Anionic Sodium Dodecyl Sulfate Research Articles

Synthesis and Characterization of a Novel Nanosized Polyaniline.

Polyaniline (PANI) is a conductive polymer easily converted into a conducting state. However, its limited mechanical properties have generated interest in fabricating PANI composites with other polymeric materials. In this study, a PANI-prevulcanized latex composite film was synthesized and fabricated in two phases following chronological steps. The first phase determined the following optimum parameters for synthesizing nanosized PANI, which were as follows: an initial molar ratio of 1, a stirring speed of 600 rpm, a synthesis temperature of 25 °C, purification via filtration, and washing using dopant acid, acetone, and distilled water. The use of a nonionic surfactant, Triton X-100, at 0.1% concentration favored PANI formation in a smaller particle size of approximately 600 nm and good dispersibility over seven days of observation compared to the use of anionic sodium dodecyl sulfate. Ultraviolet-visible spectroscopy (UV-Vis) showed that the PANI synthesized using a surfactant was in the emeraldine base form, as the washing process tends to decrease the doping level in the PANI backbone. Our scanning electron microscopy analysis showed that the optimized synthesis parameters produced colloidal PANI with an average particle size of 695 nm. This higher aspect ratio explained the higher conductivity of nanosized PANI compared to micron-sized PANI. Following the chronological steps to determine the optimal parameters produced a nanosized PANI powder. The nanosized PANI had higher conductivity than the micron-sized PANI because of its higher aspect ratio. When PANI is synthesized in smaller particle sizes, it has higher conductivity. Atomic force microscopy analysis showed that the current flow is higher across a 5 µm2 scanned area of nanosized PANI because it has a larger surface area. Thus, more sites for the current to flow through were present on the nanosized PANI particles.

Effect of biologically active amino acids based deep eutectic solvents on sodium dodecyl sulfate: A comparative spectroscopic study

Study the effects of three novel synthesized biologically deep eutectic solvents (DESs) on the micellar characteristics of anionic sodium dodecyl sulfate (SDS). The biologically active amino acids based three DESs synthesized have composed the 2:1 M of L-Aspartic acid (DES1), L-Tyrosine (DES2), L-Glutamine (DES3) and choline chloride, furthermore which characterized by FTIR. Surface tension, viscosity, UV–visible, fluorescence, and FTIR spectroscopy are a few of the techniques used to study the interactions of SDS within 5 and 10 wt% of three novel biological DESs in aqueous solutions. The presence and absence of 5 and 10 wt% of the three novel biological DESs in an aqueous solution is used to study the critical micelle concentration (CMC) and various interfacial characteristics including CMC, the efficiency of adsorption, the maximum surface excess concentration, the packing parameter, the minimum area per molecule, and the surface pressure at CMC, is assessed by the surface tension method. The calculated fluorescence data and those obtained using surface tension and UV–visible methods correspond well. The interactions that cause changes in the structure of the surfactant self-assemblies within aqueous DESs were investigated using FTIR technique. It is significant to highlight that the presence of unique biological DESs considerably facilitates the micellization process for SDS and the extent is more affinity for DES2 compared to DES1/DES3. The colloidal properties of DES and their combinations with water are anticipated to benefit from the current findings.

Binding and occupancy properties of gabapentin in mixed surfactant systems

AbstractThis research highlights the efficacy of mixed micellar systems as an innovative chemical formulation for improving the binding properties of active pharmaceutical drugs. The formulations based on the mole fraction were utilized for preparing mixed micelles with anionic sodium dioctyl sulfosuccinate (AOT) and sodium dodecyl sulphate (SDS). DLS measurements demonstrated the formation of small micelles and mixed micelles in SDS‐AOT combinations. A UV absorbance investigation demonstrated the effectiveness of the SDS‐AOT mixed micelles for determining the binding constant (Kb) and mean ion occupancy (i0) of the anticonvulsant gabapentin (GBP) drug. Kb values increased, but the occupancy (i) of GBP per micelle decreased by decreasing the mole fraction (α) of SDS from αSDS 0.9 to 0.1, predicting a shift in occupancy of drugs from the Palisade to the Stern layer. To get a better comprehension of micellization behavior and preferential interaction of the drugs under study, molecular docking studies were performed. According to the docking studies, the GBP displayed significant binding in the presence of SDS‐AOT when compared to pure SDS and AOT molecules. Ultimately, in pharmaceutical applications, mixed micelle played an important role in enhancing the binding and encapsulation efficiency of drugs.

