Critical Micelle Concentration Values Research Articles

Interaction, Surface Activity, and Application of Mixed Systems of Alcohol Ether Sulfate Anionic Surfactants with Multiple Ethylene Oxide Groups and Gemini Quaternary Ammonium Surfactant.

The surface activities and application properties for the mixtures of cationic surfactants tetramethylene-1,4-bis[N,N-bis(hydroxypropyl)-hexa/decyloxypropylammonium] bromide (GC10-P) and tetramethylene-1,4-bis[N,N-bis(hydroxyethyl)-hexa/decyloxypropylammonium] bromide (GC10-E) and anionic surfactant isomeric sodium fatty alcohol ether sulfates (iso-AE9S) were investigated using both the tensiometry and the conductometry. The interaction parameters and thermodynamic micellization parameters of GC10-P/iso-AE9S and GC10-E/iso-AE9S mixtures were evaluated by Clint-Rubingh and Motomura theoretical models. When the mole fraction of α1 for GC10-P/iso-AE9S mixed system was 0.2, the critical micelle concentration (CMC) reached a minimum of 1.61 × 10-4 mol/L, and the minimum critical micelle concentration of the GC10-E/iso-AE9S mixed system is 2.67 × 10-5 mol/L at α1 = 0.6. The CMC value of the mixed system is 1-2 orders of magnitude lower than that of any single component. The results indicate that the synergistic effects of the investigated mixed systems (evaluated by βm) are in order of GC10-P/iso-AE9S < GC10-E/iso-AE9S, with maximum βm values of -17.98 and -9.78, respectively. The change in zeta potential indicates that the poly(ethylene oxide) chain has weakened the charge density of the hydrophilic headgroup of the anionic surfactant. The interfacial tension at the oil-water interface in the mixed system of anionic/cationic surfactants is lower than that of any single component, exhibiting a higher interfacial activity. The mixed system exhibits a decreased contact angle and superior wetting ability over any single component, and it also enhances foam performance, emulsification performance, and degreasing performance.

Novel approaches to monitoring the formation of self-assembled colloids composed of cationic surfactants and alginate polysaccharide

In actual work, the self-assembly process of alginate (Alg) polysaccharide having low molecular weight (240 kDa) with cationic surfactants from the family of trimetylammonium bromide (TAB) derivatives was investigated at wide polysaccharide/surfactant molar ratio range through the interpretation of the formation of non-aggregated colloidal complexes.On one hand, the critical micelle concentration (cmc) values of the studied TAB surfactants having C12C18 chain length were determined and published for the first time in phosphate buffer solution. In addition to the applied conventional measurement procedures like tensiometry, light scattering, calorimetry, and equilibrium dialysis-based methods, the applicability of streaming potential technique was also demonstrated for the first time for these types of systems to gain a deeper insight into the formation process of the complexes built up by biocompatible polysaccharides and cationic surfactants. Through the interpretation of the change of the streaming potential values as a function of increasing surfactant's concentration it was clearly highlighted that both the individual and cooperative binding process of the surfactants can be clearly identified followed by the aggregation of the polysaccharide-surfactant colloidal complexes and the formation of surfactant micelles in the bulk dispersion.

Interfacial and aggregation behavior of ionic liquid-bile salt conjugates

Bile salt derived nontoxic surface-active ionic liquids (SAILs), 1-butyl-3-methylimidazolium cholate ([bmim]C) and deoxycholate ([bmim]DC) were synthesized by reacting [bmim] tetrafluoroborate separately with sodium cholate (NaC) and sodium deoxycholate (NaDC) which were subsequently characterized by FTIR, 1H-NMR, 13C-NMR, HRMS, PXRD, and TGA-DTA studies. Interfacial and aggregation behavior of the SAILs were assessed by surface tension, conductance, pyrene fluorescence, dynamic light scattering, and isothermal titration calorimetric studies. Critical micelle concentration values were substantially lower than their precursor sodium salts. SAILs were less surface active than their corresponding sodium salts due to enhanced aqueous solubility induced by the ionic liquid cation. Both the aggregation number and size of the SAIL micelles were higher/larger where the SAIL micelles were more compact than NaC/NaDC. Exothermic changes in the enthalpy of micellization were higher for SAILs, where the micellization processes were found to be entropy driven. Such comprehensive studies can shed further light on the microstructure, besides the fundamental understanding on SAIL aggregation. The combined advantages of surfactant and ionic liquid in the SAILs can result in superior amphiphilic characteristics. Such nontoxic aggregates are capable to enhance the limited solubility of organic compounds in water besides their possible uses in catalysis, drug delivery, and energy storage, etc.

