High Critical Micelle Concentration Research Articles

Recovery of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) from water using foam fractionation with whey soy protein

Perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) are persistent anthropogenic chemicals that are widely distributed in the environment and pose significant risks to human health. Foam fractionation has emerged as a promising method to recover PFOS/PFOA from water. However, PFOS/PFOA concentrations in wastewater are often inadequate to generate stable foams due to their high critical micelle concentrations and the addition of a cosurfactant is necessary. In this study, we developed whey soy protein (WSP) as a green frother and collector derived from soybean meal (SBM), which is an abundant and cost-effective agro-industrial residue. WSP exhibited excellent foaming properties across a wide pH range and demonstrated strong collection capabilities that enhanced the recovery of PFOS/PFOA. The mechanism underlying this collection ability was elucidated through various methods, revealing the involvement of electrostatic attraction, hydrophobic interaction, and hydrogen bonding. Furthermore, we designed a double plate internal to improve the enrichment of PFOS/PFOA by approximately 2.3 times while reducing water recovery. Under suitable conditions (WSP concentration: 300 mg/L, pH: 6.0, air flowrate: 300 mL/min), we achieved high recovery percentages of 94–98% and enrichment ratios of 7.5–12.8 for PFOS/PFOA concentrations ranging from 5 to 20 mg/L. This foam fractionation process holds great promise for the treatment of PFOS/PFOA and other per- and polyfluoroalkyl substances.

Synthesis and application of cationic fluorocarbon surfactants

In this paper, a series of cationic polyurethane fluorinated surfactants were synthesized using a series of isocyanates, and 1H, 1H, 2H,2H-tridecafluoro-1-octanol, 2-(dimethylamino)ethanol, and iodomethane as raw materials in a three-step sequential reaction. These fluorinated surfactants exhibited high surface activity and low critical micelle concentration. In addition, these fluorinated surfactants exhibited excellent wetting and emulsification properties at very low concentrations of 0.1 wt%. In addition the cationic polyurethane fluorinated surfactants are compounded into aqueous film-forming foam extinguishing agents, which exhibit excellent fire extinguishing properties. The desirable properties coupled with the simple and green preparation process make this strategy a new way to prepare sustainable alternatives to long fluoroalkyl chain surfactants.

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.

Different anionic MIL structure optimization and molecular dynamics simulation of adsorption on coal surface

Surfactants can regulate the surface wettability of low-rank coal (LRC), resulting in highly efficient coal usage. Magnetic ionic liquids (MILs), a novel form of surfactants, provide environmental protection, excellent designability, and recyclability. In this study, quantum chemical simulations were performed to optimize the structures of [C12mim]FeCl4, [C12mim]2CoCl4, and [C12mim]2NiCl4 and the structural parameters were verified. The effect of MILs on the surface wettability of LRC was investigated by measuring the critical micelle concentration (CMC) using a conductivity technique and computing the adhesion work; thus, the micro-control mechanism of wettability was clarified. The wettability investigation revealed that the three different types of MILs had higher critical micelle concentrations as the temperature increased. Molecular dynamics modeling was utilized to calculate the adsorption process simultaneously, and the results demonstrated that the three different MILs may spontaneously complete adsorption on the surface of the LRC. Thermogravimetric and X-ray photoelectron spectroscopy analyses demonstrated that after the addition of the three different types of MILs, the oxygen-containing functional groups in the LRC were covered, the LRC surface became more hydrophobic, the water content of the LRC decreased, and the wettability of the LRC was effectively controlled.

