Determination Of Critical Micelle Concentration Research Articles

Influence of Valsartan on the thermodynamics of micellization of anionic surfactant Sodium Dodecyl Sulphate

Abstract In this manuscript was investigated behaviour of drug valsartan by micellar media of anionic surfactant sodium dodecyl sulphate. As the method was used electrical conductivity for the determination of critical micelle concentration at different temperatures (T = 293.15 - 313.15 K), as well as calculated thermodynamic parameters like standard Gibbs free energy, enthalpy and entropy of micellization. According to contribution of Gibbs free energy is the process of micellization primarily controlled by entropy. Solubilization of valsartan was studied in surfactant system at 298.15 K and physiological conditions pH 7.4 using UV-spectrophotometry at different concentration range (0.001 - 0.07 mol/l) of sodium dodecyl sulphate. The solubilization of drug was observed with increasing concentration of surfactant in aqueous solution.

A Mathematical Approach to a More Accurate Determination of Critical Micelle Concentration and Other Thermodynamic Parameters of 14‐2‐14 Gemini Surfactant in Water–Organic Solvent Mixed Media at Variable Temperatures

AbstractTo explore how the solvent characteristics influence the self‐aggregation of the cationic gemini surfactant dimethylene‐1,2‐bis(tetradecyldimethylammonium bromide) (14‐2‐14) and to obtain various energetic parameters, conductometric experiments were performed on the binary mixtures in the presence of commonly used organic solvents; formamide (FA), acetonitrile (AN) and 2‐methoxyethanol (ME) in aqueous solutions at varying temperatures (298.15–323.15 K) and compositions. The procedure suggested by Carpena et al. has been utilized to analyze conductivity–concentration plots in order to obtain critical micelle concentration (CMC) and degree of counterion dissociation (α) of the micelles. This method provides more accurate results as compared to conventional treatments, and the experimental error for the evaluation of micellar parameters is reduced significantly. The results revealed that, although the process of micellization becomes less favorable with the increase in composition of FA, AN and ME in mixed systems, the increase in CMC at compositions lower than 20% (v/v) of the organic solvents is relatively less, indicating that water character is dominant in the bulk phase. As the enthalpy of micellization became more negative, the corresponding entropy change became less positive and enthalpy–entropy compensation phenomenon has been observed for 14‐2‐14 in all the mixtures within the studied temperature range.

Utilization of surface Plasmon resonance band of silver nanoparticles for determination of critical micelle concentration of cationic surfactants

We have utilized surface Plasmon resonance (SPR) band sensitivity to surfactant concentration to investigate the critical micelle concentration (cmc) of CTAB, HY and CPB. The process is based upon an in situ formation of silver nanoparticles (AgNPs) through the reduction of silver ions (Ag+) by diethylene triamine (DETA) at 25°C. In the presence of cationic surfactants, Ag+ ions can be reduced to AgNPs in a few minutes, accompanied by changes in intensity and wavelength of the SPR band. The spectral shifts of SPR band and the change of color have been used to determine CMC values of cationic surfactants.

Effect of anionic surfactants on the surface plasmon resonance band of silver nanoparticles: Determination of critical micelle concentration

We have utilized surface plasmon resonance (SPR) band sensitivity to surfactant concentration to investigate the critical micelle concentration (cmc) of AOT and SDS. The process is based on an in situ formation of silver nanoparticles (AgNPs) through the reduction of silver ions (Ag+) by diethylene triamine (DETA) at room temperature. The shift of the SPR band position (λmax) at cmc can be observed with the naked eye in the form of a color change from brown to red for SDS and from brown to yellow for AOT.

Application of Three-Dimensionally Printed Probe and Reservoir to Critical Micelle Concentration Determination by Microvolume Surface Tension Measurement

It is important to determine a critical micelle concentration (CMC) of a surfactant in a protein formulation for stabilizing the protein at maximum by preventing it from interfacial denaturation. There are several techniques for CMC determination. Among them, surface tensiometry is the most common approach because this has a long history and much data at many research fields. However, large amount of sample solution is usually required for the measurement (e.g., more than 1 mL is necessary when a standard reservoir like a glass petri dish is used). This is one of the hurdles for protein formulators because only a small amount of protein could be used at the early-stage development. In this research, we tried to minimize the required amount of sample solution for surface tension measurement by developing appropriate probe and reservoir using a three-dimensional printer (3D printer). The advantages and capabilities of 3D printer are (1) to control the shape and size of the printed material precisely, (2) to change the figure freely, and (3) to prepare the prototype quickly. After the experiments and thereby the refinement of probe as well as reservoir, we found that CMCs of polysorbate 20, polysorbate 80, and poloxamer 188 in water and protein formulations could be precisely detected using a probe 0.5 mm in diameter and small reservoir with a pocket of 7.5 mm in diameter/0.25 mm in depth which were made by a 3D printer. Furthermore, the required sample solution per each measurement could be reduced to 80 μL, which means more than 90% reduction against a standard reservoir.

