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1.
Mater Sci Eng C Mater Biol Appl ; 101: 76-87, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31029366

RESUMO

The new green-synthesised ZnO nanoparticles (NPs) using apple (var. Starking) phytochemicals present a great potential for bioimaging applications. These NPs, when compared with ZnO microparticles synthesised with pure phytochemicals (quercetin or sucrose), and water, revealed that sizes and shapes were widely dependent on the organic precursors used. Based on these findings, new insights into the synthesis of ZnO NPs using apple phytochemicals were presented. The photoluminescent properties, characterized by steady-state and time resolve photoluminescence measurements, revealed that besides the intense sharp near-UV band edge emission observed for all particles, with sub-nanosecond lifetime, a strong broad emission band peak at 2.20 eV was detected for microparticles, with longer decay times being associate to crystal defects. Additionally, the photoluminescent properties of ZnO particles, further explored by fluorescence lifetime imaging microscopy (FLIM), suggested adequacy for imaging applications. The cytotoxicity, evaluated in human dermal fibroblasts, proving the biosafety of ZnO NPs by an unaffected cellular viability, total mitochondrial activity and F-actin cytoskeleton organization, contrasted with some degree of cytotoxicity depicted for microparticles. The influence of the phytochemicals in ZnO cytotoxicity was discussed. To the authors' best knowledge this is the first report of ZnO NPs synthesised with apple extracts. The novelty of choosing a fruit widely used in the food industry will render affordable NPs through the concept of circular economy. The proved biosafety of these ZnO NPs together with their intrinsic photoluminescent properties, open perspectives for the development of cost-effective bioimaging materials with potential to be further directed into biomedical applications.


Assuntos
Materiais Biocompatíveis/farmacologia , Tecnologia Biomédica/métodos , Luminescência , Malus/química , Nanopartículas Metálicas/química , Compostos Fitoquímicos/farmacologia , Óxido de Zinco/química , Morte Celular/efeitos dos fármacos , Derme/citologia , Fibroblastos/citologia , Fibroblastos/efeitos dos fármacos , Fluorescência , Humanos , Nanopartículas Metálicas/ultraestrutura , Compostos Fitoquímicos/química , Soluções , Espectrofotometria Ultravioleta
2.
Langmuir ; 33(31): 7680-7691, 2017 08 08.
Artigo em Inglês | MEDLINE | ID: mdl-28697597

RESUMO

A strategy assisted by an inorganic template was developed to promote the organized self-assembly of meso-(tetrakis)-(p-sulfonatophenyl)porphyrin (TPPS) on pH-sensitive core-shell polyelectrolyte microcapsules (PECs) of poly(styrenesulfonate) (PSS) and poly(allylamine hydrochloride) (PAH). A key feature of this strategy is the use of template CaCO3 microparticles as a nucleation site endorsing inside-outside directional growth of porphyrin aggregates. Using this approach, TPPS self-assembly in positively charged PECs with CaCO3 (PAH/PSS)2PAH as a sequence of layers was successfully achieved using mild pH conditions (pH 3). Evidence for porphyrin aggregation was obtained by UV-vis with the characteristic absorption bands in PECs functionalized with porphyrins. Fluorescence lifetime imaging microscopy (FLIM) of the polyelectrolyte core-shell confirmed the presence of radially distributed needlelike structures sticking out from polyelectrolyte shells. Microscopic images also revealed a sequential process (adsorption, redistribution, and aggregation) for the directional growth (inside/outside) of TPPS aggregates, which highlights the importance of the core in the aggregation induction. Removing the CaCO3 core alters the porphyrin interaction in the PEC environment, and aggregate growth is no longer favored.

3.
Colloids Surf B Biointerfaces ; 146: 127-35, 2016 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-27285535

RESUMO

The interaction of DNA with 5,10,15,20-tetrakis(4-N-methylpyridiniumyl)porphyrin (TMPyP) in polyelectrolyte core-shells obtained via layer by layer adsorption of poly(sodium 4-styrenesulfonate), PSS, and poly(allylamine hydrochloride), PAH, polyelectrolytes was followed by steady state, time resolved fluorescence and by Fluorescence Lifetime Imaging Microscopy (FLIM). Our results show that DNA adsorption onto polyelectrolyte core-shell changes the TMPyP interaction within PSS/PAH core-shells structure and increase significantly the TMPyP uptake. Specific DNA/TMPyP interactions are also altered by DNA adsorption favouring porphyrin intercalation onto GC pair rich regions. Circular dichroism (CD) spectra reveal that DNA undergoes important conformational changes upon adsorption onto the core-shell surface, which are reverted upon TMPyP encapsulation.


