Triton X-100 Micellar Research Articles

Supramolecular chirality in self-assembly of zinc protobacteriochlorophyll-d analogs possessing enantiomeric esterifying groups

Zinc 3-hydroxymethyl-pyroprotopheophorbides-a esterified with a chiral secondary alcohol at the 17-propionate residue were prepared as bacteriochlorophyll-d analogs. The synthetic zinc 31-hydroxy-131-oxo-porphyrins self-aggregated in an aqueous Triton X-100 micellar solution to give red-shifted and broadened Soret and Qy absorption bands in comparison with their monomeric bands. The intense, exciton-coupled circular dichroism spectra of their self-aggregates were dependent on the chirality of the esterifying groups. The observation indicated that the self-aggregates based on the J-type stacking of the porphyrin cores were sensitive to the peripheral 17-propionate residues. The supramolecular structures of the present J-aggregates as models of bacteriochlorophyll aggregates in natural chlorosomes were remotely regulated by the esterifying groups.Graphical abstract

Self-aggregation behavior of dimeric chlorophyll-a derivatives linked with ethynylene and m-phenylene moieties.

Chlorophyll(Chl)-a derivatives inserting an ethynylene-m-phenylene group between a zinc chlorin ring and a hydroxymethyl group, in which various substituents were introduced on the benzene spacer, were prepared as model compounds for the light-harvesting antennae (chlorosomes) of photosynthetic green bacteria. These compounds were synthesized from a C3-ethynylated Chl-a derivative via sequential Sonogashira cross-coupling reaction, and the effects of the substituents on the phenylene linker on their self-aggregation behaviors were investigated by electronic absorption, circular dichroism, and infrared absorption spectroscopic measurements. These studies exhibited that some compounds gave the disordered self-assemblies including several species; however, the zinc complex of the dimeric Chl-a derivative primarily allowed a single J-aggregate species in an aqueous Triton X-100 micellar solution. Additional control experiments revealed that its self-assembly was constructed through the hydrogen and coordination bonding involving the hydroxymethyl group on benzene ring, keto-carbonyl group at C13-position, and central zinc atom, and this is consistent with a conventional chlorosomal manner.

Quantifying the spontaneous emulsification of a heavy hydrocarbon with the presence of a strong surfactant

The rate of spontaneous emulsification phenomenon of heavy hydrocarbon in a non-ionic surfactant solution was studied experimentally. The size of a diminishing oil droplet was monitored photographically with the presence of an electrolyte. The obtained data were analysed using Axisymmetric Drop Shape Analysis (ADSA) software to measure the flux of emulsion droplets formed spontaneously. In contrast to all previous reports, a stable layer confined between the oil and aqueous solution was observed with a relatively constant thickness, ∼ 100 µm. The result shows that the rate of emulsification is reduced with the presence of electrolytes and is inversely correlated to its concentration. Considerable variation of the influence of electrolyte type on the kinetic of the spontaneous emulsification process for a given condition has been observed. Consequently, a new diffusion-control mechanism has been proposed, creating an extendable model to describe the process theoretically. The experimental data of emulsifying hexadecane in Triton X-100 micellar solution with the presence of potassium chloride and sodium chloride was well fitted to the proposed model. The results have important implications for surfactant-based cleaning processes.

Theoretical and Computational Study of the Sphere-to-Rod Transition of Triton X-100 Micellar Nanoscale Aggregates in Aqueous Solution: Implications for Membrane Protein Purification and Membrane Solubilization

We present a combined theoretical and computational approach to understanding the shape transition mechanism of Triton X-100 (TX-100) micellar nanoscale aggregates in aqueous solution. The understa...

Features of Methyl Linoleate Oxidation in Triton X-100 Micellar Buffer Solutions

Features of Methyl Linoleate Oxidation in Triton X-100 Micellar Buffer Solutions

Facile 132-methylation of chlorophyll-a derivative and (132R/S)-stereoselective self-aggregation of zinc bacteriochlorophyll-d analogs

Zinc methyl 3-hydroxymethyl-(132R/S)-methyl-pyropheophorbides-a were prepared as model compounds of bacteriochlorophyll-d by the chemical modification of naturally occurring chlorophyll-a. Both the HPLC-separated 132-epimers as well as the 132-unsubstituted counterpart self-aggregated in an aqueous Triton X-100 micellar solution to form large oligomers with red-shifted electronic absorption and intense circular dichroism bands, similarly as in natural chlorosomes, the main light-harvesting antennas of photosynthetic green bacteria. The substitution with a methyl group at the 132-position did not disturb the formation of chlorosomal self-aggregates in a J-type fashion, which were slightly dependent on the stereochemistry.