In Vitro Cytocompatibility Assessment of Novel 3D Chitin/Glucan- and Cellulose-Based Decellularized Scaffolds for Skin Tissue Engineering

Background: Naturally derived sustainable biomaterials with high flexibility, mechanical properties, biocompatibility, and the ability to manipulate surface chemistry, providing a natural cellular environment, can be used for tissue engineering applications. However, only a few researchers have demonstrated the exploitation of natural architectures for constructing three-dimensional scaffolds. The chemical decellularization technique for fabricating natural scaffolds and their cytocompatibility assessment for tissue engineering applications need to be thoroughly explored and evaluated. Methods: Decellularization of natural scaffolds has been performed via a chemical method using anionic detergent sodium dodecyl sulfate (SDS) which was used for the in vitro culturing of murine embryonic NIH/3T3 fibroblasts. Techniques such as field-emission scanning electron microscopy (FE-SEM), compressive testing and swelling ratio, and biodegradation were performed to characterize the properties of fabricated decellularized natural scaffolds. Nucleic acid quantification, DAPI, and H&E staining were performed to confirm the removal of nuclear components. In vitro cytocompatibility and live/dead staining assays were performed to evaluate cultured fibroblasts’ metabolic activity and qualitative visualization. Results: 3D chitin/glucan- and cellulose-based scaffolds from edible mushroom (stem) (DMS) and unripe jujube fruit tissue (DUJF) were fabricated using the chemical decellularization technique. FE-SEM shows anisotropic microchannels of highly microporous structures for DMS and isotropic and uniformly arranged microporous structures with shallow cell cavities for DUJF. Both scaffolds exhibited good mechanical properties for skin tissue engineering and DUJF showed a higher compressive strength (200 kPa) than DMS (88.3 kPa). It was shown that the DUJF scaffold had a greater swelling capacity than the DMS scaffold under physiological conditions. At 28 days of incubation, DUJF and DMS displayed approximately 14.97 and 15.06% biodegradation, respectively. In addition, DUJF had greater compressive strength than DMS. Compared to DMS scaffolds, which had a compressive stress of 0.088 MPa at a 74.2% strain, the DUJF scaffolds had a greater compressive strength of 0.203 MPa at a 73.6% strain. The removal of nuclear DNA in the decellularized scaffolds was confirmed via nucleic acid quantification, DAPI, and H&E staining. Furthermore, both of these scaffolds showed good adherence, proliferation, and migration of fibroblasts. DMS showed better biocompatibility and high viability of cells than DUJF. Conclusions: This sustainable scaffold fabrication strategy is an alternative to conventional synthetic approaches for the in vitro 3D culture of mammalian cells for various tissue engineering and cultured meat applications.

Surfactants interaction with sulfathiazole: Spectroscopic, conductometric, and thermodynamic approach

Taking into the account the advantages of surfactant micelles as drug carrier, the interaction of sulfathiazole (STZ) with three types of surfactants, namely, cationic cetyltrimethylammonium bromide (CTAB), anionic sodium dodecyl sulfate (SDS), and non-ionic t-octylphenoxypolyethoxyethanol (TX-100) has been studied by using UV–visible spectroscope and conductivity measurements. The critical micelle concentration (CMC), degree of ionization (α), counter ion binding constant (β), free energy change of micellization (ΔG0m), relative solubility (St/S0), STZ-surfactant interaction constant (θ), approximate number (n) of STZ molecules incorporated per micelle, heat capacity (ΔC0m), and transfer of thermodynamic parameters were calculated and discussed for both the systems. The CMC values of CTAB and SDS were found to decrease in presence of increasing STZ concentrations. The values of counter ions dissociation were also found to be dependent of temperature. The ΔG0m values are obtained to be negative of both systems. A comparison of the binding constants (KC) calculated from the Kawamura equation indicated that the solubilization tendency of STZ with CTAB is much higher than that with SDS micelles. However, this interaction was weak since no significant change in the micellization phenomenon was observed with TX-100 under our experimental conditions.

