Spectral studies of N-nonyl acridine orange in anionic, cationic and neutral surfactants

The spectroscopic and photophysical properties of N-nonyl acridine orange - a metachromatic dye useful as a mitochondrial probe in living cells - are reported in water and microheterogeneous media: anionic sodium dodecylsulfate (SDS), cationic cetyltrimethylammonium bromide (CTAB) and neutral octylophenylpolyoxyethylene ether (TX-100). The spectral changes of N-nonyl acridine orange were observed in the presence of varying amount of SDS, CTAB and TX-100 and indicated formation of a dye-surfactant complex. The spectral changes were also regarded to be caused by the incorporation of dye molecules to micelles. It was proved by calculated values K(b) and f in the following order: K(bTX-100)>K(bCTAB)>K(bSDS) and f(TX-100)>f(CTAB)>f(SDS). NAO binds to the micelle regardless the micellar charge. There are two types of interactions between NAO and micelles: hydrophobic and electrostatic. The hydrophobic interactions play a dominant role in binding of the dye to neutral TX-100. The unexpected fact of the binding NAO to cationic CTAB can be explained by a dominant role of hydrophobic interactions over electrostatic repulsion. Therefore, the affinity of NAO to CTAB is smaller than TX-100. Electrostatic interactions play an important role in binding of NAO to anionic micelles SDS. We observed a prolonged fluorescence lifetime after formation of the dye-surfactant complex tau(SDS)>tau(TX-100)>tau(CTAB)>tau(water), the dye being protected against water in this environment. TX-100 is found to stabilize the excited state of NAO which is more polar than the ground state. Spectroscopic and photophysical properties of NAO will be helpful for a better understanding of the nature of binding and distribution inside mammalian cells.     

Photophysics of xanthene dyes in surfactant solution

The spectral (both absorption and fluorescence) and photoelectrochemical studies of some anionic xanthene dyes namely erythrosine B, rose bengal and eosin have been carried out in micellar solution of cationic cetyl trimethyl ammonium bromide (CTAB), anionic sodium dodecyl sulphate (SDS) and neutral triton X-100 (TX-100). The results show that all these dyes form 1:1 electron-donor-acceptor (EDA) or charge-transfer (CT) complexes with TX-100, which acts as an electron donor. There is no interaction of these dyes with SDS, whereas the interaction with CTAB is mainly electrostatic in nature. In presence of TX-100, these dyes show enhancement of fluorescence intensity with a red shift and develop photovoltage in a photoelectrochemical cell. A good correlation has been found among the photovoltage generation in the systems consisting of these dyes and TX-100, spectral shift due to complex formation and thermodynamic properties of these complexes.     

Studies on the molecular interaction of Erythrosine ‘B’ with surfactants

The spectroscopic investigation on anionic dye, Erythrosine ‘B’(EB) with three different types of surfactants such as CTAB (cationic), sodium lauryl sulphate (SLS; anionic) and Triton X-100 (TX-100),Tween-20, 40, 60 and 80 (nonionic) in aqueous media shows that EB forms a 1:1 molecular complex with TX-100, Tweens and CTAB. No interaction is observed between EB and SLS. The thermodynamic and spectrophotometric properties of these complexes suggest that EB forms a strong charge transfer (CT) complex with TX-100 and Tweens whereas the interaction of EB with CTAB is coulombic in nature. Photogalvanic and photoconductometric studies also support the above interactions. In addition to this, the electron-donating ability among the nonionic surfactants, i.e. TX-100 and Tweens towards dye, role of surface in CT interaction, the site of CT interaction and the intensity and stability of CT interaction between EB and nonionic surfactants have been pointed out.     

