Nonionic Surfactants (nonionic + surfactant)

Distribution by Scientific Domains

Selected Abstracts

Protein Refolding Mediated by Reverse Micelles of Cibacron Blue F-3GA Modified Nonionic Surfactant

Xiao-Yue Wu
An affinity-based reverse micellar system formulated with nonionic surfactant was applied to the refolding of denatured-reduced lysozyme. The nonionic surfactant of sorbitan trioleate (Span 85) was modified with Cibacron Blue F-3GA (CB) as an affinity surfactant (CB-Span 85) to form affinity-based reverse micelles in n -hexane. The water content of 15 was found optimal for lysozyme refolding in the reverse micellar system of 62.7 mmol/L Span 85 with coupled CB of 0.3 and 0.5 mmol/L. In addition, the operating conditions such as pH and the concentrations of urea and redox reagents were optimized. Under the optimized conditions, complete renaturation of lysozyme at 3,3.5 mg/mL was achieved, whereas dilution refolding in the bulk aqueous phase under the same conditions gave much lower activity recovery. Moreover, the secondary structure of the refolded lysozyme was found to be the same as the native lysozyme. Over 95% of the refolded lysozyme was recovered from CB-Span 85 reverse micelles by a stripping solution of 0.5 mol/L MgCl2. Thus, the present system is advantageous over the conventional reverse micellar system formed with ionic surfactants in the ease of protein recovery. [source]

Surface Resistance and Potentiometric Response of Polymeric Membranes Doped with Nonionic Surfactants

Liya Muslinkina
Abstract The influence of lipophilic, electrically neutral surfactants added to the membrane on the ion transfer resistance between an aqueous sample and a polymeric ion-selective membrane has been studied by electric impedance spectroscopy and potentiometry. An increase in the surface resistance and a shift of the apparently super-Nernstian response to lower sample ion activities has been observed when using the nonpolar bis(2-ethylhexyl) sebacate as plasticizer. [source]

Phosphonic acid functionalized polyethylene glycol and derivatives

Mohamed Essahli
Abstract This article describes the functionalization of polyethylene glycol, mono or bifunctional, and a nonionic surfactant by phosphonic acids without the need for protection of the functional group. The functionalization is performed in two steps, first an esterification by thioglycolic acid, secondly a radical addition of vinyl phosphonic acid on the thiol group. All products were obtained quantitatively and characterized by 1H-, 13C-, 31P-NMR spectroscopy techniques, MALDI, and step-by-step chemical titrations. Enhanced thermal properties were found while phosphonylating polyethylene glycol, particularly when the sulfur atom was oxidized into a sulfone group. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

Nasal administration of low molecular weight heparin

John Arnold
Abstract The main objective of this study was to determine if the systemic absorption of therapeutic amounts of heparin was possible following nasal administration. Sprague-Dawley rats received nosedrops containing a low molecular weight heparin (LMWH) or unfractionated heparin (UFH) formulated with or without tetradecylmaltoside (TDM). TDM is a nonionic surfactant that has been previously shown to be a potent absorption enhancer in studies with peptide drugs. LMWH/UFH absorption was determined by measuring plasma anti-Factor Xa activity. The inclusion of 0.25% TDM in nasal formulations containing LMWH resulted in a significant increase in the Cmax and area under the curve (AUC) of anti-Factor Xa activity when compared to LMWH formulated in saline alone. The addition of TDM to a nasal formulation containing UFH resulted in a much smaller increase in the Cmax and the AUC of anti-Factor Xa activity. The absolute bioavailability of LMWH was increased from 4.0,±,0.4% in the absence of TDM to 19,±,0.3% in the presence of TDM. The reversibility of the absorption enhancing effect of TDM was studied by applying LMWH nasally 60 or 120 min after the enhancer. The effect of TDM on the nasal epithelia appeared to be rapidly reversible. In conclusion, nasal delivery of LMWH, but not UFH, was successful when an absorption enhancer was included to increase nasal permeability. © 2002 Wiley-Liss Inc. and the American Pharmaceutical Association J Pharm Sci 91:1707,1714, 2002 [source]

