Formation Of Mixed Micelles Research Articles

Thermo-acoustical analysis of sodium dodecyl sulfate: Fluconazole (antifungal drug) based micellar system in hydro-ethanol solutions for potential drug topical application

Micellar systems hold excellent drug delivery applications due to their capability to solubilize a large number of hydrophobic and hydrophilic molecules. In this present work, the mixed micelle formation between the anionic surfactant sodium dodecyl sulfate (SDS) and the ‘Azole’ derivative antifungal drug fluconazole (FLZ) have been studied at four temperatures in different hydro-ethanolic solutions. The critical micelle concentration (CMC) was determined by specific conductance techniques and the experimental data was used to calculate several useful thermodynamic parameters, like standard free energy, enthalpy and entropy of micelle formation. Early micellization was found with critical micelle concentration shifting towards lower concentration (CMC) than the standard concentration of SDS in water at 25°C suggesting that drug and the solvent system facilitates the micellization process. In addition, the transport properties were examined by employing controlled approaches likely, apparent molar volume (ϕv), apparent molar adiabatic compression (ϕk), and isentropic compression (κs) of SDS in presence of FLZ. These parameters revealed the existence of intermolecular interactions within the molecules. Therefore, this study would cast light on utilizing surfactant immobilized FLZ system for better topical biological action.

Mixed Micelle Formation between an Amino Acid-Based Anionic Gemini Surfactant and Bile Salts

The mixed micelle formation in basic aqueous solutions between an anionic gemini amino acid-based surfactant derived from cysteine (C8Cys)2 and the bile salts sodium cholate (NaC) and sodium deoxycholate (NaDC) has been studied by conductivity, and the results have been compared with the ones obtained for binary solutions of (C8Cys)2 with the conventional anionic surfactant sodium dodecyl sulfate (SDS). A nonideal mixing pattern was observed for the mixed systems, and a striking behavior was found for the gemini surfactant–bile salt mixtures, with gemini–bile salt interactions changing from synergistic to antagonistic with increasing gemini surfactant composition, whereas for the (C8Cys)2/SDS mixed system, synergism was attained over all the molar fraction range studied. Regular solution theory (RST) was used to analyze the gemini surfactant–anionic surfactant binary mixtures, and the interaction parameter (β) has been evaluated, as well as mixed micelle composition.

Aggregation Behavior of PEO-PPO-PEO Tri-Block Copolymer (Pluronic®L64) in Nonionic Surfactant Additives Environment

Studies of the interaction between water soluble PEO-PPO-PEO triblock copolymers (Pluronic®polymers) and ionic/nonionic surfactants are of significant interest because the polymer–surfactant mixtures are used widely in industrial and domestic formulations. The aggregation behavior of Pluronic®L64, EO13PO30EO13, in absence and presence of conventional nonionics (PEG1500, Tween80, Brij98) and block copolymeric nonionics (F68, F127, P123) was investigated by cloud point, surface tension, viscosity and UV-Visible spectroscopic measurements. Most of the studied nonionic surfactants increase the CP of Pluronic®L64 through the formation of mixed micelles of L64 and nonionics, respectively. Only PEG1500 have decreased the CPs of Pluronic®L64. In present study, the effects of PEG1500 and copolymeric F127 on aggregation behavior of Pluronic®L64 were studied. The surface parameters of adsorption and micellization for Pluronic®L64 and its mixtures with nonionics were also determined. Newer way, Indian solid gold, curcumin has been used to study the interaction between Pluronic®L64 and nonionic surfactants. Results confirmed that Pluronic®L64 interacts with copolymeric F127 through formation of mixed micelles between them, and conventional PEG1500 only increased the polarity of the medium and no noticeable interaction or formation of mixed micelles was observed.

Mixed Micelles of Tetradecyltrimethylammonium and n-Alkyltriphenylphosphonium Bromides

The critical micelle concentrations (CMC) of binary mixtures of tetradecyltrimethylammonium bromide and n-alkyltriphenylphosphonium bromide (ATPPB) with alkyl chain length of 10, 12, 14, and 16 have been determined in water by conductivity measurements. The CMCs were lower than predicted from ideal mixing theory indicating positive synergistic interactions in mixed micelle formation. The results of the mixed systems were analyzed using the regular solution theory which allowed for the determination of the composition of the mixed micelle, the activity coefficients, and the pair-wise molecular interaction parameter β. The average β values were all negative showing significant deviation from ideality which increases as the chain length of the n-ATPPB increases. The excess free energy of the mixed systems was also calculated, and the values were all negative for the four mixed systems studied, an indication that the mixed micelles are thermodynamically stable relative to the individual component.

