Excess Sodium Dodecyl Sulfate Research Articles

Qualitative and quantitative methods detection of SDS based on polyelectrolyte microcapsules

Sodium dodecyl sulfate (SDS) is the most widely used anionic surfactant. Its frequent use causes environmental pollution and negative effects on living organisms (even at low concentrations ≈ 20 μg/ml). Thus, cheap and fast methods are needed to detect this surfactant in wastewater and surface waters in order to prevent the negative effects of SDS on the environment and human beings. We discovered that sodium dodecyl sulfate is capable of destroying polyelectrolyte microcapsules, which has been demonstrated by the number of sedimented polyelectrolyte microcapsules (PMC) before and after incubation in SDS solution. Therefore, it was proposed to use PMCs to create qualitative and quantitative diagnostic systems for the determination of SDS in solution. The qualitative system is a polyelectrolyte microcapsules containing polyallylamine labeled with a fluorescent dye—FITC. An excess SDS concentration of more than 5 μg/ml in the analyzed medium leads to the destruction of PMC and an increase in the fluorescence intensity of the solution, which is recorded by a fluorometer. The quantitative diagnostic system is based on turbidimetry of the PMC suspension before and after incubation in an anionic surfactant solution. This system has a range of detectable SDS concentrations from 10 to 50 μg/ml, with a standard deviation of no more than 11%.

Effect of polystyrene microplastics on the volatile fatty acids production from waste activated sludge fermentation

Anaerobic fermentation is crucial to resource utilization of waste activated sludge (WAS). However, accumulated microplastics (MPs) in sludge could not be ignored. Here, a typical MP, polystyrene (PS), was selected to study the effects of different concentrations of PS on anaerobic fermentation under the optimal volatile fatty acids (VFAs) production. Compared to the control, low PS concentrations (30 particles/g total solid) significantly (p = 0.002) increased the production of VFAs to 112.8 ± 2.4% due to solubilization enhancement and enzymatic activity. High concentrations of PS (90 particles/g total solid) significantly (p = 0.000) decreased VFAs production to 83.01 ± 0.76% because of the inactive related microbial activities, although organic matter release was enhanced in the initial stage. Mechanism studies showed that the toxicity of high PS concentration could be attributed to reactive oxygen species (ROS) production, excess sodium dodecyl sulfate (SDS), and synergistic toxicity of aged MPs with external pollutants.

Interfacial modification of starch at high concentration by sodium dodecylsulfate as revealed by experiments and molecular simulation

It is proposed that the interfacial compatibility of starch-based adhesives could be improved by sodium dodecylsulfate (SDS). The preparation of starch suspension with high concentration and molecular dynamics simulation were designed according to the adhesive preparation. The results showed that SDS without absorption competition expanded the molecular space and improved the starch dispersion. Additionally, the thickest interfacial layer was formed on starch containing 2% SDS due to the deeper immersion of SDS. Excessive SDS facilitated the supramolecular assembly, leading to the formation of starch colloid. SDS decreased the interfacial tension between the starch and different polarity matrix. Our simulated results accorded with the experimental results and presented the starch structure at the atomic level. Owing to the inhibition on molecular interaction of starch, SDS promoted the starch extensibility and flexibility. Moreover, three different contact forms (tail, head, and inclusion) between the starch and SDS were also presented in this work. This study is fundamental to establishing the relationship between macromolecular behaviors and product performance.

Sodium dodecyl sulfate improved stability and transdermal delivery of salidroside-encapsulated niosomes via effects on zeta potential.

Niosomes are novel carriers that show superior transdermal permeation enhancement but require the addition of charged stabilizers. In this study, niosomes were prepared using Span 40, cholesterol, and sodium dodecyl sulfate (SDS) as stabilizers for transdermal delivery of salidroside. At concentrations of 0.05-0.40% (w/v), SDS significantly increased the zeta potential of the nanovesicles from -18.5±3.2 to -157.0±5.2mV and improved the stability of the niosomal formulations. Niosomes prepared with a Span 40:cholesterol molar ratio of 4:3 and 0.1% SDS showed good stability and the highest transdermal drug delivery among all tested formulations, with 2.75-fold higher transdermal flux of 20.26±1.05μg/(cm2·h) than that of aqueous salidroside solution. However, excess SDS increased the negative charge on the vesicle surface and hence repulsion with skin cells, leading to reduced drug entrapment efficiency and cellular uptake of niosomes. Although SDS in the niosomes dose-dependently increased the in vitro cytotoxicity of the formulation in skin cells, HaCaT and CCC-ESF-1 cell viability was≥80% for formulations containing ≤0.1% SDS. No significant irritation was observed on rat skin with once-a-day topical application of the niosomal formulations for 7 consecutive days. Thus, SDS is a promising stabilizer for nanomedicines, including niosomes, for transdermal administration.

