Solubility Of Pyrene Research Articles

Pentachlorophenol association with fulvic acids from recycled wastes

The apparent water solubility of pentachlorophenol was measured at pH = 6 and at 25 °C in pure water, aqueous solutions of three salts (NaCl, KNO 3 and CaCl 2 at 0.010, 0.10 and 1.0 M) and in aqueous solutions of three fulvic acids samples extracted from a natural soil (sFA), composted sewage sludge (csFA) and composted livestock's material (lsFA). A solubility enhancement method was developed for the measurement of partition coefficients ( K oc, L/kg organic carbon). Pentachlorophenol associates strongly with the fulvic acid samples and the calculated K oc were the following (averages and standard deviations): (sFA) (211 ± 22) × 10 2, (csFA) (253 ± 26) × 10 2, (lsFA) (235 ± 10) × 10 2. For comparison purposes the K oc for pyrene were also calculated for the three FA samples and were the following: (sFA) (119 ± 10) × 10 2, (csFA) (239 ± 21) × 10 2, (lsFA) (92 ± 10) × 10 2. The analysis of variance (one-way ANOVA) of the effect of the type of FA sample on the solubilization of pentachlorophenol and pyrene shows that this factor causes significant differences on the aqueous solubilization of these two organic substances.

Effect of Synthetic Surfactants on the Solubilization and Distribution of PAHs in Water/Soil-Water Systems

The present study examined the effects of four surfactants, including three non-ionic surfactants (Tween 80, Triton X-100 and Brij 35) and an anionic surfactant SDS on the solubilization and distribution of phenanthrene (Phe) and pyrene (Pyr) in soil-water systems. All four surfactants could enhance the solubilization of Phe and Pyr in aqueous phase linearly when surfactant concentrations exceeded their respective critical micelle concentrations (CMC). Molar solubilization ratio (MSR) which indicated surfactant's solubilization capacity for Phe and Pyr, was highest for Tween 80 for both PAHs, and SDS had the lowest among the four surfactants, while Triton X-100 and Brij 35 had about the same MSR for both PAHs. Moreover, all the surfactants could provide a strong micelle partitioning phase for the more hydrophobic Pyr than Phe as revealed by their high micelle - aqueous phase partition coefficient, K mc. Batch desorption studies also demonstrated that Tween 80 had the best capacity for the desorption of both Phe and Pyr in the soil-water systems, and followed by Triton X-100 and Brij 35, while SDS seems to have no positive effect on the desorption of PAHs probably due to its relatively high CMC value. Therefore, from the application standpoint, the results obtained in this study suggest that Tween 80 would be the most suitable candidate among the four surfactants in improving solubilization and desorption of PAHs in soil-water system, which are believed to be the prerequisites for successful bioremediation technology for PAH contaminated soil.

Differential utilization of pyrene as the sole source of carbon by Bacillus subtilis and Pseudomonas aeruginosa strains: role of biosurfactants in enhancing bioavailability

Our goal is to compare the efficiency of utilization of pyrene as the sole source of carbon for growth and energy by two nonactinomycetous groups of bacteria viz., Bacillus subtilis DM-04 and Pseudomonas aeruginosa mucoid (M) and nonmucoid (NM) strains, isolated from a petroleum-contaminated soil sample of north-east India. Bacillus subtilis DM-04 and P. aeruginosa M and NM bacterial strains were capable of secreting biosurfactant in the culture medium while growing on pyrene and their pyrene utilizing efficiency was demonstrated by correlating the bacterial growth in the presence of pyrene as the sole source of carbon along with a concomitant decrease in pyrene content from the culture medium with respect to time. The biosurfactant secreted by the respective bacterial strains enhanced the apparent solubility of pyrene by factors of 5-7 and influenced the bacterial cell surface hydrophobicity resulting in higher uptake and utilization of pyrene by bacteria. The growth of B. subtilis DM-04 and P. aeruginosa M and NM strains at the expense of pyrene after 96 h showed an assimilation of about 48.0 +/- 1.1% (mean +/- SD) and 32.0 +/- 0.6% (mean +/- SD) of pyrene carbon, respectively, showing differences in metabolism of pyrene by these bacterial strains. Bacillus subtilis DM-04 strain exhibited higher utilization and cellular assimilation of pyrene compared with P. aeruginosa M and NM strains. Further, the biosurfactants produced by the bacteria under study are capable of enhancing the solubility of pyrene in aqueous media and can influence the cell surface hydrophobicity of the biosurfactant-producing strains that results in a higher uptake of pyrene. It may be suggested that the bacteria used in this study are suitable candidates for practical field application for effective in situ bioremediation of pyrene-contaminated sites.