Nonaromatic Hydrotropic Cationic Ammonium Salts as a Rheology Modifier for an Anionic/Zwitterionic Surfactant Mixture

In this article, we report additive-induced micellar growth and rheology modification for mixtures of anionic (sodium dodecyl sulfate, SDS) and zwitterionic (N-alkylated glycine derivative, Empigen BB or EBB) surfactants. Two nonaromatic hydrotropic salts (hexyltrimethylammonium bromide, C6TAB, and/or dibutylenebis(dimethylbutylammonium bromide), 4-4-4) are used as novel additives to induce micellar growth in these systems. Nuclear magnetic resonance (NMR), photon correlation spectroscopy (PCS), transmission electron microscopy (TEM), the Weissenberg effect, and rheology measurements were employed to assess mixed micelle formation, micellar growth, and rheology modifications. Finally, the manner in which the surfactants and hydrotropes self-assemble into aggregates has also been deduced from 2D NMR NOESY measurements. In this study, both hydrotropic ions have been found to contribute to similar structural modifications in the mixed micelles of the anionic and zwitterionic surfactants. However, the extent of the rheology modification in solution is found to be quite different when the gemini hydrotrope (4-4-4) versus the monomeric hydrotrope (C6TAB) is employed.

Experimental and theoretical approach to mixed surfactant system of cationic gemini surfactant with nonionic surfactant in aqueous medium

The surface and mixed micellization properties of the aqueous binary mixed system of alkanediyl-α, ω-type cationic gemini surfactant, 14–4–14 and conventional nonionic surfactant, Brij-58 in an aqueous medium have been investigated over the entire mole fractions at 298.15K. The critical micelle concentration (cmc) for each mixture have been measured by tensiometric and fluorescence measurements. The solution and adsorption characteristics like composition, activity coefficients and mutual interaction parameters have been computed using different proposed theoretical models like Clint, Rosen, Rubingh, Motomura and Maeda. The strength of interaction of the surfactant is attributed to the sterical and electrical factors on mixed monolayer and micelle formation and of surfactant–surfactant interactions. The micellar aggregation number (Nagg) has also been measured using steady state fluorescence quenching method at a total concentration of ~1mM of pure components as well as their mixtures of different ratios. The micropolarity and binding constant were determined from the ratio of intensity (I1/I3) of peaks of pyrene fluorescence emission spectrum.

Interaction between cationic gemini surfactant and related single-chain surfactant in aqueous solutions

In this paper, the gemini surfactants of type alkanediyl-α-ω-bis (alkyldimethylammonium) dibromide with different spacers containing s carbon atoms, referred to as “16-s-16” [C16H33(CH2)2N+(CH2)SN+(CH2)2C16H33·2Br−], (s=2, 6, 10 and Ar (8)) have been synthesized, purified and characterized in our laboratory. The interactions between geminis and their conventional monomeric surfactant hexadecyltrimethylammonium bromide (CTAB) have been studied using the conductivity and steady-state fluorescence quenching techniques at a certain micellar concentration range and certain temperature. Using the conductance data, the values of critical micelle concentrations (CMC) of the binary gemini–conventional mixtures having different compositions have been obtained. The micellar interaction parameters, (β), were determined from the critical micelle concentration values using the approach of Rubingh's regular solution theory. Mixed systems were exhibited negative synergism due to positive β values. The β values were found as close to zero. This indicates that the mixed micelle formation is ideal for all studied mixtures. The micelle aggregation numbers (Nagg), evaluated using steady-state fluorescence quenching at a total concentration of 2mM for CTAB/16-s-16 (s=2, 6, 10 and Ar (8)) systems. It was observed that contribution of conventional surfactants was always more than that of the geminis. Using the ratio of peak intensities, the micro-polarity, dielectric constant and binding constant (Ksv) of mixed systems were determined.

