Fluorescence of organic dyes incorporated in lipid membranes: Site of solubilization and the effects of viscosity and refractive index on lifetimes (original) (raw)
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Journal of Fluorescence, 1998
The fluorescence decay of several organic dye molecules intercalated in egg phosphatidylcholine lipid membrane vesicles is consistent with the existence of two or three prominent lifetime components rather than a single continuous distribution of lifetimes. The major lifetime components are identified with different sites of solubilization in the membrane. The variation of the lifetime of the membrane-bound dye was studied as a function of the sucrose concentration, which varied the viscosity and refractive index of the aqueous solution. The combined effect of viscosity and refractive index on the lifetime of the dye was used to identify the site of solubilization of the dye in the membrane. The study was useful to identify dye molecules on the surface which are exposed to the aqueous phase, for which the fluorescence lifetime increased systematically with sucrose (viscosity effect). More importantly, it was possible in a few cases to identify the dye molecules which are oriented in the membrane phase, and the fluorescence lifetime decreased systematically with sucrose (refractive index effect). Anomalo.us values of order parameters determined from the refractive index effect are explained in terms of an orientational distribution of the linear dye molecule weighted in favor of mutually orthogonal orientations.
Fluorescence decay of DPH in lipid membranes: Influence of the external refractive index
Biophysical Chemistry, 1993
The radiative decay rate of a fluorescent probe in an optically thin layer is known to depend on the orientation of the probe and on the refractive indices inside and outside the layer (W. Lukosz, Phys. Rev. B 22 (1980) 3030). Fluorescent probes in phospholipid bilayer membranes approximate such a system. The natural lifetime is expected to vary with the refractive index of the medium surrounding the bilayer. The lifetime variation with the refractive index depends on the orientation of the fluorescent probe. This can be used to retrieve the second-rank orientational order parameter, (Pz). The fluorescence decay of all-trans 1,6-diphenyl-1,3,5hexatriene in L-cY-dipalmitoyl-phosphatidylchohne large unilamellar vesicles (LUVs) was measured at a temperature well below that of the phase transition. The refractive index of the medium was varied by addition of glycerol or sucrose. The observed change of decay time with the refractive index followed the theoretical prediction. The value of the order parameter, (Pz), recovered is significantly lower than that obtained from fluorescence polarization data. Possible reasons for this disagreement are discussed.
Dyes and Pigments, 2019
Vital dyes are used both in intra-operative and diagnostic ophthalmology as liquid solutions wherein dyes selfassociate reducing their effects. Hence, an efficient dyes-delivery system is required to carry the maximum fraction of dye administered to the target site. In this study primarily two aspects of indocyanine green, patent blue V and brilliant blue G have been investigated. First, band profiles of UV-Vis absorption and emission spectra, acquired as a function of dye concentration in buffer solutions(pH = 7.4), have been analyzed to calculate the dimerization constant. Results demonstrate that their self-assembly properties have to be correlated to the molecular polarization. Second, the vital dyes have been loaded into liposomes prepared with the thin-film hydration method followed by extrusion. Encapsulation efficiency has been calculated to be 30%. Scanning electron microscopy and dynamic light scattering measurements have revealed that dye inclusion reduces the liposome diameter. Activation energy of liposome diffusion has been extracted by Arrhenius plots. Zeta potential measurements as a temperature function have been exploited to evaluate a dimensionless surface charge and prove that ratio charge(dye-loaded liposome)-to-charge(blank liposome) is always greater than unity and decreases with temperature.
Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, 2018
We have studied the effect of composition and the phase state of phospholipid membranes on the emission spectrum, anisotropy and lifetime of a lipophilic fluorescence probe nile red. Fluorescence spectrum of nile red in membranes containing cholesterol has also been investigated in order to get insights into the influence of cholesterol on the phospholipid membranes. Maximum emission wavelength (λ) of nile red in the fluid phase of saturated and unsaturated phospholipids was found to differ by ~10nm. The λwas also found to be independent of chain length and charge of the membrane. However, the λis strongly dependent on the temperature in the gel phase. The λand rotational diffusion rate decrease, whereas the anisotropy and lifetime increase markedly with increasing cholesterol concentration for saturated phosoholipids, such as, dimyristoyl phosphatidylcholine (DMPC) in the liquid ordered phase. However, these spectroscopic properties do not alter significantly in case of unsaturated...
Orientational distribution of linear dye molecules in bilayer membranes
The fluorescence decay of the linear dye probe DODCI in bilayer membranes is faster in the presence of sucrose in aqueous solution. This is a consequence of the effect of refractive index on the radiative rate of the oriented molecules inside the bilayer. The second-rank order parameter 〈P2(cos θ)〉, determined by the lifetime method, is consistently less than that determined by the anisotropy method. This discrepancy is satisfactorily explained by a bimodal orientational distribution whereas an unimodal distribution is not adequate.