A Rare Mono-Rhamnolipid Congener Efficiently Produced by Recombinant Pseudomonas aeruginosa YM4 via the Expression of Global Transcriptional Regulator irrE.

Rhamnolipids (RLs) are widely used biosurfactants produced mainly by Pseudomonas aeruginosa and Burkholderia spp. in the form of mixtures of diverse congeners. The global transcriptional regulator gene irrE from radiation-tolerant extremophiles has been widely used as a stress-resistant element to construct robust producer strains and improve their production performance. A PrhlA-irrE cassette was constructed to express irrE genes in the Pseudomonas aeruginosa YM4 of the rhamnolipids producer strain. We found that the expression of irrE of Deinococcus radiodurans in the YM4 strain not only enhanced rhamnolipid production and the strain's tolerance to environmental stresses, but also changed the composition of the rhamnolipid products. The synthesized rhamnolipids reached a maximum titer of 26 g/L, about 17.9% higher than the original, at 48 h. The rhamnolipid production of the recombinant strain was determined to be mono-rhamnolipids congener Rha-C10-C12, accounting for 94.1% of total products. The critical micelle concentration (CMC) value of the Rha-C10-C12 products was 62.5 mg/L and the air-water surface tension decreased to 25.5 mN/m. The Rha-C10-C12 products showed better emulsifying activity on diesel oil than the original products. This is the first report on the efficient production of the rare mono-rhamnolipids congener Rha-C10-C12 and the first report that the global regulator irrE can change the components of rhamnolipid products in Pseudomonas aeruginosa.

Solubilization and physicochemical parameters of 2-chloro and 4-chlorophenol in micellar media of cetyltrimethylammonium bromide and sodium dodecyl sulphate at different temperatures

Solubilization and thermodynamic parameters of 2-chloro and 4-chlorophenol in micellar media of Cetyltrimethylammonium bromide (CTAB) and Sodium dodecyl sulphate (SDS) are elaborated in this study. The effect of the addition of 2-chloro and 4-chlorophenol on the critical micelle concentrations (CMCs) of CTAB and SDS was investigated by using the conductivity method at different concentrations (5 mmolL−1 to 25 mmolL−1) and temperatures (25 °C to 45 °C). The plot of specific conductance versus concentration of surfactant was used to determine CMC value. The CMC values of CTAB and SDS were observed to decrease, and thus the addition of 2-chloro and 4-chlorophenol favors micellization. In addition, it was observed that the CMC values of CTAB and SDS gradually increased with an increase in temperature. Various types of thermodynamic parameters such as standard Gibbs free energy of micellization (ΔGm°), standard enthalpy of micellization (ΔHm°) as well as standard entropy of micellization (ΔSm°) were determined and explained thoroughly to investigate the interactions between additives and surfactant. The magnitudes of ΔGm°andΔHm° were shown to be negative in the whole system, which shows that the processes of micellization were energetically spontaneous and exothermic. The thermodynamic parameters of transfer (ΔGm.tr°, ΔHm.tr° and ΔSm.tr°) from water to 2-chloro and 4-chlorophenol were also calculated and discussed with appropriate reasoning.

Exploring the Impact of Cationic Surfactant Ctab on Bleu Brilliant G 250 De Cosmassie: Implications for Health Management and Environmental Sustainability