Thermosensitive Pluronic Micelles Stabilized by Shell Cross-Linking with Gold Nanoparticles

Gold nanoparticles were employed to prepare shell cross-linked Pluronic micelles that exhibit a reversibly thermosensitive swelling/shrinking behavior. Two terminal hydroxyl groups of Pluronic F127 were thiol-functionalized to form self-assembling Pluronic micelles in aqueous solution with exposed -SH groups in an outer shell layer. The thiol groups present in the outer shell were cross-linked by gold nanoparticles synthesized through NaBH4 reduction of gold precursor anions. The resultant shell cross-linked gold-Pluronic micelles exhibited a temperature-dependent volume transition: their hydrodynamic diameter was changed from 157.1 +/- 15.6 nm at 15 degrees C to 53.4 +/- 5.5 nm at 37 degrees C as determined by dynamic light scattering. The critical micelle temperature measured by a pyrene solubilization technique suggested that the reversible swelling/shrinking behavior of the micelles was caused by hydrophobic interactions of cross-linked or grafted Pluronic copolymer chains in the micelle structure with increasing temperature. Transmission electron microscopy directly revealed that the shell cross-linked micelles were indeed produced by gold nanoparticles covalently clustered on the surface. These novel self-assembled organic/inorganic hybrid micelles would hold great potential for diagnostic and therapeutic applications.

Solubilization of pyrene in aqueous micellar solutions of gemini surfactants C12-s-C12⋅2Br

Solubilization of pyrene in aqueous micellar solutions of quaternary ammonium gemini surfactants C(12)-s-C(12).2Br has been examined by UV spectra and steady fluorescence spectra at 30 degrees C. The results showed that pyrene molecules were incorporated in the palisade layers of the micelles and interacted with the quarterary ammonium head groups through cation-pi interaction, resulting in red shift of the UV absorption spectrum. C(12)-s-C(12)2Br (s=3,4,6) micelles have stronger ability for solubilization of pyrene than conventional surfactant C(12)TABr micelles. With increasing spacer length of C(12)-s-C(12).2Br, the micelles become more adaptable to solubilizing pyrene, which even forms the dimers as in the case of s=3,4,6, while pyrene solubilizes in the micelles (s=2) mainly in single-molecule form due to the more compact structure of the micelle in comparison with that at s>2.

Aggregation behavior in mixed system of double-chained anionic surfactant with single-chained nonionic surfactant in aqueous solution

The aggregation behavior of mixed systems of sodium bis(2-ethylhexyl) sulfosuccinate (AOT) or sodium bis(4-phenylbutyl) sulfosuccinate (SBPBS) with nonionic surfactant pentaethylene glycol mono- n-dodecyl ether (C 12E 5) have been studied by means of steady-state fluorescence, electrical conductivity, dynamic light scattering, transmission electron microscopy, electrophoretic light scattering and pyrene solubilization measurements. The critical concentrations for aggregation, micropolarity, mobility, solubilization capacity and morphology of aggregates are characterized. Two critical concentrations for aggregation are observed in the mixed surfactants, which may correspond to the formation of different kinds of aggregates. Moreover, it is more favorable for AOT–C 12E 5 to form mixed vesicles compared to SBPBS–C 12E 5 at higher mole fraction of C 12E 5. In addition, it is revealed that SBPBS–C 12E 5 mixture has larger solubilization capacity for pyrene than AOT–C 12E 5 system.

Production and Properties of a Biosurfactant Applied to Polycyclic Aromatic Hydrocarbon Solubilization

Microorganisms isolated from a soil sample collected from a gasoline filling station (located in Guwahati) were tested for their pyrene- and anthracene-degrading potential. Preliminary studies showed the ability of the organism to grow on carbon-free mineral medium (CFMM) supplemented with pyrene as the sole source of carbon. The organisms were found to produce a bioemulsifier when grown on CFMM with glucose or glycerol and/or pyrene as the carbon source. The organisms could also utilize anthracene when grown on mineral salt medium along with 2% glycerol. Within 2 d, anthracene concentration dropped less than 30% of the original concentration. Approximately 100 mg of the emulsifier was isolated from 25 mL of the 5-d-grown culture. The emulsifier was tested to produce emulsion with both an aliphatic and an aromatic group of hydrocarbons and resulting emulsions were found to be stable for a long period of time when kept at 10-15 degrees C. The emulsifier was also quite stable in a pH range of 3.0-11.0. In a concentration range of 0.5-10 mg/mL, it resulted in a linear increment of apparent pyrene and anthracene solubility in water.

