Micelle Formation Process Research Articles

Effect of Hydrophilic Function Groups on the Properties of Short‐Chain Fluorocarbon Surfactants

AbstractShort‐chain fluorocarbon surfactants grafted with alcohol, carboxyl and ester functional groups were prepared by quaternization with short‐chain perfluorobutyl sulfonyl fluoride as raw material. The structures of surfactants were characterized by infrared spectroscopy, nuclear magnetic resonance and mass spectrum. The surface activity, micelle formation process and micelle aggregation behavior of surfactants were studied by surface tensiometer, dynamic light scattering particle size analyzer and fluorescent spectrophotometer. The results show that the critical micelle concentration (CMC) of surfactants are 19.3, 7.8 and 2.2 mmol L−1, and the surface tension of the surfactant solution at CMC are as low as 17.3, 19.2 and 18.5 mN m−1, respectively. The standard Gibbs free energy ( ) values of surfactants are negative, and the absolute values of are less than the standard Gibbs adsorption energy ( ), illustrating that the adsorption process is easier than the micelle formation process. In addition, the size distribution of the aggregates is much larger than that of spherical micelles, showing that the surfactant self‐assembled into larger aggregates in solution. The grafted hydrophilic functional groups show a significant effect on the performance of surfactants. The ester‐based surfactant has a lower CMC value, which has the advantages of small dosage, good economy and excellent application value.

Self-assembly mechanism, physicochemical analyses and application performance investigations of branched alkyl glycosides with alcohol ether carboxylic acids of varied epoxide numbers.

Green surfactants, specifically alkyl glycosides and fatty alcohol ether carboxylic acids, are known for their biocompatibility, multiresponsiveness, and versatile applications, garnering significant attention in the realms of green and colloid chemistry. This study systematically investigated the mechanism underlying micelle formation within aqueous solutions comprising alcohol ether carboxylic acids featuring diverse EO group chain quantities (AEC-nH, where n equals 5, 7, and 9) and branched alkyl glycosides (IG). The elucidation of these mechanisms sheds light on their prospective application properties. It was observed that the self-assembly of micelles in these hybrid systems is predominantly influenced by hydrogen bonding, electrostatic interactions, and hydrophobic forces. The spherical-rod morphology of the micelles responds to the varying numbers of EO group chains, with an increased number of EO leading to the formation of rod-like micelles, which exhibit relative instability, while a decreased number of EO results in the formation of spherical micelles with relative stability. Additionally, by means of kinetic analysis, it was determined that the micelle formation process of the three hybrid systems is driven by enthalpy, and a mixed diffusion-kinetics adsorption mechanism is involved in the adsorption process. These findings significantly impact their application properties. This report stands as the first exploration of the synergistic mechanisms and application performance of two types of green surfactants in aqueous solutions, considering the influence of different numbers of EO group chains. Not only does it provide fundamental insights into their properties, but it also offers novel perspectives on the applications of green surface activation.

Casein micelle formation as a calcium phosphate phase separation process: Preparation of artificial casein micelles through vacuum evaporation and membrane processes

Industrial-scale production of artificial casein micelles (ACM) is required to produce dairy alternatives from recombinant casein. However, the currently common micelle preparation method of dropwise mixing casein and salt solutions is inefficient and may prove difficult to scale up. Here, we view casein micelle formation as a process driven by calcium phosphate phase separation in the presence of casein. On this basis, we developed novel routes to prepare ACM through vacuum evaporation, forward osmosis, or reverse osmosis. ACM prepared through these methods have similar properties and improved coagulation behaviour compared to those prepared through the currently common method and natural bovine casein micelles. The properties and functionality of the micelles depend on the preparation time and surface area available for micelle formation, with longer times and larger surfaces (i.e. lower fluxes) yielding smaller ACM that form firmer curds. These novel processes enable fast, efficient, and continuous production of ACM for application in future dairy alternatives. Industrial relevanceArtificial casein micelles can be used as a building block in the production of animal-free milk and cheese based on precision fermentation. The herein described novel processes to prepare artificial casein micelles are based on vacuum evaporation, forward osmosis, and reverse osmosis, which are mild, resource-efficient, and easily scalable processes. The processes require a dilute feed stream (e.g. caseins after precision fermentation), provide an elegant way to minimise local differences in the concentration of caseins and ions during micelle production, and offer the opportunity to design continuous micelle formation processes. These are all advantages over the existing methods to prepare artificial casein micelles with regard to industrial application.