Surface tension behavior of superspreading and non-superspreading trisiloxane surfactants

One parameter frequently considered to be relevant for superspreading of trisiloxane surfactants is surface tension kinetics. In the scientific literature, some experimental results reported for trisiloxane surfactants are in contradiction with fundamental concepts of surfactant monomer diffusion. Therefore, maximum bubble pressure tensiometry has been used to determine dynamic surface tension (DST) of two types of trisiloxane surfactants: superspreader and non-superspreader. Results show that both surfactants behave similarly at concentrations below critical micelle concentration (CMC), as expected. The CMC curves, as determined by drop shape analysis, confirmed that the more hydrophilic non-superspreader has a higher CMC as compared to the more hydrophobic superspreader. Accordingly, the lower surfactant monomer concentration of the superspreader results in a higher DST than the non-superspreader at the same surface age. So, in contrary to claims in the literature, there is nothing mysterious or unexpected concerning the surface tension behavior of trisiloxane surfactants.Graphical

СПЕКТРОФОТОМЕТРИЧЕСКОЕ ОПРЕДЕЛЕНИЕ НИТРОКСОЛИНА В ЛЕКАРСТВЕННЫХ ПРЕПАРАТАХ ПРИ ИСПОЛЬЗОВАНИИ МЕТОДОЛОГИИ ПОВЕРХНОСТИ ОТКЛИКА

It was shown by the conductometric study that the formation of micelles in the cetyltrimethylam¬monium bromide (CTAB) – dimethylsulfoxide (DMSO) – water system occurs at higher critical micelle concentrations (CMC) than in the CTAB – water system. The solubilization of nitroxoline in this system upon reaching the CMC was determined by the spectrophotometric method. The Box–Behnken design was used to obtain systems with the highest light absorption of nitroxoline, depending on the CTAB concentration, the acidity of the pH medium, and the proportion of DMSO when searching for the optimal matrix. A sensitive and selective technique suitable for micellar media and spectrophotometric analysis was developed using the response surface methodology for the determination of nitroxoline in medicines.

Hyperbranched Tetraphenylethylene Derivatives with Low Non-specific Aggregation-Induced Emission for Fluorescence Recognition of Proteins with Hydrophobic Pockets.

Proteins play an important role in the physiological process of many organisms, and their abnormal level often indicates the occurrence of some diseases. Therefore, protein analysis has important reference value and clinical significance for early diagnosis and therapy of disease. Using human serum albumin (HSA) as a model protein, a series of super-branched tetraphenylethylene (TPE) derivatives with different branching structures and terminal groups are reported herein for highly sensitive and specific recognition of proteins with hydrophobic cages. Benefiting from the hyperbranched structures, these probes showed much higher critical micelle concentrations (CMCs) than most linear TPE-based amphiphilic molecules since the hyperbranched structure not only improved their solubility but also amplified the steric hindrance effect and electrostatic repulsive force to prevent their aggregation. Dynamic light scattering experiments proved that these probes formed dense aggregates at CMC, and such aggregate structures would lead to a higher background fluorescence noise. Hence, a higher CMC is more conducive to the detection of the target with low backgrounds. Among them, P3-COOH with -COOH as the terminal unit and a relatively longer branch showed the highest CMC and the best signal to background ratio (S/N). Mechanism studies showed that P3-COOH was bound to HSA mainly through a hydrophobic force, resulting in a limited P3-COOH molecular movement and less attack from quenchers in solutions, thus leading to greatly enhanced fluorescence intensity. In addition, P3-COOH was also applied to the determination of HSA content in actual human serum samples.

Dynamic interfacial tension and adsorption kinetics of nonionic surfactants during microfluidic droplet formation process

Surfactant adsorption plays an important role in the microfluidic droplet formation process, which manifested as dynamic interfacial tension phenomenon. Due to rapid droplet expansion and convection flow around the droplet, traditional methods of interfacial tension measurement are difficult to investigate the surfactant adsorption kinetics in microfluidic process. We thus developed a differential pressure based microfluidic platform and proposed an in-situ method to determine time-evolving interfacial tension during microfluidic droplet formation according to Young-Laplace equation in this research. Four classical nonionic surfactants: Triton X-100, Tween 20, Brij 56, and Brij 58 were tested with classical n-octant/water as the working system. The concentrations of these surfactants at interface were further determined from the measured interfacial tension based on Frumkin adsorption model. The adsorption rates of surfactant showed that increasing surfactant concentration in the bulk solution and flow rate of continuous phase both promoted surfactant adsorption in the cases of Tween 20, Brij 56, and Brij 58, indicating the mass transfer-controlled mechanism of adsorption kinetics. The average thickness of mass transfer boundary layer ranged from 0.1 to 5 μm was determined from the mass transfer rate and a correlation equation was proposed to predict the thickness. However, the adsorption mechanism of Triton X-100 turned to be kinetics-controlled for its high critical micelle concentration, which helped to determine the adsorption and desorption rate constants.

