Disruption of reverse micelles and release of trapped ribonuclease A photochemically induced by Malachite Green leuconitrile derivative

Photoinduced disruption of a sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reverse micelle is triggered by a Malachite Green leuconitrile derivative (MGL). UV irradiation of MGL solubilized in an AOT-water-chloroform mixture creates a cationic surfactant that interacts electrostatically with the anionic AOT. We investigated the disruption of the reverse micelle by using proton nuclear magnetic resonance spectroscopy and found that UV irradiation of MGL decreases the number of water molecules solubilized in the interior of the AOT reverse micelles. Furthermore, the photoinduced disruption of the reverse micelle is shown to release ribonuclease A, which is trapped in the water in the interior of the AOT reverse micelle. This photoinduced release may offer a desirable transport system of biopolymers.     

Membrane Potential Photoresponse of Crowned Malachite Green Derivatives Affording Perfect Photoswitching of Metal Ion Complexation

Photoirradiation effect on potential response to metal ion concentrations and photoinduced potential change were investigated with poly(vinyl chloride) membranes based on a Malachite Green derivative carrying a bis(monoaza-15-crown-5) moiety, by comparing other Malachite Green derivatives. The Malachite Green carrying a bis(crown ether) moiety caused a potential response to potassium ion concentration changes under dark condition. In the membrane potential response, a clear-cut photoinduced switching of potential response was realized by the membrane of Malachite Green carrying a bis(crown ether) moiety, which exhibited no potential response to potassium ion concentrations (0 mV/decade) on UV irradiation. On the other hand, a Malachite Green carrying a monocyclic benzocrown ether moiety showed a considerable dependence of the membrane potential on the metal ion concentrations under both dark and UV irradiation conditions.     

Membrane Potential Photoresponse of Crowned Malachite Green Derivatives Affording Perfect Photoswitching of Metal Ion Complexation

Photoirradiation effect on potential response to metal ion concentrations and photoinduced potential change were investigated with poly(vinyl chloride) membranes based on a Malachite Green derivative carrying a bis(monoaza-15-crown-5) moiety, by comparing other Malachite Green derivatives. The Malachite Green carrying a bis(crown ether) moiety caused a potential response to potassium ion concentration changes under dark condition. In the membrane potential response, a clear-cut photoinduced switching of potential response was realized by the membrane of Malachite Green carrying a bis(crown ether) moiety, which exhibited no potential response to potassium ion concentrations (0 mV/decade) on UV irradiation. On the other hand, a Malachite Green carrying a monocyclic benzocrown ether moiety showed a considerable dependence of the membrane potential on the metal ion concentrations under both dark and UV irradiation conditions.This revised version was published online in July 2005 with a corrected issue number.     

A Study of the Solubilization of Polar Oily Materials by Alkyl Polyglucoside and Sodium Dodecyl Sulfate in Mixed Surfactant System

The effects of different alkyl chains of nonionic surfactants and solubilized polar oily material on the solubilizing capacity of binary anionic‐nonionic mixed surfactant systems were studied. This system includes surface tension measurements to determine the critical micelle concentration. Results were analyzed using regular solution theory to obtain the mixed micelle and the interaction parameter β, in order to evaluate the type of interactions of surfactants in the mixed micelle. Solubilizing capacity has been investigated by measuring the optical density of solubilized polar oily materials like octanol, decanol, and dodecanol. The solubilizing phenomenon exhibited by mixed surfactants systems showed better results than that of the individual surfactant system. The amount of solubilization in mixed surfactant increases with increase in carbon chain length of alkyl polyglucoside.     

Rheological Properties of a Novel Photosensitive Micelle Composed of Cationic Gemini Surfactant and 4-Phenylazo Benzoic Acid

A new and simple reversible photorhelogical (PR) micelle system was investigated, which is composed of the cationic Gemini surfactant propylene-(dimethyldioctadecylammonium chloride) (18-3-18) and the photoresponsive counter ion, trans-4-phenylazo benzoic acid (trans-ACA). Before UV irradiation, the 18-3-18/trans-ACA mixtures with proper compositions formed highly viscoelastic fluids, showing good viscoelasticity, thixotropy, and shear thinning properties. After UV irradiation, the rheological properties of 18-3-18/ACA micelles changed obviously, exhibiting UV photothinning properties, because the trans-ACA was isomerized to cis-ACA. For the 18-3-18/ACA (8 mM/10 mM) micelle system, after 1 hour UV irradiation at 365 nm, the reduction percentage of the relative viscosity of the micelle was nearly 90%, and its thixotropy loop disappeared. It was revealed that the rheological properties of micelles changed gradually during the process of UV irradiation. In addition, the rheological properties of UV-irradiated micelles can recover after visible light irradiation. The proposed mechanism was validated by ultraviolet-visible (UV-vis) spectra of 18-3-18/ACA micelles.     