Assuntos
DNA/metabolismo , Desenho de Drogas , Fármacos Fotossensibilizantes/metabolismo , Polieletrólitos/química , Porfirinas/metabolismo , Dicroísmo Circular , DNA/química , Fármacos Fotossensibilizantes/química , Porfirinas/química
4.
Photochem Photobiol Sci ; 13(6): 907-16, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24715103

RESUMO

The photosynthetic pigments of higher plants exist in complex oligomeric states, which are difficult to study in vivo. To investigate aggregation processes of chlorophyll a (Chl a), we used an in vitro reconstitution procedure, with this pigment incorporated into liposomes of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), micelles and pre-micelle media of the detergent n-dodecyltrimethylammonium chloride (DTAC), and mixed, spontaneous, DMPC-DTAC vesicles and micelles. Chl a oligomers were characterized by UV-visible absorption, steady-state and time-resolved fluorescence, and fluorescence lifetime imaging microscopy. Equivalent diameters of the colloidal structures were obtained by fluorescence correlation spectroscopy. In DMPC liposomes and DMPC-DTAC vesicles and micelles, three fluorescence lifetimes indicated the coexistence of Chl a monomers (≈5 ns) and oligomers (≈1-2 to ≈0.1 ns). The increase in DTAC amount, in the mixed system, induces a progressive solubilization of DMPC liposomes (from vesicles to micelles) and simultaneous disruption of Chl a aggregates; in pure DTAC micelles, mostly monomers were found. The present work aims for a better understanding of chlorophyll-chlorophyll (Chl-Chl), Chl-lipid, and Chl-detergent interactions in spontaneous colloidal micro- and nanostructures.


Assuntos
Clorofila/química , Detergentes/química , Lipossomos , Micelas , Fosfolipídeos/química , Absorção , Clorofila A , Dimiristoilfosfatidilcolina/química , Fluorescência , Microscopia de Fluorescência , Modelos Químicos , Compostos de Amônio Quaternário/química , Espectrometria de Fluorescência , Fatores de Tempo , Raios Ultravioleta
5.
J Phys Chem B ; 117(48): 15023-32, 2013 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-24175940

RESUMO

Two isomeric ß-vinylpyridinium porphyrins, 2-[2-(2-methylpyridinium)vinyl]-5,10,15,20-tetraphenylporphyrin (1, ortho isomer) and 2-[2-(4-methylpyridinium)vinyl]-5,10,15,20-tetraphenylporphyrin (2, para isomer), which have shown different photodynamic behavior were investigated in organic solvents and sodium 1,4-bis(2-ethylhexyl)sulfosuccinate (AOT) reverse micelles. In organic systems, the absorption spectra present a red-shifted band that is more intense in the para isomer, in addition to the usual Soret band. This new band presents interesting solvatochromic effects which obey the multiparametric Kamlet-Taft equation. In AOT reverse micelles, the ortho isomer exhibits a strong dependence with the parameter ω0 = [H2O]/[AOT] which indicates that the molecule resides at the interface toward the organic phase. By contrast, no evidence was detected for the encapsulation of para isomer 2 in AOT reverse micelles. The hypothesis of two ground state isomers with different contributions of trans and quinoid structures is advanced on the basis of the overall data collected from electronic absorption, steady-state, and transient-state fluorescence emission. A charge transfer state in which an electron is fully transferred from the porphyrin to the pyridinium moiety is associated to a quinoid structure in isomer 2. The trans/quinoid relative proportions may be accounted for by the orientation of the ortho-/para-pyridinium isomers relatively to the porphyrin core.