Synthesis of zinc 13-oxime-functionalized chlorophyll-a derivatives and their (131E/Z)-dependent self-aggregation

Zinc methyl 3-hydroxymethyl-pyropheophorbides-a possessing hydroxyimino, acetoxyimino, and benzoyloxyimino groups at the 131-position were prepared by chemical modification of naturally occurring chlorophyll-a. The (131E)- and (131Z)-stereoisomers of the obtained unsymmetric oximes were readily separated by column chromatography, and their stereochemistry was determined by 1H NMR spectroscopy. The synthetic O-(un)substituted oximes were monomeric in tetrahydrofuran and their electronic absorption spectra were dependent on the stereochemistry as well as the O-substituents in the oxime moiety. These chlorophyll-a derivatives self-aggregated in an aqueous Triton X-100 micellar solution to give red-shifted absorption bands. The J-aggregation ability of the (131E)-isomers was higher than that of the corresponding the (131Z)-isomers. Such stereoselective self-aggregation was comparable to that of bacteriochlorophylls-c, d, e, and f in the main light-harvesting antennas of green photosynthetic bacteria.

Effect of additional hydroxy group on self-aggregation of synthetic zinc bacteriochlorophyll-c analogs

Zinc methyl 3-hydroxymethyl-pyropheophorbides-a possessing a hydroxymethyl or 2-hydroxyethyl group at the 20-position were prepared by chemical modification of naturally occurring chlorophyll-a. The synthetic bacterio-chlorophyll-c analog bearing the 201-hydroxy group self-aggregated in an aqueous Triton X-100 micellar solution to give large oligomers with red-shifted and broadened electronic absorption bands, which was similar to the chlorophyllous J-aggregates in the main light-harvesting antennas of green photosynthetic bacteria. By contrast, the other 202-hydroxylated analog did not aggregate under the same conditions to remain its monomeric species. The red shift in the longest wavelength (Qy) band by the self-aggregation of the former analog was greater than that of the corresponding 201-methyl substitute with a similar size (CH3 ≈ OH). These results could be ascribable to the less sterically demanding and more electron-withdrawing 20-hydroxymethyl group, compared with more interacting 2-hydroxyethyl and more electron-donating ethyl groups at the 20-position.

Photodegradation of 4,4′-dibrominated diphenyl ether in Triton X-100 micellar solution

This study has investigated the photochemical reactions of 4,4′-dibrominated diphenyl ether (BDE-15) in Triton X-100 (TX-100) solution by UV light. All photolysis experiments were performed in TX-100 solutions which were all above critical micelle concentration (CMC). BDE-15 photodegradation follows the pseudo-first-order kinetics under various conditions. The results showed that the degradation rates of BDE-15 increased with the increasing concentration of TX-100, and decreased when TX-100 was used in excess, because TX-100 can act as hydrogen donor, photosensitizer and light barrier. When the pH value was in the range of 1–11, the degradation rates increased with the increasing pH value due to the proton effect and free radical reaction. When pH reached 13, the corresponding degradation rate dropped significantly, which was attributed to the decreasing surface potential of micellar retarding the degradation process. BDE-15 was debrominated into 4-dibrominated diphenyl ether (BDE-3) and diphenyl ether (DE), subsequently. In addition, dibenzofuran (DF), ortho-hydroxydiphenyl and para-hydroxydiphenyl were identified as another group of photoproducts, indicating PBDEs can also undergo the photochemical rearrangement via CO bond cleavage and recombination of the radical fragments.

Complexing Properties of Acid Alizarin Violet with Copper, Cobalt and Nickel in Micellar Media Containing SDS, CTAB and TX-100