Fluorescent polymer particles by emulsion and miniemulsion polymerization

Frédéric Tronc
Abstract We describe the synthesis and characterization of latex particles labeled with a brightly fluorescent yellow dye (HY) based on the benzothioxanthene ring structure. Three dye derivatives were synthesized with different spacers connecting the HY nucleus to a methacrylate group. For one of the dyes (HY2CMA, rA), we show that the reactivity ratios with styrene (rA = 0.71, rB = 0.25) and butyl methacrylate (rA = 0.87, rB = 0.14) should lead to random dye incorporation if the amount of dye in the feed is small. Seeded emulsion polymerization fails to lead to significant dye incorporation unless large amounts of nonionic surfactant are present. In contrast, miniemulsion polymerization worked well to yield latex particles of polystyrene, poly(butyl methacrylate), and poly(methyl methacrylate) with high monomer conversion and essentially quantitative dye incorporation. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 766,778, 2003 [source]

Disruption of fungal and bacterial biofilms by lauroyl glucose

D.H. Dusane
Abstract Aim:, The ability of enzymatically synthesized lauroyl glucose to disrupt fungal (Candida albicans, Candida lipolytica) and bacterial (Pseudomonas aeruginosa PAO1, Pseudomonas aureofaciens) biofilms was investigated. Methods and Results:, Preformed biofilms of C. albicans and C. lipolytica in polystyrene microtitre plates were disrupted upto 45% and 65%, respectively, while P. aeruginosa and P. aureofaciens biofilms were disrupted by 51% and 57%. Precoating of the microtitre wells with lauroyl glucose affected cell attachment and biofilm growth of all the cultures to a lesser extent. With C. albicans and C. lipolytica, there was 11% and 32% decrease in the development of biofilms, respectively. With P. aeruginosa and P. aureofaciens, the reduction was 21% and 12% after 48 h. Lauroyl glucose effectively inhibited the formation of biofilms on glass slide surfaces when added along with the inoculum. Analysis by confocal laser scanning microscopy showed that the growth of the biofilms was lesser as compared with the control experiments. Lauroyl glucose displayed minimum inhibitory concentration values >500 ,g ml,1 for the test cultures and was comparable to that obtained with acetyl salicylate. Conclusion:, Lauroyl glucose reduces biofilm growth of all the four test cultures on polystyrene and glass surfaces. Significance and Impact of the Study:, This report is a novel application of the enzymatically synthesized, environmental-friendly nonionic surfactant. [source]

Ammonium oxotrifluorotitanate: morphology control and conversion to anatase TiO2

Lei Zhou
Abstract Uniform ammonium oxotrifluorotitanate (NH4TiOF3) mesocrystals were synthesized from an aqueous solution containing (NH4)2TiF6 and H3BO3 in presence of nonionic surfactant. Effects of various reaction conditions on the morphology of the NH4TiOF3 mesocrystals were examined by electron microscopy techniques. Results indicate that static solution, high surfactant concentration and low reaction temperature enhance the formation of uniform NH4TiOF3 mesocrystals with regular shapes. By sintering in atmosphere, the NH4TiOF3 mesocrystals were converted to anatase TiO2, which retain the original shapes of the NH4TiOF3 precursor due to similarities on their atom structures. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Effect of solid material and surfactant presence on interactions of bubbles with horizontal solid surface

Mária Fujasová-Zedníková
Abstract The interaction of a bubble with an immersed horizontal solid surface is studied experimentally. The effect of presence of a surfactant (limited to a specific nonionic surfactant, ,-terpineol, of various concentrations) and of surface material (cleaned glass, polypropylene, polyethylene, and Teflon) is investigated. The study focuses on two particular stages of the interaction, (i) the process of bubble bounce, which includes a collision and subsequent rebound from the solid surface, and (ii) the bubble attachment, which occurs after collision in time much longer than the duration of bounce and also after disappearance of all visible bubble movement. It is observed that the effect of the surface material on the bouncing is minor, possibly due to the liquid film separating the bubble and the solid surface. The presence of surfactant significantly affects the bouncing process. It not only decreases the initial bubble velocity, but also diminishes the bubble deformation after the collision and suppresses the bubble rebound from the surface. No rebound from the surface is observed in the most concentrated (1,×,10,3,mol/L) ,-terpineol solution. The adhesion time depends both on the solid material and ,-terpineol concentration. If the ,-terpineol concentration is increased, the adhesion time increases in the case of polypropylene surface, while it decreases in the case of polyethylene and Teflon surfaces. Results of this study are relevant for the description of attachment mechanism and to determine the proper conditions for selective flotation of plastics. L'interaction d'une bulle avec une surface pleine horizontale immergée est étudiée expérimentalement. L'effet de la présence d'un agent tensio-actif (limité à un agent tensio-actif nonionique spécifique, le ,-terpinéol, de diverses concentrations) et de matériau de surface (verre nettoyé, polypropylène, polyéthylène et Téflon) est étudié. L'étude se concentre sur deux étapes particulières de l'interaction, (i) le processus de rebondissement de la bulle, incluant une collision et un rebondissement subséquent de la surface pleine, et (ii) l'adhérence de la bulle, qui se produit après la collision, d'une durée plus longue que la durée du rebondissement, et également, après la disparition de tout mouvement visible de la bulle. Il est observé que l'effet du matériau de surface sur le rebondissement est mineur, probablement dû à la pellicule liquide séparant la bulle et la surface pleine. La présence de l'agent tensio-actif affecte de manière significative le processus de rebondissement. Elle diminue nonseulement la vitesse initiale de la bulle, mais diminue également la déformation de la bulle après la collision et supprime le rebondissement de la bulle de la surface. Aucun rebondissement de la surface n'est observé dans la solution la plus concentrée de ,-terpinéol (1,×,10,3,mol/L). La durée d'adhérence dépend aussi bien de la concentration du matériau solide que de la concentration en ,-terpinéol. Si la concentration en ,-terpinéol est augmentée, la durée d'adhérence augmente dans le cas de la surface en polypropylène, alors qu'elle diminue dans le cas des surfaces en polyéthylène et en Téflon. Les résultats de cette étude sont pertinents pour décrire le mécanisme d'adhérence et pour déterminer les conditions appropriées pour la flottaison sélective des plastiques. [source]

