Principal Component Analysis of the Absorption Spectra of the Dye Thiacyanine in the Presence of the Surfactant AOT: Precise Identification of the Dye–Surfactant Aggregates

Mandal, Anil K.; Pal, Manisha

doi:10.1006/jcis.1997.4959

Cited by 28 publications

(14 citation statements)

References 27 publications

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“…As prevalently observed for pyrene derivatives, for example, ground-state aggregation could be a plausible source of the observed metachromasy. − A negatively charged microenvironment combined with hydrophobic interfaces, such as the minor groove in the DNA double strand, − binds thiacyanine dyes and propends their aggregation, resulting in pronounced spectral changes. − Furthermore, the observed bacterium-induced spectral trends (Figure ) were in agreement with the reported metachromic behavior of THIA. , Thus, the 600 nm emission peak could be ascribed to a J-like aggregate of THIA taken up by the bacterial cells…”

Section: Resultssupporting

confidence: 75%

“…The appearance of the red-shifted emission bands was a feature that set apart the bacterium induced from the solvent-viscosity-induced THIA fluorescence enhancement (Figures b and b). As we already discussed, such red-shifted fluorescence, along with the observed perturbation of the THIA absorption spectrum upon cell uptake could be ascribed to ground-state aggregation. , …”

Section: Resultsmentioning

confidence: 57%

“…The bacterium-induced perturbation of the absorption spectra and the growth of the long-wavelength emission bands hence appeared to be related. Similar kinetics indicated that they could be a corollary of the same underlying process, reasonably ascribed to THIA aggregation. , The minor slow component of the 480 nm fluorescence enhancement could plausibly be ascribed to a similar concurrent aggregation of THIA exhibiting H-like-aggregate emission…”

Section: Resultsmentioning

confidence: 68%

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Kinetics of Bacterial Fluorescence Staining with 3,3′-Diethylthiacyanine

et al. 2010

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For more than a century, colorimetric and fluorescence staining have been the foundation of a broad range of key bioanalytical techniques. The dynamics of such staining processes, however, still remains largely unexplored. We investigated the kinetics of fluorescence staining of two gram-negative and two gram-positive species with 3,3'-diethylthiacyanine (THIA) iodide. An increase in the THIA fluorescence quantum yield, induced by the bacterial dye uptake, was the principal reason for the observed emission enhancement. The fluorescence quantum yield of THIA depended on the media viscosity and not on the media polarity, which suggested that the microenvironment of the dye molecules taken up by the cells was restrictive. The kinetics of fluorescence staining did not manifest a statistically significant dependence neither on the dye concentration, nor on the cell count. In the presence of surfactant additives, however, the fluorescence-enhancement kinetic patterns manifested species specificity with statistically significant discernibility.

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Section: Resultssupporting

confidence: 75%

Section: Resultsmentioning

confidence: 57%

Section: Resultsmentioning

confidence: 68%

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Kinetics of Bacterial Fluorescence Staining with 3,3′-Diethylthiacyanine

et al. 2010

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“…Unlike DEC, the DEC/AOT complex is soluble in hexane. At its high concentration in the solution, the dye can form composite complexes, the trimer DEC 3 /AOT 3 and hexamer DEC 6 /AOT 6 [12,18]. The formation of the DEC dimer, which may be responsible for the bands at 547.5 and 562 nm, is believed to be unlikely [14], although is not completely ruled out.…”

Section: Resultsmentioning

confidence: 92%

Spectral properties of carbocyanine dyes in solutions of reverse AOT micelles

et al. 2005

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Cyanine dyes are widely used in studies of various molecularly organized and biological systems [1][2][3][4]. Examples of such organized systems are microemulsions, normal and reverse micelles, lipid vesicles, and others. In these systems, individual stages of photosynthesis are modeled, and supramolecular systems for solar energy conversion are designed [3]. The formation of J aggregates in vesicles was observed in [5], when positively charged dye molecules were adsorbed on the negatively charged vesicle interface. In this case, strong Coulomb interaction between dye molecules and the vesicle interface can lead to the formation of J aggregates only at a very high concentration of dye molecules, and the minimum number of dye molecules necessary for J aggregate formation is 60 [6]. It has been shown that dye molecules are preferentially localized in the vesicles that already contain dye molecules rather than are uniformly distributed among all vesicles [3].The behavior of cyanines in solutions was intensely studied in the presence of surfactants [7][8][9], in normal [10-12] and reverse micelles [8,9,13]. It has been shown on the basis of spectral data that the decomposition of the dimer and the conversion of the cis-monomer to the trans -isomer occurs in reverse AOT micelles [14]. This cis -trans isomerization is due to strong electrostatic interaction of the dye with hydrophilic AOT groups at the interface between the organic phase and water, whereas the isomerization effect is much weaker in reverse micelles of neutral Triton X-100. Electrostatic interaction results in polarization and alignment of charged subunits in the dye molecule along the electric field, leading to conversion of the cis -to the transisomer. Hence, the absence of dye dimers in reverse micelles, as noted in [14], is due to the fact that the trans -isomer, unlike the cis -isomer, does not tend to form dimers in an aqueous medium.The preparation of monodispersed J aggregates of a given size, including those of an extremely small size, is a fundamental problem of great practical importance.One of possible ways of its solving seems to be the use of reverse micelles.Information on possible aggregated states of cyanine dyes in reverse micelles is rather controversial. For example, it has been established [13] that one dye molecule at the most can be present in the water pool of a single micelle, and the probability of occurrence of two dye molecules is of the order of 10 -5 . On the other hand, it is stated [14,15] that in water pools of reverse micelles with W ≥ 5 ( W = [H 2 O]/[AOT]), dye J aggregates are formed even at average dye concentrations much lower than one dye molecule per micelle. Zhang and Liu [13] believe that a dye molecule in micelles with a small water-pool radius is compressed by the surfactant shell, which results in distortion of planarity of the molecule, and molecule transforms into the nonfluorescent twisted monomeric state. In micelles of a greater size, the dye molecule exists in the planar fluorescent state in the water ...

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“…Surfactant-dependent optical properties of dye offer an opportunity to study surfactant-dye interactions [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. Surfactant-induced changes in spectral absorption have frequently been used to highlight various factors that contribute towards the growth of surfactant-dye aggregates [18][19][20][21][22][23][24][25][26].…”

Section: Introductionmentioning

confidence: 99%