Confocal Raman spectroscopy at different laser wavelengths in analyzing stratum corneum and skin penetration properties of mixed PEGylated emulsifier systems

Emulsifier mixtures are widely used in cosmetics and pharmaceutics and thus, brought extensive studies for their performances on skin applications. PEG-20cetyl ether (C20) is recently proposed to induce skin irritation and is of interest to study its skin interactions when mixed with other emulsifiers. PEG-2oleyl ether (O2) and PEG-20stearyl ether (S20) are selected and in specific, 50 mM of C20, O2, S20 as well as Mix1 (50 mM C20 mixed with 50 mM O2) and Mix2 (50 mM C20 mixed with 50 mM S20) solutions were applied on skin samples. Confocal Raman spectroscopy (CRS) analyses of stratum corneum (SC) thickness and SC lipid content were performed after 4 h skin treatments. In parallel, skin penetration properties were also evaluated via CRS by applying procaine solutions with/without emulsifiers on skin samples for 24 h. In terms of the CRS measurements, two excitation wavelengths of 532 nm and 785 nm are both utilized in this study and we secondly aimed to compare their results and suitability in SC and skin analyses. Based on the experimental observations, comparable results are obtained by using both excitation wavelengths of 532 nm and 785 nm demonstrating their suitability in analyzing SC and skin samples. Thereinto, 785 nm laser wavelength shows the advantage of deeper skin penetration and allows the measurements of fluorescent skin samples; 532 nm laser wavelength enables simple measurement performance without substrate and coverslip interference. With regards to the results of emulsifier mixtures, the addition of S20 and O2 reduced the skin interactions and penetration enhancing ability of C20, giving us the hint to build milder systems with emulsifier mixtures. Besides, the CRS results of stronger skin interruption were also correlated with the higher critical micelle concentration (CMC) values of emulsifiers and their mixtures, which may provide evidence in explaining the interactions between emulsifiers and skin.

Dissolution and remobilization of NAPL in surfactant-enhanced aquifer remediation from microscopic scale simulations

In this paper, the dissolution and mobilization of non-aqueous phase liquid (NAPL) blobs in the Surfactant-Enhanced Aquifer Remediation (SEAR) process were upscaled using dynamic pore network modeling (PNM) of three-dimensional and unstructured networks. We considered corner flow and micro-flow mechanisms including snap-off and piston-like movement for two-phase flow. Moreover, NAPL entrapment and remobilization were evaluated using force analysis to develop the capillary desaturation curve (CDC) and predict the onset of remobilization. The corner diffusion mechanism was also applied in the modeling of interphase mass transfer to represent NAPL dissolution as the dominant mass transfer process. In addition, the effect of pore-scale heterogeneity on mass transfer rate coefficient and recovered residual NAPL was considered in the simulations. Sodium dodecyl sulfate (SDS) and Triton X-100 were used as the surfactant for the SEAR process. The results indicate that although surfactants enhance NAPL recovery during two-phase flow, surfactant-enhanced remediation of residual NAPL through dissolution is highly dependent on surfactant type. When SDS ─as a surfactant with high critical micelle concentration (CMC) and low micelle partition coefficient (Km)─ was injected into a NAPL contaminated site, the mass transfer rate coefficient decreased (due to considerable changes in interface chemical potentials) which leads to a significant reduction in NAPL recovery after the end of two-phase flow. In contrast, Triton X-100 (with low CMC and high Km) improved NAPL recovery, by enhancing solubility at surfactant concentrations greater than CMC which overcompensates the interphase mass transfer reduction.

Sodium Cholate-Based Active Delipidation for Rapid and Efficient Clearing and Immunostaining of Deep Biological Samples.