The Use of Detergents to Purify Membrane Proteins.

Extraction of membrane proteins from biological membranes is usually accomplished with the help of detergents. This unit describes the use of detergents to solubilize and purify membrane proteins. The chemical and physical properties of the different classes of detergents typically used with biological samples are discussed. A separate section addresses the compatibility of detergents with applications downstream of the membrane protein purification process, such as optical spectroscopy, mass spectrometry, protein crystallography, biomolecular NMR, or electron microscopy. A brief summary of alternative membrane protein solubilizing and stabilizing systems is also included. Protocols in this unit include the isolation and solubilization of biological membranes and phase separation; support protocols for detergent removal, detergent exchange, and the determination of critical micelle concentration using different methods are also included.

A novel approach to the measurement of surfactant parameters in arthropod digestive juices

In arthropods, the determination of two important parameters of digestive juices, i.e. the total surfactant concentration and the critical micelle concentration (CMC), is challenging due to small sample volumes and low surfactant concentrations. In this work, we report a successful implementation of potentiometric titrations using the surfactant ion-selective electrode (SISE) and the pyrene fluorescence method (PFM) for the determination of the total surfactant concentration and CMC in the digestive juice of terrestrial isopod crustaceans Porcellio scaber. Pooled digestive juice extracts of four (SISE) or two (PFM) animals were used per measurement run. In both cases, digestive juice extracts in 100μL of deionized water were sufficient for one measurement run. The total surfactant concentration of P. scaber digestive juice was determined to be 9.2±3.5mM and the CMC was approximately 90μM. Our work presents an important improvement towards easy CMC determination in small volume samples in comparison with the commonly used stalagmometric technique, where much larger sample volumes are usually needed. To date, the total surfactant concentration was not measured in the digestive juices of arthropods other than Homarus vulgaris, Astacus leptodactylus and Cancer pagurus, for which complex separation and analytical techniques were required. Our results obtained by SISE and PFM therefore present the first successful quantification of surfactants and their CMC in small volumes of arthropod digestive juice without prior separation or purification techniques.

Determination of critical micelle concentration of cetyltrimethylammonium bromide: Different procedures for analysis of experimental data

Conductivity of two micellar systems was measured in order to determine critical micelle concentration (CMC) of cetyltrimethylammonium bromide (CTAB). Those systems were: CTin water and CTin binary mixture acetonitrile (ACN)-water. Conductivity (?)-concentration (c) data were treated by four different methods: conventional method, differential methods (first and second derivative) and method of integration (methods A-D, respectively). As CTin water micellar system shows a sharp transition between premicellar and postmicellar part of the ?/c curve, any of the applied methods gives reliable CMC values and there is no statistically significant difference between them. However, for CTin ACN-water mixture micellar system the integration method for CMC determination is recommended due to a weak curvature of ?/c plot.

A new simple method for determining the critical micelle concentration of surfactants using surface plasmon resonance of silver nanoparticles

A new and simple determination method for critical micelle concentration (CMC) has been developed based on surface plasmon resonance (SPR) technique. In the current work, the CMCs for sodium dodecyl sulfate (SDS), cetyl trimethyl ammonium bromide (CTAB), and Triton X-100 (TX-100) were determined in aqueous media by SPR of silver nanoparticles (AgNPs). The variation of the absorbance of AgNPs in respect of bulk water is a consequence of the micelles formation from the surfactants monomer, here, SDS, CTAB, and TX-100. Under the optimal experimental conditions, CMCs for SDS, CTAB, and TX-100 using SPR technique were 8.6 × 10−3, 9.1 × 10−4, and 2.6 × 10-4 mol L−1, respectively. The potential application of SPR technique for the CMC determination has been demonstrated in this work. Comparing to the other CMC determination methods, this SPR method is universal, sensitive, and nonadditive; it can be used for the direct measurements of CMC without adding any dyes or fluorescent probes. CMC values of various surfactants including SDS, CTAB, and TX-100 determined by this method are in agreement with those determined by the other methods. The results obtained by our simple method have comparable accuracy with those obtained from more elaborate experiments.

