Triton X-100 Reverse Micelles Research Articles

Optimization and in Silico Analysis of a Cold-Adapted Lipase from an Antarctic Pseudomonas sp. Strain AMS8 Reaction in Triton X-100 Reverse Micelles

A moderate yield of a purified enzyme can be achieved by using the simple technique of reverse micellar extraction (RME). RME is a liquid–liquid extraction method that uses a surfactant and an organic solvent to extract biomolecules. Instead of traditional chromatographic purification methods, which are tedious and expensive, RME using the nonionic surfactant Triton X-100 and toluene is used as an alternative purification technique to purify a recombinant cold-adapted lipase, AMS8. Various process parameters were optimized to maximize the activity recovery of the AMS8 lipase. The optimal conditions were found to be 50 mM sodium phosphate buffer, pH 7, 0.125 M NaCl, and 0.07 M Triton X-100 in toluene at 10 °C. Approximately 56% of the lipase activity was successfully recovered. Structural analysis of the lipase in a reverse micelle (RM) was performed using an in silico approach. The predicted model of AMS8 lipase was simulated in the Triton X-100/toluene reverse micelles from 5 to 40 °C. The lid 2 was slightly opened at 10 °C. However, the secondary structure of AMS8 was most affected in the non-catalytic domain compared to the catalytic domain, with an increased coil conformation. These results suggest that an AMS8 lipase can be extracted using Triton X-100/water/toluene micelles at low temperature. This RME approach will be an important tool for the downstream processing of recombinant cold-adapted lipases.

Electrodeposited nanoporous ruthenium oxide for simultaneous quantification of ascorbic acid and uric acid using chronoamperometry at two different potentials

Nanoporous ruthenium dioxide (RuO2) was simply prepared by electrodeposition with potential cycling in RuCl3 solution in the presence of reverse micelles of Triton X-100. The electrodeposited RuO2 on Au substrate electrode showed high electroactivity for the oxidations of L-ascorbic acid (AA) and uric acid (UA), while AA oxidation started from a less positive potential compared to UA oxidation. Simultaneous quantitative analysis of AA and UA was successfully carried out via chronoamperometric measurements at two different applied potentials using RuO2 deposited electrode. Due to the oxidation potential difference between AA and UA at RuO2 electrode, only AA was oxidized at an applied potential of 0.20V vs. SCE and both AA and UA were oxidized at 0.32V vs. SCE. AA concentration was determined from the current measured at 0.20V; and then UA concentration was estimated from the current measured at 0.32V using the predetermined AA concentration. Electrodeposited nanoporous RuO2 electrode exhibited current responses linearly proportional to AA and UA concentrations in a wide concentration range (0–1mM) and fast response time (≤1s). The current sensitivities were 342.8±26.3μAmM−1cm−2 for AA at 0.20V; 377.8±18.4μAmM−1cm−2 for AA at 0.32V; and 344.2±11.6μAmM−1cm−2 for UA at 0.32V. In addition, RuO2 electrode showed a high selectivity over interferents such as 4-acetamidophenol (AP), dopamine (DA), and glucose. Reasonable stability and repeatability of RuO2 electrode were also confirmed. Selective quantification of AA and UA in an arbitrary mixture and a human urine sample demonstrated that RuO2 electrode has practical utility in real sample analysis with satisfactory results.

Visible and fluorescence spectroscopic studies on interaction of water-soluble anionic azo dyes with Triton X-100 in reverse micelle media

A series of Triton X-100 (TX-100) reverse micelles was prepared in isooctane and characterized with respect to size, polarity, and electric conductivity. Three typical azo dyes including methyl orange (MO), Acid Black 234 (AB 234) and Reactive Red 195 (RR 195) were selected and solubilized in the water phase to investigate their interaction with TX-100 reverse micelles. Effect of water content on the spectra of these dyes in the micelles was also examined. It has been revealed from the experimental results that at low water content, MO and AB 234 may be located in the polar core but outside the water pool of the micelles. Increasing water content leads to their gradual movement towards the water pools. AB 234 may bind to the micelles more closely than MO, especially at high water content. Moreover, the stronger interaction between RR 195 and TX-100 result in the complex formation. Higher water content enhances the transition from bound RR 195 to free RR 195. It can be concluded that the spectral characteristics of the three dyes in the micelles are very different owing to the space limitation and the polarity evolution of the microenvironment of the micelles.