Recent surges of optical clearing provided anatomical maps to understand structure-function relationships at organ scale. Detergent-mediated lipid removal enhances optical clearing and allows efficient penetration of antibodies inside tissues, and sodium dodecyl sulfate (SDS) is the most common choice for this purpose. SDS, however, forms large micelles and has a low critical micelle concentration (CMC). Theoretically, detergents that form smaller micelles and higher CMC should perform better but these have remained mostly unexplored. Here, SCARF, a sodium cholate (SC)-based active delipidation method, is developed for better clearing and immunolabeling of thick tissues or whole organs. It is found that SC has superior properties to SDS as a detergent but has serious problems; precipitation and browning. These limitations are overcome by using the ion-conductive film to confine SC while enabling high conductivity. SCARF renders orders of magnitude faster tissue transparency than the SDS-based method, while excellently preserving the endogenous fluorescence, and enables much efficient penetration of a range of antibodies, thus revealing structural details of various organs including sturdy post-mortem human brain tissues at the cellular resolution. Thus, SCARF represents a robust and superior alternative to the SDS-based clearing methods and is expected to facilitate the 3D morphological mapping of various organs.

Rheology and microstructure of zwitterionic-anionic surfactant for enhanced oil recovery

Surfactants have been widely used in enhanced oil recovery. The zwitterionic surfactant possesses a high critical micelle concentration, that its use requires an increased concentration and thus it is uneconomical. In this paper the use of erucic acid amidopropyl- betaine (EDAB, C22) and sodium alkyl sulfate (SDS) is proposed to construct a worm-like micelle with mass ratio of 1.5:1. The viscoelasticity and the structural morphology of worm-like micelle systems were studied using cryo-transmission electron microscopy, dynamic light scattering (DLS) and rheology. The results showed that EDAB/SDS with a mass concentration of 0.3% (0.18% EDAB + 0.12% SDS) exhibited viscoelastic fluid behavior when the pH value was 9.15 at 43 °C. The shear viscosity of the EDAB/SDS system is greater than that of the EDAB system. It shows that longer linear worm-like micelle and larger entangled three-dimensional network structure are formed in the EDAB/SDS system. The rheological properties EDAB/SDS system are affected by pH, temperature and inorganic salts. The viscoelasticity of the EDAB/SDS system increases first and then decreases with the increase of temperature and NaCl concentration. The electrostatic interaction between EDAB and SDS can be adjusted by changing the pH value to affect the aggregation behavior of worm-like micelle molecules. Worm-like micelles continue to grow longitudinally with the increase of pH value and form larger aggregate structures, which are manifested by an increase in viscosity.

Design of dual targeting immunomicelles loaded with bufalin and study of their anti-tumor effect on liver cancer

ObjectiveBufalin is an effective drug for the treatment of liver cancer. But its high toxicity, poor water-solubility, fast metabolism and short elimination half-life limit its use in tumor treatment. How to make the drug accumulate in the tumor and reduce side effects while maintaining its efficacy are urgent problems to be solved. The goal of this study is to solve these problems. MethodsA copolymer with tunable poly-N-isopropylacrylamide and polylactic acid was designed and synthesized. The corresponding dual targeting immunomicelles (DTIs) loaded with bufalin (DTIs–BF) were synthesized by copolymer self-assembly in an aqueous solution. The size and structure of DTIs–BF were determined by ZetaSizer Nano-ZS and transmission electron microscopy. Then, its temperature sensitivity, serum stability, critical micelle concentration (CMC), entrapment efficiency (EE), drug release and non-cytotoxicity of blank block copolymer micelles (BCMs) were evaluated. Next, the effects of DTIs–BF on cellular uptake, cytotoxicity, and tumor cell inhibition were evaluated. Finally, the accumulation of DTIs–fluorescein isothiocyanate (FITC) and the in vivo anti-tumor effect were observed using an interactive video information system. ResultsDTIs–BF had a small size, spherical shape, good temperature sensitivity, high serum stability, low CMC, high EE, and slow drug release. The blank BCMs had very low cytotoxicity. Compared with free bufalin, the in vitro cellular internalization and cytotoxicity of DTIs–BF against SMMC-7721 cells were significantly enhanced, and the effects were obviously better at 40 °C than 37 °C. In addition, the therapeutic effect on SMMC-7721 cells was further enhanced by the programmed cell death specifically caused by bufalin. When DTIs–FITC were injected intravenously in BALB/c nude mice bearing liver cancer, the accumulation of FITC was significantly increased in tumors. ConclusionDTIs–BF is a potentially effective nano-formulation and has broad prospects in the clinical treatment of liver cancer.