Synthesis, Characterization and Potential Antimicrobial Activity of Selenium Nanoparticles Stabilized with Cetyltrimethylammonium Chloride.

Selenium nanoparticles (Se NPs) have a number of unique properties that determine the use of the resulting nanomaterials in various fields. The focus of this paper is the stabilization of Se NPs with cetyltrimethylammonium chloride (CTAC). Se NPs were obtained by chemical reduction in an aqueous medium. The influence of the concentration of precursors and synthesis conditions on the size of Se NPs and the process of micelle formation was established. Transmission electron microscopy was used to study the morphology of Se NPs. The influence of the pH of the medium and the concentration of ions in the sol on the stability of Se micelles was studied. According to the results of this study, the concentration of positively charged ions has a greater effect on the particle size in the positive Se NPs sol than in the negative Se NPs sol. The potential antibacterial and fungicidal properties of the samples were studied on Escherichia coli, Micrococcus luteus and Mucor. Concentrations of Se NPs stabilized with CTAC with potential bactericidal and fungicidal effects were discovered. Considering the revealed potential antimicrobial activity, the synthesized Se NPs-CTAC molecular complex can be further studied and applied in the development of veterinary drugs, pharmaceuticals, and cosmetics.

Validation of an MD simulation approach for electrical field responsive micelles and their application in drug delivery

In the current work, a new type of micelle is designed that has active connectivity in respond to exterior stimulus and the desired water solubility. Two end-ornamented homopolymers, polystyrene-beta-cyclodextrin (PS-β-CD) and polyethylene oxide-ferrocene (PE-FE), can aggregate as a supramolecular micelle (PS-β-CD/PE-FE) by the guest–host interactions. Our results showed that the Lennard–Jones and hydrophobic interactions are the main powerful forces for the micelle formation process. It was found that the electrical field plays a role as a driving force in the reversible assembly-disassembly of the micellar system. Moreover, for the first time, we examined the PS-β-CD/PE-FE micelle interaction as a drug delivery system with anastrozole (ANS) and mitomycin C (MIC) anti-cancer drugs. The investigation of the total energy between PS-β-CD/PE-FE micelle and drugs predicts the drug adsorption process as favorable (Etotal = − 638.67 and − 259.80 kJ/mol for the Micelle@ANS and Micelle@MIC complexes, respectively). Our results offer a deep understanding of the micelle formation process, the electrical field-respond, and drug adsorption behaviors of the micelle. This simulation study has been accomplished by employing classical molecular dynamics calculation.

On the mechanism of the cholesterol lowering ability of soluble dietary fibers: Interaction of some bile salts with pectin, alginate, and chitosan studied by isothermal titration calorimetry.

Reducing high blood cholesterol is an important strategy to decrease the chances of a cardiovascular disease occurrence, the main cause of mortality in western developed countries. Therefore, the search for an alternative therapeutic or preventive approach being natural, biocompatible, and not toxic is still more relevant than ever. This need is particularly felt in Pediatrics for treating childhood hypercholesterolemia, due to statins interference in the production of steroid hormones in prepuberal children. Notwithstanding the general acceptance of the healthy role of the fibers in the diet, the mechanism underlying the cholesterol-lowering ability of soluble fibers is still under discussion. Therefore, we started a systematic study of the binding ability of some soluble dietary fibers (SDF) originated from different natural sources toward selected bile salts (BS) by isothermal titration calorimetry (ITC). Here we report the results of our ITC studies on the interaction of alginate, pectin and chitosan with sodium cholate (NaC), sodium deoxycholate (NaDC), sodium taurocholate (NaTC) and sodium taurodeoxycholate (NaTDC). Thermodynamic data on the micelle formation process of the above bile salts, as a premise to the study of their binding ability to the SDF, are also reported. Alginate does not show specific binding interaction with BS, while pectin shows a strong exothermic bond with NaDC in monomeric form. Chitosan, positively charged and soluble only at low pH, shows strong exothermic interactions with NaTC and NaTDC (soluble at pH = 3 in acetate buffer) with precipitate formation. For NaTC, the exothermic peak starts at about 5 mM. At this concentration NaTC bound on the fiber reaches locally the cmc value and micelles start forming on the fiber inducing its conformational change. For NaTDC the same process occurs at much lower concentrations, due to lower cmc, and with a greater quantity of heat involved. The first set of results here presented shows that for some SDF the binding of BS could be an important mechanism in cholesterol lowering but not the only one. The information here presented could be a starting point for the design of optimized functional foods with high cholesterol lowering ability.