6.
Chemphyschem ; 13(16): 3622-31, 2012 Nov 12.
Artigo em Inglês | MEDLINE | ID: mdl-22887177

RESUMO

The self-assembly and induced supramolecular chirality of meso-tetrakis(4-sulfonatophenyl)porphyrin (TSPP) on both single-wall (SWCNT) and multiwall carbon nanotubes (MWCNT) are investigated. Under mild pH conditions (pH 3), TSPP forms aggregates when CNTs are dispersed in an aqueous solution containing positively charged polyelectrolytes such as poly-L-lysine (PLL) or poly(allylamine hydrochloride) (PAH). Evidence for the geometry of the porphyrin aggregates is obtained from absorption spectra, whereby the fingerprints of J- and H-aggregates are clearly seen only in the presence of smaller-diameter nanotubes. J-aggregates are better stabilized with PLL, whereas in the presence of PAH mainly H-aggregates prevail. Excited-state interactions within these nanohybrids are studied by steady-state and time-resolved fluorescence. The porphyrin emission intensity in the nanohybrid solution is significantly quenched compared to that of TSPP alone, and this implies strong electronic interaction between CNTs and porphyrin molecules. Fluorescence lifetime imaging microscopy (FLIM) further supports that porphyrin arrays are associated with the MWCNT sidewalls wrapped in PLL. In the case of the SWCNT hybrid, spherical structures associated with longer fluorescence lifetime appeared after one week, indicative of H-aggregates of TSPP. The latter are the result of π-π stacking of porphyrin units on neighboring nanotubes facilitated by the strong tendency of these nanotubes to interact with each other. These results highlight the importance of optimum dimensions and surface-area architectures of CNTs in the control/stability of the porphyrin aggregates with promising properties for light harvesting.

7.
J Phys Chem B ; 116(8): 2396-404, 2012 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-22292964

RESUMO

The self-assembly of a neutral meso-methoxyphenylporphyrin functionalized with a dipeptide glycilglycine substituent (MGG) in water and in water-ethanol mixtures was studied by absorption and fluorescence spectroscopy. In water, hydrophobic interactions and the noncovalent intermolecular hydrogen bonding between the terminal carboxylate group of one porphyrin and the hydrogen atoms of the pyrrolic nitrogens of another porphyrin originate nonspecific disorganized H- and J-aggregates. The addition of ethanol (0.1-25% v/v) to the water creates small clusters within which porphyrin J-aggregates reorganize as revealed by a narrow intense band detected by the Rayleigh light scattering (RLS) at 443 nm. Similar phenomenology is detected in SDS premicellar aggregates. Computational DFT calculations of a model dimer formation stabilized via intermolecular hydrogen bonding estimate an energy gain of -22 kJ mol(-1) and a center-to-center and interplane distances between porphyrin moieties of 16.8 and 3.7 Å, respectively. The kinetics of the J-aggregate formation could be fitted with a time-dependent model, and an activation energy of 96 kJ mol(-1) was estimated. The aggregate's morphology of MGG was followed by transmission electron microscopy (TEM) which showed rod-type structures of 5-8 µm evolving to spherical particles with increased ethanol content. Similar images and sizes were obtained in analogous samples using fluorescence lifetime imaging microscopy (FLIM) and dynamic light scattering (DLS). The formation of excitonically coupled supramolecular MGG structures of brickwork or staircase types is proposed in these water-ethanol mixtures.


Assuntos
Dipeptídeos/síntese química , Etanol/química , Porfirinas/síntese química , Água/química , Dipeptídeos/química , Estrutura Molecular , Porfirinas/química
8.
J Biomed Opt ; 14(4): 044035, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19725746

RESUMO

A novel method to distribute proteins on solid surfaces is proposed. Proteins microencapsulated in the water pool of reverse micelles were used to coat a solid surface with well-individualized round spots of 1 to 3 microm in diameter. The number of spots per unit area can be increased through the concentration of reverse micelles, and networks of spots were obtained at high concentrations of large reverse micelles. Moreover, depending on the pool size of the water reverse micelles, proteins can be deposited far from each other or in close proximity within the range of 50 to 70 A. This proximity obtained with small reverse micelles was proved through fluorescence lifetime imaging microscopy and fluorescence resonance energy transfer (FLIM-FRET) measurements for the most relevant FRET pair in cell biology studies, the cyan and yellow fluorescent proteins. This novel procedure has several advantages and reveals the potential for study of protein-protein interactions on solid surfaces and for developing novel biomaterials and molecular devices based on biorecognition elements.


