Stability Of Mixed Micelles Research Articles

Scrutinizing micellar transitions and interfacial properties in mixed micelles comprising sodium dodecyl sulfate and sodium oleate: A tensiometric and scattering insight

Mixed micellar systems play a pivotal role in numerous scientific and industrial applications due to their inimitable solution properties and potential for enhancing solubilization and emulsification processes. The present study unveils the mixed micellization behavior of two anionically charged surfactants, sodium dodecyl sulfate (SDS) and sodium oleate (SO), in aqueous solutions through a combination of solution viscosity, tensiometric and small-angle neutron scattering (SANS) techniques. The dynamic changes in the interfacial properties of the mixed micellar system as a function of the SDS-to-SO ratio are evaluated from surface tension measurements. The results offer an insight into the formation of the stable mixed micelles with the alteration in the critical micelle concentration (CMC) as a function of the composition of both surfactants and the nature of the interaction. Surface tension data disclose the thermodynamic aspects of micelle formation and the influence of surfactant interactions on the surface activity of the system. Complementing the surface tension measurements, SANS analysis was conducted to clarify the structural aspects of the SDS-SO mixed micelles. SANS inferred the micellar size, shape, and aggregation number (Nagg), thereby shedding light on the nanoscale organization of the micellar aggregates in the aqueous solution. By combining SANS and surface tension data, a comprehensive understanding of the mixed micellization behavior of SDS and SO is achieved, addressing both interfacial and structural aspects. A computational simulation approach has also been employed to obtain the optimized parameters, which provide a better understanding of the correlation of SDS and SO molecular orbital energy levels. The results underscore the importance of surface tension and structural characterization techniques to comprehend the behavior of mixed micelles fully.

Effect of glycerol on micellization of quasi-binary mixture of zwitterionic cocamidopropyl hydroxysultaine and cetyltrimethylammonium bromide in aqueous solution

The micellization behavior of quasi-binary mixture of zwitterionic cocamidopropyl hydroxysultaine (CAPHS) with cationic cetyltrimethylammonium bromide (CTAB) was investigated both in aqueous solution and in glycerol-water. Both the tensiometric and the conductive techniques were adopted to determine the critical micelle concentrations (cmc) of individual and mixed surfactants. In the framework of the regular solution theory and based on the pseudophase separation model, some micellization and thermodynamic parameters were estimated by the Rubingh’s and the Clint’s models. The results indicate that the nonideal mixing of CAPHS with CTAB and the synergistic interaction between them play vital roles on the reduction of mixed cmc, the amplitude of synergistic interaction depends on the composition of mixture and the presence of glycerol induces the increase in the individual and mixed cmc values and the change of the participation of CAPHS in mixed micelle with the composition in bulk solution. The electrostatic repulsion, the diversity of molecular conformation and the steric hindrance can account for the formation of mixed micelle and the difference in micellar composition. Thermodynamic parameters show that the entropy makes overwhelming contributions on the spontaneous process of micellization, the release of mixing heat makes the stable mixed micelle formed and the presence of glycerol makes for reducing the contribution of entropy and forming the more stable mixed micelle. These findings help with understanding the interaction behavior between two species and the effect of glycerol and further providing some information for the design of the related surfactant formulations.

Synergistic interaction on quasi-binary mixture of amino sulfonate amphoteric surfactant with nonionic diethanolamide induced by glycerol and its concentration