Background: Surfactants are ubiquitous in both natural and industrial processes due to their unique ability to reduce surface tension and facilitate interactions between hydrophilic and hydrophobic substances. Cationic surfactants like cetyltrimethylammonium bromide (CTAB) are of particular interest because of their widespread applications in areas such as healthcare and environmental management. The interaction between surfactants and dyes, such as Bleu Brilliant G 250 de Cosmassie, is critical in industrial processes, especially in the textile industry where wastewater treatment poses significant environmental challenges. Objective: The aim of this study was to explore the thermodynamic behavior of CTAB when combined with Bleu Brilliant G 250 de Cosmassie in aqueous solutions at room temperature. It sought to determine the critical micelle concentration (CMC) and the degree of counter-ion dissociation (α), and to calculate the changes in Gibbs free energy (ΔGm), enthalpy (ΔHm), and entropy (ΔSm) of the system. Methods: The study employed conductometric and spectrophotometric techniques to analyze the CTAB-dye interactions. Solutions were prepared with varying concentrations of CTAB and Bleu Brilliant G 250 de Cosmassie in deionized water, ensuring solvent purity through stringent conductivity and pH monitoring. Electrical conductance was measured at different temperatures to determine the CMC, while absorbance spectra were recorded to observe changes in the interaction between the surfactant and dye. The degree of counter-ion dissociation was calculated by the slope ratio method, and thermodynamic parameters were computed using established equations. Results: The conductometric studies revealed an increase in CMC with temperature, indicating a stabilization of surfactant monomers at higher temperatures. For CTAB and Bleu Brilliant system 1, the CMC was found to be 0.8 with α valued at 0.83. For system 2, the CMC values were 1.55 and 1.6 with α values of 1.01 and 0.91, respectively. Thermodynamically, the system displayed a Gibbs free energy of micellization of -33.09 KJ/mol, an enthalpy change of -6.53, and an entropy change of 0.1325 JK^-1 mol^-1. Conclusion: The study concluded that the interaction between CTAB and Bleu Brilliant G 250 de Cosmassie is influenced significantly by temperature, which affects the micellization behavior and thermodynamic properties. The findings contribute to a better understanding of the fundamental thermodynamic parameters influencing surfactant-dye interactions, providing insights that may improve industrial processes and environmental sustainability.

Prediction of critical micelle concentration for per- and polyfluoroalkyl substances

ABSTRACT In this study, we focus on the development of Quantitative Structure-Property Relationship (QSPR) models to predict the critical micelle concentration (CMC) for per- and polyfluoroalkyl substances (PFASs). Experimental CMC values for both fluorinated and non-fluorinated compounds were meticulously compiled from existing literature sources. Our approach involved constructing two distinct types of models based on Support Vector Machine (SVM) algorithms applied to the dataset. Type (I) models were trained exclusively on CMC values for fluorinated compounds, while Type (II) models were developed utilizing the entire dataset, incorporating both fluorinated and non-fluorinated compounds. Comparative analyses were conducted against reference data, as well as between the two model types. Encouragingly, both types of models exhibited robust predictive capabilities and demonstrated high reliability. Subsequently, the model having the broadest applicability domain was selected to complement the existing experimental data, thereby enhancing our understanding of PFAS behaviour.

One-Pot synthesis and interfacial activity of imidazolium ionic liquid surfactants with double-chain hydrophobic

Three double-chain imidazolium ionic liquid surfactants (ILS) with varying alkyl lengths, namely [C10mimC10][OAc], [C12mimC12][OAc], and [C14mimC14][OAc], were synthesized via the one-step Debus-Radziszewskireaction. The chemical structures of these three ILS were confirmed through FT-IR, 1H NMR and ESI-MS analyses. Their surface/interface activity, wetting ability, thermal stability, and aggregation properties were investigated. The results indicated that the presence of double-chain hydrophobic groups in ILS exerted a significant influence on their surface/interface activity. Surface activity and micellization properties were assessed using surface tension measurements, revealing that the micellization process of double-chain ILS was more favorable compared to single-chain ILS. Among the three ILS examined, [C14mimC14][OAc] exhibited the lowest surface tension and critical micelle concentration (CMC) values, measuring 29.07 mN/m and 1.64 × 10-2 mmol/L, respectively. Solutions containing approximately 50 ppm of these ILS could reduce interfacial tension to below 1 mN/m. Additionally, the contact angle decreased to less than 90° within 90 s. The formation of aggregates in aqueous solutions was found to be influenced by the number of CH2 units present in the different ILS molecules.

