Mixtures Of Amphiphiles Research Articles

Antiproliferative and Morphological Effects of Fenretinide Lipid Nanosystems in Colon Adenocarcinoma Cells

Objective: Colon adenocarcinoma is characterized by the downregulation of the retinoic acid receptor, making natural retinoids such as all-trans retinoic acid, 9-cis retinoic acid and 13-cis retinoic acid effective in treatment and chemoprevention due to their ability to increase RARβ expression. However, major limitations to their use include tolerability and acquired resistance. In this study, we evaluated fenretinide, a semisynthetic derivative of all-trans retinoic acid, in an HT-29 cell line. Fenretinide was evaluated both as a free drug and encapsulated in self-assembling phosphatidylcholine nanosystems with the aim of increasing the aqueous solubility and cell availability of the drug. Methods: Fenretinide was encapsulated in lipid nanosystems obtained in water by the dispersion of an amphiphilic mixture of phospholipids, glyceryl tributyrate and polysorbate 80. The physico-chemical characterization of the nanosystems was carried out by dynamic light scattering and spectrophotometry. The biological activity was evaluated by quantitative phase imaging microscopy, MTT assay, flow cytometry and confocal laser-scanning fluorescence microscopy. Results: Fenretinide in phosphatidylcholine nanosystems was more active than free fenretinide in inhibiting HT-29 cells’ proliferation, as indicated by quantitative phase imaging data. Indeed, encapsulated fenretinide increased duplication time, decreased dry mass and decreased the rate of cell growth more efficiently than fenretinide. Moreover, encapsulated fenretinide effectively decreased the motility of the cells that survived the treatment. Conclusions: The results indicate that the proposed nanosystems can be considered a valuable alternative to natural retinoids in the chemoprevention and treatment of colorectal cancer. This is due to the favorable pharmacologic characteristics of fenretinide in colorectal cancer and the improved drug activity provided by nanoencapsulation.

Hybrid Planar Copolymer Membranes with Dual Functionality against Bacteria Growth.

Antibacterial surfaces can be classified into two categories: passive surfaces, which repel bacteria by affecting surface wettability, and active surfaces, which have bactericidal properties that disrupt cell membranes upon contact. With the increasing demand for effective antibacterial solutions that combine these properties, advanced strategies are concentrating on developing surfaces with dual antimicrobial functionalities. Here, we present surfaces with nanotexture resulting from the phase separation of two different amphiphilic block copolymers displaying efficient dual functionality against bacteria growth. This approach combines the inherent antifouling properties of poly(ethylene oxide) as the hydrophilic domain of one copolymer with the antimicrobial effect of a peptide covalently attached to the hydrophilic domain of the second copolymer. The planar membranes are generated by self-assembly of the amphiphilic copolymer mixture deposited by Langmuir-Blodgett and Langmuir-Schaffer methods on a solid support, followed by covalent attachment of the antimicrobial peptides to one of the copolymers, specifically functionalized. Combining both copolymers, in terms of their properties and functionalities on the same surface, significantly limitsEscherichia colibiofilm formation and effectively eradicates bacteria during short-term incubation. While such multifunctional antimicrobial planar polymer membranes show promising potential in the design of fine coatings for small surgical or implantable devices, they are not limited to this application. Their use can be completely changed by attaching other active molecules or assemblies to induce specific multifunctionality for the targeted application.

Structure and Characterization of Catanionic Complexes and Biocompatible Vesicles of N-Acyltaurine and Sarcosine Alkyl Ester: Encapsulation and Release Studies with 5-Fluorouracil.

