Insights Into Molecular Interaction of Antitumor Drug Mitoxantrone With Anionic Surfactant Sodium Dodecyl Sulfate at Different Temperatures

A study of the interaction of antitumor drug mitoxantrone with anionic surfactant sodium dodecyl sulfate (SDS) has been carried out by UV–Vis absorption spectroscopy at submicellar and micellar surfactant concentrations, pH 7.4 and 10, and over a temperature range of 293.15–323.15 K. The variation of the monomer drug absorbance as a function of SDS concentration indicates, at pH 7.4 and all investigated temperatures, two definite processes: process I in the submicellar range, attributed to the electrostatic interaction between mitoxantrone and SDS monomers; and process II in the micellar range, when the drug is incorporated into SDS micelles in monomer form. At pH 10, the results have indicated only the process II at micellar SDS concentrations. The monomer absorbance changes occurring as a result of the interactions between mitoxantrone and SDS were rationalized in terms of binding constant, micelle/water partition coefficient, and the corresponding thermodynamic parameters for binding and partitioning processes. Thermodynamic parameters indicate that at pH 7.4 both binding process of mitoxantrone to SDS and partition process of mitoxantrone between micellar and bulk aqueous phases are spontaneous and enthalpy controlled, while at pH 10 both processes are spontaneous and entropy controlled.     

Aqueous two‐phase micellar systems in an oscillatory flow micro‐reactor: study of perspectives and experimental performance

BACKGROUND: Aqueous two‐phase micellar systems (ATPMS) are micellar surfactant solutions with physical properties that make them very efficient for the extraction/concentration of biological products. In this work the main proposal that has been discussed is the possible applicability and importance of a novel oscillatory flow micro‐reactor (micro‐OFR) envisaged for parallel screening and/or development of industrial bioprocesses in ATPMS. Based on the technology of oscillatory flow mixing (OFM), this batch or continuous micro‐reactor has been presented as a new small‐scale alternative for biological or physical‐chemical applications. RESULTS: ATPMS experiments were carried out in different OFM conditions (times, temperatures, oscillation frequencies and amplitudes) for the extraction of glucose‐6‐phosphate dehydrogenase (G6PD) in Triton X‐114/buffer with Cibacron Blue as affinity ligand. CONCLUSION: The results suggest the potential use of OFR, considering this process a promising and new alternative for the purification or pre‐concentration of bioproducts. Despite the applied homogenization and extraction conditions have presented no improvements in the partitioning selectivity of the target enzyme, when at rest temperature they have influenced the partitioning behavior in Triton X‐114 ATPMS. Copyright © 2011 Society of Chemical Industry     

Characteristics of solubilization and encapsulation of fullerene C60 in non-ionic Triton X-100 micelles

The solubilization and encapsulation of monomeric C₆₀ 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 C₆₀ resulted in stable aqueous dispersions of C₆₀ in the micellar medium, as evidenced from UV-vis, fluorescence emission and micro-Raman spectroscopy. Cyclic voltammetry of C₆₀ encapsulated Triton X-100 in aqueous 5 mM LiClO₄ 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 C₆₀. An onset concentration of ∼0.025 mM for C₆₀ aggregation in the micellar core was substantiated from the characteristic absorption spectral broadening and quenching of pyrene fluorescence. The molar solubilization capacity of C₆₀ in aqueous Triton X-100 micellar solution was estimated spectrophotometrically to be 0.22.     

Intestinal cholesterol and oleic acid uptake from solutions supersaturated with lipids

To test the role of nonmicellar phases in lipid absorption, intestinal uptake of fatty acids and cholesterol has been studied in vitro from supersaturated and micellar solutions. The micellar solubility limit at equilibrium was established for cholesterol and oleate/monoolein (2∶1) at pH 6.7 with 10 mM taurocholate. Uptake by rat intestinal everted sacs was measured during incubation of 5 min. Cholesterol uptake increased linearly with the cholesterol content of micellar or supersaturated solutions up to a supersaturation of 150%. Oleate uptake, by contrast, remained essentially the same from either saturated or supersaturated (130–280%) mixtures. The difference between cholesterol and oleate uptake rates is explained by their distinct effects on micellar size, which is unchanged by cholesterol supersaturation but is increased by oleate. Solutions largely supersaturated (280%) with oleatemonoolein are polydisperse and contain viscous isotropic and paracrystalline phases similar to those observed during lipid absorption. These results suggest that, in the presence of such solutions, uptake occurs from both the micellar saturated and nonmicellar supersaturated phases.     