Influence of cationic dimeric and trimeric-type surfactants on the aggregation behavior of water-soluble phthalocyanine: A combined experimental and computational study

The aggregation behavior of the water-soluble phthalocyanine, namely zinc 2,9,16,23–tetra(tert–butyl)–29H,31H–phthalocyanine tetrasulphonic acids (ZnPcS4), has been examined in the presence of dimeric and trimeric-type cationic surfactants and their conventional counterpart cetyltrimethylammonium bromide (CTAB). The absorption and fluorescence studies of ZnPcS4 in water showed a different feature than that in methanol suggesting the formation of aggregated ZnPcS4 in an aqueous medium. The fluorescence studies of ZnPcS4 in the presence of examined dimeric-type cationic surfactants showed lower critical aggregation concentration (CAC = 0.62–13.6 µM) compared to that of CTAB (CAC = 16 µM). It was found that the position of the substituents affected the critical micelle concentration (CMC) value, and the ortho-dimeric surfactant had a lower CMC value compared to those surfactants with meta, and para-dimeric surfactant. It was interesting to see that the CMC for the dimeric surfactant with two groups at the para position (13.6 µM) decreased significantly (0.04 µM) by removing the (O-CH2) groups attached to the benzene which can be explained by structural parameters determined by theoretical calculations. By changing the surfactants from dimers to cationic trimers surfactants, a significant decrease in the CAC values was observed (0.04 µM for Trimer-12 with two dodecyl groups and 0.39 µM for Trimer-8 with two octyl groups). This finding indicates that the increase in tail length by four methylene groups of Trimer-12 compared to Trimer-8 results in a decrease in CAC by about one order of magnitude. These new findings suggest that the trimeric-type cationic surfactants are remarkably superior to conventional and dimeric-type surfactants, which could have a profound impact on many applications of ZnPCS4 including, but not limited to, medical, organic electronics, light harvesting, photonics, and optical sensors.

QSPR for the prediction of critical micelle concentration of different classes of surfactants using machine learning algorithms

The determination of the critical micelle concentration (CMC) is a crucial factor when evaluating surfactants, making it an essential tool in studying the properties of surfactants in various industrial fields. In this present research, we assembled a comprehensive set of 593 different classes of surfactants including, anionic, cationic, nonionic, zwitterionic, and Gemini surfactants to establish a link between their molecular structure and the negative logarithmic value of critical micelle concentration (pCMC) utilizing quantitative structure-property relationship (QSPR) methodologies. Statistical analysis revealed that a set of 14 significant Mordred descriptors (SlogP, GATS6d, nAcid, GATS8dv, GATS4dv, PEOE_VSA11, GATS8d, ATS0p, GATS1d, MATS5p, GATS3d, NdssC, GATS6dv and EState_VSA4), along with temperature, served as appropriate inputs. Different machine learning methods, such as multiple linear regression (MLR), random forest regression (RFR), artificial neural network (ANN), and support vector regression (SVM), were employed in this study to build QSPR models. According to the statistical coefficients of QSPR models, SVR with Dragonfly hyperparameter optimization (SVR-DA) was the most accurate in predicting pCMC values, achieving (R2 = 0.9740, Q2 = 0.9739, r‾m2 = 0.9627, and Δrm2 = 0.0244) for the entire dataset.

Interaction of sodium dodecyl sulfate and triton X-100 with ofloxacin drug using conductivity and UV–visible spectroscopic techniques in aqueous alcohols media at several temperatures

The current investigation explores the association and complexation of the mixture of anionic surfactant, sodium dodecyl sulfate (SDS), and antibiotic drug, ofloxacin (OFC) as well as nonionic surfactant, Triton X-100 (TRX) and OFC drug respectively in several additive solutions. The investigations were performed by applying conductivity and UV-Visible spectroscopic techniques. The impacts of drug concentration, types of solvents, and composition of aq. solutions of alcohols (methanol (MeOH), ethanol (EtOH), and 1-propanol (1-PrOH)) as well as temperature change have been investigated on the micelle formation of SDS + OFC mixture. The micellization of SDS + OFC and TRX + OFC systems has been characterized by the determination of critical micelle concentration (CMC) from conductivity vs. SDS concentration (conductivity technique) and Absorbance vs log[TRX] (UV-Visible spectroscopic technique) plots respectively. The micellization of SDS was delayed owing to the introduction of the OFC drug while the effect has been intensified as a function of OFC concentration. At a fixed OFC concentration and temperature, the CMC values were acquired to be augmented with the upsurge of alcohol concentration. The enhancement of the CMC changes has been perceived with the escalation of temperature at a definite concentration of OFC in water and 5% (w/w) aq. alcohols media. The disfavor of micellization of TRX in aq. EtOH solutions in comparison to aqueous solution also detected from UV-Visible spectroscopic technique. The binding constant (Kb) for the complexation of TRX with OFC drug was determined using the Benesi-Hildebrand plot. The Kb values were obtained to be affected by the change of solvent and temperature. The negative free energy change (∆Gmo/ ∆Gbo) of the micellization and complexation demonstrate the spontaneous occurrence of micelle formation and complex development. The enthalpy changes (∆Hmo) of micellization were negative (exothermic process) and entropy changes (∆Smo) were positive (highly disordered and entropy-dominated micellization). Other thermodynamic properties ((∆Hbo and ∆Sbo) and thermodynamics of transfer) have been evaluated and illustrated as well, for the working systems.