Complexation of Hydrophobically Modified Polyelectrolytes with Surfactants: Anionic Poly(maleic acid/octyl vinyl ether)/Anionic Sodium Dodecyl Sulfate

Interactions of surfactants with hydrophobically modified polyelectrolytes in aqueous solutions are important in several applications such as detergents, cosmetics, foods, and paints. Fundamental questions arise on the mechanisms of complexation of the polyelectrolyte and surfactant that control their behavior. In this work, the complexation was studied by examining interactions in aqueous solutions of a hydrophobically modified polymer, poly(maleic acid/octyl vinyl ether) (PMAOVE), with sodium dodecyl sulfate (SDS) by monitoring viscosity, pyrene solubility, light scattering, and analytical ultracentrifugation. When the anionic surfactant SDS was added to aqueous solutions of the similarly charged polymer PMAOVE, the surfactant was incorporated into the hydrophobic nanodomains of PMAOVE even far below the cmc of the surfactant. On the basis of viscosity, pyrene solubility, and analytical ultracentrifugation data, it is proposed that PMAOVE undergoes structural unfolding and at higher SDS concentrations mixed micelles are formed.

Solubilization of hydrophobic molecules in nanoparticles formed by polymer–surfactant interactions

The interaction between the anionic surfactant, sodium dodecyl sulfate, and the polyelectrolyte, poly(diallyldimethylammonium chloride), may lead to formation of nanoparticles dispersed in water. The morphology of the resulting nanoparticles and their ability to solubilize hydrophobic molecules were evaluated. As shown by SEM and AFM imaging, the particles are spherical, having a diameter of about 20 nm. The solubilization within the nanoparticles was tested with pyrene, a fluorescence probe, and Nile Red, a solvatochromic probe. It was found that for Nile Red the solubilization within the nanoparticles is at lower polarity than for SDS micelles, and from pyrene solubilization it appears that the hydrophobicity of the nanoparticles depends on the ratio between the SDS molecules and the charge unit of the polymer.

Dendrimers as Photochemical Reaction Media. Photochemical Behavior of Unimolecular and Bimolecular Reactions in Water-Soluble Dendrimers

Synthesis and studies of poly(alkyl aryl ether) dendrimers, possessing carboxylic acid functionalities at their peripheries, are reported. 5-Bromopentyloxy methylisophthalate was utilized as the monomer to O-alkylate the phenolic hydroxyl groups of poly(alkyl aryl ether) dendrimers. Dendrimers of first, second, and third generations, possessing 6, 12, and 24 carboxylic acids, respectively, were thus prepared. These dendrimers were soluble in alkaline aqueous solutions, and the ensuing microenvironmental properties of the aqueous solutions were assessed by pyrene solubilization studies. Upon establishing the presence of nonpolar microenvironments within the dendritic structures, solubilizations of few organic substrates were conducted and their photochemical behaviors were assessed. Specifically, the photolysis of 1-phenyl-3-p-tolyl-propan-2-one and benzoin ethyl ether and photodimerization of acenaphthylene were conducted. These studies revealed that the product distribution and the "cage effect" were more distinct and efficient for the third generation dendrimer, than for the first and second generation dendrimers. The photochemical studies of carboxylic acid functionalized dendrimers were compared to that of hydroxyl group terminated poly(alkyl aryl ether) dendrimers.

Solubility of Acenaphthene, Anthracene, and Pyrene in Water At 50 °C to 300 °C

The aqueous solubilities of acenaphthene, anthracene, and pyrene, three polycyclic aromatic hydrocarbons (PAHs), were measured at temperatures from 50 °C to 300 °C. A dynamic method was used in the production of saturated aqueous solution, and the amount of analyte was determined by gas chromatography−mass spectrometry. In solubility measurements below the melting point of the analyte, a flow-through saturation cell was applied, whereas for measurements above the melting point a new saturation cell was constructed and the experimental setup was optimized. Solubilities below the melting point correlated well with literature values. An exponential relationship between solubility and temperature was found for pyrene and anthracene. The mole fraction solubilities measured at 250 °C and 5 MPa were (1.25 ± 0.097) × 10-3 for acenaphthene, (4.97±0.89) × 10-4 for anthracene, and (2.05 ± 0.23) × 10-4 for pyrene. At 300 °C and 10 MPa, the values were (3.78 ± 0.13) × 10-3 for anthracene and (1.41 ± 0.17) × 10-3 for p...