Adsorption and dyeing characteristics of reactive dyes onto cotton fiber in nonionic Triton X-100 reverse micelles

The nonionic reverse micelles used for dyeing cotton fiber were prepared with a non-ionic surfactant Triton X-100 (TX-100) by injecting small amount of reactive dye aqueous solution. The adsorption capacity of three water-soluble anionic azo dyes including Reactive Blue 222, Reactive Red 195 and Reactive Yellow 145 onto cotton fiber was investigated. The Langmuir and Freundlich isothermals were employed to model the adsorption data. In addition, the color strength and fixation rate of cotton fabrics dyed in the reverse micelles and bulk water were examined and compared. The salt and alkali as influencing factors were also discussed. The FT-IR spectra were employed to study the polarity of water added in reverse micelles. The results indicated that the adsorption of the dyes onto cotton showed better agreement with Langmuir model. The adsorption process was monolayer adsorption. Reactive Yellow 145 with lower negative charge and higher hydrophilicity exhibited the higher adsorption capacity. The fixation percentage and color strength of the cotton fiber dyed in TX-100 reverse micelles was higher than those in bulk water. The polarity of water in TX-100 reverse micelles was lower than that in bulk water.

Degumming of Mulberry Silk with Papain in Non-Aqueous Systems

The nonionic reverse micelles used for degumming of mulberry silk were prepared with a non-ionic surfactant Triton X-100 (TX-100) by injecting small amount of papain aqueous solution. The weight loss of mulberry silk degummed at different concentration of papain in TX-100 reverse micelles was investigated. The effect of the amount of solubilized water was also discussed. The polarizing optic microscope was employed to observe the surface morphology of the mulberry silk. The results indicated that the weight loss of the mulberry silk was increased with increasing concentration of papain, but the W values exhibited the reverse trend. The good degumming of mulberry silk with papain was obtained in TX-100 reverse micelles. The strength of mulberry silk decreased with increasing concentration of papain.

Salt-Free Dyeing of Cotton Woven Fabric with Reactive Dyes in Triton X-100 Reverse Micellar Media

The nonionic reverse micelles used for dyeing cotton fiber were prepared with a non-ionic surfactant Triton X-100 (TX-100) by injecting small amount of reactive dye aqueous solution. The percentage of dye bath exhaustion in TX-100 reverse micelles and in bulk water was carried out and compared, respectively. The effect of inorganic salt was also discussed. The results indicated that the dyeing properties of the reactive dyes on cotton fabric increased with decreasing NaCl concentration and increasing initial dye concentration in TX-100 reverse micelle. The percentage of dye bath exhaustion obtained in reverse micelles was higher than that in bulk water.

Ultrafast torsional dynamics in nanoconfined water pool: Comparison between neutral and charged reverse micelles

Abstract Photophysical properties and the ultrafast excited state torsional dynamics of an amyloid fibril sensing dye, Thioflavin-T, have been investigated in Triton X-100 reverse micelle as a function of water content. This study has been undertaken to comprehend the effect of interfacial charge on the ultrafast torsional dynamics of Thioflavin-T in nanoconfined reverse micellar system. The emission intensity and the fluorescence lifetime of Thioflavin-T increases considerably in the nonionic reverse micellar system as compared to bulk water indicating a strong confinement effect on the photophysical behavior of the probe. The photophysical parameters of Thioflavin-T in Triton X-100 reverse micelle is found to be almost invariant with the increasing water content, which is in sharp contrast to its behavior in ionic reverse micelles (Journal of Physical Chemistry 113 (2009) 8532, Chemical Communication 47 (2011) 6912). This behavior has been rationalized on the basis of the differences in the localization sites of the probe in the nonionic and ionic reverse micelles. Photophysical properties of Thioflavin-T in triethyleneglycol monomethyl ether, which mimic the interior of the Triton X-100 reverse micelle, at different water content also confirms the site of localization of the probe in the nonionic reverse micelle. Present result in combination with that reported in ionic reverse micelles suggest that the reaction dynamics of the probe in the nanoconfined water pools of reverse micelle are strongly influenced by interfacial charge, which in fact control the location of the probe in the reverse micellar systems.