Aggregation properties of levofloxacin in water and ethanol and its interaction with sodium dodecyl sulphate: A thermodynamic study

This manuscript reports the determination of critical micelle concentration (CMC) of levofloxacin (LF) in two solvents, water and ethanol, by using surface tension, refractive index and absorbance measurements. The data thus obtained were used to calculate different thermodynamic parameters for micellization process like free energy of micellization, free energy of adsorption, entropy and enthalpy of micellization. The interaction of this drug with anionic surfactant (SDS) was also studied using UV/Visible spectroscopy and conductometry. With rise in temperature, CMC of the drug was found to decrease in ethanol and increase in aqueous solution indicating dominance of lipophobic desolvation over lipophilic desolvation in ethanol and reverse, in case of aqueous solution. A strong drug/surfactant interaction was found to exist. The data obtained from drug/surfactant interaction were also used to find different interaction parameters like partition constant, free energy of partition, binding constant and free energy of binding which are very useful to understand the phenomenon of solubilization. Critical micelle concentration of levofloxacin increases with temperature in aqueous solution and decreases in ethanol. Processes of micellization and adsorption of drug molecules at solution-air interface are spontaneous and results in increase in entropy. The drug shows strong interaction with anionic surfactant (SDS) due to solubilization of drug molecules between ionic head groups of micelles of SDS.

Flow-injection chemiluminescence method for determination of critical micelle concentration of surfactants

In this study, chemiluminescence (CL) behaviour of Luminol-H2O2 in the presence of the different concentrations of four surfactants, cetyltrimethylammonium bromide (CTAB), cetylpyridinium bromide (CPB), sodium dodecyl sulphate (SDS) and polyoxyethylene dodecyl ether (Brij-35), was investigated. A novel method for the direct determination of critical micelle concentration (CMC) of the surfactants using flow-injection CL is described. Under the optimum conditions, the luminescence intensity of the Luminol-H2O2 system increased gradually with increasing concentration of the surfactants before the CMC, but rapidly reached to the emission maximum at the CMC, followed by a decrease after the CMC. The concentrations of the surfactants corresponding to the luminescence maximum are in agreement with the literature CMC values. The main factors affecting the determination of CMC are discussed. The mechanistic studies show that the luminescence peaks observed in the experiment were mainly because of the protective effect of the micelle against the transition of the excited species and the retarding effect of the micelle structures on the CL reaction rate.

Studies of the physicochemical and structural properties of self-assembling cationic pyridine derivatives as gene delivery agents

New amphiphilic pyridine derivatives containing dodecyloxycarbonyl substituents at positions 3 and 5 and cationic moieties at positions 2 and 6 have been designed and synthesised. Compounds of this type can be considered as synthetic lipids. The corresponding 1,4-dihydropyridine (1,4-DHP) derivatives have earlier been proposed as a promising tool for plasmid DNA (pDNA) delivery in vitro. In this work studies of the self-assembling properties of amphiphilic pyridine derivatives leading to the formation of liposomes, determination of particle size, zeta-potential and critical micelle concentration (CMC) with dynamic light scattering (DLS) measurements are described. Furthermore, thermal analysis of pyridine derivatives was performed using thermogravimetry analysis (TGA) and differential thermal analysis (DTA) as well as the ability to deliver the pEGFP-C1 plasmid DNA (that encodes GFP reporter) into the Baby hamster kidney-derived (BHK-21) cell line was used for evaluation of gene delivery properties. We have revealed that the new pyridine derivatives possessed self-assembling properties which were proved by formation of nanoparticles with the average size from 115 to 743nm, the zeta-potentials in the range of 48–79mV and CMC values in the range of 2–67μM. DTA data showed that all processes were endothermic for all compounds. Additionally, we established that among the tested pyridines the representatives with N-methylpyrrolidinium or pyridinium moieties as cationic head-group at the positions 2 and 6 possessed higher pEGFP-C1 transfection activity into the BHK-21 cell line. Nevertheless, the obtained results indicated that correlation of the physicochemical, structural properties and gene delivery activities of the tested compounds were not completely elucidated yet. On the other hand, the synthesised pyridines as possible metabolites of promising delivery systems on the 1,4-DHP core possessed lower pDNA transfection activity than the corresponding 1,4-DHP amphiphiles.