Photochemically triggered reaction of glucose oxidase in a fused vesicle containing Malachite Green leuconitrile derivative

Glucose oxidase (GOD) was encapsulated in vesicles containing a photoionizable Malachite Green leuconitrile derivative (MGL). Subsequent UV irradiation of MGL afforded the fusion of GOD- and glucose-encapsulating vesicles and thus decreased the concentration of glucose in the vesicles. The time dependence of the vesicle fusion was studied using fluorescent probe molecules. This phototriggered fusion could be instrumental in the development of a system for the production of nanometer-sized bioreactors.     

Metal-driven viscoelastic wormlike micelle in anionic/zwitterionic surfactant systems and template-directed synthesis of dendritic silver nanostructures

In this work, metal ion-induced viscoelastic wormlike micelles in anionic/zwitterionic surfactant solutions (sodium dodecylsulfate/tetradecyldimethylammoniumpropanesulfonate, SDS/TPS) are reported. Steady and dynamic rheology and cryogenic transmission electron microscopy (cryo-TEM) are employed to characterize wormlike micelles in the SDS/TPS/Ca(NO(3))(2) system. Moreover, the surfactant mixing ratio and surfactant tail length are varied to reveal the factors that influence wormlike micelle growth and solution viscoelasticity. A series of metal ions such as Na(+), Mg(2+), Zn(2+), and Al(3+) are proven to promote viscoelastic wormlike micelle formation in the SDS/TPS system. The metal-containing wormlike micelles are expected to be good candidates for directing the synthesis of inorganic nanomaterials. In this article, dendritic silver nanostructures have been prepared in the surfactant wormlike micelle by in situ UV irradiation for the first time.     

Spectrophotometric study of the interaction of some triphenylmethane dyes and 1-carbethoxypentadecyltrimethylammonium bromide

The effect of the cationic surfactant 1-carbethoxypentadecyltrimethylammonium bromide at above and below its critical micelle concentration on the absorption spectra and the values of the apparent dissociation constant pK(2) of the dyes Phenol Red, Bromophenol Blue and Bromocresol Green has been studied, along with the influence of a strong electrolyte (NaCl) on the effects produced by the presence of surfactant micelles in the dye solution.     

A novel and highly sensitive catalytic method with oscillopolarographic detection for the determination of ultratrace amounts of iridium

Iridium(IV) has a strong catalytic effect on the slow redox reaction between Malachite Green and periodate ion in pH 4.2 acetate buffer solution at 100 degrees , and Malachite Green exhibits a sensitive single-sweep oscillopolarographic wave at -0.65 V vs. SCE. This provides the basis for a novel and highly sensitive and selective catalytic method with oscillopolarographic detection for iridium. The effect of pH, potassium periodate and Malachite Green concentrations, reaction temperature and reaction time and other variables are investigated. The detection limit is 8 ng/l. with a fixed-reaction time of 10 min. A linear calibration graph from 24 to 1600 ng/l. is obtained. Possible interferences by co-existing ions are examined.     

The photodimerization of a cinnamoyl moiety derivative in dilute solution based on the intramolecular chain interaction of gemini surfactant

A Gemini surfactant, sodium N, N'-di(4-n-butyloxy cinnamoly)-L-cystine, containing a cinnamoyl moiety in the alkyl chains and disulfide bond in the spacer was designed and synthesized. The incorporation of a cinnamoyl moiety into the alkyl chains of Gemini surfactant makes it easy to probe the conformational information of the amphiphile molecule. The UV/vis absorption spectra and steady-state fluorescence were investigated at a concentration far below the critical micelle concentration (cmc). Both blue-shift of absorption and red-shift of fluorescence emission spectra indicate the existence of intramolecular interaction between the two alkyl chains in Gemini surfactant in the singly dispersed state. Results based on the breakdown of the disulfide bond by dithiotheritol (DTT) further confirmed the conclusion. Moreover, the characteristic of intramolecular chain interaction in Gemini surfactant improves the topochemical geometrical requirements of cinnamoyl moiety and increases the local concentration of reactant in dilute solution. Utilizing the incorporation of cinnamoyl moiety into the alkyl chains of Gemini surfactant, the cinnamoyl moiety upon irradiation undergoes dimerization in dilute aqueous solution with high yield of 78%.     