Interactions in Mixed Micellar Systems of an Amphoteric Chelating Surfactant and Ionic Surfactants

Mixtures of ionic surfactants and the chelating surfactant 2-dodecyldiethylenetriaminepentaacetic acid (4-C12-DTPA) have been examined in terms of interactions in mixed micellar systems. The amphoteric 4-C12-DTPA is zwitterionic with a negative net charge at the studied pH levels. The investigated ionic surfactants were the cationic dodecyltrimethylammonium chloride (DoTAC), the anionic sodium dodecyl sulfate (SDS), and the zwitterionic dimethyldodecylamine-N-oxide (DDAO). The surfactants all have the same hydrophobic chain lengths, and the results are evaluated in terms of headgroup interactions. 4-C12-DTPA interacts with different ionic surfactants by accepting or donating protons to the aqueous solution to increase the attractive interactions between the two surfactants; i.e., the protonation equilibrium of 4-C12-DTPA is shifted in different directions depending on whether there are predominant repulsions between positively or negatively charged groups in the mixed micelles. This was monitored by measuring pH vs concentration in the mixed systems. By measuring the pH, it was also possible to study the shift in the protonation equilibrium at increasing concentration, as the composition in the micelles approaches the composition in the total solution. Following the approach of Rubingh's regular solution theory, the interaction parameter β for mixed micelle formation was calculated from the cmc values determined by NMR diffusometry. Synergism in mixed micelle formation and negative β parameters were found in all of the investigated systems. As expected, the most negative β parameter was found in the mixture with DoTAC, followed by DDAO and SDS. The self-diffusion in the 4-C12-DTPA/DoTAC system was also discussed. The self-diffusion coefficient vs concentration plots show two distinctly different curves, depending on the surfactant that is present in excess.

Cationic gemini and sodium cholate – Following the interaction of oppositely charged surfactants by calorimetry, turbidity and conductivity

The thermodynamics of the process of self-assembly of cationic gemini surfactants, [C12H25(CH3)2N(CH2)SN(CH3)2C12H25]Br2, (the spacer S being 2, 6 or 10, assigned as C12CSC12Br2) and the system of oppositely charged mixture of surfactants formed by C12CSC12Br2 and sodium cholate (NaCA) in aqueous solution has been investigated by isothermal titration calorimetry (ITC), conductivity and turbidity measurements. The critical micelle concentration values (cmc) for the gemini surfactants C12CSC12Br2 obtained from calorimetry and conductivity were found to be consistent with values reported in the literature. The enthalpies of micellization (ΔHmic) of C12CSC12Br2 are all exothermic, presenting a strong negative minimum at S=6, corresponding to the maximum in the cmc values. For the mixed system of oppositely charged surfactants (C12CSC12Br2(S=2,6,10)/NaCA), we did obtain from ITC the critical parameters for different events that take place as the concentration of gemini surfactant increases, such as the formation of NaCA-rich mixed micelles (cmcmix,ΔHmic-mix), the formation of a precipitate (immiscible liquid crystalline (LC) phase) (CP,ΔHP) and its re-dissolution (CR,ΔHR), and finally the formation of positive charge-rich mixed micelles (CM,ΔHM). It should be stressed that the values of cmcmix (gemini) are much smaller than those for pure gemini and pure NaCA. These results also show that there is a stronger synergistic effect between the two surfactants in the NaCA-rich region. The turbidity measurements proved valuable to the determination of the region of immiscible LC phase. The ITC results are combined with those obtained by conductivity and turbidity leading to a thorough discussion of the effect of the gemini spacer length on the aggregation behavior of the mixed systems.

Molecular interactions of cationic gemini surfactants (m-s-m) with an environmental friendly nonionic sugar-based surfactant (β-C12G): Interfacial, micellar and aggregation behavior

In the present study, mixtures of cationic gemini surfactants with a non-ionic sugar-based surfactant in aqueous solutions containing electrolyte (NaBr) have been studied. The experimental results were evaluated using the Regular Solution Theory. The strength of interaction of all the surfactants is attributed to the sterical and electrical factors on mixed monolayer and micelle formation and of surfactant–surfactant interactions. The results show stronger interaction at the air/water interface and greater preference for adsorbing at the air/water interface relative to mixed micelle formation in the solution phase. The alkyl chain length and spacer of gemini govern the aggregation behavior of the mixed micelles.