Embryo development of porcine oocytes after injection with miniature pig sperm and their extracts

ABSTRACT This study examined embryo development of porcine oocytes after microinjection of sperm extracts (SE) in porcine intracytoplasmic sperm injection (ICSI). SE was prepared from miniature pig sperm by a nonionic surfactant, and various concentrations (0.02, 0.04 and 0.08 mg/mL) of SE were injected into the matured oocytes with a first polar body. In the pronuclear stage, the rate of oocytes with two pronuclei and a second polar body (21.4%) in the sperm and SE (0.04 mg/mL) injection group was significantly higher (P < 0.05) compared to other groups. The rate of 2,4-cell stage in sperm and SE (0.04 mg/mL) injection group was 38.1%, and it was significantly higher than that in the sperm injection group (22.9%). The rate of blastocyst stage in sperm and SE (0.04 mg/mL) injection group was 21.4%, the value was significantly higher than those in SE (0.08 mg/mL) injection group (0%), sperm injection group (5.7%), and sperm and SE (0.08 mg/mL) injection group (2.6%). These results suggest that SE induces activation of porcine oocytes and their further embryonic development, and that SE is effective for porcine ICSI. [source]

Protein Refolding Mediated by Reverse Micelles of Cibacron Blue F-3GA Modified Nonionic Surfactant

Xiao-Yue Wu
An affinity-based reverse micellar system formulated with nonionic surfactant was applied to the refolding of denatured-reduced lysozyme. The nonionic surfactant of sorbitan trioleate (Span 85) was modified with Cibacron Blue F-3GA (CB) as an affinity surfactant (CB-Span 85) to form affinity-based reverse micelles in n -hexane. The water content of 15 was found optimal for lysozyme refolding in the reverse micellar system of 62.7 mmol/L Span 85 with coupled CB of 0.3 and 0.5 mmol/L. In addition, the operating conditions such as pH and the concentrations of urea and redox reagents were optimized. Under the optimized conditions, complete renaturation of lysozyme at 3,3.5 mg/mL was achieved, whereas dilution refolding in the bulk aqueous phase under the same conditions gave much lower activity recovery. Moreover, the secondary structure of the refolded lysozyme was found to be the same as the native lysozyme. Over 95% of the refolded lysozyme was recovered from CB-Span 85 reverse micelles by a stripping solution of 0.5 mol/L MgCl2. Thus, the present system is advantageous over the conventional reverse micellar system formed with ionic surfactants in the ease of protein recovery. [source]

Rapid synthesis of lead oxide nanorods by one-step solid-state chemical reaction at room temperature

Ya-Li Cao
Abstract A simple and facile method was reported to synthesize lead oxide nanorods. Nanorods of lead oxide were obtained directly from grinding solid metal salt and sodium hydroxide in agate mortar with the assistance of a suitable nonionic surfactant in only one step, which is different from the result of hydroxide in solution. The product has been characterized by XRD, TEM and SEM. The formation mechanism of rod-like morphology is discussed and the surfactant plays an important soft-template role in modifying the interface of solid-state reaction and according process of rod-formation. [source]