A novel pH-responsive wormlike micelles combinated sodium dodecyl sulfate (SDS) and diethylenetriamine (DETA) based on noncovalent electrostatic interaction

pH-Responsive wormlike micelles (WLMs) have attracted lots of attention due to their abundant advantages, for example, ease of adjustment and strong reversibility. We have learned that the degree of protonation of diethylenetriamine (DETA) varies with pH, and the anionic sodium dodecyl sulfate (SDS) can connect with cationic groups. Inspired by this, a novel pH-responsive WLMs was prepared based on noncovalent electrostatic interaction with sodium dodecyl sulfate (SDS) and DETA at a molar ratio of 3:1. Properties of the SDS/DETA system were assessed from the aspects of rheology, macro-morphology, aggregates diameter, and micro-morphology. When the pH decreased from 9.98 to 6.80, the SDS/DETA system represented as a weak gel with the viscosity increasing from 7.6 mPa s to 1.4 × 103 mPa·s and the average hydrodynamic radius increasing from 5.6 to 91.3 nm. The phenomenon is attributed to the protonation of DETA when reducing the pH and the formation of WLMs based on electrostatic interaction between DETA and SDS. However, when pH was further reduced by adding HCl, the SDS/DETA system would reach its isoelectric point, thus the solution became turbid with low viscosity. The SDS/DETA solution represents excellent reversibility (at least three cycles) in viscoelasticity by adjusting the pH value, and such pH-responsive WLM holds significant potential for broader applications in biomedical, oilfield chemistry, and other fields.

Synergism in mixtures of nano benzimidazolium Gemini ionic liquid and sodium dodecyl sulfate surfactants in tuning interfacial properties of crude oil−water system

The high price of newly explored surfactants is a concern in applications, but their mixture with conventional surfactants can bring about desired outcomes. Gemini surface active ionic liquids (GSAILs) have emerged as unique materials in tuning interface properties. Surfactants like sodium dodecyl sulfate (SDS), on the other hand, are known effective and commercially available. This study investigates the simultaneous effects of a benzimidazolium cationic GSAIL, [C4benzim-C6-benzimC4][Br2], and SDS surfactants on the interfacial tension (IFT), emulsification, and wettability alteration of the crude oil−water system. The results demonstrate amazing synergies up to 97.6 % in the IFT reduction. An ultra-low IFT of 0.16 mN·m−1 was achieved with an optimum GSAIL mole fraction of 0.4, attributed to the attractive interaction between the cationic GSAIL and the anionic SDS. Mixtures also give 54.3 and 72.8 % synergies in emulsification and wettability alteration, respectively. The adsorption of individual and mixture of surfactants were theoretically analyzed using the Frumkin adsorption isotherm and the non-ideal interactions of the binary mixtures (NIBM) theory. The corresponding determined parameters were consistent. To have a more comprehensive analysis, the results were compared with those obtained with an analogous structure imidazolium GSAIL.

Surfactant integrated nanoarchitectonics for controlled morphology and enhanced functionality of tungsten oxide thin films in electrochromic supercapacitors

This research focuses on tungsten oxide (WO3) as a promising material, and the study investigates the electrodeposition of WO3 thin films on fluorine-doped tin oxide (FTO) coated glass substrates using three different surfactants: cationic hexamethylenetetramine (HMTA), anionic sodium dodecyl sulfate (SDS), and non-ionic polyethylene glycol (PEG). The X-ray diffraction analysis confirms that the resulting thin films exhibit amorphous structures. Raman analysis supports the identification of the pure WO3 phase based on the stretching and vibrational modes observed in the colored and bleached states. The X-ray photoelectron spectroscopic study examines the influence of cathodic and anodic potentials on the formation of oxidized and reduced tungsten species in surfactant-aided WO3 thin films. Field emission scanning electron microscopy is utilized to investigate the impact of different surfactants on the morphology of WO3 thin films, revealing the formation of porous, clumped, and dense nanogranules on the film surface. Electrochromic energy storage investigations highlight the superior performance of the W-PEG (polyethylene glycol assisted WO3) thin film, which exhibits efficient lithium-ion accommodation and desirable bifunctional characteristics. The optimized W-PEG sample demonstrates excellent electrochromic performance, including high optical modulation (84.39 %), good reversibility (98 %), and high coloration efficiency (117.95 cm2/C). Supercapacitive measurements reveal a high areal capacitance of 44.1 mF/cm2 at a current density of 0.1 mA/cm2, as well as an energy density of 0.024 mWh/cm2 at a power density of 0.1 mW/cm2, with 85 % capacitive retention over 8000 consecutive galvanostatic charge-discharge cycles. Furthermore, the application potential of nanogranular WO3 for electrochromic energy storage is demonstrated through the successful illumination of a red and green light-emitting diode (LED) using fully colored electrochromic supercapacitor devices (4 × 3 cm2), highlighting their energy storage capability.