Temperature Dependant Mixed Micellization Behavior of a Drug-AOT Mixture in an Aqueous Medium

The mixed micellization behavior of an amphiphilic antidepressant drug amitriptyline hydrochloride (AMT) in the presence of the conventional anionic surfactant sodium bis(2-ethylhexyl) sulfosuccinate (AOT) was studied at five different temperatures and compositions by the conductometric technique. The critical micelle concentration (cmc) and critical micelle concentration at the ideal state (cmc id ) values show mixed micelle formation between the components (i.e., drug and AOT). The micellar mole fractions of the AOT (X1) values calculated using the Rubingh, Motomura, and Rodenas models show a higher contribution of AOT in the mixed micelles. The interaction parameter (β) is negative at all temperatures and the compositions show attractive interactions between the components. The activity coefficients (f1 and f2) calculated using the different proposed models are always less than unity indicating non-ideality in the systems. The ΔGm Ө values were found to be negative for all the binary mixed systems. However, ΔHm Ө values for the pure drug as well as the drug-AOT mixed systems are negative at lower temperatures (293.15- 303.15 K) and positive at higher temperatures (308.15 K and above). The ΔSm Ө values are positive at all temperatures but their magnitude was higher at T=308.15 K and above. The excess free energy of mixing (ΔGex) determined using the different proposed models also explains the stability of the mixed micelles compared to the pure drug (AMT) and surfactant micelles.

Interacting behavior between amino sulfonate amphoteric surfactant and octylphenol polyoxyethylene ether (7) in aqueous solution and pH effect

The micellization properties of binary mixtures of sodium n-dodecyl diamine sulfonate (C12AS) and octylphenol polyoxyethylene ether (7), OP-7, in aqueous solution at the pH of 3.5, 6.0, and 8.5 have been characterized mainly employing both the UV–vis spectroscopy method, using pyrene as a probe, and the tensiometric method. The interaction parameters between two surfactants, the activity coefficients, the molar fractions of components in mixed micelles, and thermodynamic parameters obtained using some theoretical treatments including the regular solution theory (RST), the phase separation model, the Rubingh model, Maeda's treatment, and so on, were evaluated and the effect of pH on the above parameters was also discussed. Reduction of the mixed critical micelle concentration and negative values of interaction parameter indicate synergistic effect between two surfactants for all mixed systems. The charge density and steric effect of head group of C12AS may play a vital role on the formation of mixed micelle, and the values of pH in aqueous solution can influence the ionic form of C12AS and this steric effect, thus resulting in different interacting behaviors between two surfactants. Thermodynamic data show that the process of micellization for all mixed systems is spontaneous, the stability of mixed micelle is mainly dependent on the components in bulk solution, and the more stable mixed micelle can form in neutral or weak acidic solution.

Thermodynamic and Interfacial Properties of DTABr/CTABr Mixed Surfactant Systems in Ethanolamine/Water Mixtures: A Conductometry Study

Mixed-micelle formation in the binary mixtures of dodecyltrimethylammonium bromide (DTABr) and cetyltrimethylammonium bromide (CTABr) surfactants in water-ethanolamine mixed solvent systems has been studied by conductometric method in the temperature range of 298.1 to 313.1 K at 5 K intervals. It was observed that the presence of ethanolamine forced the formation of mixed micelle to lower total surfactant concentration than in water only. The synergistic interaction was quantitatively investigated using the theoretical models of Clint and Rubingh. The interaction parameter β12 was negative at all the mole fractions of DTABr in the surfactant mixtures indicating a strong synergistic interaction, with the presence of ethanolamine in the solvent system resulting in a more enhanced synergism in micelle formation than in water only. The free energy of micellization ΔGM values was more negative in water-ethanolamine mixed solvent system than in pure water indicating more spontaneity in mixed micelle formation in the presence of ethanolamine than in pure water.