Microencapsulation of n -Eicosane as Energy Storage Material

Xiao-Zheng Lan
Abstract For heat energy storage application, polyurea microcapsules containing phase change material, n -eicosane, were synthesized by using interfacial polymerization method with toluene-2,4-diisocyanate (TDI) and diethylenetriamine (DETA) as monomers in an emulsion system. Poly(ethylene glycol)octyl-phenyl ether (OP), a nonionic surfactant, was the emulsifier for the system. The experimental result indicates that TDI was reacted with DETA in a mass ratio of 3 to 1. FT-IR spectra confirm the formation of wall material, polyurea, from the two monomers, TDI and DETA. Encapsulation efficiency of n -eicosane is about 75%. Microcapsule of n -eicosane melts at a temperature close to that of n -eicosane, while its stored heat energy varies with core material n -eicosane when wall material fixed. Thermo-gravimetric analysis shows that core material n -eicosane, micro- n -eicosane and wall material polyurea can withstand temperatures up to 130, 170 and 250 °C, respectively. [source]

Tensammetric Analysis of Nonionic Surfactant Mixtures by Artificial Neural Network

A. Safavi
Abstract An artificial neural network (ANN) model has been developed for tensammetric determination of a series of Brijes (Brij 30, Brij 35, Brij 56, Brij 96) as nonionic surfactants. The tensammetric method is based on the measurement of the capacitive current of the mercury electrode after adsorption of surfactants. All Brijes were analyzed in the concentration range of 1.0,100.0,,g mL,1. The proposed method shows good sensitivity and applicability to the simultaneous determination of mixtures of four Brijes in aqueous solutions. [source]

Rapid characterization of fatty alcohol ethoxylates by non-aqueous capillary electrophoresis

Mónica Arias
Abstract Fatty alcohol ethoxylates (FAE) (a mixture of nonionic surfactants) have been characterized using NACE with UV detection. Phenyl polyurethane derivatives of these compounds were previously obtained by reaction with phenyl isocyanate. The derivatization reaction only requires microwave irradiation for 30,s (600,W). Phenyl polyurethanes were separated and characterized using a BGE containing a mixture of ammonium nitrate (15,mM), acetic acid (1.5%) and 9:1 v/v methanol/ACN. After optimization of the instrumental conditions for the separation, phenyl polyurethane compounds (formed from the corresponding FAE) with ethylene oxide numbers (EON) of 6 (certified standard and industrial samples), 7 and 10 (both as industrial samples), and 5.5 (microemulsion phase) were successfully separated and characterized. The properties of these FAE nonionic surfactants are very important in the petroleum industry, which requires characterization of the quality of the purchased materials as well as the final products in the microemulsion-oil-water stream process. This analytical objective has been achieved by the proposed NACE methods, allowing FAE to be distinguished from 5.5 to 10 EON with errors below 4%, and shows advantages against to HPLC methods. [source]

Uptake and accumulation of sediment-associated 4-nonylphenol in a benthic invertebrate (Lumbriculus variegatus, freshwater oligochaete)

Valeria Croce
Abstract In the present work, the oligochaete Lumbriculus variegatus was exposed for 56 d to lake sediment spiked with 4-nonylphenol (4-NP), which is a breakdown product of alkylphenol polyethoxylates, an important class of nonionic surfactants. During the exposure period, the content of 4-NP was determined in the oligochaetes, sediment, overlying water, and pore water in order to monitor the distribution of the 4-NP in the compartments of the test system. Concentration of 4-NP in L. variegatus increased linearly over the course of the test, with an uptake rate coefficient of 1.9 × 10,2 (± 0.2 × 10,2; [g carbon/(g lipid-h)]). No steady state was reached at the end of the exposure period, suggesting that the elimination of 4-NP by the organism was negligible. Ingested sediments played an important role in the accumulation of 4-NP in L. variegatus, which may achieve very high 4-NP body concentrations. The 56-d biota sediment accumulation factor (BSAF) was 24 ± 7 g carbon/g lipid. L. variegatus also was exposed to 4-NP-contaminated field sediment, and field oligochaetes and sediments were collected for 4-NP pollution assessment in aquatic ecosystem. The 4-NP uptake with natural sediment was in accordance with that measured with spiked sediments, suggesting that the bioavailability of sediment-associated 4-NP for L. variegatus was not affected by 4-NP sediment concentration and abiotic sediment characteristics. The BSAFs measured in field oligochaetes, ranging from 39 to 55 g carbon/g lipid, was relatively higher than the bioaccumulation factor measured in laboratory tests. The results suggest that 4-NP concentration can reach high levels in benthic oligochaetes; this can be an important way of exposure for their pelagic predators. [source]