Control of the colloidal depletion force in nonionic polymer solutions by complexation with anionic surfactants

HypothesisCharge, size and concentration of depletants control the magnitude and range of depletion and structural forces. Noncovalent association of nonionic polymers with ionic surfactants may therefore synergistically enhance these forces to an extent that depends on the structure and composition of the resulting complexes. ExperimentsForces were measured between a silica sphere and a silica plate in solutions of Pluronic F108 nonionic poly(ethylene oxide – block – propylene oxide – block – ethylene oxide) triblock copolymers and anionic sodium dodecylsulfate (SDS) surfactants using colloidal probe atomic force microscopy as a function of polymer, surfactant and NaCl background electrolyte concentrations. Trends in the magnitudes of the depletion attraction minimum and the first repulsive maximum in the oscillatory structural force were interpreted with the aid of pyrene solubilization assays, sodium ion-selective electrode analysis, and dynamic light scattering measurements that characterized the formation, charge, and hydrodynamic radius of F108/SDS complexes respectively. FindingsSynergistic enhancement of the depletion force and first repulsive maximum occurred within a finite range of SDS concentrations, to an extent that depended on F108 and NaCl concentrations. This was due mainly to charging of F108/SDS complexes. Size effects were important at low NaCl concentration. Forces measured above the synergistic SDS concentration range were indistinguishable from those in polymer-free SDS solutions due to the appearance of excess unbound SDS micelles.

Impacts of Size and Deformability of β-Lactoglobulin Microgels on the Colloidal Stability and Volatile Flavor Release of Microgel-Stabilized Emulsions.

Emulsions can be prepared from protein microgel particles as an alternative to traditional emulsifiers. Prior experiments have indicated that smaller and more deformable microgels would decrease both the physical destabilization of emulsions and the diffusion-based losses of entrapped volatile molecules. The microgels were prepared from β-lactoglobulin with an average diameter of 150 nm, 231 nm, or 266 nm; large microgels were cross-linked to decrease their deformability. Dilute emulsions of 15–50 μm diameter were prepared with microgels by high shear mixing. Light scattering and microscopy showed that the emulsions prepared with larger, untreated microgels possessed a larger initial droplet size, but were resistant to droplet growth during storage or after acidification, increased ionic strength, and exposure to surfactants. The emulsions prepared with cross-linked microgels emulsions were the least resistant to flocculation, creaming, and shrinkage. All emulsion droplets shrank as limonene was lost during storage, and the inability of microgels to desorb caused droplets to become non-spherical. The microgels were not displaced by Tween 20 but were displaced by excess sodium dodecyl sulfate. Hexanol diffusion and associated shrinkage of pendant droplets was not prevented by any of the microgels, yet the rate of shrinkage was reduced with the largest microgels.

Optimisation of purification techniques for the preparation of large-volume aqueous solar nanoparticle inks for organic photovoltaics.