Hydrated dispersions containing equimolar mixtures of cationic and anionic amphiphiles, referred to as catanionic systems, exhibit synergistic physicochemical properties, and mixing single-chain cationic and anionic lipids can lead to the spontaneous formation of vesicles as well as other phase structures. In the present work, we have characterized two catanionic systems prepared by mixing N-acyltaurines (NATs) and sarcosine alkyl esters (SAEs) bearing 11 and 12 C atoms in the acyl/alkyl chains. Turbidimetric and isothermal titration calorimetric studies revealed that both NATs form equimolar complexes with SAEs having matching acyl/alkyl chains. The three-dimensional structure of the sarcosine lauryl ester (lauryl sarcosinate, LS)-N-lauroyltaurine (NLT) equimolar complex has been determined by single-crystal X-ray diffraction. The LS-NLT equimolar complex is stabilized by electrostatic attraction and multiple hydrogen bonds, including classical, strong N-H···O hydrogen bonds as well as several C-H···O hydrogen bonds between the two amphiphiles. DSC studies showed that both equimolar complexes show single sharp phase transitions. Transmission electron microscopy and dynamic light scattering studies have demonstrated that the LS-NLT catanionic complex assemblies yield stable medium-sized vesicles (diameter 280-350 nm). These liposomes were disrupted at high pH, suggesting that the designed catanionic complexes can be used to develop base-labile drug delivery systems. In vitro studies with these catanionic liposomes showed efficient entrapment (73% loading) and release of the anticancer drug 5-fluorouracil in the physiologically relevant pH range of 6.0-8.0. The release rate was highest at pH 8.0, reaching about 78%, 90%, and 100% drug release at 2, 6, and 12 h, respectively. These observations indicate that LS-NLT catanionic vesicles will be useful for designing drug delivery systems, particularly for targeting organs such as the colon, which are inherently at basic pH.

Marine Fouling Release Performance of Amphiphilic Carboxybetaine Perfluoropolyether Methacrylate Polymer Coatings

AbstractAmphiphilic polymer systems have been demonstrated to be an effective and environmentally friendly approach to combat the challenges of biofouling, especially in the real ocean environment. A variety of polymer compositions containing fluorophilic perfluoropolyether (PFPE) urethane dimethacrylate and zwitterionic carboxybetaine methacrylate (CBMA) are in situ copolymerized across a broad concentration range and anchored to chemically functionalized substrates by grafting‐through polymerization. Dynamic accumulation assays with the marine diatom Navicula perminuta and the marine bacterium Cobetia marina revealed an enhanced antifouling performance in most of the amphiphilic polymer mixtures when zwitterionic units are combined with hydrophobic PFPE compounds. It is noticed that the resulting polymer networks still possess enough orientational freedom to quickly rearrange in the presence of water. It is further observed that several of the very hydrophilic formulations and some of the moderately hydrophobic formulations exhibit low fouling against the marine fouling organisms Navicula perminuta and Cobetia marina. This correlated with increased surface roughness and the ability for underwater rearrangement. Furthermore, it is discussed whether the probability that highly hydrated hydrogels, which appear sponge‐like, may create a diffuse interphase which promotes the incorporation of silt. Latter is counteracted by the hydrophobic PFPE building blocks in the amphiphilic coatings.

Heteromultivalent Ligand Display on Reversible Self-Assembled Monolayers (rSAMs): A Fluidic Platform for Tunable Influenza Virus Recognition.

We report on the design of heteromultivalent influenza A virus (IAV) receptors based on reversible self-assembled monolayers (SAMs) featuring two distinct mobile ligands. The principal layer building blocks consist of α-(4-amidinophenoxy)alkanes decorated at the ω-position with sialic acid (SA) and the neuraminidase inhibitor Zanamivir (Zan), acting as two mobile ligands binding to the complementary receptors hemagglutinin (HA) and neuraminidase (NA) on the virus surface. From ternary amphiphile mixtures comprising these ligands, the amidines spontaneously self-assemble on top of carboxylic acid-terminated SAMs to form reversible mixed monolayers (rSAMs) that are easily tunable with respect to the ligand ratio. We show that this results in the ability to construct surfaces featuring a very strong affinity for the surface proteins and specific virus subtypes. Hence, an rSAM prepared from solutions containing 15% SA and 10% Zan showed an exceptionally high affinity and selectivity for the avian IAV H7N9 (Kd = 11 fM) that strongly exceeded the affinity for other subtypes (H3N2, H5N1, H1N1). Changing the SA/Zan ratio resulted in changes in the relative preference between the four tested subtypes, suggesting this to be a key parameter for rapid adjustments of both virus affinity and selectivity.