Adsorption Study of Reactive Dyes on Cotton Fabric in Non-Aqueous Systems

Abstract: The non-ionic reverse micelles used for dyeing cotton fabric were prepared with a non-ionic surfactant Triton X-100 (TX-100) by injecting small amount of reactive dye aqueous solution. The effect of electrolyte on the adsorption capacity of reactive dyes onto cotton fabric in this system was studied. And the adsorption properties of three water-soluble anionic azo dyes including Reactive Blue 222, Reactive Red 195 and Reactive Yellow 145 onto cotton fabric in TX-100 reverse micelle were also studied and compared. The results indicated that reactive dyes showed a better adsorption property on cotton fabric in TX-100 reverse micelle without the addition of NaCl. The adsorption of the dyes onto cotton showed better agreement with Langmuir isotherm equation. Reactive Yellow 145 with lower negative charge and higher hydrophilicity exhibited the higher adsorption capacity than the other dyes. The adsorption process follows by the chemical adsorption.

Study on the Morphology Feature of 1-Butyl-3-methylimidazolium Tetrafluoroborate Based Ionic Liquid Reverse Microemulsions

The micromorphology of 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF4)-in-cyclohexane and bmimBF4-in-triethylamine ionic liquid microemulsions was investigated by two-dimensional NMR and freeze-fracture transmission electron microscopy. The reverse micelles of Triton X-100/cyclohexane were destroyed by adding bmimBF4 and reverse microemulsions were induced to form by successively adding bmimBF4. However, no micelles appeared in triethylamine. But if adding bmimBF4 to a certain extent, a reverse microemulsion was also formed. The driving force of such aggregations could be attributed to the presence of different types of interactions between Triton X-100 and bmimBF4. A staggered arrangement of surfactant led to the irregular droplet structure and large aggregate size.

Electrocatalytic activity of nanoporous Pd and Pt: effect of structural features

The electrocatalytic activities of nanoporous palladium (npPd) and platinum (npPt) for oxygen reduction reaction (ORR) under alkaline conditions and hydrogen peroxide electrochemical reactions under neutral conditions were examined. npPd and npPt were prepared by the electrochemical deposition of each metal from the corresponding metal precursor in the presence of reverse micelles of Triton X-100, directing highly porous microstructures. The nanoporous catalysts showed excellent electrocatalytic activity for both the ORR and hydrogen peroxide electrochemical oxidation/reduction due to the increased active surface area. In particular, the npPd exhibited superior ORR activity (i.e., more positive onset and half-wave potentials, higher current density and greater number of electrons transferred) despite the smaller roughness factor than the npPt and commercial Pt. The catalytic activity for the hydrogen peroxide electrochemical reactions was also higher while using npPd (i.e., faster electrode reaction kinetics, increased current densities, etc.) compared to npPt. The higher catalytic activity of npPd than that of npPt suggests an advantage of the unique npPd structure, composed of nano- as well as micro-porosity, in facilitating mass transport through the porous metal layer. The npPd exhibited amperometric current responses, induced by the oxidation as well as reduction of hydrogen peroxide, linearly proportional to the hydrogen peroxide concentration with a rapid response time (<~2 s), high sensitivity, and low detection limit (<1.8 μM).

Determination of β-sitosterol and cholesterol in oils after reverse micelles with Triton X-100 coupled with ultrasound-assisted back-extraction by a water/chloroform binary system prior to gas chromatography with flame ionization detection

Ultrasonic back-extraction of Triton X-100 reverse micelles by a water/chloroform binary system and gas chromatography with flame ionization detection (GC-FID) was developed for extraction and determination of β-sitosterol and cholesterol in soybean and sunflower oil samples. After the homogenization of the oil samples with Triton X-100, an aliquot of 200 μL of methanol was added to the samples to form two phases. The clear Triton X-100 extract obtained by centrifugation was treated with a mixture of water (1000 μL) and chloroform (300 μL) for back-extraction of the analytes into the chloroform phase by ultrasonication. After centrifugation, the sedimented chloroform layer was withdrawn easily by a microsyringe and directly injected into the GC-FID system. The influence of several important parameters on the extraction efficiencies of the analytes was evaluated. Under optimized experimental conditions, the calibration graphs were linear in the range of 1.0–30.0 mg L −1 with coefficient of determination more than 0.994 for both analytes. The method detection limit values were in the range of 0.2–0.7 mg L −1. The lower limit of quantification values were in the range of 0.7–2.4 mg L −1. Intra-day relative standard deviations were in the range of 1.0–2.7%. This procedure was successfully applied with satisfactory results to the determination of β-sitosterol and cholesterol in spiked oil samples. The relative mean recoveries of oil samples ranged from 93.6% to 105.0%.