Assuntos
Proteínas de Bactérias/análise , Proteínas de Bactérias/química , Transferência Ressonante de Energia de Fluorescência/métodos , Proteínas de Fluorescência Verde/análise , Proteínas de Fluorescência Verde/química , Proteínas Luminescentes/análise , Proteínas Luminescentes/química , Microscopia de Fluorescência/métodos , Adsorção , Sítios de Ligação , Ligação Proteica
9.
Ann N Y Acad Sci ; 1130: 305-13, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-18596364

RESUMO

Water-soluble ionic porphyrins show an interesting self-association pattern in acidic conditions under which highly ordered aggregates are stabilized. Herein we give an overview of the template effect of biological interfaces in tetrakis(4-sulfonatophenyl)porphyrin TSPP self-aggregation, in which we point out the possibility of tuning this process by screening the charge repulsion through ionic strength and pH. We give special emphasis to the use of fluorescence lifetime imaging microscopy and of fluorescence correlation spectroscopy to visualize and characterize these molecular aggregates.


Assuntos
Biomimética , Luz , Micelas , Nanotubos de Carbono/química , Porfirinas/química , Espectrometria de Fluorescência/métodos , Dimerização , Humanos , Concentração de Íons de Hidrogênio , Lactoglobulinas/química , Conformação Molecular , Ligação Proteica , Prótons , Albumina Sérica/química
10.
J Fluoresc ; 18(3-4): 601-10, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-18264814

RESUMO

The interaction between a free-base, anionic water-soluble porphyrin, TSPP, and the drug carrier protein, bovine serum albumin (BSA) has been studied by time-resolved fluorescence anisotropy (TRFA) and fluorescence correlation spectroscopy (FCS) at two different pH-values. Both rotational correlation times and translational diffusion times of the fluorescent species indicate that TSPP binding to albumin induces very little conformational changes in the protein under physiological conditions. By contrast, at low pH, a bi-exponential decay is obtained where a short rotational correlation time (phi (int) = 1.2 ns) is obtained, which is likely associated to wobbling movement of the porphyrin in the protein binding site. These physical changes are corroborated by circular dichroism (CD) data which show a 37% loss in the protein helicity upon acidification of the medium. In the presence of excess porphyrin formation of porphyrin J-aggregates is induced, which can be detected by time-resolved fluorescence with short characteristic times. This is also reflected in FCS data by an increase in molecular brightness together with a decrease in the number of fluorescent molecules passing through the detection volume of the sample.


Assuntos
Porfirinas/química , Soroalbumina Bovina/química , Algoritmos , Sítios de Ligação , Dicroísmo Circular , Polarização de Fluorescência , Concentração de Íons de Hidrogênio , Porfirinas/metabolismo , Ligação Proteica , Conformação Proteica , Estrutura Secundária de Proteína , Soroalbumina Bovina/metabolismo , Espectrometria de Fluorescência
11.
Biophys Chem ; 133(1-3): 1-10, 2008 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-18068890

RESUMO

Free base porphyrin (PPhe), derivatized with aminosulfonyl groups linked to the aromatic amino acid phenylalanine at the meso-positions, was mixed with DMPC vesicles. The resulting interaction was studied by absorption, steady-state and transient state fluorescence, at different pHs. At pH=2 to pH=9, the aforementioned porphyrin predominates as an aggregated species, with a co-facial arrangement of the molecules taking into account the blue shift of the Soret band (414 nm for the monomer and 401 nm for the aggregate). Upon interaction with DMPC vesicles, the competing hydrophobic interactions with the bilayer destabilize the aggregated species in favor of monomer incorporation. Fluorescence lifetimes also show that the long component assigned to the monomer contributes only 30% to the overall decay in solution (e.g. pH=7.0) whereas in DMPC vesicles this contribution increases up to 85% independent of the solution pH, which confirms a location of the probe in an environment "protected" from free water. The picture changes completely in the case of TSPP, an anionic porphyrin which does not incorporate in DMPC vesicles. Remarkably, at pH=2.5 all the experimental findings point to the self-assembling of the porphyrin units in J-aggregates induced at the surface of the DMPC vesicle. In fact, upon removal of the aqueous solvent, we could define by fluorescence lifetime imaging microscopy (FLIM) regions where the fluorescence lifetime is that characteristic of the J-aggregate ( 0.11 ns).