Micellization Behavior of Butanediyl-1, 4-Bis(Dimethyldodecylammonium Bromide) Gemini Surfactant in Presence of Organic Additives

The surface and micellar properties of cationic gemini surfactant butanediyl-1, 4-bis(dimethyldodecylammonium bromide), referred to as C12-C 4 -C12, has been studied in pure aqueous solutions and in the presence of alcohols (butanol (C4OH), pentanol (C5OH), hexanol (C6OH)), and the corresponding amines (butylamine (C4NH2), pentylamine (C5NH2), hexylamine (C6NH2)) by surface tension measurements at 303 K. Parameters such as critical micelle concentration (CMC), C20 (the surfactant concentration required to reduce the surface tension of solvent by 20 mN m−1), the ratio of C20 and CMC, Γmax (maximum surface excess concentration at the air/solution interface), and Amin (minimum area per surfactant molecule) were evaluated. The CMC value of the gemini decreased with increasing concentration of additives. Mixed micelles were formed in each case and the CMC values of the mixtures were used to compute interaction parameters for mixed micelle formation in aqueous medium (βm), interaction parameters for mixed monolayer formation at the solution/air interface (βσ), and activity coefficients (f1 and f2). A synergistic interaction was observed both in the micelle as well as at the interface, as evident from the interaction parameters. Free energies of micellization () and adsorption () were also calculated.

Application of bile acids in drug formulation and delivery

Bile acids are naturally produced in humans and are known to provide human health benefits through their endocrinological, microfloral, metabolic and other åffects that are still to be elucidated. In recent years, there has been a growing interest in using bile acids as absorption enhancers for drug delivery. Bile acids are amphiphilic molecules with a unique ability to facilitate and promote drug permeation through biological membranes. The role of bile acids in promoting drug permeation has been experimentally illustrated in various pharmaceutical formulations including oral, nasal, ocular, buccal, pulmonary and rectal delivery as well as through the blood–brain barrier. Recently, bile acids have drawn attention in the field of drug delivery due to their ability to act as a drug carrier system in the form of mixed micelles, bilosomes and chemical conjugates with drug molecules. Bile acids have demonstrated a unique ability to enhance the epithelial transport of hydrophilic drugs through the paracellular route and that of hydrophobic compounds through both paracellular and transcellular routes. The aim of this review is to discuss various chemical and pharmaceutical aspects of BAs and their potential applications in drug formulation and delivery.

Micellization and interfacial properties of cationic gemini surfactant (12–4–12) in the presence of additives in aqueous electrolyte solution: A tensiometric study

The critical micelle concentration (CMC) of cationic gemini surfactant butanediyl-1, 4-bis(dimethyldodecylammonium bromide) with additives (primary linear alcohols (butanol, pentanol, hexanol) and primary linear amines (butylamine, pentylamine, hexylamine)) in presence of inorganic salt potassium nitrate is measured by surface tension measurements at 303K in the present study. The CMC value of the gemini decreased with increasing concentration of additives and the extent of the effect observed was in the order: C6OH>C5OH>C4OH; C6NH2>C5NH2>C4NH2. The surfactant concentration required to reduce the surface tension of solvent by 20mNm−1, C20, ratio of C20 and CMC, maximum surface excess concentration at the air/solution interface, Γmax, and minimum area per surfactant molecule, Amin, were evaluated. The interaction parameters βσ (for mixed monolayer formation at the solution/air interface), βm (for mixed micelle formation in aqueous medium) and f1m, f2m (activity coefficients) were also reported. As evident from interaction parameters, a synergistic interaction was observed both in the micelle as well as at the interface. Rubingh and Rosen models were used to evaluate the interaction parameters for the mixed micelles and at mixed monolayer, respectively. The ∆G0m, standard free energy of micellization, and ∆G0ads, free energy of adsorption, were also calculated.

Interaction Between Cationic Gemini and Monomeric Surfactants: Micellar and Surface Properties

Attraction effects in the mixed micelle of gemini (C16-12-C16, 2Br− and monomeric surfactants i.e., cetyltrimethylammonium bromide (CTAB), cetyltriphenylphosphonium bromide (CTPB) and cetyltributylphosphonium bromide (CTBuPB) mixtures in aqueous solution were investigated by conductivity and surface tension measurements. The attractive interaction of surfactants in the mixed micelle leading to non-ideality has been theoretically treated by Clint’s and Rubingh’s model in the light of regular solution theory. The experimental critical micelle concentration (cmc) values were lower than predicted from ideal mixture theory. The negative values of interaction parameters (m and for mixed micelle formation indicate the attractive interaction for all the systems. The Motomura’s theory was used to determine the composition of each compound in mixed micelles (Xideal. The excess free energy of the mixed systems was also calculated and the obtained negative values for all the mixed systems studied give an indication that the mixed micelles are thermodynamically more stable relative to the individual component