Exploring the pH-Responsive Interaction of β-Blocker Drug Propranolol with Biomimetic Micellar Media: Fluorescence and Electronic Absorption Studies.

Interaction of neutral and charged lipophilic beta-blocker drug, propranolol (PPL) with biomimicking nanocavities formed by micelles bearing same and opposite charges namely, cationic cetyltrimethylammonium bromide (CTAB), a surface-active ionic liquid 1-hexadecyl-3-methylimidazolium chloride (HDMIC) and anionic sodium dodecyl sulphate (SDS) have been investigated using fluorescence and absorption spectroscopic techniques. Binding of PPL to SDS at pH < pKa is characterised by biphasic interactions with decrease in fluorescence intensity at lower concentrations and subsequent increase post micellization. All the surfactants show significant interactions with the neutral drug molecule at pH > pKa, which is evident from the strongest binding constant ( ) values at pH 10.4. Results of quenching studies indicate that the location of drug molecule is determined by its charge, which is influenced by both pH and charge on micelle surface. For PPL-CTAB and PPL-HDMIC systems, quenching was strongest at pH 10.4, moderate at pH 7.4 and was absent at pH 3.5. However, the PPL-SDS system displayed similar values at all pH conditions, suggesting that the probe is at the same position regardless of pH. Non-covalent interactions, which play crucial role in biological systems, are similarly the primary driving force governing the interaction between PPL and surfactant micelles.

Tensiometry-based sensing of aggregation and of evaporation behavior of a volatile amphiphile in mixed solutions with ionic and nonionic surfactants

Mixed surfactants solutions containing volatile amphiphiles, e.g. fragrances, are envisaged to exhibit correlations between aggregation behavior, molecular interactions, composition of the mixed adsorbed layers and the concentration of the volatile component in the vapors. These issues are addressed with tensiometric methods by considering dynamic and steady-state interfacial adsorption-evaporation behavior at both sides of air-liquid interface in mixed solutions of geraniol and micelle-forming ionic and non-ionic surfactants. Pendant drop tensiometry proved to be a sensitive method in assessing the concentration of geraniol in the vapors above mixed solutions. Differences in the release of the fragrance from the mixed interfacial layers are explained by competitive contributions of specific barrier mechanisms and concentration-dependent aggregation in bulk solutions. Synergetic effect in reducing surface tension was evident for mixtures of geraniol with anionic sodium dodecyl sulfate (SDS) and cationic dodecyltrimethylammonium bromide (DTAB) surfactants. Dynamic anti-synergetic effect in SDS-geraniol mixtures is attributed to strong aggregation behavior, which was found to hinder the evaporation of geraniol. Measurements of the headspace concentration indicated weak interactions between geraniol and micelles of non-ionic highly surface active Brij-35 surfactant. The presented results extend the traditional analytical toolbox for evaluating factors which affect the mass transfer of volatile organic amphiphiles between aqueous and gas phases.

Thermodynamics of modulation of interaction of α-helix inducer 2, 2, 2-trifluoroethanol with lysozyme in presence of cationic, anionic and non-ionic surfactants

The interactions of anionic sodium dodecyl sulphate (SDS), cationic cetyltrimethylammonium bromide (CTAB) and nonionic triton X-100 (TX-100) surfactants with lysozyme at pH = 2.4 have been studied individually as well as in combination with 2,2,2-trifluoroetanol (TFE). Urea has also been used in combination with surfactants. By using these combinations, efforts have been made to obtain partially folded conformations of the protein in the presence of surfactants and effect of α-helix inducer 2,2,2-trifluoroethanol on these intermediate states. Thermodynamic analysis of all these interactions has been done employing a combination of UV-visible, fluorescence and circular dichroism spectroscopies. The results have been correlated with each other and characterized qualitatively as well as quantitatively. At lower concentration of surfactant, the thermodynamic parameters indicated the destabilizing effect of SDS, stabilizing effect of CTAB and unappreciable destabilizing impact of TX-100 on lysozyme. The enhancement in destabilization effect or reduction in stabilization effect of surfactants on lysozyme in the presence of TFE and urea has also been indicated. Communicated by Ramaswamy H. Sarma