Spectral studies of N-nonyl acridine orange in anionic, cationic and neutral surfactants

The spectroscopic and photophysical properties of N-nonyl acridine orange – a metachromatic dye useful as a mitochondrial probe in living cells – are reported in water and microheterogeneous media: anionic sodium dodecylsulfate (SDS), cationic cetyltrimethylammonium bromide (CTAB) and neutral octylophenylpolyoxyethylene ether (TX-100). The spectral changes of N-nonyl acridine orange were observed in the presence of varying amount of SDS, CTAB and TX-100 and indicated formation of a dye–surfactant complex. The spectral changes were also regarded to be caused by the incorporation of dye molecules to micelles. It was proved by calculated values K_b and f in the following order: K_b TX-100 > K_b CTAB > K_b SDS and f_TX-100 > f_CTAB > f_SDS. NAO binds to the micelle regardless the micellar charge. There are two types of interactions between NAO and micelles: hydrophobic and electrostatic. The hydrophobic interactions play a dominant role in binding of the dye to neutral TX-100. The unexpected fact of the binding NAO to cationic CTAB can be explained by a dominant role of hydrophobic interactions over electrostatic repulsion. Therefore, the affinity of NAO to CTAB is smaller than TX-100. Electrostatic interactions play an important role in binding of NAO to anionic micelles SDS. We observed a prolonged fluorescence lifetime after formation of the dye–surfactant complex τ_SDS > τ_TX-100 > τ_CTAB > τ_water, the dye being protected against water in this environment. TX-100 is found to stabilize the excited state of NAO which is more polar than the ground state. Spectroscopic and photophysical properties of NAO will be helpful for a better understanding of the nature of binding and distribution inside mammalian cells.     

Interaction of Nonionic Surfactant Triton-X-100 with Ionic Surfactants

The interaction in two mixtures of a nonionic surfactant Triton-X-100 (TX-100) and different ionic surfactants was investigated. The two mixtures were TX-100/sodium dodecyl sulfate (SDS) and TX-100/cetyltrimethylammonium bromide (CTAB) at molar fraction of TX-100, α_TX-100 = 0.6. The surface properties of the surfactants, critical micelle concentration (CMC), effectiveness of surface tension reduction (γ_CMC), maximum surface excess concentration (Γ_max), and minimum area per molecule at the air/solution interface (A _min) were determined for both individual surfactants and their mixtures. The significant deviations from ideal behavior (attractive interactions) of the nonionic/ionic surfactant mixtures were also determined. Mixtures of both TX-100/SDS and TX-100/CTAB exhibited synergism in surface tension reduction efficiency and mixed micelle formation, but neither exhibited synergism in surface tension reduction effectiveness.     

Influence of surfactants on the adsorption and elektrokinetic properties of the system: guar gum/manganese dioxide

The adsorption of non-ionic polysaccharide—guar gum (GG) in the presence or absence of the surfactants: anionic SDS, cationic CTAB, nonionic TX-100 and their equimolar mixtures SDS/TX-100, CTAB/TX-100 from the electrolyte solutions (NaCl, CaCl₂) on the manganese dioxide surface (MnO₂) was studied. The increase of GG adsorption amount in the presence of surfactants was observed in every measured system. This increase results from formation of complexes between the GG and the surfactant molecules. This observation was confirmed by the determination of the influence of GG on surfactants adsorption on the MnO₂ surface. The increase of GG adsorption on MnO₂ was the largest in the presence of the surfactant mixtures (CTAB/TX-100; SDS/TX-100) which is the evidence of the synergetic effect. The smallest amounts of adsorption were obtained in the presence of TX-100, which results from non-ionic character of this surface active agent. In the case of single surfactant solution CTAB has the best efficiency in increasing the amount of GG adsorption on MnO₂ which results from strong interactions with GG and also with the negatively charged surface of the adsorbent. In order to determine the electrokinetic properties of the system, the surface charge density of MnO₂ and the zeta potential measurements were performed in the presence of the GG macromolecules and the above mentioned surfactants and their mixtures. The obtained data showed that the adsorption of GG or GG/surfactants complexes on the manganese dioxide surface strongly influences the diffused part of the electrical double layer (EDL)—MnO₂/electrolyte solution, but has no influence on the compact part of the electric double layer. This is the evidence that the polymers chains are directly bonded with the surface of the solid and the surfactants molecules are present in the upper part of the EDL.     