In this study we have optimised the preparation conditions for large-volume nanoparticle inks, based on poly(3-hexylthiophene) (P3HT):indene-C60 multiadducts (ICxA), through two purification processes: centrifugal and crossflow ultrafiltration. The impact of purification is twofold: firstly, removal of excess sodium dodecyl sulfate (SDS) surfactant from the ink and, secondly, concentration of the photoactive components in the ink. The removal of SDS was studied in detail both by a UV–vis spectroscopy-based method and by surface tension measurements of the nanoparticle ink filtrate; revealing that centrifugal ultrafiltration removed SDS at a higher rate than crossflow ultrafiltration even though a similar filter was applied in both cases (10,000 Da Mw cut-off). The influence of SDS concentration on the aqueous solar nanoparticle (ASNP) inks was investigated by monitoring the surface morphology/topography of the ASNP films using atomic force microscopy (AFM) and scanning electron microscopy (SEM) and photovoltaic device performance as a function of ultrafiltration (decreasing SDS content). The surface morphology/topography showed, as expected, a decreased number of SDS crystallites on the surface of the ASNP film with increased ultrafiltration steps. The device performance revealed distinct peaks in efficiency with ultrafiltration: centrifuge purified inks reached a maximum efficiency at a dilution factor of 7.8 × 104, while crossflow purified inks did not reach a maximum efficiency until a dilution factor of 6.1 × 109. This difference was ascribed to the different wetting properties of the prepared inks and was further corroborated by surface tension measurements of the ASNP inks which revealed that the peak efficiencies for both methods occurred for similar surface tension values of 48.1 and 48.8 mN m−1. This work demonstrates that addressing the surface tension of large-volume ASNP inks is key to the reproducible fabrication of nanoparticle photovoltaic devices.

Highly stable and reduction responsive micelles from a novel polymeric surfactant with a repeating disulfide-based gemini structure for efficient drug delivery

The synthesis of a novel polymeric surfactant with a repeating disulfide-based gemini structure (poly(gemini surfactant)) and its micellar properties for GSH-dependent intracellular drug delivery are described. A linear polyethylene glycol (PEG) was end-functionalized with N-stearoylcysteine and the cysteine thiol groups of the telechelic surfactant were oxidized intermolecularly in the micellar state to produce poly(gemini surfactant). Compared with the telechelic surfactant, poly(gemini surfactant) possessed a lower critical micelle concentration and higher solubilization capacity for doxorubicin (DOX). Moreover, the poly(gemini surfactant) micelles revealed excellent colloidal stability against excess sodium dodecyl sulfate (SDS) as a micelle-destabilizing agent. Cytotoxicity experiments showed that poly(gemini surfactant) composed of PEG, cysteine, and stearic acid was virtually non-cytotoxic up to 100 mg L−1. In the presence of glutathione (GSH), poly(gemini surfactant) was degraded back into the telechelic surfactant, leading to the release of encapsulated DOX to induce cytotoxicity against cancer cells.

Effect of adsorption of catanionic surfactant mixtures on wettability of quartz surface

The adsorption behaviors of dodecyl trimethyl ammonium bromide (C12TAB) and the catanionic mixtures of C12TAB with sodium dodecyl sulfate (SDS), sodium dodecyl sulfonate (SDDS) and sodium dodecanoate (DAS) on quartz surface have been investigated. Physicochemical parameters such as the critical micelle concentration (CMC), surface tension, contact angle, adhesional tension and work of adhesion have been estimated. At the interface of quartz and aqueous solution of catanionic mixture, there is a competition between anionic surfactants and quartz surface in attracting cationic surfactants. SDDS and DAS fail to inhibit the adsorption of C12TAB because of the smaller size and less negative charge of the head-groups, even the amount of anionic surfactants well surpasses that of C12TAB. Instead the anionic surfactants are dragged by cationic surfactants to quartz surface and form a mixed monolayer on the quartz surface. The insert of anionic surfactants reduces the repulsion between the cationic molecules and results in closer packing of molecules in adsorption layers. Thus, SDDS-C12TAB and DAS-C12TAB have displayed stronger hydrophobic modification at quartz surface than pure C12TAB. However, the electrostatic attraction between excessive SDS and C12TAB is strong enough to constrain C12TAB and decreases the adsorption on quartz surface. Only a small amount of catanionic complexes with the structure like zwitterionic surfactant adsorb on quartz through the interaction between the positive sites of surfactant complexes and negative sites of quartz. Over CMC, bilayers are formed on quartz surface in the systems of SDDS-C12TAB and DAS-C12TAB, while micelle structures are adsorbed on quartz surface for SDS-C12TAB.

