Photophysical Properties of Some Fluorescent Dyes in SDS Micellar Solutions.

Photophysical properties of fluorescent dyes such as Safranin T, Acridine Orange, Pyronin B and Pyronin Y in SDS micelles were examined by using spectroscopic techniques. Firstly, spherical micelles in deionized water were prepared with Sodium Dodecyl Sulfate (SDS) surfactants and they were transformed into their layered structures (lamellar micelles) by the aid of NaCl (sodium chloride). SEM studies confirmed the transformation of SDS micelles from the spherical structures to the lamellar structures. Secondly, absorption and fluorescence characteristics of the dyes in deionized water and the SDS micelles aqueous solutions were characterized in the presence of various NaCl concentrations at above the critical micelle concentration (CMC). Moreover, the photophysical properties of the dyes in various media were discussed by fluorescence quantum yield and fluorescence lifetime data. The micellar structures called a mimetic membrane system changed the photophysical properties of the dyes compared to those in deionized water.

Photophysical and photodynamic properties of Pyronin Y in micellar media at different temperatures.

In this study, photophysics and photodynamical properties of Pyronin Y (PyY) in different liquid media were investigated. Interactions of PyY, which is a positively charged pigment compound pertaining to the xanthene derivatives with surfactants possessing distinct charges, were determined by using the molecular absorption and fluorescence spectroscopy techniques. It was observed that band intensities of absorption and fluorescence spectra belonging to PyY increase in proportion to the water when compared to three micelle systems, cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS) and Triton X-100 (TX-100). This suggests that interactions in micelle systems are different from those in deionized water, and solvation and surface interactions modify. It is determined that the strongest interaction occurs between PyY dye and SDS, anionic surfactant, and this interaction arises from the electrostatic forces. Calculated photophysical parameters indicated that the microenvironment of PyY in SDS micelle is different to that of other systems. In temperature studies, it was reported that increasing the temperature of the samples increased non-radiative transitions. Steady-state fluorescence anisotropy values were calculated by using fluorescence intensities of PyY compound in pre-micellar, micellar and post-micellar systems. Once the PyY fluorescence probe is added to the surfactant containing solutions below the critical micelle concentrations, the measured anisotropy values were found to be low because the probe remains in the deionized water phase. When the surfactant concentration of the medium becomes closer to the critical micelle concentrations, the steady-state anisotropy value prominently increases. This is because of the restrictions on the rotational diffusion of the probe in micellar solution. It is observed that positively charged PyY shows a higher affinity to the negatively charged SDS compared with the positively charged CTAB and neutral TX-100 surfactants. This can be explained by Coulombic interactions.

Photophysics and photodynamics of Pyronin Y in n-alcohols.

The photophysical properties and photodynamics of Pyronin Y (PyY) dye compound in seven polar protic solvents (n-alcohols) were examined as a function of temperature by using UV-visible, steady-state and time-resolved fluorescence spectroscopy techniques. To understand dye-solvent interactions, photophysical parameters including Stokes' shifts, fluorescence quantum yields and fluorescence lifetimes were determined. To examine the effect of solvent polarity, the difference between the ground state dipole moment and the excited state dipole moment was determined. For this purpose, the multiple regression analysis and the Kamlet-Taft technique were used. Moreover, photodynamic parameters, rotational relaxation times and steady-state anisotropy were calculated. The result showed that the specific interactions of PyY with the solvent molecules take place through hydrogen bonding. As the hydrocarbon chain of the alcohols gets longer, photophysical parameters diminish, probably because of weaker hydrogen bonding. Furthermore, it was found out that the dipole moment of excited states (µe ) is higher than that of the ground state (µg ). In addition, Brownian motions increased with the increasing temperature that weakened the fluorescence character of PyY. It was also revealed that the rotation of PyY increased with a prolonged hydrocarbon chain of alcohol series, due to the lesser extent of hydrogen bonding.

Exploring Biological Interactions: A New Pyrazoline as a Versatile Fluorescent Probe for Energy Transfer and Cell Staining Applications.

Fluorescent dyes are used in biological systems, because they are highly sensitive and selective. In this work, we investigated the fluorescent probe properties of 2-(5-(pyridin-2-yl)-1H-pyrazol-3-yl) phenol (PYDP) in two media [sodium dodecyl sulfate (SDS) and human serum albumin (HSA)]. Energy transfer parameters, photophysical and thermodynamic parameters of probe were determined. We investigated cytotoxicity of PYDP against colorectal adenocarcinoma cell lines (HT-29), breast cancer cell lines (MCF-7) and 3T3-L1 adipocytes (3T3 L1) cells. The cell staining property of PYDP was monitored using a confocal microscope. The results showed that PYDP binds to HSA, bindings are due to electrostatic/ionic interactions, and the binding process is spontaneous. PYDP was found to exhibit negligible cytotoxicity at high concentrations, and confocal microscope images showed that PYDP stained the cytoplasm of MCF-7 cells.

Fluorescence interactions of a novel chalcone derivative with membrane model systems and human serum albumin.

A novel chalcone derivative (4-(5-(pyridin-2-yl)-4,5-dihydro-1H-pyrazol-3-yl) phenol (PDP) was synthesized, characterized and investigated for its potential as a fluorescent probe. The structure of the synthesized molecule was determined by FTIR, 1H NMR, 13C NMR and LC-MS/MS. The interactions of PDP with fluorescent dyes in aqueous SDS environment and HSA were studied by using fluorescence resonance energy transfer (FRET) technique and steady-state and time-resolved fluorescence spectroscopy techniques. In addition, the cytotoxic effects of PDP against various cell lines (MCF -7, HT -29, and 3 T3-L1) as well as their corresponding healthy cell lines were tested by MTT assay and visualization of FRET efficiency of PDP in vitro was monitored by confocal microscopy. MTT assay showed that PDP has no significant cytotoxic effect on HT -29 cancer cells and moderate cytotoxicity on MCF -7 and 3 T3-L1 cells even at a concentration of 250 µM. Combining confocal microscopes with the FRET technique showed that PDP significantly stained the cytoplasm of MCF -7 cell lines. These results suggest that PDP could be used in fluorescence microscopy for cell staining.

Safranin T- SDS- GO ternary system: A fluorescent pH sensor.

Graphene oxide (GO), one of the popular materials in recent years, has been synthesized according to the modified Hummers' method. Stable dispersions of different amounts of negatively charged GO were prepared in aqueous media. The GO/dye composites were prepared in deionized water by a simple method with the positively charged Safranin T compound (SfT), which is known to have strong fluorescence properties. By changing the GO/dye ratio, it was obtained stable composites in aqueous media. It was investigated the interaction of SfT with GO in an aqueous solution under the critical micelle concentration (CMC), at the CMC and above the CMC by adding sodium dodecyl sulfate (SDS). It was clarified the formation of GO-SfT composites by using spectroscopic techniques. In these composites, the effect of GO layers on the SfT's photophysical properties was examined by absorption and fluorescence spectroscopy techniques. The change in the quenching effect of GO was monitored both adding a stabilizing electrolyte (NaCl) to the media and changing the pH of the medium. The evaluation was on the probability of the GO-SfT-SDS ternary system being a pH sensing biological sensor material. As a result of this study, it was thought that the GO-SfT-SDS system could be functionalized as a fluorescent pH sensor by taking advantage of GO's sensitivity to pH.