Investigation of an onsite wastewater treatment system in sandy soil: Site characterization and fate of anionic and nonionic surfactants

Allen M. Nielsen
Abstract This study reports on the fate of linear alkylbenzene sulfonate (LAS), alcohol ethoxylate (AE), and alcohol ether sulfate (AES) surfactants in a home septic system near Jacksonville (FL, USA) that has been used since 1976. The drainfield at this site resides in fine sand (<6% silt and clay) with an unsaturated zone that ranges from 0 to 1.3 m. During the wettest times of the year, it is likely that effluent from the septic system passes directly into the groundwater without exposure to an unsaturated zone of soil. Groundwater was collected during two sampling events, representing seasonal high and low groundwater table levels, and analyzed for the surfactants LAS, AES, and AE. During the wet season, the unsaturated zone was approximately 0.01 m beneath the drainfield. During the dry season, the unsaturated zone was about 0.4 m below the drainfield. Alcohol ethoxylate was not detected in any groundwater samples during either sampling. Alcohol ether sulfate was not found in the dry season sampling, but traces of AES had migrated downgradient about 4.7 m horizontally and 1.8 m vertically in the wet season. Linear alkylbenzene sulfonate was detected in some dry season samples and had moved downgradient some 11.7 m horizontally and 3.7 m vertically in the wet season. These observations demonstrate that these surfactants were removed to a great extent; otherwise, they would have traveled more than 260 m downgradient, which is the calculated distance that a conservative tracer like bromide would have moved downgradient over the life of the system. The most likely removal mechanisms for these surfactants were biodegradation and sorption. Therefore, this study indicates that LAS, AE, and AES are readily removed from groundwater in soils below septic system drainfields even in situations with minimal unsaturated soil zones. [source]

Acute toxicity of para -nonylphenol to saltwater animals,

Suzanne M. Lussier
Abstract para -Nonylphenol (PNP), a mixture of alkylphenols used in producing nonionic surfactants, is distributed widely in surface waters and aquatic sediments, where it can affect saltwater species. This article describes a database for acute toxicity of PNP derived for calculating a national saltwater quality criterion. Using a flow-through exposure system with measured concentrations, we tested early life stages of four species of saltwater invertebrates and two species of fish. Static 96-h tests were also conducted on zoeal Homarus americanus, embryo-larval Mulinia lateralis, and larval Pleuronectes americanus. The number of organisms surviving the flow-through test was measured at 2, 4, 8, and 12 h and daily through day 7. Mortality for most species plateaued by 96 h. The ranked sensitivities (96-h 50% lethal concentrations, measured in micrograms per liter) for the species tested were 17 for Pleuronectes americanus, 37.9 (48-h 50% effective concentration) for Mulinia lateralis, 59.4 for Paleomonetes vulgaris, 60.6 for Americamysis bahia (formerly Mysidopsis bahia), 61.6 for Leptocheirus plumulosos, 70 for Menidia beryllina, 71 for Homarus americanus, 142 for Cyprinodon variegatus, and > 195 for Dyspanopius sayii. Values for the seven most sensitive of these species ranged over a factor of only 4.2. The narrow range of responses for PNP implies that exceeding a threshold concentration would endanger a large proportion of the aquatic community. [source]

Targeted delivery of salicylic acid from acne treatment products into and through skin: role of solution and ingredient properties and relationships to irritation