Properties and Extraction for [Ni(NH3)6]2+ of ATPS-a Formed by Aqueous Cationic–Anionic Surfactant Mixtures

The properties and extraction for [Ni(NH3)6]2+ of anionic aqueous two-phase systems (ATPS-a) that formed in mixtures of cetyltrimethylammonium bromide (CTAB) and excess sodium dodecyl sulfate (SDS) aqueous solutions were investigated. The results showed that the properties and extraction effects were strongly affected by the surfactant concentration, the temperature of system, and the mole fraction of surfactants. The increase of temperature induces narrower phase region and larger phase volume ratio. In addition, [Ni(NH3)6]2+ was extracted into the surfactant-rich phase with higher distribution coefficient when the liquid crystal had the birefringent properties. Moreover, the distribution coefficient can be improved through reducing the concentration of surfactant from 0.15 to 0.05 mol · L−1 or increasing mole fraction of CTAB from 21.9% to 23.1%. The results showed that ATPS of cationic–anionic surfactants was efficient for [Ni(NH3)6]2+ extraction with distribution coefficients of 13.5 when the total surfactant concentration was 0.05 mol · L−1, mole fraction of CTAB was 21%, and temperature was 34°C.

Atomic force microscopy imaging of dialyzed single-walled carbon nanotubes dispersed with sodium dodecyl sulfate

The existence of excess sodium dodecyl sulfate (SDS) molecules in a single-walled carbon nanotube (SWNT) solution dispersed by hybridization with SDS leads to unstable atomic force microscopy (AFM) imaging. In this study, we demonstrate sequential dialysis against pure water in order to remove excess SDS molecules from an SDS-SWNT hybrid dispersion. A 1:102 volume ratio of SDS-SWNT dispersion to water in the dialysis was found to be effective in realizing stable AFM observations of the SDS-SWNT hybrids despite imperfect filtering of SDS via dialysis. On the other hand, the SDS-SWNT hybrids were stable even when this volume ratio was 1:106. Further, the SDS-SWNT hybrids were present in the solution even when the dialyzed samples were stored for 14 days. Our results reveal that dialysis under optimal conditions enables improved handling of SDS-SWNT hybrids, particularly for stable AFM observations.

Mixtures of Cationic Copolymers and Oppositely Charged Surfactants: Effect of Polymer Charge Density and Ionic Strength on the Adsorption Behavior at the Silica–Aqueous Interface

This study addresses polymer-surfactant interactions at solid-liquid interfaces and how these can be manipulated by modulating the association between ionic surfactant and oppositely charged polymer, with a particular focus on electrostatic interactions. For this purpose, the interaction of a series of cationic copolymers of vinylpyrrolidone and quaternized vinylimidazol with sodium dodecyl sulfate (SDS) at the silica-aqueous interface was followed by in situ ellipsometry. To reveal the nature of the interaction, we performed measurements for different copolyion charge densities, in the absence and presence of added salt. The path-dependence of the interaction was studied by comparing the adsorption under two different conditions, adsorption from premixed solutions and sequential addition of surfactant to the polymer solution, but the same end state. The reversibility of the adsorption process was studied by following the effect of dilution on the adsorbed layer. All copolyions adsorbed to both silica and hydrophobized silica, revealing the importance of both hydrophobic and electrostatic attractive interactions. On both types of surface, an increase in adsorbed amount was found on lowering the fraction of charged units. An increased ionic strength gave an increased adsorbed amount in all cases, but especially on hydrophobic surfaces. The adsorbed amount on silica from mixtures of the copolyions with SDS peaked at an SDS concentration corresponding closely to the concentration of cationic charges of the different polyions. Around the region of charge equivalence, there was also a phase separation in the bulk. At higher concentrations of SDS, a redissolution in the bulk, and a decrease in adsorbed amount, occurred as a result of excess SDS binding to the complexes. For the most highly charged polyions, we observed a decrease in adsorbed amount, and a shift in the adsorption maxima to lower SDS concentrations, with increasing ionic strength.

Wettability switching of SDS-doped polyaniline from hydrophobic to hydrophilic induced by alkaline/reduction reactions

In this paper, sodium dodecyl sulfate (SDS) is used as dopant to manipulate both morphology and wettability of polyaniline (PANI). When SDS amount is controlled within a certain range, micro/nano double-rough PANI with hydrophobic surface can be obtained, while insufficient or excess SDS can only lead to hydrophilic PANI. The double-rough PANI shows stimuli-responsive change in wettability to either alkaline reaction or reduction reaction from hydrophobicity to hydrophilicity. This quick response can be applied to quantitatively estimate NaOH concentrations within the range of 10−3–10−1M and to detect various reducing liquids.