Rheology, viscoelasticity and microstructural properties of OAPB-SDS mixtures at different temperature and pH conditions

Viscoelastic surfactant (VES) fluids are widely used in the hydraulic fracturing process to increase oil and gas productivity. Zwitterionic (carbon-18) surfactant solution, which is commonly used in VES fluids, has high critical micelle concentration, resulting in high used concentration and lack of economy. Furthermore, it is not applicable to high-temperature conditions. The oleylamidopropyl betaine (OAPB, carbon-25) with longer carbon chain has lower critical micelle concentration (CMC) and better high temperature resistance. In addition, it behaves better viscosity increasing capacity combining with anionic sodium dodecyl sulfate (SDS) surfactant. In this study, the viscoelasticity and microstructural properties of OAPB-SDS (OADS) mixtures at different temperature and pH conditions were investigated deeply. Rheology and structural morphology properties of the OADS mixed fluids were investigated by rheometer, and transmission electron cryo-microscopy. The results showed that OADS solution demonstrated elastic gel-like fluid behavior with zero shear viscosity of 3.5 × 106 mPa.s at neutral pH and room temperature, while OAPB solution demonstrated viscous fluid behavior with zero shear viscosity (ηo) of 62 mPa.s. The viscoelasticity and microstructural properties of OADS solution were influenced by concentration, pH and temperature. It was gel-like fluid at 25–40 °C, viscoelastic fluid at 60–80 °C and totally viscous fluid at 90 °C. The OADS was viscous at 0.5 wt% concentration, viscoelastic at 0.6 wt% concentration and elastic at 0.75 wt% concentration. The OADS solution showed viscous, viscoelastic and elastic behaviors at pH value of 3, 4, and 7 respectively. The fluid exhibited viscosity switch ability by reversibly altering pH values. The Cryo-TEM images confirmed that the OADS micelle experience microstructural transformed from long wormlike micelles (WLMs) to spherical micelles as the pH changes. The mixture fluid improved viscoelastic and aggregation properties than that of individual surfactant component, possessing lower used surfactant concentration. This study is useful in understanding the properties of mixed zwitterionic-anionic fluids, which is thermo-pH responsive, valuable in the fracturing.

Effects of static magnetic field on the surface tension of surfactant solutions

AbstractThe magnetic field (MF) effects resulting from water or solution treatments are still of significant interest. However, a relatively small number of papers have been published dealing with the pure surfactant solutions alone. On the other hand, surfactants are applied in many industrial processes as well as in everyday life and are also present in different waste waters. Therefore, it seemed interesting to investigate whether some effects would appear after the MF treatment of pure aqueous surfactant solutions. In the earlier published papers after MF action the changes in water evaporation rate and the surface tension were found for both the cationic dodecyltrimethylammonium bromide (DTAB) and anionic sodium dodecyl sulfate (SDS) solutions. The gradient MF originated from three connected ring magnets inside which the solutions were placed. The objective of this paper is to study whether using the same magnets but in a different position the effects of the MF are observed. The given surfactant solution in a closed vessel was placed in an uniform MF when the magnets were in the “lying” position. The investigated solutions on the magnet surface remained for 24 h. In this paper, despite SDS and DTAB also the cationic hexadecyltrimethylammonium bromide (CTAB) and nonionic Triton X‐100 solutions were applied. It appeared that in the uniform MF the surface tension of cationic and anionic surfactant solutions changes. However, larger changes were observed in the gradient MF. Generally, the changes of surface tension depend on the surfactant kind and its concentration. Stronger MF influence was found for the cationic surfactant and almost no changes were observed for nonionic Triton X‐100.

Enhanced electronic absorption and solubility of Mammeigin in aqueous micelles and protein aggregate solutions compared to water

The physicochemical properties of plant polyphenol Mammeigin (MMG) from Mesua ferrea, upon interactions with carrier molecules like surfactants and Hen Egg-White Lysozyme (HEWL) aggregates were investigated using UV–Vis and Fluorescence spectroscopy; and Zeta potential (ZP) measurements in aqueous solutions. The role of surfactant charge on the interactions of MMG was studied using anionic Sodium Dodecyl Sulfate (SDS), cationic Cetyltrimethylammonium Bromide (CTAB), and neutral Tween 20 (T20). It was observed that ionic surfactants offered more stability to the system, which was enhanced in the presence of salt at physiological concentration and lower amounts of surfactant. The environment of MMG in these micelles was proposed to be partially semi-polar in nature based on solvent studies in organic and binary solvent systems. A similar favorable environment was found in early and partially exposed aggregates of HEWL at pH 2 and pH 9 respectively, which significantly diminished at later stages of aggregation and fibrillation at pH 2. With growing interest in plant polyphenols as bioactive, a major challenge for their utility in biological systems is the aqueous insolubility and thus, research in the field of drug/compound delivery is expanding. Our study could provide insights for developing better molecular carriers and formulations of MMG at physiological conditions for therapeutic applications with improved efficacy.