A series of sensitive and visible fluorescence-turn-on probes for CMC of ionic surfactants: Design, synthesis, structure influence on CMC and sensitivity, and fast detection via a plate reader and a UV light

We recently developed a unique and sensitive fluorescence-turn-on probe (THP-1, a C-6 unsubstituted tetrahydropyrimide) for critical micelle concentration (CMC) of ionic surfactants based on its unusual properties: no emission in micelles but strong aggregation-induced emission (AIE) in solution. Herein other fifteen THPs (THP-2–16) were designed and synthesized to investigate into structure influence on the CMC values of ionic surfactants (anionic SDS, cationic CTAB and zwitterionic CHAPS) and their fluorescent sensitivities. All these THPs show the unusual properties in these surfactant solutions as THP-1 and can be used as fluorescence-turn-on probes. The determined CMC values are in the range reported. It was found that 4-CF3 is a crucial functional group for increase of sensitivities of THP probes. Compared with THP-1, the concentration detecting CMC decreased by 10.8 times but fluorescence intensity increased 2.8 times. It worth mentioning that the changes in the fluorescent intensity of THPs about CMC of SDS and CTAB are so sensitive that the CMC values of SDS and CTAB can be detected using a simple UV light. In addition, we investigated into the practical applications of THPs in semi-micro and high throughput CMC determination. Since AIE fluorophores and surfactants have wide applications, it is expected these highly sensitive fluorescence-turn-on probes for CMC based on unusual no emission in surfactant micelles but strong AIE in surfactant solutions can be used in wide practical application areas.

CMC determination of nonionic surfactants in protein formulations using ultrasonic resonance technology

Biological products often contain surfactants as stabilizers in their formulations to avoid surface adsorption, interfacial denaturation and aggregation of the protein drug and thereby improve the overall pharmaceutical quality of the product. On the other hand, when the surfactant concentration exceeds the critical micelle concentration (CMC) in a protein formulation, protein-loaded micelles could be formed which could potentially be the cause of immunogenicity. Therefore, the actual CMC and the presence of micelles generally need to be confirmed for each protein formulation because the CMC is affected by the presence of protein and other formulation factors. In this study, the ultrasonic resonance technology (URT) was applied to determine CMC of surfactants in pharmaceutical protein solutions in comparison with surface tensiometry (TE) and dynamic light scattering (DLS). According to our results, the ultrasonic resonance technology can easily and precisely provide CMCs of surfactants in protein formulations while it is not working for protein-free formulations. This indicates that the signal we measure with ultrasonic velocity comes from complex micelles composed of surfactant and protein molecules. DLS did not provide reliable data for protein/surfactant systems. Interestingly, a protein formulation with arginine and polysorbate 20 behaved differently when studied with TE and URT allowing us to see that arginine is bound to protein and that the complex interacts with the surfactant.

Fluorophotometric Determination of Critical Micelle Concentration (CMC) of Ionic and Non-Ionic Surfactants with Carbon Dots Based on the Stokes Shift

Fluorophotometric Determination of Critical Micelle Concentration (CMC) of Ionic and Non-Ionic Surfactants with Carbon Dots Based on the Stokes Shift

In Vitro Liberation of Indomethacin from Chitosan Gels Containing Microemulsion in Different Dissolution Mediums

The objective of this research is to outline the liberation of indomethacin from different chitosan gels containing O/W microemulsion. The influence of surfactant, sodium lauryl sulfate, in two concentrations (0.5% and 0.75%, w/w) was determined in dissolution medium on the release of indomethacin, which was used as poor water-soluble model drug. Chitosan gels were prepared in four different concentrations of chitosan-1%, 1.5%, 2%, and 3% (w/w). Microemulsion enhanced the liberation of the indomethacin from chitosan gels into all dissolution mediums. Adding the surfactant into phosphate-buffered saline decreased the amount of liberated indomethacin from microemulsion, gel mixture, but increased the drug liberation from pure chitosan gels. It was detected that with the increased concentration of chitosan in the samples, the amount of indomethacin liberated (p < 0.05) also increased. A conclusion was drawn that the liberation of indomethacin from chitosan gels was influenced by increased pH of the samples. The high viscosity induced a higher release of indomethacin from 3% (w/w) chitosan hydrogel at pH 5.8 as compared with 3% (w/w) chitosan hydrogel at pH 3.8. The highest percentage of released indomethacin was determined when a mixture of microemulsion gel with higher chitosan content was used.