PH-sensitive micelles self-assembled from star-shaped TPGS copolymers with ortho ester linkages for enhanced MDR reversal and chemotherapy

TPGS approved by FDA can be used as a P-gp inhibitor to effectively reverse multi-drug resistance (MDR) and as an anticancer agent for synergistic antitumor effects. However, the comparatively high critical micelle concentration (CMC), low drug loading (DL) and poor tumor target limit its further clinical application. To overcome these drawbacks, the pH-sensitive star-shaped TPGS copolymers were successfully constructed via using pentaerythritol as the initial materials, ortho esters as the pH-triggered linkages and TPGS active-ester as the terminated MDR material. The amphiphilic star-shaped TPGS copolymers could self-assemble into free and doxorubicin (DOX)-loaded micelles at neutral aqueous solutions. The micelles exhibited the lower CMC (8.2 × 10−5 mg/ml), higher DL (10.8%) and long-term storage and circulation stability, and showed enhanced cellular uptake, apoptosis, cytotoxicity, and growth inhibition for in vitro MCF-7/ADR and/or MCF-7/ADR multicellular spheroids and in vivo MCF-7/ADR tumors via efficiently targeted drug release at tumoral intracellular pH (5.0), MDR reversal of TPGS, and synergistic effect of DOX and TPGS. Therefore, the pH-sensitive micelles self-assembled from star-shaped TPGS copolymers with ortho ester linkages are potentially useful to clinically transform for enhanced MDR cancer treatment.

Micellization and Solvation Properties of Newly Synthesized Imidazolium- and Aminium-Based Surfactants

This work aimed to study the solvation properties of newly synthesized cationic surfactants: 1-hexyl-1-methyl-1H-imidazol-1-ium bromide (R6Im), 1-dodecyl-1-methyl-1H-imidazol-1-ium bromide (R12Im), N,N,N-tributylhexan-1-aminium bromide (R6N4), and N,N,N-tributyldodecan-1-aminium bromide (R12N4) in water and ethanol–water solvents with a 0.237 mole fraction of ethanol at 298.15 K using conductivity, refractive index, surface tension, and density measurements. Critical micelle concentration (CMC) for the synthesized surfactants was determined and discussed. Thermodynamic parameters including association constant, molal volume, and polarizability were calculated and discussed. Some surface properties of surfactants including excess surface concentration and minimum area per molecule were also calculated and discussed. A good agreement was found between the CMC values obtained from different techniques, such as conductivity, refractive index, and surface tension. Imidazolium surfactants had been proved to decrease the CMC and increase the association constant with the increase of ethanol mole fraction, while tributylamine had been proved to increase the CMC and decrease the association constant with the increase of ethanol mole fraction. Also, imidazolium surfactants had been proved to have higher CMC than tributylamine, which may be related to higher solvation of imidazolium surfactants than that of tributylamine. Both surfactants (R12Im) and (R12N4) were proved to have lesser CMC.