Interaction of flavonoids within organized molecular assemblies of anionic surfactant

The interaction of various flavonoids (compounds having C6-C3-C6 configuration) with sodium dodecyl sulfate (SDS) an anionic surfactant was studied through absorption spectroscopy as a function of the concentration of surfactant above and below the critical micelle concentration (CMC) of the surfactant. A mechanism was proposed for the interaction between these flavonoids and anionic surfactants. The approximate number of additive molecules (flavonoids) incorporated per micelle was estimated at a particular concentration of SDS. Incorporation of additive in micelles shifts the UV absorption bands towards higher wavelengths of different magnitude. The spectral shift also depends upon the nature of the surfactant head group. The absorption spectra of the flavonoids in aqueous solution and in methanol are also reported.     

Ionic-conductivity switching of vinyl malachite green leuconitrile copolymers based on photoinduced carrier generation

Copolymers of bis[4-(N,N-dimethylamino)phenyl]-4-vinylphenylmethanenitrile (vinyl Malachite Green leuconitrile) with methyl methacrylate or ω-methoxyoligo(oxyethylene) methacrylate have been synthesized, aiming at designing one-component-type organic polymers for photoswitchable ion-conducting films. The triphenylmethanenitrile copolymers with ω-methoxyoligo(oxyethylene) methacrylate were found to undergo ionic-conductivity switching by turning on and off UV light at ambient temperature, owing to their low glass transition temperature. © 1993 John Wiley & Sons, Inc.     

Screening and confirmation of triphenylmethane dyes and their leuco metabolites in trout muscle using HPLC-vis and ESP-LC-MS.

An extraction and clean-up protocol for the determination of Malachite Green and Crystal Violet and the corresponding leuco compounds in trout muscle has been developed. Final determination is by HPLC with visible (screening) or ESP-MS (confirmation) detection. In both cases lead(IV) oxide was used on-line to oxidise the leuco compounds back to the parent after chromatographic separation and prior to detection. The procedure was validated down to 2 micrograms kg-1. Intra- and inter-batch precision was measured at 3 levels for all compounds. Recoveries were in the range 66-116% with RSD of 1-17% for determination by HPLC with visible detection. For LC-MS determination, recoveries were in the range 61-94% with RSD of 4-15%. Limited surveillance data indicated that Malachite Green usage was more effectively monitored by including the leuco compound as well as the parent (9 positives for the leuco compound as opposed to 1 for Malachite Green out of 31 samples analysed).     

Photoinduced phase separation

A novel approach of photoinduced phase separation has been demonstrated with a photolabile anionic surfactant, mixed with an inert nonionic surfactant in the presence of salting-out electrolyte. Breakdown of the photolyzable surfactant results in hydrophobic photoproducts, which are emulsified by the remaining inert surfactant; added electrolyte resolves the emulsion into macroscopic oily and aqueous phases. The initial micellar systems can disperse an insoluble additive marker dye (shown), which may be spatially segregated from the aqueous environment by the action of UV light.     

Extraction and spectrophotometric determination of molybdenum(VI) with Malachite Green and p-chloromandelic acid

Molybdenum(VI) reacts with p-chloromandelic acid to form a complex extractable into chlorobenzene with Malachite Green, from aqueous solution at pH 2.0-4.0 at room temperature, and can then be determined indirectly by measuring the absorbance of the Malachite Green in the extract, at 630 nm. The calibation graph is linear for molybdenum over the range 0.26-10.0 x 10(-6)M (0.10-4.0 mug); the apparent molar absorptivity is 1.06 x 10(5) l.mole(-1).cm(-1). The method has been applied to the determination of molybdenum in mild steels with satisfactory results.     

Interfacial Rheological Property and Rheokinetics of a Novel Photoreversible Micellar System

A new photorheologically reversible micelle composed of a polymerizable cationic surfactant N-cetyl dimethylallyl ammonium chloride (CDAAC) and trans-4-phenylazo benzoic acid (trans-ACA) was prepared. Exposing the CDAAC/trans-ACA (14 mM/10 mM) micellar system to the UV light (365 nm) resulted in a decrease in the relative viscosity, and in turn, the relative viscosity increases to its initial value when the micellar system was exposed to visible light (460 nm), which is caused by the photoisomerization of ACA. The interfacial tension and modulus of the micellar system change significantly after UV irradiation and show the reversible interfacial rheological properties when irradiated by visible light. Furthermore, for the first time the dynamic changing of the rheological properties, i.e., the decreasing of viscosity and viscoelasticity during the UV irradiation, has been studied and well described by a rheokinetics model.     

