Journal of Surfactants and Detergents最新文献

This study investigates the influence of glucose in inducing the micellar growth/transition in several structurally diverse, longer, and shorter chain polyoxyethylene (POE)-based nonionic surfactants, commercially known as Kolliphor® HS15 (Solutol), Kolliphor EL®, Akypo®, Brij®-78, Pluronic® (P103 and F77), Tetronic® (T1304), and Tyloxapol® in aqueous solution environment. It was observed that the addition of glucose induces dehydration of the POE moieties or chains in the tested systems, thereby enhancing the inter-micellar interactions via hydrogen bonding in the hydrophilic part of the selected surfactants. This dehydration leads to an interesting clouding behavior across all the studied surfactant systems. Also, the dynamic light scattering (DLS) technique accounted for the probable self-assembly and micellar growth in water and 1 M glucose (fix) across various temperatures. Being pharmaceutical excipients, these micellar entities were successfully employed to assay the hydrophobic anticancer drug curcumin (Cur) solubilized, as confirmed by the peak intensity variation from UV–visible spectroscopy. Cur solubilization into glucose-containing micelles revealed enhanced solubility expressed in terms of drug loading efficiency (DL%), encapsulation efficiency (EE%), partition coefficient (log P), and standard free energy of solubilization (ΔG°), which is due to the glucose-induced hydrophobicity in the examined nonionic micellar systems.

This study investigates the use of rheology to detect phase inversion in surfactant–oil–water (SOW) systems, offering a rapid method for identifying “optimal formulations.” Phase inversion through temperature or salinity variation provides a faster alternative compared with equilibrium scans. Using well-defined polyethoxylated surfactants (C₈EO₃, C₁₀EO₄, C₁₂EO₅), phase inversion was monitored through viscosity measurements at a constant shear rate, with temperature as formulation variable. Emulsion viscosity reaches a minimum at the phase inversion point, which corresponds to an ultra-low interfacial tension condition. A strong correlation between the reported fish-tail temperature (T*) and the phase inversion temperature (PIT) was observed. While identifying optimal conditions through a formulation scan in a series of test tubes is relatively quick, evaluating the surfactant system's ability to reduce interfacial tension can take several weeks due to the requirement of equilibrium. Formulation conditions at which minimal emulsion viscosity occurs are related to those where three-phase systems are obtained, with the magnitude of interfacial tension inversely proportional to this value. An empirical approach linking the emulsion destabilization zone with the interfacial tensions is proposed. By measuring this interval, it is possible to roughly predict interfacial tension for model systems.

Biosurfactants are gaining attention due to their biobased nature, including reduced toxicity and enhanced biocompatibility. This research work investigates the characteristics of the biosurfactant extracted from the halophilic strain Pa84 of Pseudomonas aeruginosa and optimizes its production using a statistical model. The identity of biosurfactant from P. aeruginosa strain Pa84 as rhamnolipid was determined by comparing the genomic sequences of strain Pa84 with high-yielding strains of P. aeruginosa that produce rhamnolipid, through Fourier transform infrared and liquid chromatography-mass spectrometer analyses, and by the presence of rhlA, rhlB, and rhlC genes in the genome of strain Pa84 that are responsible for the production of rhamnolipid. A methodical strategy using a time-course assessment and statistical software optimized the production of rhamnolipids. After optimization using central composite design-response surface methodology, the medium composition of 3.34 g/L of NH₄Cl, 1.03 g/L of NaCl, and 4 g/L of glycerol were chosen, yielding 7.48 ± 0.0217 g/L of biosurfactant. These findings will help in the development of effective and sustainable bioprocess that produce rhamnolipid biosurfactants, for use in a variety of sectors.