An investigation on the hydrophobic binding stability of Azithromycin to the hydrocarbon chains of Tween: Based on micellization thermodynamics

Based on micellization thermodynamics, the difference in hydrophobic binding stability between Azithromycin and the hydrocarbon chain of Tween was investigated. Initially, the critical micelle concentration (CMC) of AZM-loaded Tween micelles was determined by measuring surface tension, followed by subsequent analysis and discussion of the associated parameters of micellization thermodynamics. The findings indicated that AZM-loaded Tween 20 and AZM-loaded Tween 80 micelles both exhibited a lower CMC value, enhanced stability at the air/water interface, and a more pronounced tendency towards micellization. This suggested that Azithromycin exhibited a stronger affinity towards the hydrophobic hydrocarbon chains of Tween 20 and Tween 80, leading to a more robust hydrophobic binding between them, thereby promoting the formation of AZM-loaded micelles. Subsequently, the transmittance, particle size, and in vitro release of each micelle system were assessed. The findings demonstrated that both AZM-loaded Tween 20 and AZM-loaded Tween 80 micelles exhibited excellent physical stability. Furthermore, in terms of antibacterial activity, AZM-loaded Tween 20 and AZM-loaded Tween 80 micelles exhibited stronger antibacterial efficacy. In summary, the variation in the hydrocarbon chain of Tween exerts an influence on the stability of the hydrophobic binding between Tween and Azithromycin, consequently impacting the pertinent attributes of drug-loaded micelles. This finding offers a valuable point of reference for the investigation of hydrophobic drug micelles in academic research.

Imidazolium surface-active ionic liquids as antifungal agents in wood protection

This research focuses on five newly surface-active ionic liquids (SAILs) whose commitment to sustainable chemistry allows for their utilization as effective wood protection agents alternatives to traditional surfactants. The synthesis yields were above 93 %, while the purity ranged from 97 to 99 %. Also, a series of properties such as surface activity, wettability, antifungal properties were studied. The demonstrated relationship between critical micelle concentration (CMC) and elongation on alkyl chain length of the investigated imidazolium SAILs aligns with expectations. Moreover, it was shown that all tested SAILs exhibited lower CMC values (ranged from 0.34 to 8.46 mmol⋅L−1) than conventional surfactants such as didecyldimethylammonium chloride (DDAC) and decyltrimethylammonium bromides (CTAB) proving that the synthesized compounds can serve as substitutes for surfactants. 3-Decyloxymethyl-1-methylimidazolium dicyanamide (SAIL-3) showed the best antifungal properties, which does not translate into contact angle (CA) values. The mechanical properties measured for the impregnated wood samples were consistently inferior to those of the control wood samples. However, wood treated with SAIL-3, in contrast, exhibited a reduced uptake of free water compared to the untreated control wood. The results presented validate our hypothesis regarding the distinctive nature of SAILs and affirm their suitability for wood impregnation.

Interaction of sodium dodecyl sulfate and cetyl trimethyl ammonium bromide surfactants with amantadine drug in aqueous solution: Conductometric and molecular dynamics studies