Mechanism of the Micellar Solubilization of Curcumin by Mixed Surfactants of SDS and Brij35 via NMR Spectroscopy.

The micellar solubilization mechanism of curcumin by mixed surfactants of SDS and Brij35 was investigated at the molecular scale by NMR spectroscopy. Through the investigation of the micelle formation process, types and structures of mixed micelles and solubilization sites, the intrinsic factors influencing the solubilization capacity were revealed. For systems with αSDS = 0.5 and 0.2, the obtained molar solubilization ratios (MSRs) are consistent with the MSRideal values. However, for αSDS = 0.8, the solubilization capacity of curcumin is weakened compared to the MSRideal. Furthermore, only one single mixed SDS/Brij35 micelles are formed for αSDS = 0.5 and 0.2. However, for αSDS = 0.8, there are separate SDS-rich and Brij35-rich mixed micelles formed. In addition, NOESY spectra show that the interaction patterns of SDS and Brij35 in mixed micelles are similar for three systems, as are the solubilization sites of curcumin. Therefore, for αSDS = 0.5 and 0.2 with single mixed micelles formed, the solubility of curcumin depends only on the mixed micelle composition, which is almost equal to the surfactant molar ratio. Although curcumin is solubilized in both separate micelles at αSDS = 0.8, a less stable micelle structure may be responsible for the low solubility. This study provides new insights into the investigation and application of mixed micelle solubilization.

Free energy calculations in associative polymers using molecular dynamics

ABSTRACT In this work, equilibrium molecular dynamics is used to predict the change in the Helmholtz free energy () for solutions of associative polymers of the telechelic type. is calculated using the thermodynamic integration method, wherein molecular chains are simulated in a coarse-grain scale within an NVT ensemble. Simulations take place in the concentration interval , such that aggregate formation is possible. The initial configuration is that of dispersed free chains; the increase of interactions among stickers signals the onset of the micelle formation process. The solution with high concentration experiences substantial micelle aggregation despite little conformation changes. Therein, transient networks among micellar flowers are formed. The decrease in free energy is related to the formation of aggregates to achieve stability. When solutions are thermodynamically stable, the free energy and configurational entropy decrease and increase non-linearly with concentration, respectively. Below critical micellar concentration, this behaviour is associated with a step-by-step process along which the sticker groups gather to form the first thermodynamically stable aggregate. Above critical micellar concentration, the most probable distribution increases with concentration, therefore, free energy decreases with increasing aggregates that form the network.

Evaluation of tribological characteristics of technical oils with fullerene compositions

The paper presents experimental studies of the tribological characteristics of liquid lubricants of various viscosity classes and various groups of operation when using fullerene compositions. Tribological characteristics were evaluated on a four-ball friction machine according to GOST 9490. The use of fullerene compositions in the form of a finely dispersed fullerene powder, pre-dispersed (dissolved) in vegetable high oleic oils, for example, rapeseed, with the subsequent addition of the resulting composition to technical oils of various viscosity classes and various groups of operation, leads to the following positive effect. The anti-wear properties of oils, which are assessed by the wear indicator, increase by 20,0…30,7 %, and the critical load on 18,8…25,0%. These indicators significantly exceed similar indicators when using fullerene fine powders without preliminary dispersion in vegetable oils, where the effect is on the border 11,1…15 %. Fullerene additives do not affect the extreme pressure properties of base oils, which are assessed by the scuffing load. This result makes it possible to state that the way to improve the tribological properties of lubricants by introducing a fine powder of fullerenes into base technical oils is ineffective. The experimental results obtained confirm the hypothesis about the possibility of the micelle formation mechanism in the lubricant under the action of the electrostatic field of the friction surface. The presence of a surfactant solvent (vegetable oil) allows you to "start" the micelle formation process at lower fullerene concentrations and to obtain the effect of increasing anti-wear properties.