Mass Transfer of Polyaromatic Hydrocarbons (PAHs) in a Two-Liquid-Phase System

Studies were conducted to observe the solubility of phenanthrene, anthracene, and pyrene in four water-immiscible liquids (WILs) and the mass transfer of PAH in a two-liquid-phase (TLP) system. The order of solubility in WILs for three different PAHs was phenanthrene > pyrene ≫ anthracene. Among the WILs tested in a TLP system, paraffine oil did not affect the mass transfer of three PAHs, while silicone oil reduced the mass transfer of anthracene significantly because paraffine oil had a higher solubilizing capacity for anthracene than silicone oil. When initial PAHs concentration increased up to 2500 mg PAHs/kg soil, the mass transfer of phenanthrene and pyrene were hardly influenced, while that of anthracene was reduced to 40%. As the amount of light paraffine oil decreased, the mass transfer of anthracene decreased significantly compared to that of phenanthrene and pyrene. Based on the present results, it was confirmed that the mass transfer of PAHs from soil to WIL was governed mainly by the solubilizing capacity of WIL for PAHs. This is the first report on the mass transfer of PAHs from soil to WIL, in which the mechanism of TLP process can be understood more clearly.

Solubilization and Desorption of Pahs in Soilaqueous System by Biosurfactants Produced from Pseudomonas Aeruginosa P-CG3 Under Thermophilic Condition

Surface-active agents (surfactants) can enhance bioremediation of soils contaminated with PAHs by reducing sorption of PAHs or increasing desorption rates. The effectiveness of nonionic surfactant (Tween 80) and biosurfactants to enhance the solubilization and desorption of phenanthrene (Phe) and pyrene (Pyr) in soil-aqueous systems under thermophilic conditions was investigated using batch studies. Tween 80 and biosurfactants produced from Pseudomonas aeruginosa strain, ATCC 9027 and a strain isolated in our laboratory, P-CG3 were tested in this study. The results showed that all the surfactants could effectively enhance the solubility of both Phe and Pyr under thermophilic condition (55°C), which was linearly proportional to the concentrations of surfactants at concentrations above their respective critical micelle concentration (CMC). When the surfactants' concentrations in aqueous phase were above their respective CMCs, substantial amounts of PAHs were desorbed from soil into the aqueous phase. Among the three surfactants used, the biosurfactant produced from our own isolate, P-CG3 was more effective in enhancing the solubilization and desorption of PAHs, implying that it might have the potential to be further applied in the bioremediation of PAH contaminated soils.

Solubilisation of polyaromatic hydrocarbons in aqueous solutions of poloxamine T803

The solubilisation of exemplar polyaromatic hydrocarbons (PAHs) in aqueous solutions of the block co-polymeric surfactant T803 has been investigated. The PAHs used were naphthalene, phenanthrene and pyrene. T803 is a tetrafunctional block co-polymer derived by way of the coupling of ethylene oxide and propylene oxide to ethylene diamine. The presence of the ethylene diamine moiety provides the compound with pH functionality. In particular, micellisation in these systems is shown to be pH dependent. As a consequence, solubilisation in T803 solutions is also shown herein to be pH dependent, giving rise to considerable changes in the apparent aqueous solubilities of the PAHs. A switch in pH from 4 to 10.3 changes the apparent aqueous solubility of naphthalene, phenanthrene and pyrene by one, two and three orders of magnitude, respectively. Likewise, changes in temperature from 25 to 40 °C also produce changes of similar orders of magnitude in the apparent aqueous solubilities of phenanthrene and pyrene at a pH of 5.6 and T803 concentration of 5 mM.