The interaction of the dye acid alizarin violet (AVN) with three transition metals was followed spectrophotometrically in water and in micellar solutions of the cationic cetyltrimethylammonium bromide (CTAB), the anionic sodium dode- cyl sulfate (SDS) and the nonionic triton X-100 (TX-100). The stoichiometric ratios for the complexes of AVN with each metal ion were determined by the mole ratio and the continuous variation methods. In water, the metal to dye ratios in the complexes were 1:2, 1:3 and 1:1 for Cu2+, Co2+ and Ni2+, respectively. For Ni2+ the ratio changed to 1:3 in micellar CTAB. All other ratios were unchanged in the three micellar solutions. The formation constant (βn) of the complex in water was 1.00 × 1010 for Cu2+, 4.66 × 1014 for Co2+ and 9.03 × 104 for Ni2+. βn decreased in micellar TX-100: for Cu2+ to 6.88 × 108, for Co2+ to 1.56 × 1014 and for Ni2+ to 8.65 × 104. By contrast, micellar CTAB increased βn for Cu2+ and Ni2+. For Cu2+, the increase was to 5.19 × 1010, but for Ni2+ a large jump was observed, to 1.16 × 1015. For Co2+, βn dropped to 2.16 × 1014 in CTAB. Micellar SDS decreased βn for Cu2+ and Co2+ complexes to 5.38 × 109 and 1.76 × 1014, respectively, but increased that of the Ni2+ complex to 4.40 × 105. These observations were explained in terms of structural properties.

Kinetic Study of the Quenching Reaction of Singlet Oxygen by Pyrroloquinolinequinol (PQQH2, a Reduced Form of Pyrroloquinolinequinone) in Micellar Solution

A kinetic study of the quenching reaction of singlet oxygen ((1)O(2)) with pyrroloquinolinequinol (PQQH(2), a reduced form of pyrroloquinolinequinone (PQQ)), PQQNa(2) (disodium salt of PQQ), and seven kinds of natural antioxidants (vitamin C (Vit C), uric acid (UA), epicatechin (EC), epigallocatechin (EGC), α-tocopherol (α-Toc), ubiquinol-10 (UQ(10)H(2)), and β-carotene (β-Car)) has been performed. The second-order rate constants k(Q) (k(Q) = k(q) + k(r), physical quenching and chemical reaction) for the reaction of (1)O(2) with PQQH(2), PQQNa(2), and seven kinds of antioxidants were measured in 5.0 wt % Triton X-100 micellar solution (pH 7.4), using UV-visible spectrophotometry. The k(Q) values decreased in the order of β-Car > PQQH(2) > α-Toc > UA > UQ(10)H(2) > Vit C ∼ EGC > EC ≫ PQQNa(2). PQQH(2) is a water-soluble antioxidant. The singlet oxygen-quenching activity of PQQH(2) was found to be 6.3, 2.2, 6.1, and 22 times as large as the corresponding those of water-soluble antioxidants (Vit C, UA, EGC, and EC). Further, the activity of PQQH(2) was found to be 2.2 and 3.1 times as large as the corresponding activity of lipid-soluble antioxidants (α-Toc and UQ(10)H(2)). On the other hand, the activity of PQQH(2) is 6.4 times as small as that of β-Car. It was observed that the chemical reaction (k(r)) is almost negligible in the quenching reaction of (1)O(2) by PQQH(2). The result suggests that PQQH(2) may contribute to the protection of oxidative damage in biological systems, by quenching (1)O(2).

Impact of ultrasonication time on elution of super heavy oil and its biomarkers from aging soils using a Triton X-100 micellar solution

An ultrasound-enhanced elution system with Triton X-100 solution was used to remediate aging soils contaminated with super heavy oil. We used GC/MS, SEM, and X-ray diffraction (XRD) to analyze the effect of ultrasonic time (0–1800 s) on the elution of super heavy oil and its three characteristic biomarkers (C 26–34 17α 25-norhopanes, C 26–28 triaromatic steroid [TAS], and C 27–29 methyl triaromatic steroid [MTAS]). The oil and biomarkers remaining in the treated soils followed similar second-order functions with increasing ultrasonication times. Biomarker elution was closely related to carbon numbers in the marker. For C 26–34 17α 25-norhopanes, the smaller molecules were more readily eluted during 0–360 s ultrasound. This trend was reversed upon application of ultrasound during 1080–1800 s, with improved elution of larger molecules and elution followed a similar second-order function. For C 26–28 TAS, smaller molecules were more readily eluted but the elution of larger molecules followed a similar second-order function. For C 27–29 MTAS, elution of larger molecules was close to that of C 26–34 17α 25-norhopanes. Results of SEM and XRD indicated that the mineral and chemical compositions of soils eluted at ultrasonication times of 1080–1800 s closely resembled clean soils.