Adsorption of Acid Dyes onto Wool in TX-100 Reverse Micelles

The non-ionic reverse micelles used for dyeing wool were prepared with a non-ionic surfactant Triton X-100 (TX-100) by injecting small amount of acid dye aqueous solution. And the adsorption properties of three water-soluble anionic acid dye including Mordant Black 9, Acid Black 234 and Acid Orange 156 onto wool in TX-100 reverse micelle were studied and compared. Then effect of W value (molar ratio of the injected water to TX-100) and pH level on dye adsorption was also investigated. The results indicate that Higher W value and Low pH level would increase the adsorption amount of the dye onto wool. The adsorption of the dye onto wool showed better agreement with Langmuir isotherm equation. Mordant Black 9 with lower molecular weight and one sulfonic group exhibited the higher adsorption capacity than the other dyes.

Specifics of the preparation of anisotropically shaped gold nanoparticles in triton X-100 reverse micelles

The influence of the form of micelles and reactant concentrations on the formation and growth of gold nanoparticles in reverse micelles based on Triton X-100 (polyoxyethylene octyl phenyl ether) was studied. It was shown that spherical nanoparticles of 3–4 nm in size are formed in the presence of sodium sulfite and ascorbic acid and particles of an extended shape are formed in the presence of ascorbic acid alone. It was found that the ultimate shape and size of the nanoparticles depend not only upon the form of micelles but also on the acid concentration, since the products of its oxidation can be selectively sorbed on the surface of the particles and act as additional shape modifiers.

Catalytic hydrogenation of dimethyl itaconate in non-ionic microemulsions: influence of the size of micelle

The structural dimensions of two different microemulsions were extracted and correlated with the catalytic hydrogenation of dimethyl itaconate (DMI) performed in such media using the water-soluble catalyst complex Rh–TPPTS. The commercial, polyoxyethylene-based non-ionic surfactants Igepal CA-520 and Triton X-100 were used to obtain two different types of microemulsions with cyclohexane and water; pentanol as a cosurfactant was added to the Triton system. Dynamic light scattering (DLS) and small angle neutron scattering (SANS) measurements were used to determine the characteristic sizes of the Igepal and Triton microemulsions, respectively, showing a linear dependence between the initial hydrogenation rate of DMI and the radius of the micelles. The initial hydrogenation rate of DMI in bulk water is exceeded in both microemulsions. Indications of deformation of the originally spherical Triton X-100 reverse micelles upon addition of the water-soluble catalyst complex Rh–TPPTS were found.

Studies on absorption spectra of uniform gold nanoparticles prepared in Triton X-100 reverse micelles

A procedure for preparation of uniform gold nanoparticles in the ternary Triton X-100/water/cyclohexane system in the presence of sodium sulfite is suggested. The formation and stabilization of nanoparticles in Triton X-100-based reverse micelles in the above ternary system and in the quaternary system (additionally containing n-hexanol) have been explored. The mechanism for formation of Au(0) and growth of gold clusters was found to depend on the initial concentration of HAuCl 4 and Na 2SO 3. The mean size of nanoparticles formed in reverse micelles in the ternary system was markedly smaller (less 5 nm) than of those formed in the quaternary system (from several to dozens nanometers).

Excited-State Proton Transfer of 2-(2‘-Pyridyl)benzimidazole in Microemulsions: Selective Enhancement and Slow Dynamics in Aerosol OT Reverse Micelles with an Aqueous Core