Assuntos
Dimiristoilfosfatidilcolina/química , Porfirinas/química , Água/química , Dicroísmo Circular , Concentração de Íons de Hidrogênio , Soluções , Espectrometria de Fluorescência , Espectrofotometria Ultravioleta
12.
Chemistry ; 12(4): 1046-57, 2006 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-16250056

RESUMO

We have investigated the interaction of two water-soluble free-base porphyrins (negatively charged meso-tetrakis(p-sulfonatophenyl)porphyrin sodium salt (TSPP) and positively charged meso-tetrakis(N-methylpyridinium-4-yl)porphyrin (TMpyP)) with two drug-carrier proteins (human serum albumin (HSA) and beta-lactoglobulin (betaLG)) in bis(2-ethylhexyl)sulfosuccinate (AOT)/isooctane/water reverse micelles (RM) by using steady-state and transient-state fluorescence spectroscopy. TSPP exhibited a complex pattern of aggregation on varying the RM size and pH in the absence of the protein: at low omega0 (the ratio of water concentration to AOT concentration, the emission of H-aggregates prevails under acidic or neutral "pH(ext)" conditions. Upon formation of the water-pool, J-aggregates and monomeric diacid species dominate at low "pH(ext)" but only monomer is detected at neutral "pH(ext)". The aggregation number increases with omega0 and the presence of the protein does not seem to contribute to further growth of the aggregate. The presence of protein leads to H-deaggregation but promotes J-aggregation up to a certain protein/porphyrin ratio above which, complexation with the monomer bound to a hydrophobic site of the protein prevails. The effective complex binding constants are smaller than in free aqueous solution; this indicates a weaker binding in these RM probably due to some conformational changes imposed by encapsulation. Only a weak quenching of TMpyP fluorescence is detected due to the presence of protein in contrast to the negative porphyrin.


Assuntos
Albuminas/química , Lactoglobulinas/química , Porfirinas/química , Succinatos/química , Micelas , Solubilidade , Espectrometria de Fluorescência , Água/química
13.
Eur J Biochem ; 271(4): 734-44, 2004 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-14764089

RESUMO

The effect of beta-lactoglobulin encapsulation in sodium bis(2-ethylhexyl) sulfosuccinate reverse micelles on the environment of protein and on Trp was analysed at different water contents (omega0). CD data underlined the distortion of the beta-sheet and a less constrained tertiary structure as the omega0 increased, in agreement with a concomitant red shift and a decrease in the signal intensity obtained in steady-state fluorescence measurements. Fluorescence lifetimes, evaluated by biexponential analysis, were tau1 = 1.28 ns and tau2 = 3.36 ns in neutral water. In reverse micelles, decay-associated spectra indicated the occurrence of important environmental changes associated with omega0. Bimolecular fluorescence quenching by CCl4 and acrylamide was employed to analyse alterations in the accessibility of the two Trp residues in beta-lactoglobulin, induced by changes in omega0. The average bimolecular quenching constant was found not to depend on omega0, confirming the insolubility of this quencher in the aqueous interface, while increases with omega0. The drastic decrease with omega0 of kq, associated with the longest lifetime kq2(CCl4), comparatively to the increase of kq2(acrylamide), emphasizes the location of beta-lactoglobulin in the aqueous interfacial region especially at omega0> or = 10. The fact that (omega0 = 30) >> kq2(acrylamide) (water) also confirms the important conformational changes of encapsulated beta-lactoglobulin.


Assuntos
Ácido Dioctil Sulfossuccínico/química , Lactoglobulinas/química , Acrilamida/química , Animais , Bovinos , Dicroísmo Circular , Cinética , Micelas , Modelos Moleculares , Conformação Proteica , Espectrometria de Fluorescência/métodos , Triptofano/química , Água/química
14.
Photochem Photobiol Sci ; 2(5): 605-10, 2003 May.
Artigo em Inglês | MEDLINE | ID: mdl-12803085

