Differential behavior of sodium laurylsulfate micelles in the presence of nonionic polymers

Protective effects of extracts from Acer truncatum leaves on SLS-induced HaCaT cells

Introduction:A. truncatum Bunge (Sapindaceae or formerly Aceraceae) is a tall deciduous tree native to China. Traditionally, the leaves of A. truncatum are decocted and used by Chinese Mongolians, Koreans, and Tibetans to treat skin itching, dry cracks, and other skin ailments, which indicates A. truncatum leaves may have a potential inhibitory effect on various skin inflammations.

Methods: To examine the protective effect against skin inflammations of A. truncatum leaf extract (ATLE), an in vitro dermatitis model was established using sodium dodecyl sulfate (SLS)-induced HaCaT cells. The anti-inflammatory effect of ATLE was evaluated by analyzing cell viability, apoptosis, reactive oxygen species (ROS), interleukin 6 (IL-6), and prostaglandin E2 (PGE2) levels.

Results: Orthogonal experiments showed that the pretreatment with ATLE can reduce the IL-6 levels, PGE2 levels, and apoptosis increased in SLS-stimulated HaCaT cells, which indicates that ATLE has positive efficacy for dermatitis. Furthermore, three flavonoid compounds kaempferol-3-O-α-L-rhamnoside, quercetin-3-O-α-L-rhamnopyranoside, kaempferol-3,7-di-O-α-L-rhamnoside, and 1,2,3,4,6-Penta-O-galloyl-β-D-glucopyranose (PGG) were isolated and identified. Among them, kaempferol-3,7-di-O-α-L-rhamnoside was isolated from this plant for the first time. These compounds have been proven to have an anti-inflammatory effect. They may contribute to the efficacy of A. truncatumin treating skin inflammation.

Discussion: The results revealed that ATLE has the potential to be used as an additive in various skin care products to prevent skin inflammations and may be incorporated in formulations for topical application as a therapeutic approach against dermatitis.

Thermodynamics of Aggregation between the Cationic Surfactant and Polymer Based on Biodegradable Poly(vinyl Alcohol)

The formation of aggregates between carboxylated (PVCOOH) or neutral hydrolyzed (PVOH) poly(vinyl alcohol) and hexadecylpyridinium chloride (C₁₆PyCl) was examined by conductimetry, turbidimetry, and isothermal titration calorimetry (ITC) in the presence of different NaCl concentrations. The interaction between the polymers and C₁₆PyCl in pure water showed a critical aggregation concentration (cac = 0.8 mmol L^-1) only for the neutral polymer. PVCOOH interacted with the surfactant through electrostatic attraction, forming macroscopic aggregates. Integral enthalpy changes for aggregate formation (ΔH_agg) obtained from ITC curves varied from -0.61 (for the PVOH system in pure water) to -4.14 kJ mol^-1 (for PVOH in the presence of 10.0 mmol L^-1 NaCl), indicating that the formation of the aggregates was enthalpically favored. However, hydrophobic interactions drove the process for low surfactant concentration for both polymers. Saturation concentrations (C2) obtained from conductimetry were smaller than those from ITC, revealing that the binding of C₁₆PyCl on the chain of the polymers at higher surfactant concentrations shows the same electric properties as that of free micelles on the solution. Increase of the ionic strength favored the aggregation and decreased the complexity of the ITC curves, suggesting that the reorganization of the surfactant monomers on the polymeric chain with the increase in their concentration was suppressed.

Investigating the effect of a simplified perfume accord and dilution on the formation of mixed-surfactant microemulsions

The phase analysis of a mixed surfactant system is much more complex than that for a single surfactant system. The addition of fragrance further enhances the complexity of such colloidal systems. The wide variation in structure and log P values of perfume raw materials influence its partitioning into the micellar phase. Herein, we have created a simplified perfume accord consisting of three perfume raw materials (3-PRM) and investigated its loading within a mixed-surfactant system consisting of sodium trideceth-2 sulfate/ST2S and cocamidopropyl betaine/CAPB, along with citric acid and dipropylene glycol. We performed a systematic phase diagram analysis and identified the isotropic phases and compositions of interest. Select compositions from the phase diagram were further investigated to learn how the geometry of the surfactant self-assembly and the localization of the PRMs within the surfactant self-assembly changed when water or perfume is added. A combined small-angle neutron scattering/SANS and NMR methodology was used to identify variation in colloidal domains and positioning of perfume molecules at varying dilutions/rinse off scenarios. The results obtained were utilized to better distinguish distorted micelles from true microemulsions. The systematic investigation here provides a fundamental understanding about the self-assembly, encapsulation and perfume release from a commercially relevant mixed surfactant system.