Interfacial properties, decompression, and augmented injection of amphiphilic carbon dots and surfactant mixtures

The mixing properties of amphiphilic carbon dots named C12-SCDs with a cationic surfactant (Dodecyl trimethyl ammonium bromide, DTAB) and an anionic surfactant (Sodium dodecyl sulfate, SDS) were investigated. Results indicated that surfactants DTAB and SDS show a synergistic effect in reducing surface tension with C12-SCDs. The synergistic effect of the DTAB/C12-SCDs mixture is more prominent than the SDS/C12-SCDs mixture, which may result from the electrostatic attraction between DTAB and C12-SCDs. Meanwhile, adding inorganic salts, the surface tension of these mixtures shows a trend of first decreasing slightly and then increasing. The DTAB/C12-SCDs mixture resists strong acids but not alkali environments. However, the surface tension of the SDS/C12-SCDs mixture gradually increases with the increase in pH. In addition, these mixtures have temperature-resistance properties. C12-SCDs and surfactants (DTAB and SDS) also have a synergistic effect in reducing the crude oil-water interfacial tension. Meanwhile, the DTAB/C12-SCDs and SDS/C12-SCDs mixtures have excellent wettability alternation performance. C12-SCDs and surfactants can form a mixed adsorption layer to promote the wettability alternation performance. The depressurization rates of DTAB, SDS, C12-SCDs, DTAB/ C12-SCDs mixture, and SDS/C12-SCDs mixture are 10.42 %, 11.54 %, 22.91 %, 26.32 %, and 24.75 %, respectively. The DTAB/C12-CDs and SDS/C12-CDs mixtures can effectively remove the oil film on the core surface, thus improving the channel of injected water. At the same time, these mixtures can be adsorbed on the surface of the hydrophilic core to form a hydrophobic surface, and the injection of water produces a hydrophobic slip effect. Finally, reducing the surface tension of water can also effectively reduce the injection pressure.

An Overview on Microemulsion as a Topical Drug Delivry System

Due to their extended shelf life, enhanced drug solubilization, and simplicity in preparation and administration, microemulsions are among the greatest possibilities for new drug delivery systems. Microemulsions are liquid mixtures of amphiphile, water, and oil that are thermodynamically stable and optically isotropic. They have become cutting-edge drug delivery systems that enable controlled or sustained release for parenteral, ophthalmic, percutaneous, topical, and transdermal medication administration.Because of their low viscosity, transparency, and, more precisely, their thermodynamic stability, microemulsions may be easily distinguished from regular emulsions. Microemulsions have a wide range of uses and applications, including in the pharmaceutical, agrochemical, cutting oil, biotechnology, food, and cosmetic industries as well as in analytical applications and environmental detoxification. This review paper's main goal is to talk about using microemulsions as a medicine delivery mechanism with other potential uses.

Mixed micellization analysis of tri-substituted SAIL and amphiphilic drug mixture in aqueous/salt media at diverse temperatures

Abstract The present work aimed to study the mixed micellar behaviour of a tri-substituted imidazolium based surface-active ionic liquid (SAIL), 1-tetradecyl-2,3-dimethylimidazolium bromide [C14bmim][Br], with a drug Nortriptyline hydrochloride (NOT) in the water/salt (Na2SO4) medium using surface tension measurements (298.15 K) alongwith conductivity measurements (298.15K–313.15K). Lower experimentally obtained cmc values compared to their ideal values suggest that the investigated amphiphiles interact strongly. The values of micellar mole fraction (X 1) based on the several proposed models (Rubingh, Motomura, and Rodenas) and the ideal micellar mole fraction (X id ) were assessed, and the predicted outcomes indicate that NOT has a significant contribution to the formation of mixed micelles, which increases as the [C14bmim][Br] mole fraction is increased. The negative values of micellization’s Gibbs free energy (ΔGm 0) between the examined amphiphiles were an indication of spontaneous mixed micelle formation. Micellar changes in entropy (ΔSm 0) and enthalpy (ΔHm 0) were also computed and discussed. Using surface tension measurements, surface-active parameters like surface tension at cmc (γ cmc ), minimum surface area per IL molecule (A min), maximum surface excess concentration (τ max), effectiveness of surface tension reduction (π cmc ), and cmc of mixed system have been estimated. The results showed an improved adsorption and micellization properties of these mixtures which will surely contribute to the tremendous rise of these mixed systems in drug delivery applications.