L. Rhein
Salicylic acid (SA) is a beta-hydroxy acid and has multifunctional uses in the treatment of various diseases in skin such as acne, psoriasis, and photoaging. One problem often cited as associated with salicylic acid is that it can be quite irritating at pH 3,4, where it exhibits the highest activity in the treatment of skin diseases. We have identified strategies to control the irritation potential of salicylic acid formulations and have focused on hydroalcoholic solutions used in acne wipes. One strategy is to control the penetration of SA into the skin. Penetration of the drug into various layers of skin, i.e. epidermis, dermis, and receptor fluid, was measured using a modified Franz in vitro diffusion method after various exposure times up to 24 h. A polyurethane polymer (polyolprepolymer-15) was found to be an effective agent in controlling delivery of SA. In a dose-dependent fashion it targeted delivery of more SA to the epidermis as compared to penetration through the skin into the receptor fluid. It also reduced the rapid rate of permeation of a large dose of SA through the skin in the first few hours of exposure. A second strategy that proved successful was incorporation of known mild nonionic surfactants like isoceteth-20. These surfactants cleanse the skin, yet due to their inherent mildness (because of their reduced critical micelle concentration and monomer concentration), keep the barrier intact. Also, they reduce the rate of salicylic acid penetration, presumably through micellar entrapment (either in solution or on the skin surface after the alcohol evaporates). Cumulative irritation studies showed that targeting delivery of SA to the epidermis and reducing the rapid early rate of penetration of large amounts of drug through the skin resulted in a reduced irritation potential. In vivo irritation studies also showed that the surfactant system is the most important factor controlling irritancy. SA delivery is secondary, as formulations with less SA content reduced the rate of delivery to the receptor and yet were some of the most irritating formulations tested, presumably due to the action of the specific anionic surfactant on the barrier. Alcohol content also did not appreciably affect irritation and SA delivery; formulations with considerably low alcohol content but containing anionic versus nonionic surfactant systems exhibited considerably higher irritancy. Thus the surfactant type was again the predominant factor in those studies, although arguably alcohol plays some role (solubilization of SA). Results showed that both polymers and mild surfactants work in concert to provide the optimal formulation benefits of targeted delivery and reduced irritation. Synergistic relationships among hydroalcoholic formulation components will be discussed along with the mechanisms likely involved in controlling delivery of SA to skin. [source]

Self-emulsifying O/W formulations of paclitaxel prepared from mixed nonionic surfactants

Jen-Ting Lo
Abstract Nonionic self-emulsifying oil-in-water (O/W) formulations free of Cremophore® were developed as drug delivery vehicles for paclitaxel. The surfactants used included phosphatidylcholine purified from egg yolk (EPC), Tween, and Span. Oils phases were either pure components or blends from benzyl alcohol, 2-phenylethanol benzyl benzoate, and tributyrin. Among these surfactants, mixtures of EPC and Tween-80 gave really stable emulsions in proper sizes ranging from 70 to 200,nm, mainly depends on the ratio of EPC to Tween-80 and amount of oils. Paclitaxel could be well preserved without any loss in oily stocks, namely mixtures of oils and paclitaxel as well as surfactants, stored at 4°C for more than 8 months. Only gentle mixing on oily stocks with aqueous diluents is enough to make paclitaxel-contained emulsions. The optimum formulation contains oils from 1 to 3 wt%, Tween-80 and EPC from 0.4 to 1.2 wt%, respectively. Consequently, near 500,ppm of paclitaxel can be contained in emulsions. Moreover, these paclitaxel-containing emulsions are compatible with commonly used injection fluids. No precipitation is observed upon preparation of emulsion from dilution of oily stocks. Negligible cytotoxicity on these emulsions assessed with NIH/3T3 cells implied their good biocompatibility and promising applications as drug delivery carriers. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99: 2320,2332, 2010 [source]

The role of surfactants in the reversal of active transport mediated by multidrug resistance proteins

Katrijn Bogman
Abstract A variety of seven nonionic, one amphoteric and, one anionic surfactant that are applied or investigated as surfactants in drug formulation, were analyzed for their capacity to modulate carrier-mediated transport by efflux pumps. Two cell lines, murine monocytic leukemia cells overexpressing P-glycoprotein (P-gp) and Madin-Darby canine kidney cells stably overexpresssing human multidrug resistance-associated protein 2 (MRP2), were used as test systems. The modulation of P-gp and of MRP2 function was studied by the reversal of rhodamine 123 and of methylfluorescein-glutathione conjugate transport, respectively. Mechanisms that were not transporter related and could lead to misinterpretations were identified, such as probe quenching, probe encapsulation by micelles, and membrane damage. P-gp-mediated rhodamine 123 transport was inhibited by five nonionic surfactants in a concentration-dependent manner and in the order TPGS,>,Pluronic PE8100,>,Cremophor EL,>,Pluronic PE6100,,,Tween 80. In contrast, none of the surfactants showed a significant inhibition of MRP2-mediated efflux in Madin-Darby canine kidney/MRP2 cells. In conclusion, the results indicate that surfactants demonstrate a transporter-specific interaction, rather than unspecific membrane permeabilization. The present analysis offers insight in the possible mechanisms of surfactant interactions with biological membranes and could help to identify specific drug formulations. © 2003 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 92:1250,1261, 2003 [source]

Effects of annealing lyophilized and spray-lyophilized formulations of recombinant human interferon-,