RESUMO

The singlet excited-state quenching of Acridine Orange (AO) by methyl viologen (MV2+) and the non-steroidal anti-inflammatory drug Piroxicam (Prx), incorporated in sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/isooctane/water and Triton X-100 (Trx-100)/cyclohexane-hexanol/water (w/o) microemulsions, was followed by steady- and transient-state fluorescence. The water content was varied by using different values of omega 0 (omega 0 = [H2O]/[S]) at fixed AOT (0.1 M) and Trx-100 (0.2 M) concentrations. In AOT, MV2+ resides at the interface, while Prx partitions between the interface and bulk water, but considerably biased towards the latter compared to AO. The quenching process efficiency increases with increasing omega 0, but reaches a diffusional value similar to that of free water only for the case of Prx, underlining the electrostatic effect of the AOT interface. The quenching process in Trx-100 microemulsions is more efficient for Prx than for MV2+, pointing to a similar polyoxyethylene intra-chain location for the former and AO. In both cases, data obtained allowed the microviscosity of the aqueous interior at different omega 0 to be extrapolated and indicate an increase in eta w values with water content, reflecting changes in the shape of Trx-100 microemulsions, which occur at omega 0 = 8.


Assuntos
Laranja Acridina/química , Anti-Inflamatórios não Esteroides/química , Piroxicam/química , Emulsões , Fluorescência , Cinética , Octoxinol
15.
Biophys J ; 82(3): 1607-19, 2002 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-11867473

RESUMO

The interaction of meso-tetrakis(p-sulfonatophenyl)porphyrin (TSPP) sodium salt to human serum albumin and beta-lactoglobulin was studied by steady-state and dynamic fluorescence at different pH of aqueous solutions. The formation of TSPP J-aggregates and a noncovalent TSPP-protein complex was monitored by fluorescence titrations, which depend on pH and on the protein nature and concentration. The complex between TSPP and protein displays a heterogeneous equilibrium with large changes in the binding strength versus pH. The large reduction of the effective binding constant from pH 2 to 7 suggests that electrostatic interactions are a major contribution to the binding of TSPP to the aforementioned proteins. TSPP aggregates and TSPP-protein complex exhibit circular dichroism induced by the presence of the protein. Circular dichroism spectra in the ultraviolet region show that the secondary structure of both proteins is not extensively affected by the TSPP presence. Protein-TSPP interaction was also examined by following the intrinsic fluorescence of the tryptophan residues of the proteins. Fluorescence quenching by acrylamide and TSPP itself also point to small changes on the protein tertiary structure and a critical distance R(0) approximately 56 A, between tryptophan and bound porphyrin, was estimated using the long distance Förster-type energy transfer formalism.


Assuntos
Porfirinas/química , Espectrofotometria/métodos , Água/química , Acrilamidas/química , Dicroísmo Circular , Relação Dose-Resposta a Droga , Humanos , Concentração de Íons de Hidrogênio , Lactoglobulinas/química , Modelos Químicos , Ligação Proteica , Estrutura Secundária de Proteína , Albumina Sérica/química , Espectrometria de Fluorescência , Fatores de Tempo , Triptofano/química , Raios Ultravioleta
16.
Photochem Photobiol Sci ; 1(7): 500-6, 2002 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-12659161

RESUMO

The confined aqueous medium of Triton X-100/cyclohexane-hexanol/water microemulsions was studied and compared with that of AOT/isooctane/water. The microenvironment generated was assessed by following the photophysical behaviour of the cationic dye, acridine orange (AO). This dye presents an acid-base equilibrium in free bulk water (pKa approximately equal to 10.2) which is clearly affected in Triton X-100 microemulsions where the neutral species is stabilised at low omega0. The addition of water contributes to the appearance of the protonated species. This, however, presents spectral features that show a less polar and/or protic character of the encapsulated water even at high contents. The "anomalous" microviscosity dependence on the amount of solubilised water (omega0 = [H2O]/[Surf]) in Triton X-100 microemulsions obtained from steady-state anisotropy data was used to discuss the existence of bulk free water within these confined media, where at omega0 = 8, properties seem to change. In AOT, a complex AO-AOT is detected in equilibrium with the protonated AO, at pH = 7. The two-state excited-state formalism was applied to describe the transient data which in the case of AOT introduces a rate constant that accounts for the water quenching (kq = 0.51 +/- 0.03 x 10(8) M(-1) cm(-1)).

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