Preparation of uniformly dispersed YAG ultrafine powders by co-precipitation method with SDS treatment

Uniformly dispersed yttrium aluminum garnet (Y 3Al 5O 12, YAG) ultrafine powders were synthesized by co-precipitating a mixed solution of aluminum and yttrium nitrates with ammonium hydrogen carbonate in the presence of sodium dodecyl sulfate (SDS) as dispersing agent. The primary purpose of introducing SDS was to protect YAG particles from agglomeration. The evolution of phase composition and micro-structure of the as-synthesized YAG powders were characterized by thermogravimetry/differential scanning calorimetry, X-ray diffraction, infrared spectra and scanning electron microscopy. The results showed that phase-pure YAG powders could be achieved by calcination of the precursor at 900 °C for 2 h. Uniformly dispersed YAG powders with a particle size of approximately 90–100 nm were obtained with optimum molar ratio of Al 3+ to SDS at 2. And excessive SDS restrained good dispersion of the YAG powders. The dispersion mechanism of SDS in the preparation process was discussed.

Preparation of uniformly dispersed YAG ultrafine powders by coprecipitation method with SDS treatment

Uniformly dispersed yttrium aluminum garnet (Y3Al5O12, YAG) ultrafine powders are synthesized by coprecipitating a mixed solution of aluminum and yttrium nitrates with ammonium hydrogen carbonate in the presence of sodium dodecyl sulfate (SDS) as a dispersing agent. The primary purpose of introducing SDS is to protect YAG particles from agglomeration. The evolution of phase composition and microstructure of the as-synthesized YAG powders are characterized by thermogravimetry/differential scanning calorimetry, X-ray diffraction, infrared spectra, and scanning electron microscopy. The results show that phase-pure YAG powders can be achieved by calcination of the precursor at 900°C for 2 h. Uniformly dispersed YAG powders with a particle size of approximately 90–100 nm are obtained with the optimum molar ratio of Al3+ to SDS of 2, and excessive SDS restrains good dispersion of the YAG powders. The dispersion mechanism of SDS in the preparation process is discussed.

Study on radiation‐induced grafting of hydrophilic monomers onto chitosan

AbstractThe graft polymerization of 2‐Hydroxyethyl acrylate, 2‐Hydroxyethyl methacrylate, and N‐vinylpyrrolidone onto chitosan in aqueous solution initiated by γ‐ray irradiation was carried out. The effect of various conditions such as the absorbed dose, concentration of monomer, and solvent on grafting was investigated. The grafting yield increased with the increase in absorbed dose. The degree of grafting increased with increase in the radiation dose. The obtained graft copolymers showed the solubility in water in wide pH interval. The interactions between grafted chitosan copolymers with sodium dodecyl sulfate (SDS) were studied in an aqueous solution. It was found that there is a narrow molar ratio of SDS/cation (∼ 0.40–0.70) depending on different grafted copolymers, at which the turbidity of SDS‐grafted chitosan complex has a maximum due to the formation of water insoluble interpolymer aggregates via the SDS attached on the polymer chain. The turbidity falls sharply with the further addition of excessive SDS, which forms micelle in the solution and causes the de‐aggregation of the interpolymer aggregates and also because of the precipitation of complexes and returns to the original level. The morphologic properties of thin films of SDS‐ grafted chitosan complex were investigated. It was observed that upon heating the insoluble complex of SDS and grafted chitosan in water, superstructures were formed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Complexation between Sodium Dodecyl Sulfate and Amphoteric Polyurethane Nanoparticles

The complexation between negatively charged sodium dodecyl sulfate (SDS) and positively charged amphoteric polyurethane (APU) self-assembled nanoparticles (NPs) containing nonionic hydrophobic segments is studied by dynamic light scattering, pyrene fluorescent probing, zeta-potential, and transmission electron microscopy (TEM) in the present paper. With increasing the mol ratio of SDS to the positive charges on the surface of APU NPs, the aqueous solution of APU NPs presents precipitation at pH 2, around stoichiometric SDS concentration, and then the precipitate dissociates with excess SDS to form more stable nanoparticles of ionomer complexes. Three stages of the complexation process are clearly shown by the pyrene I1/I3 variation of the complex systems, which only depends on the ratio of SDS/APU, and demonstrate that the process is dominated by electrostatic attraction and hydrophobic aggregation.