Impacts of several salts on the clouding development, nature of interactions and associated physico-chemical variables of mixture of promethazine hydrochloride and conventional nonionic surfactant

Herein, in the presence of electrolytes, the cloud points (CPs) of the mixture of a conventional uncharged amphiphile (triton X-100 (TX-100)) and promethazine hydrochloride (PMH; phenothiazine medicine) were measured and explained in great details. The CP values of the employed surfactant + PMH system were reduced with enhancing salts contents (NaCl, Na2SO4, NH4Cl, and (NH4)2SO4)), while the CP values of the study system followed the trend: Na2SO4 < NaCl and (NH4)2SO4 < NH4Cl. The different thermodynamic parameters of phase separation, including standard free energy (ΔG 0 c), enthalpy (ΔH 0 c), and entropy (ΔS 0 c) changes were also calculated and discussed elaborately. The values of free energy change (ΔG 0 c) were obtained to be positive, indicating that the clouding phenomena are non-spontaneous. Different transfer properties (free energy (ΔG 0 c.t), enthalpy (ΔH 0 c,t ), and entropy (ΔS 0 c,t ) of transfer), intrinsic enthalpy gain (ΔH 0,*c) and compensation temperature (T c) of the inspected system have also been assessed and discussed.

Stabilizing Differential Interfacial Curvatures by Mismatched Molecular Geometries: Toward Polymers with Percolating 1 nm Channels of Gyroid Minimal Surfaces

Soft materials with self-assembled networks possess saddle-shaped interfaces with distributed negative Gaussian curvatures. The ability to stabilize such a geometry is critically important for various applications but can be challenging due to the possibly "deficient" packing of the building blocks. This nontrivial challenge has been manifested, for example, by the limited availability of cross-linkable bicontinuous cubic (Q) liquid crystals (LCs), which can be utilized to fabricate compelling polymers with networked nanochannels uniformly sized at ∼1 nm. Here, we devise a facile approach to stabilizing cross-linkable Q mesophases by leveraging the synergistic self-assembly from pairs of scalably synthesized polymerizable amphiphiles. Hybridization of the molecular geometries by mixing significantly increases the propensity of the local deviations in the interfacial curvature specifically required for Q assemblies. "Normal" (type 1) double gyroid LCs possessing 1 nm ionic channels conforming to minimal surfaces can be formulated by simultaneous hydration of the amphiphile mixtures, as opposed to the formation of hexagonal or lamellar mesophases exhibited by the single-amphiphile systems, respectively. Fixation of the bicontinuous network in polymers via radical polymerization has been efficaciously facilitated by the presence of the bifunctional polymerizable groups in one of the employed amphiphiles. High-fidelity lock-in of the ordered continuous 1 nm channels has been unambiguously confirmed by the observation of single-crystal-like diffraction patterns from synchrotron small-angle X-ray scattering and large-area periodicities by transmission electron microscopy. The produced polymeric materials exhibit the required mechanical integrity as well as chemical robustness in a variety of organic solvents that benefit their practical applications for selective transport of ions and molecules.

Wetting and Nonwetting near a Tricritical Point.

The dihedral contact angles between interfaces in three-fluid-phase equilibria must be continuous functions of the bulk thermodynamic fields. This general argument, which we propose, predicts a nonwetting gap in the phase diagram, challenging the common belief in "critical-point wetting," even for short-range forces. A demonstration is provided by exact solution of a mean-field two-density functional theory for three-phase equilibria near a tricritical point (TCP). Complete wetting is found in a tiny vicinity of the TCP. Away from it, nonwetting prevails and no wetting transition takes place, not even when a critical endpoint is approached. Far from the TCP, reentrant wetting may occur, with a different wetting phase. These findings shed light on hitherto unexplained experiments on ternary H_{2}O-oil-nonionic amphiphile mixtures in which nonwetting continues to exist as one approaches either one of the two critical endpoints.

Surface and emulsifying properties of raw ethanolic extracts from legumes containing soyasaponins and proteins

The development of new amphiphilic compounds of natural origin is a challenging field of research in surfactant science. In this scenario, surfactants obtained from renewable organic sources is a valuable option to be exploited. The present work proposes raw ethanolic extracts containing soyasaponins, proteins and polysaccharides from legumes as surface active mixtures and stabilizers for emulsified systems. These extracts are produced by a green extraction process using an hydroalcoholic mixture (70:30 w/w) as solvent and six different legumes soybean, lentils, peas, beans, chickpeas, wild peas as starting materials. After freeze-drying, extracts were characterized in terms of total soyasoponin (from 1377 to 7354 mg/100 g), soyasaponin I (from 15 to 1459 mg/kg), soyasaponin VI (from 13 to 1076 mg/kg) and protein (16–28 g/100 g) contents. All extracts aqueous solutions show good surface active properties, being able to reduce the air-water surface tension to values comparable to those of the commonly employed surfactants (28–33 mN/m). Differences are observed in terms of emulsifying ability, since only lentils and soybeans extracts, thanks to their high soyasaponins and protein content, can act as stabilizers for emulsions containing up to 10% w/w of ethyl oleate (as oil phase) over six months of storage at 4 °C. These extracts are promising amphiphilic natural mixtures, potentially employable for food or pharmaceutical applications. Their relevance is also related to the possibility of using legumes derived from industrial wastes of food manufacturing, thereby giving valorization of by-products and residues in the context of a “circular economy” model.