Thermodynamics of surfactant-dye complex formation in aqueous solutions. Sodium alkyl sulfates and azo oil dye systems

Thermodynamics of surfactant-dye complex formation have been studied, in terms of equilibrium coefficient, using a spectrophotometer. The systems are 6 sodium alkyl sulfates, which have different alkyl chain lengths, and 4-phenylazo-1-naphthylamine. A pronounced spectral change in the dye solution occurs on addition of the surfactant; the change has a definite isosbestic point and a new absorption band at 535 nm because of surfactant-dye complex formation, which is caused by hydrophilic-hydrophilic interaction. As the alkyl chain length in the surfactant increases, the values of free energy change (negative) increase, while the value of enthalpy change (negative) increases and the value of entropy change (positive) decreases. The longer the alkyl chain length in surfactant increase, the more stable the surfactant-dye complex becomes.Surfactant-dye complex will form due to hydrophilic-hydrophilic interaction and will become more stable due to hydrophobic-hydrophobic interaction.     

Effect of Molecular Weight on the Interfacial Dilational Viscoelasticity of Anionic Polyelectrolyte/Surfactant Systems

In this article, the effect of molecular weight on the interfacial tension and interfacial dilational viscoelasticity of polystyrene sulfonate/surfactant adsorption films at the water-octane interface have been studied by spinning drop method and oscillating barriers method respectively. The experimental results show that different interfacial behaviors can be observed in different type of polyelectrolyte/surfactant systems. PSS/cationic surfactant CTAB systems show the classical behavior of oppositely charged polyelectrolyte/surfactant systems and can be well explained by electrostatic interaction. Molecular weight of PSS plays a crucial role in the nature of adsorption film. The complex formed by CTAB and higher molecular weight PSS, which has larger dimension and stronger interaction, results in higher dilational modulus at lower surfactant bulk concentration. In the case of PSS/anionic surfactant SDS systems, the co-adsorption of PSS at interface through hydrophobic interaction with alkyl chain of SDS leads to the increase of interfacial tension and the decrease of dilational modulus at lower surfactant bulk concentration. For PSS/nonionic surfactant T × 100 systems, PSS may form a sublayer contiguous to the aqueous phase, which has little effect on interfacial tension but slightly decreases dilational modulus.     

Studies on the Interaction of Surfactants with Cationic Dye by Absorption Spectroscopy

The interaction of methyl violet, a cationic dye, with various surfactants, viz. anionic (SDS), nonionic (Triton X-100), and cationic (CTAB), has been investigated spectrophotometrically in submicellar and micellar concentration range. While in the submicellar concentration region of SDS the higher aggregates of the dye are found, in the micellar concentration region the monomer of the dye predominates. With nonionic surfactant the dye is solubilized primarily as the monomer. CTAB produces no perturbation to the visible spectra of the dye. In the presence of strong electrolytes such as NaNO(3) and NaCl the dye aggregates are formed at a much lower SDS concentrations. Copyright 2000 Academic Press.     

Spectrophotometric study of interaction and solubilization of procaine hydrochloride in micellar systems

The interaction of Procaine hydrochloride (PC) with cationic, anionic and non-ionic surfactants; cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS) and triton X-100, were investigated. The effect of ionic and non-ionic micelles on solubilization of Procaine in aqueous micellar solution of SDS, CTAB and triton X-100 were studied at pH 6.8 and 29°C using absorption spectrophotometry. By using pseudo-phase model, the partition coefficient between the bulk water and micelles, K_x, was calculated. The results showed that the micelles of CTAB enhanced the solubility of Procaine higher than SDS micelles (K_x = 96 and 166 for SDS and CTAB micelles, respectively) but triton X-100 did not enhanced the solubility of drug because of weak interaction with Procaine. From the resulting binding constant for Procaine-ionic surfactants interactions (K_b = 175 and 128 for SDS and CTAB surfactants, respectively), it was concluded that both electrostatic and hydrophobic interactions affect the interaction of surfactants with cationic procaine. Electrostatic interactions have a great role in the binding and consequently distribution of Procaine in micelle/water phases. These interactions for anionic surfactant (SDS) are higher than for cationic surfactant (CTAB). Gibbs free energy of binding and distribution of procaine between the bulk water and studied surfactant micelles were calculated.      

光度法研究染料与非离子表面活性剂的相互作用

染料与表面活性剂的相互作用对纺织品的染色有重要影叫,一直是广泛研究的课题.近年来由于胶束增溶光度法的发展,它又引起了分析化学家的注意.但是现有的研究多集中于染料与电性相反的离子型表面活性剂的相互作用,且缺乏深入的定量研究.本文研究一种阴离子染料——漂蓝6B与非离子表面活性剂Triton X-100间的相互作用,用光度法定量地确定了二者的结合比,并进而研究了阴离子表面活性剂SDS对此种相互作用的影响.     

