorescence Band ◽  
Organic Substrates ◽  
Fluorescent Indicator ◽  
Physico Chemical ◽  
Phosphorus Containing ◽  
Absorbance Band

Protolytic, absorbance and fluorescence properties of β-diketone phosphorus-containing dendrimers based on cyclotriphosphazene core were studied. Dendrimer solutions in acetone are characterized by intense absorbance band at ≈ 340 nm (ε340≈ 8.5·104L/mol·сm) and fluorescence band with maximum at 440 nm. Position of these maxima does not change in various solvents, unlike the bands of monomer β-diketone. It was found that dendrimer aggregation is accompanied by appearance of a second absorbance band ε400≈ 4.5·103L/mol·сm, by red shift of emission spectra ∆λ ≈ 10 nm and also by decrease in surface tension of acetone solution. Ability of dendrimer aggregates to solubilize organic substrates was observed with the fluorescent indicator acridine.

Decoration of specific sites on freeze-fractured membranes

1978 ◽  
Vol 36 (2) ◽  
pp. 140-141
Author(s):  
H. Gross ◽  
H. Moor
Keyword(s):  
Pure Water ◽  
Freeze Fracture ◽  
Chemical Properties ◽  
Surface Forces ◽  
Sulfate Pentahydrate ◽  
Copper Sulfate Pentahydrate ◽  
Physico Chemical ◽  
Water Of Hydration ◽  
Small Container ◽  
Binding Forces

Fracturing under ultrahigh vacuum (UHV, p ≤ 10-9 Torr) produces membrane fracture faces devoid of contamination. Such clean surfaces are a prerequisite foe studies of interactions between condensing molecules is possible and surface forces are unequally distributed, the condensate will accumulate at places with high binding forces; crystallites will arise which may be useful a probes for surface sites with specific physico-chemical properties. Specific “decoration” with crystallites can be achieved nby exposing membrane fracture faces to water vopour. A device was developed which enables the production of pure water vapour and the controlled variation of its partial pressure in an UHV freeze-fracture apparatus (Fig.1a). Under vaccum (≤ 10-3 Torr), small container filled with copper-sulfate-pentahydrate is heated with a heating coil, with the temperature controlled by means of a thermocouple. The water of hydration thereby released enters a storage vessel.

Physico-Chemical Properties of Recombinant Desulphatohirudin

1990 ◽  
Vol 63 (03) ◽  
pp. 499-504 ◽  
Author(s):  
A Electricwala ◽  
L Irons ◽  
R Wait ◽  
R J G Carr ◽  
R J Ling ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Gel Filtration ◽  
Chemical Properties ◽  
Alpha Helix ◽  
Apparent Molecular Weight ◽  
Correlation Spectroscopy ◽  
Nmr Studies ◽  
Recombinant Hirudin ◽  
Physico Chemical ◽  
Recombinant Molecule

SummaryPhysico-chemical properties of recombinant desulphatohirudin expressed in yeast (CIBA GEIGY code No. CGP 39393) were reinvestigated. As previously reported for natural hirudin, the recombinant molecule exhibited abnormal behaviour by gel filtration with an apparent molecular weight greater than that based on the primary structure. However, molecular weight estimation by SDS gel electrophoresis, FAB-mass spectrometry and Photon Correlation Spectroscopy were in agreement with the theoretical molecular weight, with little suggestion of dimer or aggregate formation. Circular dichroism studies of the recombinant molecule show similar spectra at different pH values but are markedly different from that reported by Konno et al. (13) for a natural hirudin-variant. Our CD studies indicate the presence of about 60% beta sheet and the absence of alpha helix in the secondary structure of recombinant hirudin, in agreement with the conformation determined by NMR studies (17)

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