Composition triggered Aggregation/Solubilization behaviour of mixed counter charged gemini Surfactants: A Multi-technique investigations

• Fluorescence parameters can be used to detect the interaction between counter charged geminis. • Composition variation modulates the apparent dielectric constant of the mixed micelle. • Mixing can tune micelles of different architectures which further depend on spacer nature. • Zeta (ζ) values show charge reversal during composition variation. • A correlation has been proposed for the dependence of MSR on the micellar environment- morphology- composition. Aqueous association behaviour of counter charged gemini surfactants has been studied by fluorometry, dynamic light scattering (DLS), Zeta(ζ)-potential and SANS measurements at 303 K. For the purpose, P, P'-1,4-butanedieyl, P, P'-didodecylester, disodium salt, anionic surfactant(12–4-12A) and cationic gemini surfactants: Butanediyl-1,4-bis (N, N-dimethyl-N-tetradecyl-ammonium) dibromide (14–4–14); Ethane-1,2-diyl bis (N, N-dimethyl-N-tetradecyl-ammonium acetoxy) dichloride (14-Eg-14) and (D-isosorbate-1,4-diyl bis (N, N-dimethyl-N-tetradecylammonium acetoxy) dichloride (14-Isb-14) were mixed for varying mole fraction range ( x = 0–1). Fluorescence data using pyrene as a probe are used to obtain CMC values which were theoretically treated using regular solution theories. It has been observed that mixing causes non spherical micelles and even vesicle formation was observed in one of the combinations (12–4-12A + 14–4–14) at x = 0.4. Various compositions are used to solubilize polycyclic aromatic hydrocarbon (pyrene, anthracene and phenanthrene) in order to have an idea of solubility enhancement efficacy. Micellar morphology/environment has been used to draw a correlation between apparent dielectric constant (D exp ) - composition - solubilization potential. Findings can be used for loading various hydrophobic materials in an appropriate amphiphilic mixture for various applications such as dye solubilization, drug solubilization, drug delivery or drug targeting.

Nanoporous Vesicular Membranes of Amphiphilic Polymers Containing Trans / Cis Isomers

Nanoporous Vesicular Membranes of Amphiphilic Polymers Containing <i>Trans</i> / <i>Cis</i> Isomers

Improving the flotation recovery of Cu from flash smelting slags by utilizing cellulose-based frother formulationss

• First published study using polymer-surfactant mixes as frothers in Cu slag flotation. • Using the PS-mix improved overall Cu recovery compared to commercial frother. • PS-mix significantly increased productivity, i.e. similar froth product in less time. • PS-mix demonstrated superior tolerance in performance when reducing xanthate dosage. Froth flotation is an operation currently used for the recovery of Cu from pyrometallurgical smelting slags due its simple operation and relatively low operational costs. While it has been utilized for many decades, it may be necessary to develop strategies that improve Cu recovery from slags, as the unprecedented increase in Cu demand has made industrial waste and side streams economically relevant sources of metals. This study presents a novel chemistry-based approach for the flotation of Cu from smelting slags by utilizing an amphiphilic cellulose-surfactant mixture as a flotation frother, hereby referred to as CellFroth. The present work pursues two main objectives: i) to improve the performance of flotation for the treatment of smelting slags and ii) to accomplish a first proof of concept for frothers produced from renewable sources in the context of industrial waste treatment. The flotation performance of CellFroth was compared with a commercially available additive (i.e., DowFroth250) and hydroxypropyl methyl cellulose (HPMC). The results showed significant advantages in performance for CellFroth. At the highest collector concentration, Cu recovery was higher with CellFroth compared to DowFroth 250 and pure HPMC (73%; 62% and 65% respectively). A 75% reduction in xanthate concentrations had negligible effects on Cu recovery for CellFroth (70%), while recoveries decreased drastically with DowFroth250 (47%) and pure HPMC (50 %). Finally, CellFroth consistently reached comparable concentrate productivity (grade and recovery) as DF250 within significantly shorter flotation times. The use of CellFroth thus offers the possibility of increasing the Cu recovery from flash smelting slags, while reducing the environmental impact of the process by using a frother produced from sustainable sources and simultaneously reducing xanthate consumption.