2014
Indian Chemical Society, 92, Acharya Prafulla Chandra Road, Kolkata-700 009, India <em>E-mail</em> : drrahulchem@rediffmail.com Department of Chemistry, West Bengal State University (Barasat), Kolkata-700 126, India <em>E-mail </em>: ranjan.das68@gmail.com <em>Manuscript received online 07 December 2012, revised 09 January 2013, accepted 11 March 2013</em> <strong>The photophysics of a dye, <em>N</em>-[[4'-<em>N,N</em>-diethylamino-3-hydroxy-6-flavonyl]methyl]-<em>N</em>-methyl-<em>N</em>-(3-sulfopropyl)- 1-dodecanaminium, inner salt (F2N12S), in the large unilamellar vesicles of neutral egg yolk phosphatidylcholine (EYPC) and negatively charged egg yolk phosphatidylglycerol (EYPG) lipids were investigated by steady state and time-resolved fluorescence spectroscopy. The fluorescence spectra display a dramatic variation of the relative intensity of dual emission bands attributed to the norma...
European Biophysics Journal, 1988
Phosphoinositide metabolism in the plasma membrane is linked to transmembrane signal transduction. In this study we have investigated some physical properties (e.g. molecular order and dynamics) of phosphatidylinositol (PI) in various membrane preparations by time-resolved fluorescence techniques, using a synthetic PI derivate with a cis-parinaroyl chain on the sn-2 position. Phospholipid vesicles, normal and denervated rat skeletal muscle sarcolemmal membranes, and acetylcholine receptor rich membranes from Torpedo marmorata were investigated both at 4 °C and 20 °C. For comparison we have also included 2-parinaroyl-phosphatidylcholine (PC) in this study. The fluorescent lipids were incorporated into the membrane preparations by way of specific phospholipid transfer proteins, to ensure an efficient and non-perturbing insertion of the lipid-probes. In the Torpedo membranes the order parameters measured for the parinaroyl derivatives of both PC and PI were higher than in phospholipid vesicles. For the Torpedo membrane preparations the acyl chain order for the PI was lower than that for PC, whereas the opposite was true for the vesicles. This inversion strongly suggests that PI has different interactions with certain membrane components as compared to PC. This is also suggested by the significantly higher rate of restricted rotation of PI as compared to PC. In contrast to the order parameters, the correlation times were almost identical for both probes and showed little difference between vesicles and the Torpedo membranes. In * To whom offprint requests should be sent Iir parallel fluorescence intensity component: I± perpendicular fluorescence intensity component; SET-buffer, 0.25 M Sucrose, I mM EDTA, 10mM Tris-HC1, pH 7.4
Cell Biochemistry and Biophysics, 2013
Two novel precursors of fluorescent dyes (PFD813 and PFD814) have been studied for their ability to photo-activation, transfer across the biomembrane and cells staining. The fluorescent dyes Rho813 and Rho814 formed by photo-activation of their precursors PFD813 and PFD814 inside cells were used for the optical detection of particular features in vitro (HaCat cells, human epithelial carcinoma A431, epidermoid carcinoma of the cervix HeLa and chinese hamster ovary CHO cells). One of the possibilities to visualize and track the pathways of macromolecules or organelles in a "living" cell is to monitor them after staining with these PFDs during the real time measurements. A bright fluorescent signal from the photoactivated dye molecules inside the small spot in the cell can be monitored during their movement into the cell dark region (where the dye was not activated and did not fluoresce). The obtained data are important for further application of these precursors of the fluorescent dyes ("caged" dyes) for microscopic probing of biological objects.
Intracellular dye heterogeneity determined by fluorescence lifetimes
Biochimica et Biophysica Acta (BBA) - Biomembranes, 1984
The cellular localization of a fluorescent probe molecule depends on both the chemical structure of the dye and the cellular environment. To study the number and types of environments in an epithelial cell line, we have measured in Madin-Darby canine kidney (MDCK) cells the fluorescence lifetimes of three structurally distinct fluorescent dyesrhodamine-B, 3,3'-dihexadecylindocarbocyanine-(C_3) (diD, and Collareinincorporated into these cells. The latter is a rhodamine-cardiolipin conjugate that we designed and synthesized for the property of exclusive localization in the plasma membrane. The former two dyes required at least two exponential components to fit their fluorescence decay curves, while the decay of Collarein was characterized by a single exponential. These data are consistent with fluorescence microscopic observations, in which dil and rhodamine-B exhibit heterogeneous spatial distributions, while Collarein appears to be located on the cell surface.