The fluorescence resonance energy transfer between dye compounds in micellar media

The fluorescence resonance energy transfer from fluorescein to merocyanine 540 in aqueous sodium dodecyl sulfate, cetyltrimethylammonium bromide and Triton X-100 micellar solutions as well as deionized water was investigated at room temperature using steady-state and time-resolved fluorescence spectroscopy techniques. Fluorescence resonance energy transfer rate constants (k_T), obtained using both Stern–Volmer and Förster theories, were in good agreement. Moreover, energy transfer efficiency values of 0.14, 0.38, 0.77 and 0.85 for deionized water, sodium dodecyl sulfate, TX-100 and cetyltrimethylammonium bromide micellar solution were obtained at the highest acceptor concentration at which fluorescence resonance energy transfer was achieved. The data obtained from steady-state absorption, fluorescence spectral studies and time-resolved lifetime measurements indicated that the fluorescence resonance energy transfer from fluorescein to merocyanine 540 occurred most effectively in aqueous cetyltrimethylammonium bromide micellar solutions.     

Proton NMR Study of Micelle Formation in Surfactant Mixtures

Abstract

Proton spin-lattice relaxation times (T ₁′s) of micellar solutions of the nonionic surfactant Triton X-100 (TX-100, an alkylbenzenepolyethoxy alcohol) and of mixed micellar systems of TX-100 and n-dodecanol, n-dodecylamine, dodecyltrimethylammonium chloride, or sodium dodecylsulfate were determined. The results indicate that the hydrocarbon chains of the second surfactant penetrate to the aromatic rings of the TX-100 molecules, but do not extend to the region occupied by the alkyl chains of the TX-100. Ionic cosurfactants appear to produce a general loosening of the micellar structure, presumably because of their mutual coulombic repulsion.     

The key role of support surface tuning during the preparation of catalysts from reverse micellar-synthesized metal nanoparticles

Silica-supported cobalt catalysts have been prepared by depositing cobalt nanoparticles synthesized in reverse micellar systems. Two different reverse microemulsions comprising both a neutral (Triton X114) or an ionic (AOT) surfactant were used for the synthesis of nanoparticles. The materials have been characterized by ²⁹Si MAS NMR, XRD, FTIR, H₂-TPR, and TEM. Protection of the hydroxyl groups on the silica surface by silylation prior to loading of the cobalt nanoparticles has been found crucial for attaining the desired metal dispersions in the final catalyst owing to a higher chemical compatibility between the hydrophobic support surface and the microemulsion during the deposition step.     

胶束中的磺化酞菁镓,磺化酞菁的二聚行为研究

本文研究了二磺化酞菁镓，三磺化酞菁在胶束中的二聚行为，计算了Ｓ３Ｐｃ，Ｓ２ＰＣＧａ在胶束中的二聚常数ＫＤ及分配系数Ｋ，并对磺化酞菁在胶束中的增敏，解聚机理进行了探讨。     

Headspace solid-phase microextraction for determination of micellar solubilization of methyl<Emphasis Type="Italic">tert</Emphasis>-butyl ether (MTBE)

Headspace analysis using solid-phase microextraction (SPME) was tested as a rapid method to evaluate micellar solubilization of methyl tert-butyl ether (MTBE) with sodium dodecyl sulfate (SDS) and cetylpyridinium chloride (CPC). At equilibrium between aqueous phase and vapor phase, free MTBE in vapor phase (i.e., not solubilized MTBE by SDS or CPC) was analyzed by GC-FID (Hewlett Packard 5890 series II) equipped with a capillary HP1 column (30 m × 0.25 mm). This method showed a good analytical performance such as linearity of calibration curve and precision (RSD less than 5%). Extent of MTBE solubilization was expressed as a function of molar ratio of SDS to MTBE and CPC to MTBE, and was saturated at about 57% and 37% with over the value of ratio 13 for SDS and CPC, respectively. This technique can be applied to analyze micellar solubilization potential of various surfactants on volatile and semi-volatile compounds.     