Characterization of saponin foam from Saponaria officinalis for food applications

Soapwort (Saponaria officinalis) is a natural source of saponins, which are known for their surface-active properties and ability to form metastable foams. The properties of saponin extract from soapwort have not been well characterized. This study examines the chemical and physical properties of soapwort extract as well as its foaming behavior under food relevant conditions. We show that the extract produces metastable solid-like foams, with high foam capacity and stability. Further, the surfactant has a higher critical micelle concentration (CMC) than other natural sources, and shows some ionic character, although changes in pH only slightly affect its behavior. For a comprehensive understanding, the foaming properties were analyzed in the presence of other molecules commonly used in food systems. The presence of sodium chloride, sucrose, ethanol, and low pH was found not significantly to affect foam properties. Addition of heat increases the foam capacity, whereas ethanol at high concentrations is unfavorable. The extract presents a promising alternative surfactant for foams and other dispersions in diverse food systems.

Novel polymer surfactants based on the branched silatrane-containing polyesters and polyethers

Objectives. Biologically active polymeric surfactants are a new promising class of macromolecules that can find application in medicine, cosmetology, and agriculture. In this study, a number of new biologically active amphiphilic polymers based on branched silatrane-containing polyesters and polyethers were obtained, and their surface-active properties were investigated.Methods. The branched polymers were represented by polyethers and polyesters, obtained respectively via the anionic polymerization of 1,2-epoxypropanol or a combination of equilibrium polycondensation and ring opening polymerization. The polymers were modified with 3-isocyanopropylsilatrane and trimethylethoxysilane to obtain the amphiphilic compounds containing silatrane groups bonded to the polymer backbone by the urethane bond. The structure of the synthesized polymer silatranes was confirmed via nuclear magnetic resonance spectroscopy and gel permeation chromatography. The surface active properties of all the copolymers obtained were investigated in connection with their obvious amphiphilicity. In particular, the formation of micelles in aqueous solutions is such a property. The critical micelle concentrations were determined by a method of quenching the fluorescence of the polymers.Results. It was shown that the values of the critical micelle concentrations and the hydrophilic-lipophilic balance values of polymers determined by the Griffin equation correlate well with each other. A linear relationship between the hydrophilic-lipophilic balance and the critical micelle concentrations was established. At the same time, polyether-based polymers generally showed higher critical micelle concentrations than polyester-based polymers, although the hydrophilic-lipophilic balance values for polymers of different series, but with close degrees of substitution, were close. It was found that the use of all synthesized polymers as stabilizers of direct and reverse emulsions leads to an increase in the aggregative stability of both types of emulsions. The stability of emulsions depended both on the degree of substitution of peripheral hydroxyl groups of polymers by silatranes and on the molecular weight and structure of the branched block of polymers. The stability of direct emulsions increased for all polymers, while that of inverse emulsions decreased with an increasing degree of substitution of hydroxyl groups by silatranes. The increase of the branched block molecular weight led to an increase of droplet sizes for both direct and inverse emulsions. The smallest droplet size for direct and inverse emulsions was obtained using polymers with low molecular weight branched polyester blocks as surfactants.Conclusions. The results obtained prove the possibility of creating polymer surfactants containing silatrane groups. By varying the structure of the polymer, its molecular weight and the degree of substitution of peripheral functional groups, it is possible to obtain surfactants with desired surface properties.

Quaternary ammonium surfactants derived from leucine and methionine: Novel challenging surface active molecules with antimicrobial activity

Surfactants are versatile excipients, which are commonly employed in several pharmaceutical formulations as emulsifiers, stabilizing or solubilizing agents. In this field, current research is aimed at the design or discovery of amphiphilic molecules with improved characteristics in terms of safety (toxicological profile) and biological activities (e.g. antimicrobial activity, interaction with biomembranes). Quaternary ammonium surfactants derived from amino acids are one such class of compounds with significant potential for pharmaceuticals. In this work, quaternary ammonium surfactants derived from the amino acids leucine and methionine and esterified with fatty acids of different lengths (C10, C12 and C14) were synthesized. These amphiphiles were characterized in terms of critical micelle concentration (CMC) by tensiometry and conductivity measurements, cytotoxicity (MTS and LDH assay on Caco-2 and Calu-3 cell lines) and antimicrobial activity on selected Gram-positive (S. aureus and E. faecalis), Gram-negative (E. coli and P. aeruginosa) and the fungus C. albicans. The derivatives bearing a C12 or a C14 chain displayed CMC, EC50 (from cytotoxicity assays) and minimum inhibition concentration (MIC) values that are comparable to those of benzalkonium chloride (used as reference), especially towards Gram-positive and C. albicans. On the contrary, derivatives bearing a C10 chain have higher CMC, EC50 and MIC values, highlighting the crucial role of the hydrophobic tail in determining both physicochemical and biological properties. The C12-C14 synthesized derivatives may represent a promising alternative to benzalkonium chloride as surface active molecules and antimicrobial agents.