In the present work, the interaction of sodium dodecyl sulfate and cetyl trimethyl ammonium bromide surfactants with amantadine drug in aqueous solutions was studied using conductometric measurements and molecular dynamic simulation. Conductometric data were used to determine the critical micelle concentration (CMC) values of surfactants on various amantadine aqueous solutions at T= (300.2, 310.2 and 320.2) K and 0.1 MPa. The effect of amantadine concentration (m = 0.0005, 0.0010, 0.0015 and 0.002 mol.kg−1) on CMC of sodium dodecyl sulfate and cetyl trimethyl ammonium bromide surfactants was investigated. It was observed the CMC value of sodium dodecyl sulfate surfactant increases with increasing of amantadine concentration whereas the CMC values of cetyl trimethyl ammonium bromide surfactant decrease with increasing of amantadine concentration at the same temperature. Then, the thermodynamic properties such as standard Gibbs free energy, enthalpy, and entropy for micellization in aqueous solutions were determined. In addition, molecular dynamic simulation was carried out to understand the interaction sodium dodecyl sulfate and cetyl trimethyl ammonium bromide surfactants with amantadine at the molecular level and microscopic interactions. The root-mean-square deviations and electrostatic, hydrogen binding and hydrophobic interactions were determined by MD simulations. It was seen, the electrostatic and hydrogen bonding interactions play a crucial role in sodium dodecyl sulfate and amantadine aqueous system. The obtained results showed the simulation and experimental data are in agreement with each other.

Synergistic effects between a non-ionic and an anionic surfactant on the micellization process and the adsorption at liquid/air surfaces.

Predicting the behaviour of solutions with surfactants of significantly different critical micelle concentration (CMC) values remains a challenge. The study of the molecular interactions within micelles and interfaces in surfactant combinations used in everyday products is essential to understand these complex systems. In this work, the equilibrium and dynamic surface tension in the presence of mixed non-ionic (tristyrylphenol ethoxylates) and anionic (sodium benzene sulfonate with alkyl chain lengths of C10-C13) surfactants, commonly encountered as delivery systems in agrochemicals, were studied and their CMC values were determined. For the surfactant mixtures, four molar ratios were examined: nEOT/nNaDDBS = 0.01, 0.1, 1, 4 and two different cases were analysed, the premixed and the add one by one surfactant. The surface tension for single surfactants stabilised quickly, while the mixtures needed a long time to reach equilibrium; up to 15 h for the premixed mixtures and 40 min when surfactants were added one by one. The CMC values for the nEOT/nNaDDBS = 0.01, 0.1 premixed surfactant mixtures were found to be in between the CMC values of the single surfactants, but those for the nEOT/nNaDDBS = 1 and 4 mixtures were lower than the CMCs of both single surfactants. Calculations based on the regular solution theory suggested that there are attractive forces in the mixed micelles and at the interface layers, while the supramolecular assemblies in the bulk (i.e., micelles) and at interfaces (surfactant films) are preferentially enriched in EOT.

The effect of aromatic side chains on the dilational rheological properties of N-acyltaurate amphiphiles at water-decane interfaces.

To elucidate the effect of aromatic side chains on dilational rheological properties of N-acyltaurate amphiphiles at the decane-water interface, the interfacial rheological properties of sodium N-2-(2-naphthoxy)-tetradecanoyltaurinate (12+N-T) and sodium N-2-(p-butylphenoxy)-tetradecanoyltaurinate (12+4B-T) were investigated utilizing the drop shape analysis method. The effects of adsorption time, interfacial pressure, oscillating frequency, and bulk concentration on the interfacial dilational modulus and phase angle were explored. The results show that the 12+4B-T molecule with a longer hydrophobic chain shows a higher ability for reducing the interfacial tension (IFT). In addition, the interfacial films of both 12+N-T and 12+4B-T are dominated by diffusion exchange at high concentrations. The rigidity of molecules controls the diffusion exchange at low concentrations, while the molecular hydrodynamic radius determines the diffusion exchange at high concentrations. Thus, at low concentrations, the stronger intermolecular interaction between 12+4B-T molecules results in higher dilational modulus values than 12+N-T. When approaching the CMC (critical micelle concentration) value, the rapid diffusion exchange of 12+4B-T between the sublayer micelles and the interface causes a significant decrease in the dilational modulus, while the relatively rigid structure of 12+N-T enables a higher dilational modulus than 12+4B-T. What's more, the longer hydrophobic chain allows 12+4B-T molecules to escape from the interface more easily, resulting in a higher phase angle at low concentrations. However, the diffusion exchange of 12+4B-T is slower than that of 12+N-T, which results in lower phase angles for 12+4B-T than 12+N-T at high concentrations. In general, the introduction of a rigid naphthalene ring in the molecular structure gives the interfacial film greater strength at high concentration. The research results in this paper provide a new technique for the strength regulation of interfacial surfactant adsorption films.