The system made by water, isooctane and a blend of Sodium dioctyl sulfosuccinate (AOT) with its more hydrophilic homologue sodium dihexyl sulfosuccinate (SDHS) can give raise to Winsor I, III and II equilibria at room temperature by slight changes in salinity. The phase transitions have been tracked using diffusion NMR, and solubilized volume fractions while small-angle X-ray scattering (SAXS) provided insight into the characteristic lengths (ξ) within the microemulsions' structures. Our findings reveal a peculiar linear correlation between the reciprocal of these characteristic lengths (ξ⁻¹) and the HLD values. For HLD <0, ξ⁻¹ decreases linearly with HLD with a slope = −0.0056 Å⁻¹ but just above HLD = 0 the slope reverses (+0.0056 Å⁻¹) and ξ⁻¹ increases linearly with HLD demonstrating that the HLD reflects the direction of interfacial curvature. However, at the optimal composition where the curvature is null and HLD = 0, the linear trends observed for ξ⁻¹ below and above HLD = 0 converge at a ξ⁻¹ value that is significantly greater than 0. This indicates that HLD is a measure of the interface/volume ratio and not of the interface curvature. This work aims to deepen the understanding of the relationship between the semi-empirical HLD equation and the spontaneous curvature of microemulsions.

Biosurfactants prevent agglomeration of nanoparticles by reducing the surface tension and offer stability over time by forming a stable layer on the surface of nanoparticles. The current study focuses on the biosynthesis of silver nanoparticles (SNP) coated with a rhamnolipid biosurfactant (BS) and its use as an additive in fabric cleaning detergent. Rhamnolipids were extracted from a Pseudomonas aeruginosa strain, Pa84, that was isolated from a halophilic environment, Sambhar Salt Lake, Rajasthan, India. The reduction of silver ions was achieved by the rhamnolipid-coated SNP (BS-SNP). BS, SNP, and BS-SNP demonstrated antibacterial efficacy against a variety of microorganisms. Lipase, present in the crude biosurfactant, was immobilized on modified chitosan microbeads (Ch-BS-SNP) and used for washing fabrics. The conjugate was found to be effective as a laundry detergent additive. The immobilized lipase showed high relative activity ranging from 66% to 110% and performed better than free lipase or standards. Our results highlight a potential claim for a commercially viable laundry detergent additive.

We report the synthesis of silver nanoparticles (Ag NPs) functionalized with L-cysteine (Ag-cys NPs) for colorimetric detection of contaminants: Hg²⁺, Pb²⁺, Cr⁶⁺ (CrO₄²⁻/Cr₂O₇²), and As³⁺ in water samples. AgNPs synthesized were obtained in water from the mixture of the cationic and non-ionic surfactants, cetyltrimethylammonium bromide (CTAB) and nonylphenol ethoxylate (NP-10), respectively. Physicochemical characterization demonstrated a monomodal distribution of spherical nanoparticles with an average size of 8.25 nm. The stability of the Ag-cys NPs was evaluated by determining the surface charge, which was found to be +27.95 mV, indicating the stability of Ag-cys NPs against flocculation. The interaction between Ag-cys NPs and solutions of contaminants was studied. This was done by measuring the shift in LSPR band of Ag NPs covered with cys in the region of 400–450 nm. We observed a change or disappearance of color visually, indicating aggregation or oxidation of the Ag NPs. Concentration of cys, as well as the pH of the nanoparticles, were crucial in studying the aggregation process. This is a preliminary study in search of benefits such as low cost, in situ usability, ease of use, and rapid response making it a potential alternative to traditionally employed spectroscopic methods.

Systems with elongated cylindrical micelles, also known as worm-like micelles (WM) or viscoelastic surfactants (VES), have high surface activity and high viscosity, which makes them attractive in different applications such as improved oil recovery, friction reducing agents in heating and cooling fluids, household and personal care products. This study examines the carbon's chain length of alkyl propoxylated sodium sulfate anionic surfactants (C₁₆O(PO)₁₅S, C₁₄O(PO)₁₅S, and C₁₂O(PO)₁₅S) mixed with a nonionic ethoxylated surfactant on viscoelastic properties and interfacial tension. Results show that the larger the surfactant's carbon chain, the greater the possibility of forming WM. Furthermore, the propylene oxides' (PO) number and the nonionic surfactant's type of tail (linear or branched) is studied, not only on WM formation but also on WM/crude interfacial tension values. It is observed that the surfactant's molecular structure plays an important role in WM formation. By increasing the anionic surfactant's PO from 15 to 20 units, the maximum value of zero viscosity goes from 4.507 to 0.092 Pa.s and by changing the structure of the nonionic surfactant from linear (C_12-13EO₈) to branched (C_12-14EO₉) keeping the PO number of the extended surfactant constant, the zero viscosity value goes from 4.507 to 0.28 Pa.s. Likewise, the WM/crude interfacial tension reached values of the order of 10⁻³ mN/m in the salinity range studied, which makes these systems very interesting for polymer substitution in enhanced crude oil recovery (EOR).