Studies on the molecular interaction of safranin-T with surfactants

The spectrophotometric studies of safranin-T (Saf-T) dye in an aqueous solution containing three different types of surfactants such as CTAB (cationic), SLS (anionic) and Triton X-100 (TX-100), Tween-20, 40, 60 and 80 (nonionic) show that Saf-T forms a 1:1 molecular complex with TX-100, Tweens and SLS. Such a type of interaction is absent in Saf-T and CTAB. The thermodynamic and spectrophotometric properties of these complexes suggest that Saf-T forms a strong charge transfer (CT) complex with TX-100 and Tweens, whereas the interaction of Saf-T with SLS is coulombic in nature. Photogalvanic and photoconductometric studies also support the above interactions. In addition to this, the electron-donating ability among the nonionic surfactants i.e. TX-100 and Tweens towards dye, role of surface in CT interaction, the site of CT interaction and the intensity and stability of CT interaction between Saf-T and nonionic surfactants have been pointed out.     

Effect of Sodium Barbital on the Physico‐chemical Properties of Surfactants with Different Charges

The effects of sodium barbital (SB) on the solubility of different kinds of surfactants viz., CTAB (cationic head group), SDS (anionic head group) and Triton X‐100 (non ionic head group) in solution phase as well as their first and second critical micelle concentrations (CMC1 and CMC2), the change in Kraft temperatures (T_K) and cloud points (CP) have been studied. Furthermore, the article reports SB‐surfactant interaction study, which is application oriented and highlights the underlying physico‐chemical aspects of the system through florescence and conductivity measurements. The results show that the solubility of CTAB and Triton X‐100 increases with the addition of SB, and that of SDS increases in the presence of small amounts of SB and decreases in the presence of large amounts of SB. With the increasing SB concentration, the CMC of CTAB and CMC1 of Triton X‐100 both increase, while the CMC of SDS decreases, and the CMC2 of Triton X‐100 has no obvious change. The addition of SB decreases the T_K of CTAB sharply, but it increases the T_K of SDS and the CP of Triton X‐100. The different effects of SB on the physico‐chemical properties of differently charged surfactants may be related to its different interactions with the surfactants.     

表面活性剂对海藻酸钠稀水溶液剪切粘度的影响

通过粘度法考察了不同pH值时, 阴离子聚电解质海藻酸钠(NaAlg)与阴离子表面活性剂十二烷基硫酸钠(SDS)、阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)、非离子表面活性剂辛基酚聚氧乙烯醚(TritonX-100)以及它们的复配体系的相互作用. 研究表明, 在酸性条件下, SDS和TritonX-100与NaAlg之间主要是疏水作用, 随着表面活性剂浓度的增加, 体系粘度下降直到基本不变, CTAB与NaAlg主要发生静电作用和疏水作用, 体系粘度随CTAB浓度的增加呈现先上升后下降的趋势. 在实验条件下, TritonX-100浓度为0.05 mmol·L-1时, SDS的加入, 使得NaAlg/TritonX-100体系的零剪切粘度下降, 而CTAB的加入, 在pH=3.0和5.0时, NaAlg/TritonX-100体系的零剪切粘度出现上升, 在pH=6.4时, 该体系零剪切粘度下降.     

吲哚方酸菁染料在表面活性剂水溶液中的光降解

考察了4种含有不同N位取代基的对称吲哚方酸菁染料在阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)、阴离子表面活性剂十二烷基硫酸钠(SDS)和非离子表面活性剂曲拉通(TX-100)水溶液中的光降解行为,结果表明,表面活性剂对染料分子具有保护作用,其影响大小为CTAB>TX-100>SDS,分子中有羧基的染料受影响程度最大。在表面活性剂浓度较低时,染料光降解程度随着表面活性剂浓度的增加而增加,但形成胶束后,染料的光降解程度则随着表面活性剂浓度的升高而降低。     

Absorption spectra of 7, 7, 8, 8-tetracyanoquinodimethane in micellar solutions.