Molecular interaction about a quasi-binary mixtures of an amino sulfonate surfactant, sodium 3-(N-dodecyl ethylenediamino)-2-hydroxypropyl sulfonate (DES), with a fatty acid diethanolamide derived from coconut oil (CDA) in aqueous solutions containing both the glycerol of 0.100 mol/L and 0.200 mol/L was investigated using the surface tension measurement. The interfacial parameters indicate that the mixing of DES with CDA can promote the formation of the more compact distribution of molecules adsorbed in the mixed monolayer, the mixing ratio of the mixture induces the difference in the adsorption behaviors at air–liquid interface, and the standard free energy of adsorption at air–liquid interface implies the benefit of adsorption and the change of adsorption behavior based on both the concentration of glycerol in solutions and the mixing ratio in the mixture. In the framework of pseudo-phase separation model, thermodynamic models including the Clint’s model, the Rubingh’s model and the Maeda’s model were employed to effectively estimate the related micellization and thermodynamic parameters. The nonideal mixing of DES with CDA and their synergistic interactions in the mixed micelle depend on both the mixing ratio of the mixture and the concentration of glycerol in solutions. The abundant amount of DES in mixed micelle will result in the absence of synergistic interaction in aqueous solutions containing the glycerol of 0.100 mol/L, and whereas the abnormal case does not again emerge on increasing the concentration of glycerol to 0.200 mol/L. The compatibility in molecular conformation, the steric hindrance, the electrostatic repulsion and the hydrogen-bond formation are adopted to theoretically explain the interaction behavior. Thermodynamic parameters obtained using the Maeda’s treatments also confirm the absence or the presence of synergistic interaction and the formation of stable mixed micelle. These findings will help with understanding the intermolecular behavior and the effect of alcohol concentration.

Micelle formation and physico-chemical variables for the sodium dodecyl sulfate/cetylpyridinium chloride and their mixture in aqueous propranolol hydrochloride drug solvent: Conductivity and theoretical analysis

Herein, study of both single and mixed micelle development of an anionic surfactant sodium dodecyl sulfate (SDS) and a cationic surfactant cetylpyridinium chloride (CPC) in propranolol hydrochloride (PPH) drug medium has been performed using a conductometric technique at different temperatures and compositions. The critical micelle concentration (CMC) along with degree of ionization (g) were assessed from the specific conductivity (κ) versus [surfactant] plots. Within the concentration of surfactant studied, a single CMC was achieved in the situations of pure and mixed surfactant micellization. The CMC and g values have been noticed reliant on the employed drug concentrations, variations of mole fractions of the mixture of surfactants and experimental temperature. For the micellization of single SDS/ CPC surfactants in aq. PPH drug medium, PPH drug causes delayed micelle development which has been detected as the upsurge of CMC values of SDS/CPC in PPH drug media. For the association of SDS/ CPC surfactants in aq. PPH drug medium, the CMC values experienced a lessening with the growth of study temperature. At a fixed temperature, the experimental CMC values, of the SDS + CPC mixture, endure a decline through the upsurge of mole fractions of CPC (α1), attain a minimum value and the CMC values tend to enhance at and above α1= 16.2 × 10-5. The ideal critical micelle concentrations (CMCid) are detected always as higher values than experimental CMC up to the α1= 10.8 × 10-5. The -β values and |β| > |ln(CMC1/ CMC2)| for the present study reveal that the interaction among the amphiphiles under analysis is synergistic. The negative free energy (-ΔGmO) of micellization were obtained throughout the study. The enthalpy (ΔHmO) and entropy (ΔSmO) of micellization reveal the presence of hydrophobic interaction as the principal type of interaction among the studied constituents. The negative excess free energy (ΔGex) values inferred that stable mixed micelles are formed for the mixture of SDS + CPC in aq. PPH drug medium. The micellar mole fractions (both experimental and ideal values), activity coefficients of components in mixed micelles as well as enthalpy–entropy compensation parameters were also measured and illustrated. It is possible that the knowledge gained from the current analysis may be used to enhance pharmaceutical formulations, drug delivery carriers, along with drug act proficiency.

Effects of ionic liquid on micellar aggregate formed by pluronic (F-127) and non-ionic surfactant (TX-100) in aqueous solution

Although ionic liquids have a great deal of application, a few of the most popular ones are in separations, battery electrolyte development, and electrocatalysis. The synergistic interaction between surface-active ionic liquid (1-hexadecyl-3-methylimidazolium chloride, SAIL) and pluronic (F-127)/non-ionic surfactant (TX-100) has been investigated at 298.15 K. The examined mixture's critical micelle concentration (cmc) values for various compositions are significantly lower than those of pure amphiphiles (due to the strong attractive interaction between components). In this study, the surface tension method was used to calculate the cmc values of single and mixed amphiphiles. The mole fractions of the components in the mixed micelle as well as the mixed monolayer and interaction parameter were specified by regular solution theory (RST) using the data from experimental observations. Several thermodynamic parameters were also calculated for the mixed micellization of SAIL with F-127/TX-100. In the current mixed systems, the data obtained show that the ΔGM and ΔGIdealM are negative while ΔSM is positive, implying a spontaneous process of micellization. Using Maeda's theory, it was found that the stability of mixed micelles in these systems depended profoundly on chain-chain interactions. UV-visible spectroscopy further supports the positive interaction between SAIL and nonionic surfactants. The SAIL absorption spectra demonstrate an increase in absorption with increasing surfactant concentrations without any shift, supporting the creation of a new complex. The F-127+SAIL mixture has a higher binding constant value, indicating that SAIL interacts with pluronic more effectively.