新显色剂2-磺酸基苯基-1,4-二氨基重氮偶氮苯的合成及其与镍(Ⅱ)的显色反应

介绍了新显色剂2-磺酸基苯基-1,4-二氨基重氮偶氮苯的合成及其与镍(Ⅱ)的显色反应。实验表明,在非离子表面活性剂Triton X-100的存在下,在pH10.5的硼砂—氢氧化钠缓冲介质中,镍(Ⅱ)与SDADA形成量比=1∶3的红色络合物,在545 nm处有一最大吸收峰,在433 nm处有一最大负吸收峰。镍(Ⅱ)质量浓度在0.12~0.28μg/mL的范围内符合比耳定律,表观摩尔吸光系数为9.60×105L.mol/cm。     

Aqueous lipid phases of relevance to intestinal fat digestion and absorption

The phase behavior of monoglyceride/water systems, with oleic and linoleic acid as the dominating fatty acid residues, was investigated. Increased solubilization of triglycerides (oil) or oleic acid in the cubic liquid-crystalline phase formed by monoglyceride and water resulted in the formation of a reversed hexagonal liquid-crystalline phase followed by an L2-phase. The liquid-crystalline phases have different dispersion properties compared to each other in dilute micellar bile salt solutions. The cubic phase is found to be easily dispersed. The relevance of aqueous lipid phases other thah micellar is discussed in relation to intestinal lipid digestion and absorption.     

Photophysics of the phenoxazine dyes resazurin and resorufin in direct and reverse micelles

The photophysics of the phenoxazin-3-one dyes resazurin and resorufin was studied in a micellar solution of cetyltrimethylammonium chloride and in reverse micelles of 1,4-bis(2-ethylhexyl)sulfosuccinate and benzylhexadecyldimethylammonium chloride. Absorption and fluorescence emission spectra, as well as fluorescence lifetimes and T–T transient absorption spectra were determined as a function of surfactant concentration. In the presence of direct micelles of cetyltrimethylammonium chloride, both dyes displayed red shifts in the absorption and fluorescence spectra together with a simultaneous fluorescence lifetime increase. The electrostatic attraction between the anionic dyes and the positive micellar interface favors the location of the dyes closer to the head groups of the surfactant molecules. In reverse micellar systems the spectral properties depended upon the charge of the surfactant and water content. In the case of 1,4-bis(2-ethylhexyl)sulfosuccinate, at low water content both dyes were incorporated into the interface; as the water content increased their spectral properties tended to those in pure water. In contrast, in the case of cationic surfactant, the dyes were located in the interfacial pseudophase as a result of electrostatic interactions.     

Interaction of porcine pancreatic colipase with a nonionic detergent,triton X-100: Spectrophotometric studies

Strong perturbation of the ultraviolet spectrum of the tyrosines of porcine pancreatic colipase A is observed in the presence of Triton X-100 at concentration above the critical micellar concentration. Spectrophotometric titration of the phenolic groups of the protein shows that the apparent pKa value for two tyrosines is about 10.3, while the third tyrosine has a higher pKa value above 11.6. This residue is still protonated at pH 13 in the presence of Triton X-100. All perturbations induced by the nonionic detergent can be interpreted as resulting from interactions between colipase and Triton X-100 molecules at a hydrophobic site of the protein that includes the tyrosine residues. Results obtained in studies with Triton X-100 are similar to those already reported by Sari et al. (Eur. J. Biochem. 58∶561 (1975) on the interaction of colipase with taurodeoxycholate. It is likely that the binding of both types of detergent occurs at the same specific site on the protein molecule. Data presented in this communication give further support to the hypothesis that a hydrophobic domain (residues 49–57), including all three tyrosines of the colipase molecule, participate to the well characterized interaction of the lipase cofactor with triglycerides at lipid-water interfaces.     