Structural and physiochemical characterization of rhamnolipids produced by Acinetobacter calcoaceticus, Enterobacter asburiae and Pseudomonas aeruginosa in single strain and mixed cultures

Rhamnolipids are naturally occurring biosurfactants with a wide range of potential commercial applications. As naturally derived products they present an ecological alternative to synthetic surfactants. The majority of described rhamnolipid productions are single strain Pseudomonas spp. cultivations. Here we report rhamnolipids producing bacteria Acinetobacter calcoaceticus, Enterobacter asburiae and Pseudomonas aeruginosa that were cultivated separately and as mixed populations. The ratio and composition of rhamnolipid congeners was determined by tandem mass spectrometry with negative electrospray ionization. Mono-rhamnolipid and di-rhamnolipid homologues containing one or two saturated or monounsaturated 3-hydroxy fatty acids were found in all strains.Physiochemical characterization of rhamnolipids was evaluated by the critical micelle concentration determination, the emulsification test, oil displacement test and phenanthrene solubilization. Critical micelle concentrations of rhamnolipids produced by both single strain and mixed cultures were found to be very low (10–63mg/l) and to correspond with saturated/unsaturated fatty acid content of rhamnolipid homologues. The rhamnolipids produced by all strains effectively emulsified crude petroleum in comparison with synthetic surfactants Tween 80 and sodium dodecyl sulfate (SDS). Good performance of phenanthrene solubilization was exhibited by rhamnolipids from E. asburiae.The single strain and co-cultures cultivations were proposed as a possible way to produce rhamnolipid mixtures with a specific composition and different physiochemical properties, which could be exploited in bioremediation of various hydrophobic contaminants.

UTILITY OF HADKAR FACTOR IN THE DETERMINATION OF CRITICAL MICELLE CONCENTRATION OF SURFACTANTS

The drop weight method was used to determine the interfacial tension between organic liquid and solutions of different concentrations of the surfactant, sodium lauryl sulphate (SLS), using Hadkar factor. Two experiments were performed to determine the interfacial tension. In the first experiment the drop weight method was used to determine the interfacial tension between water or aqueous surfactant solutions and benzene (liquid lighter than water) using Hadkar factor H1. In the second experiment the drop weight method was used to determine the interfacial tension between water or surfactant solutions and carbon tetrachloride (liquid heavier than water) using Hadkar factor H2. The plot of interfacial tension between benzene or CCl4 and SLS solutions versus concentration of surfactant solution was used to determine the critical micelle concentration (CMC) of the surfactant. The results were in good agreement with the reported values of CMC for SLS showing the utility of Hadkar factor in the determination of CMC of surfactants.

Fluorophotometric determination of critical micelle concentration (CMC) of ionic and non-ionic surfactants with carbon dots via Stokes shift

A new and facile method for the determination of critical micelle concentration (CMC) of ionic and non-ionic surfactants is proposed in this article. Carbon dots exhibited substantial fluorescence and therefore enhanced the sensitivity of this evaluation. Understanding the formation of surfactant micelles is vital for the applications of biomedicine such as drug fabrication and smart molecular vehicles in delivering therapeutic dosage to various molecular sites. The fluorescence property of carbon dots was utilized for the first time to estimate the critical micelle concentration of surfactants. The central concept of the approach is based on the Stokes shift determination of a system composed of constant amount of carbon dots with varying concentrations of ionic and non-ionic surfactants. The synthesized carbon dots were characterized by FTIR, TEM, XRD, Raman, UV, and fluorescence spectroscope. The carbon dots were excited at 280nm so as to obtain maximum emission for the Stokes shift measurement. The CMC value of cetyltrimethyl ammonium bromide (CTAB), sodium dodecyl sulfate (SDS), Triton X-100, dodecyldimethyl(3-sulfopropyl)ammonium hydroxide (SB-12) evaluated by this approach was found to be 0.98, 7.3, 0.19, and 3.5mM, respectively. The signals of spectra were assigned and explained in terms of both electron transitions between specific molecular orbital and the interaction with solvent.

Unique Micellization and CMC Aspects of Gemini Surfactant: An Overview

Critical micelle concentration (CMC) is an essential fundamental property of surfactant molecules, as the CMC value provides significant information regarding the surfactant for industrial use. The industrial efficacy of surfactant molecules totally depends on its CMC value. Without a complete perceptive approach of CMC, it is impractical to employ surfactant molecules efficiently. This article provides an elaborate discussion of dimeric gemini surfactant and pays particular attention to the aggregation behavior, that is, micelle formation, CMC, and thermodynamics of micellization. Micelles structures, packing parameters, and properties of the micelles are summarized. The principles and techniques involved in the determination of CMC are discussed. Thermodynamics of micellization of dimeric surfactants including free energy, enthalpy, and entropy is successively reviewed. Superiority of gemini surfactant in respect of their CMC values is interpreted.