Living cationic polymerization of a coumarin‐substituted vinyl ether and reversible photoinduced crosslinking of the resulting homopolymers and amphiphilic block copolymers

Living cationic polymerization of 4‐methyl‐7‐(2‐vinyloxyethoxy)coumarin (CMVE) was achieved using SnCl₄ in the presence of nBu₄NBr as an added salt at 0 °C. The number‐average molecular weight of the resulting polymers increased in direct proportion to the monomer conversion while retaining relatively low polydispersity. Structural analysis revealed that the resulting polymers carried pendant coumarinyl moieties. These coumarinyl moieties were crosslinked by irradiation with UV light at λ_max = 366 nm, and the crosslinked sites were then cleaved by irradiation with UV light at λ_max = 254 nm. The crosslinking behaviors of the polymers were studied by UV and FTIR spectroscopic measurement. PolyCMVE was soluble in dichloromethane but was found to be insoluble upon UV light irradiation. We also synthesized amphiphilic block polymers bearing coumarinyl moieties by living cationic copolymerization with an amphiphilic vinyl ether. The resulting block polymers were soluble in an aqueous medium and also formed micelle‐like aggregates. Upon UV irradiation of aqueous solutions above the critical micelle concentration, an efficient crosslinking reaction occurred. Photoinduced structural changes of these polymer aggregates in the solution state were further investigated. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

A Study on the Location and Aggregation of Tetrahydrophenylporphyrin with a Single Hexadecyl Chain in Triton X-100 Micelle

The location and aggregation of 5,10,15-tris(4-hydroxyphenyl)-20-(hexadecyloxyphenyl)porphyrin (P) in nonionic polyoxyethylene (9.5) octylphenol (Triton X-100) micelle solutions were studied by means of UV–Vis and fluorescence spectra. P forms premicelle surfactant–porphyrin aggregates when the surfactant concentration is below and approaching the CMC. In Triton X-100 micelle solutions, different types of H-aggregates of P were formed when the concentration of P is higher than 3.9×10^-6?mol?dm^-3. As the bulk pH is changed, a transfer process for the porphyrin moiety in Triton X-100 micelle occurs. In neutral Triton X-100 micelle solutions, P may be located at the inner layer of the micelle; in basic conditions, the porphyrin moiety may transfer to the outer surface of the micelle. The kinetic study of porphyrin complexed with Cu(II) in Triton X-100 micelle solutions shows that the metalation rate could be controlled by changing the pH.     

芳香反离子与离子表面活性剂胶团的相互作用

用紫外吸收光谱的方法研究了多种芳香反离子与离子表面活性剂胶团之间的相互作用。发现阳离子表面活性剂和阴离子表面活性剂胶团对芳香反离子的吸收光谱有着显著不同的影响,芳香反离子结构的细微变化可导致光谱特性显著不同。这被解释为阳离子表面活性剂胶团与芳香环之间的阳离子-π相互作用。阳离子-π相互作用需要阳离子表面活性剂分子与芳香反离子具有合适的相对位置与距离。通过测定各混合体系的吸附量证明,不同的芳香反离子在胶团表面有不同的排列方式。NMR的实验结果支持了上述解释。     

Synthesis of gold nanoparticles by reduction of HAuCl4 under UV irradiation

Gold nanoparticles were prepared in surfactant solutions by reduction of HAuCl₄ under UV irradiation without adding extra reductants or other organic substances. The effect of the structure and the property of surfactant on the size and the optical properties of prepared gold nanoparticles were studied. It was found that the longer the alkyl chain of the surfactant, the larger gold particles are obtained. On the other hand, lengthen the geminis spacer benefits the formation of smaller gold particles. The formation of adduct micelles composed of the charged surface active portion of the surfactant molecule and the (Au^IIICl₄)⁻ ion in cationic surfactant solution serves as the gold source and favors the formation of gold particles with larger sizes. While the repulsion between the (Au^IIICl₄)⁻ ion and the negative charged surface of anionic surfactant micelle is in favor of the formation of gold nanoparticles with smaller sizes. The nonionic surfactants can also assist the formation of dispersed gold nanoparticles.