Surfactants Based on Bis-Galactobenzimidazolones: Synthesis, Self-Assembly and Ion Sensing Properties

A series of new non-ionic amphiphiles based on bis-galactobenzimidazolones have been synthesized by grafting alkyl bis-benzimidazolone units as hydrophobic tails on hydroxypropyloxygalacto-pyranose moieties as hydrophilic heads. Their surface and self-aggregation properties in water were evaluated. The compounds show very low critical micellar concentrations (CMCs) that decrease with increasing chain length; values for the minimal area per molecule at the interface (A _min) follow the same trend. The synthesized compounds also form hexagonal liquid crystals in water for a certain range of hydrophobic tail lengths. On the other hand, the new amphiphiles show characteristic UV?CVis absorption and fluorescence emission bands associated with the benzimidazolone moiety. The fluorescence emission is quenched with a certain degree of selectivity by cations, due to their strong affinity towards the benzimidazolone group, which shows ion complexation properties. Hence, the reported new amphiphiles are candidates as self-assembling chemosensors. The quenching efficiency and also ion sensing sensitivity is higher in the monomeric state as compared to the micellar state. The fluorescence emission intensity is higher for compounds with a shorter alkyl chain.     

Effect of cefoperazone sodium on the physicochemical properties of surfactants

The effects of cefoperazone sodium (CS), a pharmaceutical compound, on the critical micelle concentration (CMC) of surfactants with different charges [cetyl trimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS), and Triton X-100], the cloud point of Triton X-100, and the Krafft temperatures of SDS and CTAB were studied. The interaction of CS with differently charged surfactants was determined by ultraviolet and fluorescence spectrophotometry. The results show that with increasing CS concentration, the Krafft temperature increases and the CMC decreases in the SDS/H₂O system, whereas the opposite results are obtained in the CTAB/H₂O system. Both the cloud point and the CMC of Triton X-100 increase with the addition of CS. The above results are attributed to the different micellar interactions between CS and surfactants with different charges.     

Enhanced sorption of phenanthrene on activated carbon in surfactant solution

Distribution of a hazardous hydrophobic organic compound (HOC) and a nonionic surfactant in aqueous/activated carbon systems was investigated. Phenanthrene was selected as a representative HOC and Triton X-100 as a surfactant. Three activated carbons that differed in size (Darco 20-40, 12-20 and 4-12 mesh sizes) were used in the adsorption experiments. The system was analyzed using a mathematical partitioning model and compared with intrinsic sorption of phenanthrene without the effect of sorbed surfactant. Phenanthrene was sorbed onto activated carbon in a greater amount than an estimated value by intrinsic sorption, even though surfactant molecules covered most of surfaces. The sorbed surfactant was much more effective as a sorbent for phenanthrene, in the range of 1.2-98 for effectiveness factor, than was activated carbon, particularly at high surfactant doses. We introduced surface molar solubilization ratio (MSR_s) for sorbed micelles of surfactant and mathematically estimated using effectiveness factor and available carbon fraction of activated carbon after surfactant sorption. The MSR_s for sorbed surfactant was 5-46 times higher than the MSR for micellar surfactant in bulk solution. The sorbed surfactant onto activated carbon can more effectively remove hazardous organic compounds in liquid environmental samples.     

phenanthrene biodegradation in soil slurry systems: Influence of salicylate and triton X-100