Spectroscopically Quantifying the Influence of Salts on Nonionic Surfactant Chemical Potentials and Micelle Formation.

The influence of two salts (NaSCN and Na2SO4) on the micellization of a nonionic surfactant (1,2-hexanediol) is quantified using Raman multivariate curve resolution spectroscopy, combined with a generalized theoretical analysis of the corresponding chemical potential changes. Although the SCN- and SO42- anions are on opposite ends of the Hofmeister series, they are both found to lower the critical micelle concentration. Our combined spectroscopic and theoretical analysis traces these observations to the fact that in both salt solutions the ions have a greater affinity for (or are less strongly expelled from) the hydration shell of the micelle than the free surfactant monomer, as quantified using the corresponding chemical potentials and Wyman-Tanford coefficients. This probe-free experimental and theoretical analysis strategy may readily be extended to micelle formation processes involving other surfactants, salts, and cosolvents, as well as to other sorts of aggregation and binding processes.

Downhill, Ultrafast and Fast Folding Proteins Revised.

Research on the protein folding problem differentiates the protein folding process with respect to the duration of this process. The current structure encoded in sequence dogma seems to be clearly justified, especially in the case of proteins referred to as fast-folding, ultra-fast-folding or downhill. In the present work, an attempt to determine the characteristics of this group of proteins using fuzzy oil drop model is undertaken. According to the fuzzy oil drop model, a protein is a specific micelle composed of bi-polar molecules such as amino acids. Protein folding is regarded as a spherical micelle formation process. The presence of covalent peptide bonds between amino acids eliminates the possibility of free mutual arrangement of neighbors. An example would be the construction of co-micelles composed of more than one type of bipolar molecules. In the case of fast folding proteins, the amino acid sequence represents the optimal bipolarity system to generate a spherical micelle. In order to achieve the native form, it is enough to have an external force field provided by the water environment which directs the folding process towards the generation of a centric hydrophobic core. The influence of the external field can be expressed using the 3D Gaussian function which is a mathematical model of the folding process orientation towards the concentration of hydrophobic residues in the center with polar residues exposed on the surface. The set of proteins under study reveals a hydrophobicity distribution compatible with a 3D Gaussian distribution, taken as representing an idealized micelle-like distribution. The structure of the present hydrophobic core is also discussed in relation to the distribution of hydrophobic residues in a partially unfolded form.

Equilibrium model for estimating micellar aggregation number from surface equation

The Aggregation Surface Equation (ASE) is attained by coupling the Gibbs adsorption equation and surface aggregation isotherm. The resulting equation can be used to study fluid-fluid interfaces in connection with the micelle formation process. This new equation contains two boundary conditions in the vicinity of the saturation region: (i) the critical micelle concentration (CMC), which corresponds to the onset of micelle formation; and (ii) the critical spherical micelle concentration (CSC) (i.e. the completion of spherical micellar aggregates). These boundary conditions, which appear within a narrow surfactant concentration range, provide the basis to calculate the average aggregation number under the assumption of constant average aggregation number and spherical micelles geometry. The resulting Surface Equation (SE) contains the maximum surface concentration of the surface monolayer, the critical micelle concentration and the micelle average aggregation number. The mass action law allows extending the ASE as a function of the free monomer, as opposed to the total or nominal surfactant concentration, which was recently performed in the STAND model (Langmuir, 32, (16), (2016), 3917-3925). This paper presents a simple and direct method to calculate the micellar average aggregation number from surface tension data and the proposed surface equation.