Impact of ultrasonic power density on elution of super heavy oil and its biomarkers from aging soils using Triton X-100 micellar solution

An ultrasound-enhanced elution system employing Triton X-100 solutions was used for remedying aging soils contaminated with super heavy oil. The effect of varying the ultrasonic power density on the elution of the oil and three characteristic biomarkers was analyzed using GC/MS and FTRS. The oil and biomarkers remaining in treated soils decreased as a similar first-order function of increasing ultrasonic power density. Elution of the three biomarkers in the absence of ultrasound was closely related to carbon numbers in the marker: smaller molecules were more readily eluted. This trend was reversed upon application of ultrasound at higher power densities, with improved elution of molecules containing a greater carbon numbers. The two ratios, both 22 S/(22 S + 22 R) of C 26–34 17α 25-norhopanes and 20 S/(20 S + 20 R) of C 26–28 triaromatic steroids, in treated soils decreased with increasing power density from 20 to 100 W L −1. The results of SEM, FTRS, XRD, and energy spectroscopy experiments indicated that the mineral and chemical compositions of soils eluted at power densities greater than 60 W L −1 closely resembled clean soils.

Kinetic Study of the Antioxidant Activity of Pyrroloquinolinequinol (PQQH2, a Reduced Form of Pyrroloquinolinequinone) in Micellar Solution

Kinetic study of the aroxyl radical-scavenging action of pyrroloquinolinequinol [PQQH(2), a reduced form of pyrroloquinolinequinone (PQQ)] and water-soluble antioxidants (vitamin C, cysteine, glutathione, and uric acid) has been performed. The second-order rate constants (k(s)) for the reaction of aroxyl radical with PQQH(2) and water-soluble antioxidants were measured in Triton X-100 micellar solution (5.0 wt %) (pH 7.4), using stopped-flow and UV-visible spectrophotometers. The k(s) values decreased in the order PQQH(2) > vitamin C >> cysteine > uric acid > glutathione. The aroxyl radical-scavenging activity of PQQH(2) was 7.4 times higher than that of vitamin C, which is well-known as the most active water-soluble antioxidant. Furthermore, PQQNa(2) (disodium salt of PQQ) was easily reduced to PQQH(2) by reaction of PQQNa(2) with glutathione and cysteine in buffer solution (pH 7.4) under nitrogen atmosphere. The result suggests that PQQ exists as a reduced form throughout the cell and plays a role as antioxidant.

Stopped-Flow Kinetic Study of the Aroxyl Radical-Scavenging Action of Catechins and Vitamin C in Ethanol and Micellar Solutions

Kinetic study of the aroxyl radical-scavenging action of catechins (epicatechin (EC), epicatechin gallate (ECG), epigallocatechin (EGC), and epigallocatechin gallate (EGCG)) and related compounds (methyl gallate (MG), 4-methylcatechol (MC), and 5-methoxyresorcinol (MR)) has been performed. The second-order rate constant ( k s) for the reaction of these antioxidants with aroxyl radical has been measured in ethanol and aqueous Triton X-100 micellar solution (5.0 wt %). The k s values decreased in the order of EGCG > EGC > MC > ECG > EC > MG >> MR in ethanol, indicating that the reactivity of the OH groups in catechins decreased in the order of pyrogallol B-ring > catechol B-ring > gallate G-ring > resorcinol A-ring. The structure-activity relationship in the free radical-scavenging reaction by catechins has been clarified by the detailed analyses of the pH dependence of k s values. From the results, the p K a values have been determined for catechins. The monoanion form at catechol B- and resorcinol A-rings and dianion form at pyrogallol B- and gallate G-rings show the highest activity for free radical scavenging. It was found that the free radical-scavenging activities of catechins are 3.2-13 times larger than that of vitamin C at pH 7.0.

Characteristics of solubilization and encapsulation of fullerene C 60 in non-ionic Triton X-100 micelles

The solubilization and encapsulation of monomeric C 60 in Triton X-100 micelles were investigated. Characteristic hydrophobic interactions of the type π–π and CH–π between the Triton X-100 micelle and C 60 resulted in stable aqueous dispersions of C 60 in the micellar medium, as evidenced from UV–vis, fluorescence emission and micro-Raman spectroscopy. Cyclic voltammetry of C 60 encapsulated Triton X-100 in aqueous 5 mM LiClO 4 solution revealed a quasi-reversible one-electron reduction peak with E 1/2 = −0.61 V and a reversible reduction peak at E 1/2 = −1.11 V vs. Ag/AgCl reference electrode at a scan rate of 10 mV s −1, a redox behaviour drifting substantially from that of pure C 60. An onset concentration of ∼0.025 mM for C 60 aggregation in the micellar core was substantiated from the characteristic absorption spectral broadening and quenching of pyrene fluorescence. The molar solubilization capacity of C 60 in aqueous Triton X-100 micellar solution was estimated spectrophotometrically to be 0.22.