Mechanisms Underlying the Impacts of Lipids on the Diverse Bioavailability of Per- and Polyfluoroalkyl Substances in Foods.

Food is a major source of human exposure to per- and polyfluoroalkyl substances (PFASs), yet little is known about their bioavailability in food matrices. Here, the relative bioavailability (RBA) of PFASs in foods was determined using an in vivo mouse model. Pork, which had the highest lipid content, exhibited the greatest effect on bioavailability by increasing the RBAs of perfluoroalkyl acids (PFAAs) while reducing those of fluorotelomer phosphate diesters (diPAPs). During intestinal digestion of lipids, the bioaccessibility of PFAAs increased due to their greater partition into the stable mixed micelles. However, diPAPs were more likely to partition into the undigested oil phase due to their strong hydrophobicity. Both in vitro incubation and molecular docking results indicated that the PFAAs exhibited stronger binding affinities with mouse blood chylomicrons (CMs) than with diPAPs. Collectively, both lipid digestion in the intestine and the carrier effect of CMs played important roles in modulating the bioavailability of PFASs in food. More attention should be given to further evaluating the health risks of PFASs associated with the intake of high-lipid foods.

Physicochemical Characterization and Pharmacological Evaluation of Novel Propofol Micelles with Low-Lipid and Low-Free Propofol.

We developed safe and stable mixed polymeric micelles with low lipids and free propofol for intravenous administration, to overcome the biological barrier of the reticuloendothelial system (RES), reduce pain upon injection, and complications of marketed propofol formulation. The propofol-mixed micelles were composed of distearoyl-phosphatidylethanolamine-methoxy-poly (ethylene glycol 2000) (DSPE mPEG2k) and Solutol HS 15 and were optimized using Box Behnken design (BBD). The optimized formulation was evaluated for globule size, zeta potential, loading content, encapsulation efficiency, pain on injection, histological evaluation, hemolysis test, in vivo anesthetic action, and pharmacokinetics, in comparison to the commercialized emulsion Diprivan. The optimized micelle formulation displayed homogenous particle sizes, and the free drug concentration in the micelles was 60.9% lower than that of Diprivan. The paw-lick study demonstrated that propofol-mixed micelles significantly reduced pain symptoms. The anesthetic action of the mixed micelles were similar with the Diprivan. Therefore, we conclude that the novel propofol-mixed micelle reduces injection-site pain and the risk of hyperlipidemia due to the low content of free propofol and low-lipid constituent. It may be a more promising clinical alternative for anesthetic.

Interactions of tricyclic antidepressant drug chlomipramine hydrochloride with imidazolium based surface active ionic liquid in aqueous solution

Tricyclic antidepressant drug, Chlomipramine hydrochloride (CLP) with surface active ionic liquid (SAIL), 1-octyl-3-methylimidazolium chloride, was investigated using electrical conductivity. Various theoretical models were employed to calculate various interaction parameters and thermodynamic parameters. Different mole fractions of CLP with SAIL were studied to evaluate the critical micelle concentration (CMC) using electrical conductivity measurements. The change in Gibbs free energy of micellization, change in enthalpy of micellization, change in entropy of micellization, micellar mole fraction, χ1, of the CLP, and the interaction parameter, β, activity coefficients ƒ1 and ƒ2were calculated. The χIdeal and χ1 values were observed to increase on increasing the mole fraction of CLP from 0.4 to 0.6. This may be an indication of drug molecules being adsorbed on the micellar surface. As a result the mixed system (CLP and SAIL) were found to form stable mixed micelles.