Dynamical Anomaly of Aqueous Amphiphilic Solutions: Connection to Solution H-Bond Fluctuation Dynamics?

We have investigated the possible connection between “dynamical anomaly” observed in time-resolved fluorescence measurements of reactive and nonreactive solute-centered relaxation dynamics in aqueous binary mixtures of different amphiphiles and the solution intra- and interspecies H-bond fluctuation dynamics. Earlier studies have connected the anomalous thermodynamic properties of binary mixtures at very low amphiphile concentrations to the structural distortion of water. This is termed as “structural anomaly.” Interestingly, the abrupt changes in the composition-dependent average rates of solute relaxation dynamics occur at amphiphile mole fractions approximately twice as large as those where structural anomalies appear. We have investigated this anomalous solution dynamical aspect by considering (water + tertiary butanol) as a model system and performed molecular dynamics simulations at several tertiary butanol (TBA) concentrations covering the extremely dilute to the moderately concentrated regimes. The “dynamical anomaly” has been followed via monitoring the composition dependence of the intra- and interspecies H-bond fluctuations and reorientational relaxations of TBA and water molecules. Solution structural aspects have been followed via examining the tetrahedral order parameter, radial and spatial distribution functions, numbers of H bonds per water and TBA molecules, and the respective populations participating in H-bond formation. Our simulations reveal abrupt changes in the H-bond fluctuations and reorientational dynamics and tetrahedral order parameter at amphiphile concentrations differing approximately by a factor of 2 and corroborates well with the steady-state and the time-resolved spectroscopic measurements. This work therefore explains, following a uniform and cogent manner, both the experimentally observed structural and dynamical anomalies in microscopic terms.

The assembly of amitriptyline hydrochloride + triton X-45 (non-ionic surfactant) mixtures: Effects of simple salt and urea

In this work, the surface and micellization behavior of amitriptyline hydrochloride (AMT) and a triton X-45 (TX-45) surfactant were studied in detail by surface tension measurement in the presence of simple salt NaCl and urea at 298.15 K. The mixtures of amphiphiles were analyzed by varying their compositions. The critical micelle concentration (cmc and cmc*), activity coefficients, interaction parameters, minimum area per molecule, interfacial adsorption, packing parameter (P), and various thermodynamic parameters for AMT + TX-45 mixtures with and without NaCl and urea at 298.15 K have been determined. Clint’s, Rubingh’s, and Maeda’s models were used to analyze the results. The findings indicate attractive interactions in the AMT and non-ionic TX-45 mixture and suggest effective participation of the TX-45 when mixtures are employed in the absence and presence of additives. The average micellar composition of surfactant (X1Ru), along with mixed monolayer composition of TX-45 (X1σ) value, in every solvent used contained over 70% TX-45, demonstrating that mixed mixed micelles and mixed monolayers contain much more TX-45 than AMT. In general, NaCl enhanced the micellization and surface activity, whereas urea lessened the activity of the studied system. UV–visible and Fourier transform infrared (FTIR) spectroscopy were also used to extract information on the interaction of AMT and TX-45 in aqueous solution. The current study aims to use TX-45 as an efficacious drug delivery vehicle for antidepressant drugs.

The interaction of the surface active ionic liquid with nonionic surfactants (Triton X-100 and Triton X-405) in aqueous solution by using tensiometry method