Comparative screening of tetra-chlorometallate anions in novel magnetic metallogeminisurfactant catalysts for advanced synthesis of an anti-tumor benzothiazol-based aminophosphonate drug (ACBTAP)

Due to the high surface activity and low critical micelle concentration (CMC) of metallogemini-surfactants (MGSs), in this work various magnetic MGSs (MMGS1s) were prepared by simple grinding of low-cost hydrated salts of Fe3+, Co2+, Mn2+ and Ni2+ with GS1 synthesized by an improved solvent-free method. These new MMGS1s, which are complexes of 2FeCl4−, CoCl42−, MnCl42−, and NiCl42− with GS1, were characterized by UV–Vis, FT-IR, and melting point (mp) analyses. So, the maximum UV–Vis absorption wavelength was due to the GS12+·CoCl42− and the minimum mp and pH were due to the GS12+ ·2FeCl4− (MFeGS1). The results of the catalytic activities of MMGS1s in solvent-free synthesis of anticancer O,O′-diethyl-α-(benzothiazole-2-yl)amino(phenylmethyl) phosphonate (ACBTAP) revealed the superiority of MFeGS1, although catalysts were isolated as aqueous magnetic liquids (MLs) by addition of water. The aqueous MLs were further prepared in 0.01 and 0.1 molar concentration and analyzed by pH, surface tension (ᵞ), superconducting quantum interface device magnetometer (SQUID), and magnetic tests. Similar to GS1, all MMGS1s reduced the ᵞ of water by a half time ratio, while the magnetic activity of their aqueous MLs confirmed by magnetic drop-deviation and drop-movement over organic phase. The SQUID analysis of the aqueous MLs supported ferromagnetic properties for solution of MCoGS1, MNiGS1, and MMnGS1 in water and paramagnetic properties for the aqueous solution of GS12+·2FeCl4−. The as-prepared MLs are novel polar alternatives for organic solvents, water-treatment sorbents, and magnetic delivery of biomaterials.

Interaction between a Nonsteroidal Anti-inflammatory Drug (Ibuprofen) and an Anionic Surfactant (AOT) and Effects of Salt (NaI) and Hydrotrope (4-4-4).

Ibuprofen (IBF), 2-(4-isobutylphenyl) propionic acid, is a surface-active, common nonsteroidal anti-inflammatory drug (NSAID), and it possesses a high critical micelle concentration (cmc) compared to that of conventional surfactants. The interactions of this common NSAID with an anionic surfactant, sodium octyl sulfosuccinate, were studied by tensiometric, fluorimetric, and calorimetric measurements to investigate this system as a possible model drug-delivery system for an NSAID like IBF, particularly in a high-dose regime for IBF. The interactions between the drug and the surfactant were modeled using a regular solution theory approach in the presence and absence of a model electrolyte (sodium iodide) and a novel nonaromatic, gemini hydrotrope, tetramethylene-1,4-bis( N, N-dimethyl- N-butylammonium)bromide (4-4-4). Both the simple and the hydrotropic electrolyte were shown to have an effect on the solution properties (aggregation parameters, interfacial properties, and thermodynamics of aggregate formation) of the drug-surfactant mixtures and on the interaction between the drug and the surfactant. Surface charges of all self-assembled systems were estimated from ζ-potential measurements, whereas density functional theory calculations showed the interaction energy comparison among all of the binary and ternary combinations. All of these results were interpreted in terms of how altering the subtle balance of hydrophobic and electrostatic forces can significantly improve the ability of these self-assembled systems to transport drug molecules.