Solubilization of pyrene by anionic–nonionic mixed surfactants

Surfactant-enhanced remediation (SER) is an effective approach for the removal of sorbed hydrophobic organic compounds from contaminated soils. The solubilization of pyrene by four anionic–nonionic mixed surfactants, sodium dodecyl sulfate (SDS) with Triton X-405 (TX405), Brij35, Brij58, and Triton X-100 (TX100), has been studied from measurements of the molar solubilization ratio (MSR), the micelle–water partition coefficient ( K mc), and the critical micelle concentration (CMC). The MSRs of pyrene in mixed surfactants are found to be larger than those predicted according to an ideal mixing rule. The mixing effect of anionic and nonionic surfactants on MSR for pyrene follows the order of SDS–TX405 > SDS–Brij35 > SDS–Brij58 > SDS–TX100 and increases with an increase in the hydrophile–lipophile balance (HLB) value of nonionic surfactant in mixed systems. In addition, the mixture of anionic and nonionic surfactants cause the K mc value for pyrene to be greater than the ideal value in SDS–TX405 mixed system, but to be smaller than the ideal value in SDS–Brij35, SDS–Brij58, and SDS–TX100 mixed systems. Meanwhile, in the four mixed systems, the experimental CMCs are lower than the ideal CMCs at almost all mixed surfactant solution compositions. The mixing effect of anionic and nonionic surfactants on MSR for pyrene can be attributed to the conjunct or the net result of the negative deviation of the CMCs from ideal mixture and the increasing or decreasing K mc.

Polyethylene glycol–polyamidoamine dendritic micelle as solubility enhancer and the effect of the length of polyethylene glycol arms on the solubility of pyrene in water

Unimolecular dendritic micelles designed as solubility enhancers were obtained by coupling polyethylene glycol (PEG) to Starburst TM polyamidoamine (PAMAM) dendrimers. Micelles-750, -2000, and -5000 have a generation 3.0 dendrimer core (32 primary amine end groups) and PEG arms with molecular weights of 750, 2000, and 5000, respectively. The conjugate of dendrimer core and PEG was characterized by MALDI-TOF MS and 1H NMR. 1H NMR was also used to estimate the average number of PEG arms on each dendrimer molecule. A typical hydrophobic compound, pyrene, was sonicated in an excess amount together with micelles at 50 °C for 6 h to produce its saturated water solution. The change of the solubility of pyrene was monitored at 334 nm, its maximum adsorption wavelength, by UV–VIS spectra. Concentrated micelles tended to dissolve more pyrene. However, there is no obvious linear relationship between micelle type and the amount of pyrene entrapped within micelles. Micelle-2000 could solubilize more pyrene than micelle-750. It is hypothesized that micelle-5000 did not solubilize more pyrene than micelle-2000 because of the PEG shell disruption by adjacent interpenetration of individual micelles when PEG arm length increased.

Synergistic solubilization of polycyclic aromatic hydrocarbons by mixed anionic–nonionic surfactants

Water solubility enhancements of naphthalene (Naph), acenaphthylene (Acen), anthracene (An), phenanthrene (Phen) and pyrene (Py) by micellar solutions of single and mixed anionic–nonionic surfactants were measured and compared. Effects of typical inorganic ions, such as NH 4 +, Na + and Mg 2+ coexisted with the organic pollutants (in soils) on water solubilities of polycyclic aromatic hydrocarbons (PAHs) in the presence of single and mixed surfactants were also investigated. Solubilities of PAHs in water are greatly enhanced in a linear fashion by each of Triton X-100 (TX100), Triton X-305 (TX305), Brij 35, and sodium dodecyl sulfate (SDS). Solubility enhancement efficiencies of surfactants above the critical micelle concentration (CMC) follow the order of TX100 > Brij 35 > TX305 > SDS. PAHs are solubilized synergistically in mixed anionic–nonionic surfactant solutions, especially at low surfactant concentrations. The synergistic power of the mixed surfactants is SDS–TX305 > SDS–Brij 35 > SDS–TX100. Synergistic effect of a given mixed-surfactant solution on different PAHs also appears to be linearly related to the solute log K ow. The noted synergism for the mixed surfactants is attributed to the formation of mixed micelles, the lower CMC of the mixed-surfactant solutions, and the increase of the solute’s molar solubilization ratio or micellar partition coefficients ( K mc) because of the lower polarity of the mixed micelles. Suitable quantity of inorganic cations can enhance the solubilization capacities of anionic–nonionic mixed surfactants, the effect being Mg 2+ > NH 4 + > Na +. The water solubility of pyrene was slightly increased by anthracene and significantly increased by 1,2,3-TCB in the presence of SDS–Brij 35. Mixed surfactants may improve the performance of surfactant-enhanced remediation of soils and sediments by decreasing the applied surfactant level and thus the remediation cost.