The synergistic interactions of the surface active ionic liquid (1-dodecyl-3-methylimidazolium bromide, IL) with non-ionic surfactants TritonX-100 (TX-100) and TritonX-405 (TX-405) were investigated in aqueous solution at various mole fractions by using the surface tension technique at 298.15 K. In this work, the pendant drop method was used for surface tension measurement of solutions. The surfactant properties such as critical micelle concentration (CMC), micellar mole fractions (X1Rub), interaction parameter (βm), and activity coefficients of components in the mixed micelle (f1Rub and f2Rub) were calculated by theoretical Clint and Rubingh models. Also, surface and adsorption parameters, maximum surface excess values (Γmax), minimum area per molecule (Amin), surface tension at CMC (σCMC), and surface pressure at the CMC (πCMC) values have been estimated in (TX-405/TX-100 + IL + water) systems. The synergistic effects operating in these amphiphile mixtures were confirmed by the negative values of the interaction parameter. Generally, the CMC value of surfactant solution increases with the addition of ionic liquid in the mixture. It was demonstrated that IL can be judiciously used at different mole fractions for modifying the physicochemical properties of (TX-100 and TX-405). Different thermodynamics parameters were computed for mixtures and were also discussed in detail. The Gibbs free energy change of micellization (ΔGmo), the standard Gibbs energy of adsorption (ΔGado) and the excess free energy of micellization (ΔGexRub) values have been estimated at different compositions. The calculation of thermodynamic parameters shows that the micellization process is spontaneous and becomes more favorable with addition of the non-ionic component in mixture.

Exploring the Interactions of Ionic Liquids with Bio-Organic Amphiphiles Using Computational Approaches

Bio-organic amphiphiles have been shown to effectively impart unique physicochemical properties to ionic liquids resulting in the formation of versatile hybrid composites. In this work, we utilized computational methods to probe the formation and properties of hybrids prepared by mixing three newly designed bio-organic amphiphiles with 14 ionic liquids containing cholinium or glycine betaine cations and a variety of anions. The three amphiphiles were designed such that they contain unique biological moieties found in nature by conjugating (a) malic acid with the amino acid glutamine, (b) thiomalic acid with the antiviral, antibacterial pyrazole compound [3-(3,5-dimethyl-1H-pyrazol-1-yl)benzyl]amine, and (c) Fmoc-protected valine with diphenyl amine. Conductor-like screening model for real solvents (COSMO-RS) was used to obtain sigma profiles of the hybrid mixtures and to predict viscosities and mixing enthalpies of each composite. These results were used to determine optimal ionic liquid-bio-organic amphiphile mixtures. Molecular dynamics simulations of three optimal hybrids were then performed, and the interactions involved in the formation of the hybrids were analyzed. Our results indicated that cholinium-based ILs interacted most favorably with the amphiphiles through a variety of inter- and intramolecular interactions. This work serves to illustrate important factors that influence the interactions between bio-organic amphiphiles and bio-ILs and aids in the development of novel ionic liquid-based composites for a wide variety of potential biological applications.

Lipid Vesicles and Other Polymolecular Aggregates—From Basic Studies of Polar Lipids to Innovative Applications

Lipid vesicles (liposomes) are a unique and fascinating type of polymolecular aggregates, obtained from bilayer-forming amphiphiles—or mixtures of amphiphiles—in an aqueous medium. Unilamellar vesicles consist of one single self-closed bilayer membrane, constituted by the amphiphiles and an internal volume which is trapped by this bilayer, whereby the vesicle often is spherical with a typical desired average diameter of either about 100 nm or tens of micrometers. Functionalization of the external vesicle surface, basically achievable at will, and the possibilities of entrapping hydrophilic molecules inside the vesicles or/and embedding hydrophobic compounds within the membrane, resulted in various applications in different fields. This review highlights a few of the basic studies on the phase behavior of polar lipids, on some of the concepts for the controlled formation of lipid vesicles as dispersed lamellar phase, on some of the properties of vesicles, and on the challenges of efficiently loading them with hydrophilic or hydrophobic compounds for use as delivery systems, as nutraceuticals, for bioassays, or as cell-like compartments. Many of the large number of basic studies have laid a solid ground for various applications of polymolecular aggregates of amphiphilic lipids, including, for example, cubosomes, bicelles or—recently most successfully—nucleic acids-containing lipid nanoparticles. All this highlights the continued importance of fundamental studies. The life-saving application of mRNA lipid nanoparticle COVID-19 vaccines is in part based on year-long fundamental studies on the formation and properties of lipid vesicles. It is a fascinating example, which illustrates the importance of considering (i) details of the chemical structure of the different molecules involved, as well as (ii) physical, (iii) engineering, (iv) biological, (v) pharmacological, and (vii) economic aspects. Moreover, the strong demand for interdisciplinary collaboration in the field of lipid vesicles and related aggregates is also an excellent and convincing example for teaching students in the field of complex molecular systems.