Structural changes and phase analyses of a three-PRM accord in sodiumtrideceth-2 sulfate and cocamidopropyl betaine, citric acid and diproplylene glycol surfactant system as a function of dilution.

The Additive Influence of Propane-1,2-Diol on SDS Micellar Structure and Properties

Micellar systems are colloids with significant properties for pharmaceutical and food applications. They can be used to formulate thermodynamically stable mixtures to solubilize hydrophobic food-related substances. Furthermore, micellar formation is a complex process in which a variety of intermolecular interactions determine the course of formation and most important are the hydrophobic and hydrophilic interactions between surfactant–solvent and solvent–solvent. Glycols are organic compounds that belong to the group of alcohols. Among them, propane-1,2-diol (PG) is a substance commonly used as a food additive or ingredient in many cosmetic and hygiene products. The nature of the additive influences the micellar structure and properties of sodium dodecyl sulfate (SDS). When increasing the mass fraction of propane-1,2-diol in binary mixtures, the c.m.c. values decrease because propane-1,2-diol is a polar solvent, which gives it the ability to form hydrogen bonds, decreasing the cohesivity of water and reducing the dielectric constant of the aqueous phase. The values of ΔGm0 are negative in all mixed solvents according to the reduction in solvophobic interactions and increase in electrostatic interaction. With the rising concentration of cosolvent, the equilibrium between cosolvent in bulk solution and in the formed micelles is on the side of micelles, leading to the formation of micelles at a lower concentration with a small change in micellar size. According to the ¹H NMR, with the addition of propylene glycol, there is a slight shift of SDS peaks towards lower ppm regions in comparison to the D₂O peak. The shift is more evident with the increase in the amount of added propane-1,2-diol in comparison to the NMR spectra of pure SDS. Addition of propane-1,2-diol causes the upfield shift of the protons associated with hydrophilic groups, causing the shielding effect. This signifies that the alcohol is linked with the polar head groups of SDS due to its proximity to the SDS molecules.

The progress on sulfhydryl modified polymers with regard to synthesis, characterization and mucoadhesion

The concepts of mucoadhesion and mucoadhesive polymers were introduced in the 20th century, leading to several advantages. These included enhanced drug absorption and extended residence at specific site of action. Polymeric excipients underwent chemical modification with sulfhydryl groups on the polymeric backbone so as to improve mucoadhesive features as well as potential. This modification resulted in compounds mimicking the nature of secreted mucus glycoproteins. Thus, these thiol group-bearing excipients presented the ability to attach covalently to the mucosa by the disulfide bonding. Nevertheless, the first generation of these thiol-modified polymers, named thiomers, presented disadvantages such as low stability in aqueous media and/or the high susceptibility towards oxidation along with the drawback of low sufficient reactive functional moieties on the polymeric backbone at lower pH. Therefore, in the 21st century, a second generation of preactivated or S-protected polymers with protected thiol moieties were developed, as well as a third generation of thiomers, solving some of the previously described problems. This review article aimed to highlight the progess on a potent sulfhydryl modification during the last decades and the posterior characterization and in vitro/ex vivo/in vivo mucoadhesiveness.

Multiscale Microstructure, Composition, and Stability of Surfactant/Polymer Foams

Inclusion of polymer additives is a known strategy to improve foam stability, but questions persist about the amount of polymer incorporated in the foam and the resulting structural changes that impact material performance. Here, we study these questions in sodium dodecyl sulfate (SDS)/hydroxypropyl methylcellulose (HPMC) foams using a combination of flow injection QTOF mass spectrometry and small-angle neutron scattering (SANS) measurements leveraging contrast matching. Mass spectrometry results demonstrate polymer incorporation and retention in the foam during drainage by measuring the HPMC-to-SDS ratio. The results confirm a ratio matching the parent solution and stability over the time of our measurements. The SANS measurements leverage precise contrast matching to reveal detailed descriptions of the micellar structure (size, shape, and aggregation number) along with the foam film thickness. The presence of HPMC leads to thicker films, correlating with increased foam stability over the first 15-20 min after foam production. Taken together, mass spectrometry and SANS present a structural and compositional picture of SDS/HPMC foams and an approach amenable to systematic study for foams, gathering mechanistic insights and providing formulation guidance for rational foam design.