Membrane-Disruptive Effects of Fatty Acid and Monoglyceride Mitigants on E. coli Bacteria-Derived Tethered Lipid Bilayers.

We report electrochemical impedance spectroscopy measurements to characterize the membrane-disruptive properties of medium-chain fatty acid and monoglyceride mitigants interacting with tethered bilayer lipid membrane (tBLM) platforms composed of E. coli bacterial lipid extracts. The tested mitigants included capric acid (CA) and monocaprin (MC) with 10-carbon long hydrocarbon chains, and lauric acid (LA) and glycerol monolaurate (GML) with 12-carbon long hydrocarbon chains. All four mitigants disrupted E. coli tBLM platforms above their respective critical micelle concentration (CMC) values; however, there were marked differences in the extent of membrane disruption. In general, CA and MC caused larger changes in ionic permeability and structural damage, whereas the membrane-disruptive effects of LA and GML were appreciably smaller. Importantly, the distinct magnitudes of permeability changes agreed well with the known antibacterial activity levels of the different mitigants against E. coli, whereby CA and MC are inhibitory and LA and GML are non-inhibitory. Mechanistic insights obtained from the EIS data help to rationalize why CA and MC are more effective than LA and GML at disrupting E. coli membranes, and these measurement capabilities support the potential of utilizing bacterial lipid-derived tethered lipid bilayers for predictive assessment of antibacterial drug candidates and mitigants.

Photochemical cyclopropanation in aqueous micellar media - experimental and theoretical studies.

While in nature, reactions occur in water-based confined compartments, for a long time, water has been often regarded as an unsuitable medium for organic reactions. We have, however, found that photochemical cyclopropanation of styrenes with diazo compounds or their precursors can be performed in micellar systems. COSMO-RS studies revealed that the reactivity correlates with the predicted critical micelle concentration (CMC), with higher CMC values delivering higher yields.

Development and evaluation of redox-responsive alginate–SS–ibuprofen derivative based anti-tumor target drug delivery system for the controlled release of doxorubicin

Nowadays, self-assembled polymeric micelles from amphiphilic polymer conjugates are urgently needed to enhance drug targeting and release efficiency. On account of the excellent properties of alginate and the redox-responsiveness of disulfide bonds, a redox-sensitive alginate–SS–ibuprofen derivative (LSA–SS–IBU) based anti-tumor target drug delivery system was created by attaching the hydrophobic ibuprofen (IBU) onto the hydrophilic alginate molecular skeleton through disulfide linkages for glutathione (GSH) triggered delivery of doxorubicin hydrochloride (DOX). The structure and self-assembly behavior of the synthesized LSA–SS–IBU was systematically evaluated by FT-IR spectrometer, 1H NMR spectrometer, fluorescence spectrophotometer (FM), transmission electron microscope (TEM) and dynamic light scattering (DLS). Furthermore, the in vitro release of drugs from the LSA–SS–IBU micelles loaded with DOX was examined, along with the assessment of their cytotoxicity to HeLa cells. The resultant LSA–SS–IBU had a critical micelle concentration (CMC) value of 0.19 mg/mL that was able to self-assemble into the spherical micelles with the particle size and zeta potential of 148.2 ± 4.3 nm (PDI = 0.25) and −47.2 ± 0.4 mV, respectively. At a mass ratio of 3:10 for DOX/LSA–SS–IBU, the LSA–SS–IBU micelles achieved drug loading ratio (DLR) and encapsulation efficiency (EE) values of 12.2 % and 46.3 %, respectively. Furthermore, the in vitro drug release study indicated that the total drug release percentage of the drug-encapsulated LSA–SS–IBU micelles in PBS with the presence of 10 mmol/L GSH for 12 h exceeded 67.0 %, demonstrating a substantial increase compared to that in GSH-free PBS. The in vitro cytotoxicity findings indicated that LSA–SS–IBU had good biocompatibility, while the IC50 value and the cell viability of DOX-loaded LSA–SS–IBU micelles cultured with HeLa cells for 48 h was 2.2 μg/mL and less than 20.1 %, respectively, which could significantly inhibit the growth of HeLa cells. Therefore, redox-responsive LSA–SS–IBU micelles had potential applications in cancer therapy for hydrophobic anti-tumor drug delivery.

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

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