Characteristics and antitumor activity of polysorbate 80 curcumin micelles preparation by cloud point cooling

Curcumin is a natural bioactive compound with known potential for cancer treatment and prevention. However, a major barrier for clinical application is its poor solubility and bioavailability. Nanotechnology is an effective approach to enhance the bioavailability of insoluble drugs. We explored a novel way to prepare micellar curcumin in the common food additive, polysorbate 80, by utilizing the process of micelle formation that occurs during slow cooling below its cloud point. Curcumin molecules were thus dissolved and encapsulated. Micellar curcumin was stable during storage and was more tolerant to harsh pH conditions than free curcumin. The ~20 nm-sized nanocurcumin micelles showed improved antitumor effect than free curcumin in SUM149 human breast cancer xenografts in mice. This new method overcame the difficulty of dissolving curcumin in aqueous solution of polysorbate 80, and may find application in the production of other functional nutraceuticals.

How is a micelle formed from amphiphilic polymers in a dialysis process: Insight from mesoscopic studies

Self-assembly of amphiphilic polymers into micelles in dialysis process is dynamic, and the phase transition process is therefore very challenging to observe experimentally. In this study, we built a dynamic modeling by applying dissipative particle dynamics (DPD) simulations to explore the entire micelle formation process during the dynamic. The self-assembled aggregates undergo four stages in the process of dialysis: (i) Dispersed stage, (ii) Pre-micellar stage, (iii) Over-micellar stage. (iv) The final micellar stage. The study thus provides great advantages in simulating the processing dynamics of drug delivery systems, which would further expand the application scope of DPD simulations.

Features of self-organization of sodium dodecyl sulfate in water-ethanol solutions: Theory and vibrational spectroscopy

In this work, experimental and theoretical studies of the micelle formation processes of sodium dodecyl sulfate in water-ethanol solutions with different ethanol content - 0% by volume, 8% by volume, 15% by volume, 30% by volume were carried out. For the first time, the manifestation in the vibrational spectra of the features of self-organization of sodium dodecyl sulfate (SDS) molecules in water-ethanol solutions was found. In the studied concentration ranges of ethanol and SDS it was found that in the presence of SDS, the strengthening of hydrogen bonds in solutions is observed in a wider range of changes in the concentration of ethanol than in the absence of SDS. The behavior of the band at 1060 cm−1 at low concentrations of ethanol (8%) indicates the dual behavior of ethanol molecules as a co-surfactant and co-solvent in the process of micelle formation. The obtained experimental data are confirmed by theoretical calculations. For the first time, a contactless express method was proposed for determining the critical micelle concentration of SDS in water-ethanol solutions with different ethanol content from Raman spectra. The measured values of SDS critical micelle concentration are in good agreement with the literature data.

Comparative evaluation of the micelle formation process of phospolipids of rapeseed and sunflower lecithines in nonpolar solvents

Comparative evaluation of the micelle formation process of phospolipids of rapeseed and sunflower lecithines in nonpolar solvents

Increase of aggregative and sedimentation stability of slag suspensions by ultrasound

The paper discusses the relevance of the use of metallurgical wastes crushed to a fine state in the production of building materials. Domain granulated slag (DGS) was used as a research object. A method for introducing fine ground slag (FGS) into the cement composition in the form of a slag suspension instead of mixing water has been developed. To establish the uniform distribution of FGS particles in the cement matrix, the behavior of slag particles in an aqueous dispersion medium was previously studied. The optimal parameters of ultrasonic dispersion of slag suspensions are established: the frequency of ultrasonic vibrations is 44 kHz; temperature of dispersion - 25±2°C; dispersion time - 15 min. It has been established that the application of UST to slag suspensions with the observance of optimal dispersion parameters can increase the aggregative and sedimentation stability of the FGS suspension by 2–3 times as compared with mechanical mixing, accelerate the micelle formation process, and enhance the electrostatic factor of aggregative stability.