Serena D. Webb
Abstract The purpose of this study was to examine the effects of adsorption of recombinant human interferon-, (rhIFN-,) on ice surfaces and subsequent drying during processing by spray-lyophilization and lyophilization. Ice/liquid interfacial areas were manipulated by the freezing method as well as by the addition of an annealing step during lyophilization; that is, rhIFN-, adsorption was modified by the addition of nonionic surfactants. rhIFN-, was lyophilized or spray-lyophilized at a concentration of 1 mg/mL in 5% sucrose, 5% hydroxyethyl starch (HES),±,0.03% polysorbate 20 in 140 mM KCl, and 10 mM potassium phosphate, pH 7.5. After the samples were frozen, half were annealed on the lyophilizer shelf. Recovery of soluble protein was measured at intermediate points during processing. On drying, the secondary structure of rhIFN-, was determined by second-derivative infrared (IR) spectroscopy, specific surface areas (SSAs) were measured, scanning electron micrographs (SEM) were taken, and dissolution times were recorded. Adsorption of rhIFN-, to ice/liquid interfaces alone was not responsible for aggregation. Rather, drying was necessary to cause aggregation in lyophilized sucrose formulations. Addition of an annealing step to the lyophilization cycle resulted in more native-like secondary protein structure in the dried solid, eliminated cracking of the dried cakes, and suppressed both the formation of air/liquid interfaces and rhIFN-, aggregation on reconstitution. © 2003 Wiley-Liss, Inc. and the American pharmaceutical Association J Pharm Sci 92:715,729, 2003 [source]

Study of the solubilization of gliclazide by aqueous micellar solutions

Khouloud A. Alkhamis
Abstract It was of interest to increase the solubility of gliclazide in aqueous media. Therefore, solubilization of gliclazide in a variety of surfactants was investigated. Anionic and cationic surfactants exhibited dramatic solubilizing ability for gliclazide, whereas nonionic surfactants showed significantly lower solubilizing ability. It was found that gliclazide solubility increases with increasing the carbon chain length of cationic surfactants and decreases with increasing the carbon chain length of anionic surfactants. The solubilization data were analyzed on the basis of a pseudo-phase model with gliclazide exhibiting moderate partition coefficients into the micellar phase. The possible sites of solubilization of gliclazide in the micelle were examined by studying the effect of NaCl on solubilization and by comparing the absorption spectra of gliclazide in different solvents. The results obtained from these two experiments indicated that gliclazide is solubilized mainly in the inner core of the cationic surfactant micelles and in the outer regions of the anionic surfactant micelles. © 2003 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 92:839,846, 2003 [source]

Synthesis and characterization of the PEG-based nonionic surfactants endowed with carboxylic acid moiety at the hydrophobic terminal

Hiroshi Morikawa
As a new class of stimulus-responsive surfactants, a series of ,-methyl-,-alkyl PEGs endowed with a carboxylic acid moiety at the hydrophobic terminal was successfully synthesized with 56,97% yields. They were characterized by IR, NMR spectroscopic and MALDI-TOF MS analyses. It is suggested by DLS measurement that the collapse of the micelle-like aggregation occurred under basic condition. This synthetic procedure would be applicable to surfactants with sufficient hydrophilic and lipophilic balances, allowing precise control of pH-responsive micellar systems. [source]

Separation techniques for the analysis of artists' acrylic emulsion paints

Dominique Scalarone
Abstract Emulsion paints are complex chemical systems. The main problems in their characterization are related to the similarities in polymer composition and to the presence of many different types of additives. Thus high resolution separations, sensitivity, and response specificity are required to identify simultaneously the polymer matrix and the minor components. Especially surfactants and pigments are thought to affect significantly the properties of the paint layers during ageing and their identification is the first step in evaluating the behaviour of these products in working conditions. Representative samples of acrylic emulsion paints for artists have been investigated by pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) and size exclusion chromatography-Fourier transform infrared spectroscopy (SEC-FTIR), and the results have been compared. All the analysed samples were bound in ethyl acrylate-methyl methacrylate, poly(EA-co-MMA), or n -butyl acrylate-methyl methacrylate, poly(nBA-co-MMA), copolymers. Two types of nonionic surfactants, ethoxylated fatty alcohols and alkylaryl polyethoxylates, commonly used as emulsifiers and dispersive agents have been identified, together with a number of organic pigments. [source]

Use of a whole-cell biosensor to assess the bioavailability enhancement of aromatic hydrocarbon compounds by nonionic surfactants

