Influence of Polarity and Viscosity of the Micellar Interface on the Fluorescence Quenching of Pyrenic Compounds by Indole Derivatives in AOT Reverse Micelles Solutions

Altamirano, Marcela S.; Borsarelli, Claudio D.; Cosa, Juan J.; Previtali, Carlos M.

doi:10.1006/jcis.1998.5650

Cited by 19 publications

(19 citation statements)

References 37 publications

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“…As already observed for several molecules and molecular complexes, 33,41,42 all the above results indicate the effect of specific interactions of the flavins in the internal micellar interface, which depends on the increment of the size and fluidity of the RM governed by the hydration degree of the micellar interface. This assumption is supported by the time-resolved fluorescence experiments presented in the following section.…”

Section: Ground-and Singlet Excited State Properties Of Flavins In Rmsupporting

confidence: 81%

“…These results are compatible with the polarity and fluidity increments of the solvation sphere of FMN as w 0 increases. [18][19][20][21][22][23][24][25][26]42 Table 2 collects the DAS parameters for the blue-and red-shifted bands of the flavins in AOT solutions as a function of w 0 . In all cases, the blue-shifted emission (λ b = 492-505 nm) showed smaller decay time (τ b ) and relative emission area (F b ) than those (e.g.…”

Section: Fluorescence Dynamic Behavior Of the Flavins In Rmmentioning

confidence: 99%

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Hydrogen-bonding modulation of excited-state properties of flavins in a model of aqueous confined environment

Valle

Vieyra

Borsarelli

2012

Photochem Photobiol Sci

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The singlet and triplet excited states properties of lumiflavin (LF), riboflavin (RF), flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) in reversed micelles (RM) of sodium docusate (AOT) in n-hexane solutions were evaluated as a function of the water to surfactant molar ratio, w(0) = [H(2)O]/[AOT], by both steady-state and time-resolved absorption and fluorescence spectroscopy. The results indicated that hydrogen-bonding interactions between the isoalloxazine ring of the flavins with the water molecules of the micellar interior play a crucial role on the modulation of the excited state properties of the flavins. Fluorescence dynamic experiments in the RM, allowed the calculation of similar values for both the internal rotational time of the flavins (θ(i)) and the hydrogen-bonding relaxation time (τ(HB)), e.g.≈ 7 and 1.5 ns at w(0) = 1 and 20, respectively. In turn, the triplet state lifetimes of the flavins were also enlarged in RM solutions at low w(0), without modifications of their quantum yields. A hydrogen bonding relaxation model is proposed to explain the singlet excited state properties of the flavins, while the changes of the triplet state decays of the flavins were related with the global composition and strength of the hydrogen bonding network inside of the RM.

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Section: Ground-and Singlet Excited State Properties Of Flavins In Rmsupporting

confidence: 81%

Section: Fluorescence Dynamic Behavior Of the Flavins In Rmmentioning

confidence: 99%

Hydrogen-bonding modulation of excited-state properties of flavins in a model of aqueous confined environment

Valle

Vieyra

Borsarelli

2012

Photochem Photobiol Sci

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“…Accordingly, alsointeractions between pyrene and Trp are possible. It has been demonstrated that Trp can quench fluorescence emission of various pyrene derivatives in micellar solutions (Encinas and Lissi, 1986;Altamirano et al, 1998). An additional possibility is chain reversal (Holopainen et al, 1999) causing accommodation of the pyrene moiety into a more polar environment upon the binding of the peptide to the lipid bilayer, thus increasing the polarity of the microenvironment of the fluorophore and causing decrement in quantum yield.…”

Section: Impact Of Magainin 2 and Indolicidin On Bilayer Lipid Dynamicsmentioning

confidence: 99%

Comparison of the Membrane Association of Two Antimicrobial Peptides, Magainin 2 and Indolicidin

Zhao

Mattila

Holopainen

et al. 2001

Biophysical Journal

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Interactions of two antimicrobial peptides, magainin 2 and indolicidin, with three different model biomembranes, namely, monolayers, large unilamellar vesicles (LUVs), and giant liposomes, were studied. Insertion of both peptides into lipid monolayers was progressively enhanced when the content of an acidic phospholipid, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol (POPG) in a film of 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine (SOPC) was increased. Indolicidin and magainin 2 penetrated also into lipid monolayers containing cholesterol (mole fraction, X = 0.1). Membrane association of magainin 2 attenuated lipid lateral diffusion in POPG-containing LUVs as revealed by the decrease in the excimer/monomer fluorescence ratio I(e)/I(m) for the pyrene fatty-acid-containing phospholipid derivative 1-palmitoyl-2-[10-(pyren-1-yl) decanoyl]-sn-glycero-3-phospho-rac-glycerol (PPDPG). Likewise, an increase in steady-state fluorescence anisotropy of the membrane-incorporated diphenylhexatriene (DPH) was observed, revealing magainin 2 to increase acyl chain order and induce segregation of acidic phospholipids. Similar effects were observed for indolicidin. The topological effects of magainin 2 and indolicidin on phospholipid membranes were investigated using optical microscopy of giant vesicles. Magainin 2 had essentially no influence on either SOPC or SOPC:cholesterol (X = 0.1) giant liposomes. However, effective vesiculation was observed when acidic phospholipid (X(PG) = 0.1) was included in the giant vesicles. Indolicidin caused only a minor shrinkage of giant SOPC vesicles whereas the formation of endocytotic vesicles was observed when the giant liposome contained POPG (X(PG) = 0.1). Interestingly, for indolicidin, vesiculation was also observed for giant vesicles composed of SOPC/cholesterol (X(chol) = 0.1). Possible mechanisms of membrane transformation induced by these two peptides are discussed.

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“…Another example is the study of the fluorescence quenching of some pyrene derivatives by indolic compounds in reverse micelles carried out by Altamirano et al [46]. Probes were anchored to the AOT reverse micelles' interface.…”

Section: Micelles As Receptorsmentioning

confidence: 99%

Kinetics of Photochemical Reactions under Restricted Geometry Conditions

Marchena

Sánchez

2010

Progress in Reaction Kinetics and Mechanism

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Kinetics of ground state reactions under restricted geometry conditions have been rationalized generally taking as a basis the Pseudophase Model, whose basic hypothesis is: The distribution of the reactants between the pseudophases is at equilibrium, that is, the rate of the reaction is slow in relation to the rates of entry and exit of the reactant to and from the receptor. However, photochemical reactions are generally very rapid, so the following question emerges: is the Pseudophase Model still applicable to photochemical reactions? To answer this question has been the primary objective of this work in which photochemical reactions in micelles, polymers and cyclodextrins have been reviewed. The lifetime of the fluorophore and the distributions of the quencher and the probe are crucial properties; they must be taken into account to obtain a proper description of the behaviour of a given system. The models of Infelta, Almgren and Quina visualise different scenarios with varied combinations of these properties. It is shown that, in some cases, the Pseudophase Model holds at least formally.

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Influence of Polarity and Viscosity of the Micellar Interface on the Fluorescence Quenching of Pyrenic Compounds by Indole Derivatives in AOT Reverse Micelles Solutions

Cited by 19 publications

References 37 publications

Hydrogen-bonding modulation of excited-state properties of flavins in a model of aqueous confined environment

Hydrogen-bonding modulation of excited-state properties of flavins in a model of aqueous confined environment

Comparison of the Membrane Association of Two Antimicrobial Peptides, Magainin 2 and Indolicidin

Kinetics of Photochemical Reactions under Restricted Geometry Conditions

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