Catalyzed oxidation of 2,6-dimethylphenol in Triton X-100 micellar solution

The oxidative coupling reaction of 2,6-dimethylphenol with H 2O 2 catalyzed by a copper(II) Schiff complex in aqueous and Triton X-100 micellar solution under mild conditions was investigated. The kinetics of formation of 3,3′,5,5′-tetramethyl-4,4′-diphenoquinone (DPQ) was studied. Rate constant k 2 were obtained. The optimum pH for DPQ generation reaction is 7.25. The main product was DPQ in aqueous buffer solution, but PPE and the oxidized products of PPE remained in Triton X-100 micellar solution.

Efficient peroxide decoloration of azo dye catalyzed by polyethylene glycol-linked manganese chlorin derivative

We reported here that polyethylene glycol (PEG)-linked manganese pyrochlorophyllide a (PEG-MnPChlide a) possesses remarkable catalytic activity comparable to horseradish peroxidase (HRP). The PEG-MnPChlide a catalyzed the oxidation decoloration reaction of C.I. Acid Orange 7 by hydrogen peroxide under a mild aqueous condition, pH 8.0 at 25 °C. The manganese pyrochlorophyride a methylester (MnPChlide a ME) dissolved in a Triton X-100 micellar solution also exhibited the catalytic activity, indicating the micellar environment plays an important role in the catalytic reaction. The reaction rate was accelerated by addition of imidazole. The catalytic reactions were analyzed by Michaelis–Menten kinetics, revealing that the higher reactivity of catalyst–substrate complex is responsible for the present catalytic reaction system.

Exciton Coupling of Tetra(p-hydroxyphenyl)porphyrin Controlled by Substituents of Counterions in Triton X-100 Micellar Solution

The interactions of nonionic meso-tetra(p-hydroxyphenyl)porphyrin (THPP) with CX3COOH (X = F, Cl, Br) in Triton X-100 (TX) micellar solution have been investigated by optical absorption, resonance light-scattering, and fluorescence spectroscopies. The double red-shifted absorption bands and strong resonance light scattering (RLS) signal imply that the assemblies induced by trihalo acetic acids belong to J-aggregates. The fluorescence of porphyrin is quenched due to the aggregate formation. The kinetics of assemblies trigged by CBr3COOH is studied via stopped-flow techniques. No characteristics of autocatalyzed reactions are observed, and there is only a log phase. The nature of the exciton coupling of transition dipole moment can be systematically changed by the haloid substituents of the organic counteranion.

Highly Selective and Simple Zero and First Order Derivative Spectrophotometric Determination of Palladium by Using α-Benzilmonoxime in Triton X-100 Micellar Solution

The reaction of <TEX>${\alpha}$</TEX>-Benzilmonoxime with palladium(II) produces a green complex in triton X-100 micellar media. Palladium has been determined using zero and first derivative spectrophotometric methods. The absorbances of Pd(II)- <TEX>${\alpha}$</TEX>--benzilmonoxime complex at 441.8 and 677.0 nm in 0.10 M perchloric acid solution were monitored and linear working ranges of 0.3-12.0 and 0.7-20 <TEX>${\mu}$</TEX>g mL<TEX>$^{-1}$</TEX> with detection limits of 0.07 and 0.10 <TEX>${\mu}$</TEX>g <TEX>$mL^-1$</TEX> were obtained, respectively. Also, recoveries in the range of 92.8 to 100.1% and relative standard deviations in the range of 0.4 to 7.1% were obtained. First derivative spectrophotometry has also been applied for palladium determination under the optimum condition. The linear dynamic range of 0.2-24.0 <TEX>${\mu}$</TEX>g <TEX>$mL^{-1}$</TEX> palladium with relative standard deviations of 0.6-6.9% and recoveries in the range of 94.9-102.5% has been obtained by first derivative spectrophotometry. The method shows high selectivity because of the high concentration of acid used, which prevents formation of complexes of <TEX>${\alpha}$</TEX>--benzilmonoxime with the other cations. The palladium complex formed was stable at least one day. The method was successfully applied to the determination of palladium in some synthetic palladium alloys and palladium-charcoal powder.