Kinetic study of Ru(III) – catalyzed oxidation of L-phenylalanine by hexacyanoferrate(III) in an anionic surfactant medium

Abstract The kinetic investigation of Ru(III) promoted oxidation of L-phenylalanine (L-PheAla) by [Fe(CN)6]3− has been performed in anionic sodium dodecyl sulfate (SDS) micellar medium by recording the decrease in absorbance at 420 nm corresponding to [Fe(CN)6]3− using an UV–visible spectrophotometer. Using the pseudo-first-order condition, the course of the reaction was studied as a function of [Fe(CN)6 3−], ionic strength, [OH−], [SDS], [Ru3+], [L-PheAla] and temperature by changing one variable at a time. The results exhibit that [OH−], [SDS], and [L-PheAla] are the crucial parameters that have an appreciable influence on the reaction rate. The reaction exhibits first-order kinetics in concentration ranges of Ru(III), [Fe(CN)6]3− and at low [L-PheAla] and [OH−] concentrations. The incremental trend observed in the reaction rate with electrolyte concentration shows a positive salt effect. The reaction rate is almost 10 times faster in SDS micellar medium than in aqueous medium. [Fe(CN)6]3− has no appreciable effect on the CMC of SDS, since the polar head of SDS and [Fe(CN)6]3− are both negatively charged. The K+ obtained from K3[Fe(CN)6] and KNO3 decreases the repulsion between the negatively charged heads of the surfactant molecules, which decreases the CMC of SDS. The activation parameters also support the outer-sphere electron transfer mechanism.

Magnetic nanoparticles Fe&lt;sub&gt;3&lt;/sub&gt;O&lt;sub&gt;4&lt;/sub&gt; modified with sodium dodecyl sulphate for removing methylene blue from water

We show that surface-modified magnetic iron oxide nanoparticles with an average size of about 10 nm have a high adsorption capacity for sorption of pollutants from wastewater. A significant advantage of using magnetic materials is the ability to extract the sorbent using an external magnetic field, which makes the purification process more efficient. We found that the anionic substance sodium dodecyl sulfate increases the electrostatic attraction to the cationic compound methylene blue, and also prevents the aggregation of nanoparticles, thus increasing the active surface. The sorption capacity of magnetic nanoparticles after surface functionalization increased by a factor of 250 compared to unmodified iron oxide nanoparticles. The mechanism and kinetic parameters of the sorption process were determined, as well as the optimal conditions for increasing the efficiency of the sorption process.

Characterization and stabilization of iron ore suspension and influence of the mixture of natural additive Sapindus mukorossi and SDS on the slurryability

The traditional way of transporting iron ore from mine to end-use plants often causes the industry significant economic hardship and degradation of the ecological system. Hydrotransportation of slurry through a pipeline is a remarkably viable strategy for effectively transporting iron ore in terms of economics, dependability, and safety, with minimal environmental impact. In the present investigation, a blend of bimodal samples is prepared by mixing medium and coarse particles of Indian iron ore of size 38–75 (I-2) and 75–106 (I-3) µm, respectively, with finer particles of size <38 µm (I-1) in 10–40% (by weight) proportion. Rheological characterization of the blend samples is done to finalize the optimum particle size. To enhance the flowability and stability of the concentrated iron ore samples, they are amalgamated with a mixture of plant-based nonionic saponin extracted from Sapindus mukorossi (Ritha) and the anionic sodium dodecyl sulfate (SDS) surfactants. The correct proportion of SDS in saponin is obtained through a thorough analysis of critical micellar concentration, zeta potential, and rheological parameters. Finally, the stability and slurryability of iron ore suspension with a Saponin–SDS mixture are established through rheological properties, dispersant concentration, and stabilization mechanisms. It is found that the optimum proportion of a mixture of saponin–SDS significantly improved the slurryability and stability of iron ore suspension and the maximum iron ore loading was enhanced by up to 81% by weight. The head loss and specific energy consumption analysis successfully evidence the significance of the surfactants in transporting the slurry through pipelines.