Impact of the green tea ingredient epigallocatechin gallate and a short pentapeptide (Ile-Ile-Ala-Glu-Lys) on the structural organization of mixed micelles and the related uptake of cholesterol

BackgroundHigh levels of blood cholesterol are conventionally linked to an increased risk of developing cardiovascular disease (Grundy, 1986). Here we examine the molecular mode of action of natural products with known cholesterol-lowering activity, such as for example the green tea ingredient epigallocatechin gallate and a short pentapeptide, Ile-Ile-Ala-Glu-Lys. MethodsMolecular Dynamics simulations are used to gain insight into the formation process of mixed micelles and, correspondingly, how active agents epigallocatechin gallate and Ile-Ile-Ala-Glu-Lys could possibly interfere with it. ResultsSelf-assembly of physiological micelles occurs on the order of 35–50 ns; most of the structural properties of mixed micelles are unaffected by epigallocatechin gallate or Ile-Ile-Ala-Glu-Lys which integrate into the micellar surface; the diffusive motion of constituting lipids palmitoyl-oleoyl-phosphatidylcholine and cholesterol is significantly down-regulated by both epigallocatechin gallate and Ile-Ile-Ala-Glu-Lys; ConclusionsThe molecular mode of action of natural compounds epigallocatechin gallate and Ile-Ile-Ala-Glu-Lys is a significant down-regulation of the diffusive motion of micellar lipids. General significanceNatural compounds like the green tea ingredient epigallocatechin gallate and a short pentapeptide, Ile-Ile-Ala-Glu-Lys, lead to a significant down-regulation of the diffusive motion of micellar lipids thereby modulating cholesterol absorption into physiological micelles.

Effect of sodium chloride on the interactions of ciprofloxacin hydrochloride with sodium dodecyl sulfate and hexadecyl trimethylammonium bromide: Conductometric and spectroscopic approach

Interactions of ciprofloxacin hydrochloride (CF) with sodium dodecyl sulfate (SDS) and hexa- decyl trimethylammonium bromide (HTAB) have been studied in aqueous as well as in aqueous NaCl medium by conductivity measurement over a temperature range. Values of critical micelle concentration (CMC), degree of ionization (α) and various thermodynamic parameters have been determined for both the systems. In aqueous medium the CMC values of HTAB decrease while CMC values of SDS increase in the presence of CF. In the presence of NaCl, CMC values of both the surfactants are found to decrease and ΔGmᴼ values are negative which indicate drug mediated ionic micelle formation process is thermodynamically more spontaneous in the presence of NaCl. In addition to it absorption spectra of CF have been recorded as a function of surfactant concentration ranging from pre-micellar region to post-micellar region in aqueous medium as well as in the presence of 10 mM NaCl solution. UV–visible studies were used to calculate partitioning/binding constant (K) and free energy of partitioning/binding (ΔGxᴼ) in the post-micellar region. The presence of NaCl increases the partitioning/binding of CF to both the surfactant micelles. This leads to enhancement of hydrophobic interactions for both the surfactants and thus CF supported ionic micelle formation is much favored in the presence of NaCl. Proton NMR studies have been performed in aqueous and NaCl solution to determine the locus of solubilization of CF within micelle.

An implantable depot capable of in situ generation of micelles to achieve controlled and targeted tumor chemotherapy.

The promicelle polymer-co-electrospun fibers are developed to form a micelle-generating depot after implantation onto the tumor. The promicelle polymers are continuously released and simultaneously self-assemble into folate-targeted and glutathione-sensitive micelles, ensuring sustained micelle delivery for more than 30 days. The process of micelle formation in the tumor tissue is visualized in vivo for the first time based on the mechanism of aggregation-induced emission. This in situ micelle formation also prevents premature drug release and rapid clearance from the bloodstream. In addition, these fibers deliver anti-cancer agents directly within tumor cells via dual selectivity (i.e. spatially selective accumulation in tumor tissues via implantation and selective internalization into tumor cells via folate receptor-mediated endocytosis) and on-demand drug release in response to cytosol GSH. They exhibit superior tumor inhibitory efficacy with minimal systemic toxicity, and prevent from malignant metastasis of cancer cells.