Angela Keane
Abstract The whole-cell bioluminescent biosensor Pseudomonas putida F1G4 (PpF1G4), which contains a chromosomally-based sep-lux transcriptional fusion, was used as a tool for direct measurement of the bioavailability of hydrophobic organic compounds (HOCs) partitioned into surfactant micelles. The increased bioluminescent response of PpF1G4 in micellar solutions (up to 10 times the critical micellar concentration) of Triton X-100 and Brij 35 indicated higher intracellular concentrations of the test compounds, toluene, naphthalene, and phenanthrene, compared to control systems with no surfactants present. In contrast, Brij 30 caused a decrease in the bioluminescent response to the test compounds in single-solute systems, without adversely affecting cell growth. The decrease in bioluminescent response in the presence of Brij 30 did not occur in the presence of multiple HOCs extracted into the surfactant solutions from crude oil and creosote. The effect of the micellar solutions on the toluene biodegradation rate was consistent with the bioluminescent response in single-solute systems. None of the surfactants were toxic to PpF1G4 at the doses employed in this study, and PpF1G4 did not produce a bioluminescent response to the surfactants nor utilize them as growth substrates. TEM images suggest that the surfactants did not rupture the cell membranes. The results demonstrate that for Pseudomonas putida F1, nonionic surfactants such as Triton X-100 and Brij 35, at doses between 2 and 10 CMC, may increase the bioavailability and direct uptake of micellar phase HOCs that are common pollutants at contaminated sites. Biotechnol. Bioeng. 2008;99: 86,98. © 2007 Wiley Periodicals, Inc. [source]

A metal-chelate affinity reverse micellar system for protein extraction

Xiao-Yan Dong
Abstract A new nonionic reverse micellar system is developed by blending two nonionic surfactants, Triton X-45 and Span 80. At total surfactant concentrations lower than 60 mmol/L and molar fractions of Triton X-45 less than 0.6, thermodynamically stable reverse micelles of water content (W0) up to 30 are formed. Di(2-ethylhexyl) phosphoric acid (HDEHP; 1,2 mmol/L) is introduced into the system for chelating transition metal ions that have binding affinity for histidine-rich proteins. HDEHP exists in a dimeric form in organic solvents and a dimer associated with one transition metal ion, including copper, zinc, and nickel. The copper-chelate reverse micelles (Cu-RM) are characterized for their W0, hydrodynamic radius (Rh), and aggregation number (Nag). Similar with reverse micelles of bis-2-ethylhexyl sodium sulfosuccinate (AOT), Rh of the Cu-RM is also linearly related to W0. However, Nag is determined to be 30,90 at W0 of 5,30, only quarter to half of the AOT reverse micelles. Then, selective metal-chelate extraction of histidine-rich protein (myoglobin) by the Cu-RM is successfully performed with pure and mixed protein systems (myoglobin and lysozyme). The solubilized protein can be recovered by stripping with imidazole or ethylinediaminetetraacetic acid (EDTA) solution. Because various transition metal ions can be chelated to the reverse micelles, it is convinced that the system would be useful for application in protein purification as well as simultaneous isolation and refolding of recombinant histidine-tagged proteins expressed as inclusion bodies. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2010 [source]

Water Soluble Cruciforms: Effect of Surfactants on Fluorescence

Juan Tolosa Dr.
Abstract Brighten up! Adding surfactants to aqueous solutions of three different water-soluble cruciforms (XF) improves their fluorescence quantum yields. Additionally, changes are observed in the emission wavelength of the XF around the critical micelle concentration (cmc) of the surfactant. Three 1,4-bis-(aminostyryl)-2,5-bis(phenylethynyl) benzenes carrying four, six, or eight acetic acid units were investigated for their surfactochromicity. Anionic, cationic, and nonionic surfactants as well as a surfactant-like protein (bovine serum albumin, BSA) were added to buffered solutions of the XFs in water, causing,in most cases,the fluorescence quantum yield to increase significantly and a blue- or red-shifted emission to be observed. The addition of cationic (cetyltrimethylammonium bromide, CTAB) and neutral (Brij 35, TWEEN 20 and Triton X-100) surfactants to XFs causes a red shift in their emission at low or very low surfactant concentrations that we attribute to surfactant-induced excimer formation. The fluorescence quantum yield is in most cases a monotonous function of surfactant concentration. For the investigated ionic surfactants, the fluorescence quantum yield of the XFs does not change much after the critical micelle concentration (CMC) of the surface is reached. However, in the case of non-ionic surfactants, the fluorescence quantum yields of the XFs starts to increase after the CMC has been reached, suggesting that different effects are involved. [source]