The surface activities and application properties of aqueous solution surfactants are greatly influenced by their structure, especially the spacer group that connects the polar head groups. Herein, four new non-ionic Gemini surfactants with different spacers were designed and synthesized, and their surfactant properties and biodegradability were studied. The synthesis of these compounds involves a two-step procedure. The first step is the formation of an amide from lauric acid and diethanolamine. The second step is the reaction of lauryl diethanolamide with four different spacers, the latter being flexible-hydrophilic, and rigid-hydrophobic in structure, respectively. Their structures were characterized using ¹H NMR, ¹³C NMR, FT-IR, and ESI-MS. The critical micelle concentration (CMC), the surface tension at CMC (γ_CMC), the efficiency of these compounds to reduce the surface tension by 20 mN/m (C₂₀ and pC₂₀), the effectiveness (π_CMC), the maximum surface excess (Γ_max), and the minimum surface area (A_min) were measured at 20, 40, and 50°C. The molecular architecture of the spacers in these compounds strongly influences the thermodynamic parameters, such as the standard change for Gibbs free energy of adsorption (ΔG°_ads) and the standard change for Gibbs free energy of micellization (ΔG°_mic). The ability of these surfactants to reduce surface tension is particularly good, but their distinguishing characteristic is their high relative propensity to form micellar aggregates. This aggregation ability improves as the hydrophilicity and flexibility of the spacer increase. Finally, in less than 30 days, all non-ionic Gemini surfactants were determined to be 99% biodegradable in river water.

The wide use of antibiotics can lead to antimicrobial resistance. Biosurfactant rhamnolipids are not prone to induce antimicrobial resistance due to their potential to target microbial membranes in both bacteria and fungi. However, the membrane interaction of anionic rhamnolipids with microbials has never been visually observed. This study applied previously synthesized anionic fluorescent Trisodium 8-hydroxypyrene-1,3,6-trisulfonate (HPTS)-based surfactants, with hydrophobic tails from C8 to C18, to examine their interaction with the plant pathogen Alternaria alternata. The antifungal potency of the surfactants exhibited a positive correlation with the increase in hydrophobic chain length, culminating in C16, which demonstrated the highest activity. Subsequently, a modest reduction in potency was noted for the C18. Fluorescence microscopy confirmed the membrane targeting of HPTS-C16, and molecular dynamics simulations supported its specific membrane interaction. HPTS-C16 was notably more effective against spores than mycelium, consistent with its binding affinity. This research provides a fluorescent method to dissect the relationship between surfactant properties and microbial membrane characteristics, guiding the development of antimicrobials to combat resistance.

N-lauroyl derivatives of amino acids have widely been reported as environmentally benign surfactants. Although N-lauroyl-l-glutamate is reported in the literature, the effect of the two carboxylate groups in it has not been specifically addressed. In this study, we report the interactions of bovine serum albumin (BSA) with N-lauroylglutamate (S1) and an N-lauroyl derivative of a tripeptide of glutamic acid (S2), respectively. The surfactant S1 has two and S2 has four carboxylic acid groups making them different from other N-lauroyl amino acids, which have just one carboxylic acid group. The aim of this study is to understand the role of the number of carboxylate groups present in these amino acid-based anionic surfactants while interacting with biomolecules such as BSA. The critical micelle concentration (CMC) of the surfactants were measured both in the presence and absence of BSA using fluorescence spectroscopy. The fluorescence of BSA was quenched on addition of the surfactants. The mechanisms of fluorescence quenching were established by studying the fluorescence at three different temperatures. CD studies were performed to calculate the temperature at which BSA unfolds completely in the presence and absence of the surfactants. Conformational changes in the secondary structure of BSA were also observed on the addition of S1 and S2. The results of these studies are compared with those previously reported for the interactions between BSA and N-lauroylglycinate. We find that S1 has a lower CMC than S2 and lauroylglycinate. The surfactant S1 stabilized the secondary structure of BSA better at higher temperatures.