The absorption spectra of 7, 7, 8, 8-tetracyanoquinodimethane (TCNQ) with nonionic surfactant. Triton X-100, anionic surfactant, SLS and cationic surfactant, CTAB in aqueous and nonaqueous media have been studied. The spectral studies show that TCNQ forms 1:1 charge-transfer (CT) complex with Triton X-100 in both media. The aqueous solution of TCNQ shows an absorption maxima at 610 nm, which is unperturbed in the presence of SLS but is shifted to 650 nm in the presence of CTAB, indicating the interaction of TCNQ with the cationic surfactant and not with the anionic surfactant. In addition to this, the stability of TCNQ-Triton X-100 complex has been determined and the probable site of CT interaction has been pointed out.     

Micellar Catalysis on Pentavalent Vanadium Ion Oxidation of D-Sorbitol in Aqueous Acid Media: A Kinetic Study

Vanadium(V) oxidation of D-sorbitol shows a first-order dependency on the concentrations of D-sorbitol, vanadium(V), H⁺ and HSO₄⁻. These observations remain unaltered in the presence of externally added surfactants. The effects of the cationic surfactant (i.e., CPC), anionic surfactant (i.e., SDS) and neutral surfactant (i.e., TX-100) have been studied. CPC inhibits the reactions whereas SDS and TX-100 accelerate the reaction to different extents. SDS and TX-100 can be used as catalysts in the production of D-glucose from D-sorbitol.     

Fluorescence probing of albumin-surfactant interaction

Protein-surfactant interactions were studied using bovine serum albumin (BSA) and the three surfactants sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB), and poly(oxyethylene)isooctyl phenyl ether (TX-100). The surfactants used belong to three broad classes, i.e., anionic, cationic, and nonionic. These categories of surfactants were used to elucidate the mechanism of surfactant binding to BSA, at pH 7. The interactions were followed fluorimetrically using both intrinsic tryptophan (Trp) fluorescence and the fluorescence of an external label. The aggregation behavior of the surfactants were studied in the presence of BSA. Steady-state fluorescence studies indicate that all three surfactants bind to BSA in a cooperative manner. This cooperative binding affects the binding of the external label to BSA. All these effects are also manifested in time-resolved fluorescence studies. The effects of surfactants on acrylamide quenching and energy transfer from Trp in BSA to bound dye provided valuable insights into the structural modification of BSA in presence of surfactants. The surfactant-induced conformational change of BSA was also confirmed by circular dichroism studies. However, among the three categories of surfactants, the nonionic surfactant shows the least interaction with BSA.     

Ultrafast photoinduced electron transfer from dimethylaniline to coumarin dyes in sodium dodecyl sulfate and triton X-100 micelles

The primary steps of photoinduced electron transfer (PET) from N,N-dimethylaniline (DMA) to five coumarin dyes are studied in an anionic micelle [sodium dodecyl sulfate (SDS)] and a neutral micelle [triton X-100 (TX-100)] using femtosecond upconversion. The rate of PET in micelle is found to be highly nonexponential. In both the micelles, PET displays components much faster (approximately 10 ps) than the slow components (180-2900 ps) of solvation dynamics. The ultrafast components of electron transfer exhibit a bell-shaped dependence on the free energy change. This is similar to Marcus inversion. The rates of PET in TX-100 and SDS micelle are, in general, faster than those in cetyltrimethylammonium bromide (CTAB) micelle. In the SDS and TX-100 micelle, the Marcus inversion occurs at -DeltaG0 approximately 0.7 eV which is lower than that (approximately 1.2 eV) in CTAB micelle. Possible causes of variation of PET in different micelles are discussed.     

Quenching of zinc phthalocyanine excited states by viologen surfactant assemblies——The influence of microenvironment

A series of functional surfactants of N-alkyl-N'-butyl viologens has been synthesized.The quenching of excited singlet and triplet states of zinc phthalocyanine was studied in DMSOand in mixed micelles containing the functional surfactant as one and cationic cetyl trimethylam-monium bromide(CTAB),anionic sodium dodecylsulfate(SDS)and neutral TX-100 surfactantas the other component.Fluorescence quenching and laser photolysis studies indicate that thefunctional surfactants are solubilized at different sites in micelles,the process depends on chainlength and exerts great influence on the quenching of zinc phthalocyanine excited states.