Size control of poly( d, l-lactide- co-glycolide) and poly( d, l-lactide- co-glycolide)-magnetite nanoparticles synthesized by emulsion evaporation technique

Emulsion evaporation method was used to prepare poly(lactide- co-glycolide) (PLGA) nanoparticles with oleic acid stabilized superparamagnetic iron oxide nanoparticles, in the presence of sodium dodecyl sulfate (SDS) as a surfactant. The magnetite nanoparticles, initially obtained as water soluble particles, were surface functionalized with oleic acid to ensure their efficient entrapment in the PLGA matrix. The inclusion of magnetite with oleic acid (MOA) into the PLGA nanoparticles was accomplished in the organic phase. Synthesis was followed by dialysis, performed to eliminate the excess SDS, and lyophilization. The PLGA–magnetite nanoparticles were compared with naked PLGA nanoparticles. Naked PLGA nanoparticles ranged in size from 38.6 to 67.1 nm; when MOA was entrapped in the PLGA matrix, the nanoparticle size ranged from 78.8 to 115.1 nm. The MOA entrapment efficiency varied from 57.4 to 91.9%. The efficiency of SDS removal by dialysis from the nanoparticles varied from 51.0 to 88.8%. SDS concentration played a critical role in controlling the nanoparticle size. A three-fold increaser in the PLGA concentration was possible with the proposed method without increasing the size of the empty PLGA nanoparticles over 100 nm The size and uniformity of the MOA suspension, was found critical in forming small and uniform magnetic–polymeric nanoparticles (M-P NPs).

Synthesis of Poly(DL-Lactide-Co-Glycolide) Nanoparticles with Entrapped Magnetite by Emulsion Evaporation Method

The goal of this study was to synthesize Poly(DL-lactide-Co-glycolide) nanoparticles with entrapped magnetite, of under 100 nm in diameter, for future drug delivery applications. The emulsion evaporation method was selected to form poly(lactide-co-glycolide) (PLGA) nanoparticles with entrapped magnetite (Fe3O4) in the polymeric matrix, in the presence of sodium dodecyl sulfate (SDS) as a surfactant. Magnetite, a water-soluble compound, was surface functionalized with oleic acid to ensure its efficient entrapment in the PLGA matrix. The inclusion of magnetite with oleic acid (MOA) into the PLGA nanoparticles was accomplished in the organic phase. Synthesis was followed by dialysis, performed to eliminate the excess SDS, and lyophilization. The synthesized nanoparticles ranged in size from 38.6 to 67.1 nm for naked PLGA nanospheres and from 78.8 to 87.2 nm for MOA-entrapped PLGA nanospheres. The entrapment efficiency ranged from 57.36% to 77.3%.

Surfactant and polyelectrolyte gel particles for encapsulation and release of aromatic oils.

Associative phase separation occurs when oppositely charged surfactants and polyelectrolytes are mixed in near-stoichiometric proportions. This behavior has been exploited in the production of gel particles that range between approximately 100 and 4000 µm in diameter. Here, we investigate their performance as materials for the encapsulation and release of the aromatic oil cymene. The gel particles ( 1500 µm in diameter) are prepared by dropwise addition of an oil-in-water suspension made of cymene droplets dispersed in a viscous solution of sodium dodecyl sulfate (SDS) and ,,-trimethylammonium derivatized hydroxyethyl cellulose (JR-400) to a gelling solution of excess SDS. The release of cymene into aqueous (5 wt.% SDS and 4 wt.% pentanol in water) and organic (isooctane) solutions is measured using UV-VIS spectroscopy and analyzed with the shrinking core model. The experimental data and model analysis indicate that the release rate is determined by the effective diffusivity and solubility of the oil in the aqueous gel matrix, both of which depend on the presence of surfactant in the receiving solution, and the swelling of the gel particle.