The effects of a nonionic surfactant (Triton X-100) and a metabolic inducer (salicylate) were investigated in order to enhance the biodegradation rate of phenanthrene in soil slurry systems. The addition of salicylate reduced the time for the complete degradation of phenanthrene up to about 3 times (12.9 mg/L-d) even at highly concentrated soils of 650 mg/kg. The inducer was beneficial not only by increasing metabolic activity of existing cells, but also by increasing cell mass since it was utilized as an additional carbon source. The fraction of fast growing bacteria in total with salicylate addition was much higher compared to that without salicylate. The addition of Triton X-100 ranging from 0 to 10 g/L increased the apparent solubility of phenanthrene in soil slurry, but significantly inhibited the phenanthrene degradation in both slurry and pure liquid systems without any inhibition to cell growth. The phenanthrene degradation was inhibited much more with increasing the surfactant concentration. The inhibition by surfactant addition might be due to the prevention of bacterial adhesion to phenanthrene sorbed to soil and/or decrease of micellar-phase bioavailability     

Polymer-bound pyrrole compounds. V. On the optical properties of an insoluble polystyrene matrix bearing di- and tetrapyrroles covalently anchored

The absorption and fluorescence spectra of samples of variable particle size, consisting of an insoluble polystyrene matrix bearing different covalently attached di- and tetrapyrroles, are studied and compared with solutions of the same chromophores present as their methyl ester derivatives. The specific chromophores consist of xanthobilirubinic acid, N′-methyl xanthobilirubinic acid, bilirubin IX-α, biliverdin IX-α, mesoporphyrin IX and Zn(II) mesoporphyrin IX, anchored as esters to α-4-[(ylmethyl-3-nitrobenzamido)benzyl]-poly(styrene-co-1%-divinylbenzene). The spectral differences observed are: (1) an apparent decrease in the extinction coefficient of the high energy band relative to the low energy band of the verdin and porphyrin chromophores; and (2) variable shifts of the absorption wavelength maxima depending on the specific system. Scattering by the polymer is mainly responsible for the first, but chromophore aggregation also contributes to band shifts. Both phenomena are more important in particles of comparatively larger size, as has been confirmed by comparing spectroscopic properties of micellar and vesicular systems containing the same chromophores. The present systems are interesting because: (1) one can derive qualitative information on several aspects of the polymer matrix itself, such as the interactions of a given site with its immediate surroundings; and (2) they serve as models for investigations of chromophore-imbedded tissue optics, and in general, of energy absorption by dyes in a light-scattering medium.     

Preparation of trioctylamine-impregnated polystyrene–divinylbenzene porous resins for the collection of precious metals from water

A water-insoluble extracting solvent, trioctylamine (TOA), was solubilized in the aqueous micellar solution of a polyoxyethylene-type nonionic surfactant, polyethyleneglycol (10)-mono-4-nonylphenyl ether (PONPE-10). By mixing the solution and a polystyrene–divinylbenzene porous resin (Amberlite XAD-4), TOA was successfully impregnated into the resin. Gold(III), platinum(II), and palladium(II) were well extracted from hydrochloric acid to the TOA-impregnated resins. The extents of the extraction of platinum(II) and palladium(II) increased with increasing the amount of TOA impregnated. The TOA-impregnated filter disk was also prepared by passing aqueous mixture of PONPE-10 and TOA through an Empore disk involving polystyrene–divinylbenzene. The disk was useful for concentrating precious metals in water prior to their graphite furnace atomic absorption spectrometric analysis.     

Comparison of a pair of synthetic tea-catechin-derived epimers: synthesis, antifolate activity, and tyrosinase-mediated activation in melanoma

Despite bioavailability issues, tea catechins have emerged as promising chemopreventive agents because of their efficacy in various animal models. We synthesized two catechin-derived compounds, 3-O-(3,4,5-trimethoxybenzoyl)-(-)-catechin (TMCG) and 3-O-(3,4,5-trimethoxybenzoyl)-(-)-epicatechin (TMECG), in an attempt to improve the stability and cellular absorption of tea polyphenols. The antiproliferative and pro-apoptotic activities of both compounds were analyzed with various cancer cell systems, and TMCG, which was easily synthesized in excellent yield, was more active than TMECG in both melanoma and non-melanoma cell lines. TMCG was also a better inhibitor of dihydrofolate reductase and was more efficiently oxidized by tyrosinase, potentially explaining the difference in activity between these epimers.