Effect of nonionic and anionic surfactant on ecotoxicity and micellization behaviors of dodecyl trimethyl ammonium bromide (DTAB)

Mixtures of surfactants are extensively present in industrial applications for better performance and lower cost. The toxicity of cationic dodecyl trimethyl ammonium bromide (DTAB) against Photobacterium phosphoreum was investigated in the presence of other common surfactants, such as nonionic fatty alcohol-polyoxyethlene ether (AEO), and anionic sodium dodecyl benzene sulfonate (SDBS) as well as sodium dodecyl sulfate (SDS). The mechanism of the combined toxicity was explored based on the micellization behaviors and the characteristics of mixed micelles in surfactant systems. The toxicity of cationic DTAB was significantly higher than that of anionic SDBS, SDS and nonionic AEO, and was not affected by the combination with AEO or SDBS. However, the toxicity of the DTAB/SDS mixture was remarkably lower than that of DTAB alone. Scanning electron microscopy (SEM) images verified that the mixing of DTAB and SDS indeed hindered their action against the bacteria. The micellization behavior of binary mixtures showed an antagonistic effect in DTAB/AEO and DTAB/SDBS systems, but a synergistic effect in DTAB/SDS systems. Thus, the synergism facilitated the formation of mixed micelles and greatly reduced the toxicity of DTAB/SDS mixtures. Furthermore, the formation of mixed micelles in DTAB/SDS systems not only decreased the electrostatic effect of DTAB with the bacteria but also inhibited the interaction of surfactant molecules with bioactive protein, resulting in the lowest toxicity of DTAB/SDS mixtures with mass ratios of 2:3 and 1:4. These results can provide a reference for the development of highly efficient and environmentally friendly composite surfactants.

Denaturation and Digestion Increase the Antioxidant Capacity of Proteins

It has been estimated and demonstrated that the antioxidant capacity of proteins is increased as a result of digestion in the gastrointestinal tract, which can be contributed by denaturation and digestion. This study aimed to evaluate the effect of denaturation and proteolytic digestion on the antioxidant activity of bovine serum albumin (BSA) and chicken egg white proteins in model systems. Denaturation with an anionic detergent (sodium dodecyl sulfate) and digestion with papain and trypsin increased the antioxidant activity/capacity of the proteins, apparently due to the increased exposure of amino acid residues responsible for the antioxidant activity of proteins (tyrosine, tryptophan, cysteine, histidine, arginine, and cystine in the ABTS● decolorization assay; cysteine, tryptophan, tyrosine, and cystine in the FRAP assay). As the increase in the protein antioxidant activity/capacity was limited in extent, it does not invalidate the use of the antioxidant capacity of proteins to be consumed as a rough measure of their antioxidant capacity after modifications in the gastrointestinal tract.

Photoinduced phase transition between vesicles and coacervates using low-molecular-weight catanionic amphiphiles

Amphiphiles form various molecular self-assemblies in the aqueous phase, such as vesicles and coacervates, depending on molecular properties. Recently, phase transitions between vesicles and coacervates have drawn much attention because the switching between “closed” and “open” compartments could achieve the controllability of molecular sequestrations. We expect that the photoinduced drastic change in the molecular structure of catanionic amphiphiles comprising azobenzene-containing cationic amphiphiles (Azo) and anionic sodium dodecyl sulfate causes the transition. Self-assemblies prepared by a thin-film hydration method were observed using microscopy under UV and subsequent visible-light illumination. Additionally, investigation of selectivity for molecular sequestration and assay of enzymatic reactions in the self-assemblies were conducted. Photoinduced reversible phase transitions between vesicles and coacervates occurred owing to the photoisomerization of Azo. The formed coacervates had selectivity for molecular sequestration. Additionally, the transition achieved fusion of different vesicles via coacervates. Although coacervates are generally known to facilitate enzymatic reactions, the reactions were inhibited in the presence of the formed self-assemblies due to the deactivation of enzymes. Our results represent rapid and non-invasive systems of reversible vesicle–coacervate transitions. Furthermore, the findings provide a new aspect of coacervates in which catanionic low-molecular-weight amphiphiles could act as suppressors of chemical reactions.