Excited-state proton transfer (ESPT) of 2-(2'-pyridyl)benzimidazole (2PBI) in reverse micelles has been studied by steady-state and time-resolved fluorescence spectroscopy. The nanometer sized water pool in the n-heptane/Aerosol OT (AOT)/water microemulsion is found to promote tautomer emission of this probe, as is evident from the emergence of a Stokes shifted band at 450 nm at the expense of the normal emission band on increasing the water content of the system. In the nonaquous microemulsion with a methanol core, the normal emission is quenched but no tautomer emission is obtained. With an acetonitrile core, there is no change in emission properties. Similarly, there is no evidence of ESPT in Triton X-100 reverse micelles. This indicates the requirement of ESPT to occur in microheterogeneous media; the medium should be a ternary system comprised of water and a hydrophobic phase separated by a negatively charged interface. In the microemulsions with an aqueous core, the fluorescence decays of 2PBI at the red end exhibit rise times of 0.8 ns and the time-resolved area-normalized emission spectra (TRANES) exhibit an isoemissive point, indicating slow dynamics of the two-state ESPT of 2PBI in aqueous AOT reverse micelles. The origin of the selective enhancement in AOT microemulsions as well as the slow dynamics is explored using fluorescence spectroscopic techniques, with support from quantum chemical calculation.

Synthesis and Stabilization of Gold Nanoparticles in Reverse Micelles of Aerosol OT and Triton X-100

Mechanisms of the formation and stabilization of gold nanoparticles in reverse micelles of micro-emulsions based on Triton X-100 (TX-100) and Aerosol OT (AOT) are studied. The instability of AOT-based microemulsions is shown to be caused by the oxidative degradation of gold nanoparticles in micelle water pools. Methods are proposed for the stabilization of these microemulsions. It is revealed that the mean size of gold nanoparticles synthesized in TX-100 reverse micelles in the presence of sodium sulfite is markedly smaller than that of particles prepared in AOT reverse micelles. This is explained by the fact that gold clusters are formed in the micelle shell rather than in the water pool. In the shell, the clusters are stabilized by oxyethylene groups of TX-100 molecules.

Kinetics of dissociation of tris-(2,2′-bipyridyl) iron(II) in water solubilized by Triton X-100 reverse micelles

The dissociation of tris-(2,2′-bipyridyl) iron(II) ([Fe(bipy) 3] 2+) has been studied in the Triton X-100/hexanol/cyclohexane reverse micellar medium. The reaction obeys simple first-order kinetics with no evidence of autoinhibition. The first-order rate constant ( k 1 ) has been determined at different values of W ([H 2O]/[Triton X-100]). The rate ( k 1 ) decreases with increasing value of W. k 1 also increases with increase in Triton X-100 concentration at constant values of W, showing that the reaction takes place at greater speed at the micellar interface. The kinetic results can be interpreted by the monomolecular pseudo-phase model. The effect of W on rate ( k 1 ) is more pronounced in the range of W from 1.55 to 4.2 but less pronounced at higher W. The reaction is further accelerated by Cl − and SCN − ions and the kinetic results provide evidence for the formation of ion pairs between the cation [Fe(bipy) 3] 2+ and each of these anions. The formation of such ion pairs has not been observed in aqueous medium but has been reported earlier in aqueous–alcohol mixtures. This result therefore provides evidence for the lower micropolarity of solubilized water compared to ordinary water.

Metachromatic effects and photodegradation of basic blue on nanocrystalline titania films.

Titania nanocrystalline films have been deposited on solid substrates by a sol-gel procedure carried out in Triton X-100 reverse micelles. When the dye Basic Blue is adsorbed on these films, it demonstrates a strong metachromatic effect; that is, it aggregates, resulting in a blue shift of its absorption spectrum. Metachromasy in this system is related to the hydrophilicity of the film surface and to the humidity of the film environment. Films composed of 67% titania and 33% silica gave an intense and reversible metachromatic effect that can be exploited to make a handy humidity sensor. Photodegradation of Basic Blue on titania films is faster in humid environments than in dry environments, and this goes in parallel with metachromatic effects.

Energy transfer—a tool for probing micellar media

The non-ionic polyoxyethylene chain-containing surfactant Triton X-100 (TX-100) forms well-defined micelles and reverse micelles in aqueous and hydrocarbon media, respectively. Nonradiative energy transfer between two charged fluorescent dyes, fluorescein (FL) and acridine orange (AO) has been used to probe the micelles and reverse micelles of TX-100. In the energy transfer system employed, FL acts as the donor and AO as the acceptor. This is borne out by the fluorescence spectral data. Time-resolved studies further corroborate the steady-state results. As the fluorescence emission spectra of the two dyes show a considerable amount of overlap, they are resolved into individual donor and acceptor components using the principal component analysis (PCA) method. This study also focuses on the more important role played by hydrophobic forces (compared with electrostatic interactions) in promoting energy transfer between charged species in micellar media.