Coadsorption of Sodium Dodecyl Sulfate with Hydrophobically Modified Nonionic Cellulose Polymers. 1. Role of Polymer Hydrophobic Modification

We examined coadsorption from mixtures of the anionic surfactant sodium dodecyl sulfate (SDS) with either hydroxypropyl cellulose (HPC) or hydrophobically modified hydroxyethyl cellulose (hmHEC). Coadsorption to nonselective, hydrophobic poly(dimethylsiloxane) (PDMS) surfaces was compared with coadsorption to negatively charged silica surfaces that were selective for the polymers. Optical reflectometry provided the total extent of adsorption as well as the adsorption kinetics. We referenced SDS concentrations against the critical association concentration (cac) and saturation concentration (csat) for solution-phase polymer/surfactant binding as determined by pyrene solubilization and fluorescence spectroscopy methods. Depending on the bulk SDS concentration, the total adsorbed mass could be either increased or decreased compared to the adsorbed mass attained from SDS-free polymer solutions. Above the cac, the total adsorbed amount decreased with increasing SDS concentration, for either polymer on either t...

Role of the C-terminal Extensions of α-Crystallins: SWAPPING THE C-TERMINAL EXTENSION OF αA-CRYSTALLIN TO αB-CRYSTALLIN RESULTS IN ENHANCED CHAPERONE ACTIVITY

Several small heat shock proteins contain a well conserved alpha-crystallin domain, flanked by an N-terminal domain and a C-terminal extension, both of which vary in length and sequence. The structural and functional role of the C-terminal extension of small heat shock proteins, particularly of alphaA- and alphaB-crystallins, is not well understood. We have swapped the C-terminal extensions between alphaA- and alphaB-crystallins and generated two novel chimeric proteins, alphaABc and alphaBAc. We have investigated the domain-swapped chimeras for structural and functional alterations. We have used thermal and non-thermal models of protein aggregation and found that the chimeric alphaB with the C-terminal extension of alphaA-crystallin, alphaBAc, exhibits dramatically enhanced chaperone-like activity. Interestingly, however, the chimeric alphaA with the C-terminal extension of alphaB-crystallin, alphaABc, has almost lost its activity. Pyrene solubilization and bis-1-anilino-8-naphthalenesulfonate binding studies show that alphaBAc exhibits more solvent-exposed hydrophobic pockets than alphaA, alphaB, or alphaABc. Significant tertiary structural changes are revealed by tryptophan fluorescence and near-UV CD studies upon swapping the C-terminal extensions. The far-UV CD spectrum of alphaBAc differs from that of alphaB-crystallin whereas that of alphaABc overlaps with that of alphaA-crystallin. Gel filtration chromatography shows alteration in the size of the proteins upon swapping the C-terminal extensions. Our study demonstrates that the unstructured C-terminal extensions play a crucial role in the structure and chaperone activity, in addition to generally believed electrostatic "solubilizer" function.

Physicochemical Properties of Quaternized Poly(amidoamine) Dendrimers with Four Octyl Chains

A cationic dendrimer-type tetrameric surfactant (C 8qbG0) with four octyl chains and four ammonium groups was synthesized by the reaction of poly(amidoamine) dendrimers with generation of zero and glycidyldimethyloctylammonium bromide. The physicochemical properties of C 8qbG0 and of their mixtures with sodium dodecyl sulfate (SDS) were characterized by investigating surface tension, electrical conductivity, fluorescence of pyrene, and dynamic light-scattering. The critical micelle concentration (cmc) of C 8qbG0 was 13 mmol dm −3 at the concentration of one terminal group and the surface tension at the cmc attained 34 mN m −1. The occupied area of C 8qbG0 was 1.94 nm 2 molecule −1, indicating that the tetrameric dendrimers adsorb widely at the air/water interface. The fluorescence intensity ratio of the first-to-third band in the emission spectra of pyrene for C 8qbG0 decreased from around the cmc obtained by the surface tension measurement. The hydrodynamic radius of C 8qbG0 determined by dynamic light-scattering was about 1.3 nm. The addition of SDS to the aqueous solutions of C 8qbG0 enhanced the surface activities; the mixtures exhibited lower cmc, lower surface tension, and higher solubilization of pyrene than SDS alone. It was found that the mixtures of C 8qbG0 and SDS form large aggregates due to the interactions between their alkyl chains as well as hydrophilic groups.