The Effect of Ethanol on Nanostructures of Mixed Cationic and Anionic Surfactants

AbstractMicellization of tetradecyl trimethyl ammonium bromide (TTAB) and sodium dodecyl sulfate (SDS) in water–ethanol (ET) micellar solutions, with the weight percent of ET changing within the range 0–30, was studied by means of surface tension and conductivity measurements. Surface tension measurements also provided information about the dependence of the surface excess concentration, the minimum area per surfactant molecule, and the standard Gibbs energy of adsorption on the added weight percent of the organic solvent. Information about the degree of counterion dissociation and phase transition was obtained through conductivity measurements. Cyclic voltammetry (CV) and dynamic light scattering (DLS) was also employed to investigate the mixed micellar behavior of the binary mixtures. It was shown that an excess of cationic surfactant and ET resulted in a phase transition of vesicles and large micelles to mixed micelles. The regular solution theory approximation was used to determine various micellar parameters of ideal systems. The regular solution interaction parameter (β) suggests that the formation of mixed micelles is due to the synergistic interactions in the case of TTAB/SDS systems and becomes affected by the water/ET ratio.

Thermodynamics of sodium dodecyl sulphate-salicylic acid based micellar systems and their potential use in fruits postharvest

Micellar systems have excellent food applications due to their capability to solubilise a large range of hydrophilic and hydrophobic substances. In this work, the mixed micelle formation between the ionic surfactant sodium dodecyl sulphate (SDS) and the phenolic acid salicylic acid have been studied at several temperatures in aqueous solution. The critical micelle concentration and the micellization degree were determined by conductometric techniques and the experimental data used to calculate several useful thermodynamic parameters, like standard free energy, enthalpy and entropy of micelle formation. Salicylic acid helps the micellization of SDS, both by increasing the additive concentration at a constant temperature and by increasing temperature at a constant concentration of additive. The formation of micelles of SDS in the presence of salicylic acid was a thermodynamically spontaneous process, and is also entropically controlled. Salicylic acid plays the role of a stabilizer, and gives a pathway to control the three-dimensional water matrix structure. The driving force of the micellization process is provided by the hydrophobic interactions. The isostructural temperature was found to be 307.5K for the mixed micellar system. This article explores the use of SDS-salicylic acid based micellar systems for their potential use in fruits postharvest.

Surface and Solution Properties of Cationic Gemini Surfactants with Primary Linear Alkanols

Using surface tension and fluorescence methods, the surface and solution properties of two cationic gemini surfactants {pentanediyl-1,5-bis(dimethylcetylammonium bromide) and hexanediyl-1,6-bis(dimethylcetylammonium bromide)} (referred to as 16-5-16 and 16-6-16) have been studied in the presence and absence of primary linear alkanols. Parameters studied include the critical micelle concentration (CMC), C20 (the surfactant concentration required to reduce the surface tension of the solvent by 20 mN·m−1), Гmax (maximum surface excess), and Amin (minimum surface area per molecule). These parameters indicate mixed micelle formation and, therefore, surfactant-additive interaction parameters in mixed micelles and mixed monolayers, as well as activity coefficients, were calculated. A synergistic effect was observed in all instances and was found to be correlated with the chain length of the alkanols. The CMC values of 16-s-16 (s = 5, 6) decrease with increasing alkanol concentration and the extent of this effect follows the sequence: 1-octanol (C8OH) > 1-heptanol (C7OH) > hexan-1-ol (C6OH) > 1-pentanol (C5OH) > butanol (C4OH). The micelle aggregation number (Nagg) of mixed micelles has been obtained using the steady state fluorescence quenching method. The micropolarity of gemini/alkanol systems has been evaluated from the ratio of intensity of peaks (I1/I3) of the pyrene fluorescence emission spectra. Results are interpreted on the basis of the structure of mixed micelles and monolayers.