Improving vitamin D3 stability to environmental and processing stresses using mixed micelles

Deficiency of vitamin-D is prevalent globally and can lead to negative health consequences. The fat-soluble nature of vitamin-D, coupled with its sensitivity to heat, light and oxygen limits its incorporation into foods. Mixed micelles (MM) have potential to enhance bioavailability of vitamin-D. This study explores the stability of MM to food processing regimes and their ability to protect vitamin-D. Subjecting MM to a range of shearing speeds (8,000–20,500 rpm) and to high pressure processing (600 MPa, 120sec) resulted in no change in MM size (4.1–4.5 nm). MM improved the retention of vitamin-D following exposure to UV-C light, near UV/visible light, and heat treatment. MM suspensions protected vitamin-D over a four week storage period at refrigeration or freezer conditions. Overall MM show potential to protect vitamin-D from degradation encountered in food processing and storage and may be beneficial as a mechanism to fortify foods with vitamin-D.

Vitamin D3 bioaccessibility: Influence of fatty acid chain length, salt concentration and l-α-phosphatidylcholine concentration on mixed micelle formation and delivery of vitamin D3

Vitamin D (VD) is a fat-soluble vitamin with high deficiency levels evident globally. Bioaccessibility of VD is influenced by formation of mixed micelles (MM) during digestion. This study assessed the impact of fatty acid (FA) type, phospholipid concentration on MM formation and stability of MM to salts. MM formation occurred at NaCl and KCl concentrations ranging from 20 to 100 mM, when octanoic acid (C8) or stearic acid (C18) were used. MM hydrodynamic size increased with increasing l-α-phosphatidylcholine concentration (1.5–7.5 mM) for both C8 and C18, above which concentration MM did not form. FA chain length impacted MM with hydrodynamic size increasing from 3.8 nm for decanoic acid (C10) to 4.4 nm for C18. VD3 incorporation in MM was not influenced by the FA used (C10 or C18). Understanding stability and formation of MM and VD3 loading is an essential first step towards manipulating food structures for improving delivery of VD.

Partitioning isotherm and kinetic of erythromycin into mixed reverse micelle during forward transfer

The capacity of AOT (sodium bis (2-ethylhexyl) sulfosuccinate) and SB3-12 (3-(N, N-dimethyldodecylammonio) propanesulfonate) mixed reverse micelle for erythromycin adsorption was assessed using the Langmuir, Freundlich, and Sips isotherm models. The kinetic of erythromycin transport was also evaluated using the two-film model. The results indicated that the Langmuir isotherm model exhibits the highest precision based on the regression coefficient data, however, this applies only for the condition of 80.0 to 160.0 g/L of AOT concentration. Error analysis revealed that for a condition where AOT concentration was low, the process fits the Freundlich isotherm model, suggesting that at a surfactant concentration around 20.0 g/L, forward transfer of erythromycin shows physisorption criteria. The Langmuir isotherm data for higher AOT concentration (80.0 g/L) denotes the chemisorption characteristics, by which erythromycin transfer was at the highest degree. This also signifies that high AOT concentration is a favourable condition where stable mixed reverse micelle was available and erythromycin adsorption was accelerated. In addition, the kinetic data complements the two-film theory for a flat interface model and shows that dissemination of erythromycin into the interfacial layer of mixed reverse micelles depended on surfactant concentration. Overall, this study confirms previous findings and contributes additional evidence for erythromycin extraction, under the influence of anionic-zwitterionic surfactant combination and shows superiority towards solubilising biomolecules.

Synthesis, characterization and mixed micellization study of benzene sulphonate based gemini surfactant with sodium dodecyl sulphate

Herein, we have shown the mixed micelle formation between anionic benzene sulphonate (viz., sodium 4,4′-(16,25-dioxo-15,17,24,26-tetraaza-hexatriacontane15,26-diyl) dibenzenesulphonate [BSC14-C6-14CSB] and sodium 4,4′-(18,27-dioxo-17,19,26,28-tetraaza-tetracontane15,26-diyl) dibenzenesulphonate [BSC16-C6-16CSB]) with conventional anionic surfactant (sodium dodecyl sulphate [SDS]) by conductivity and fluorometry methods. The conductivity measurements were done over a range of mole fractions of SDS at different temperatures to study the mixed micellization and thermodynamic parameters, while fluorescence measurements were performed over entire range of mole fraction of SDS in order to observe the aggregation and micro-polarity. The conductometric study confirms the synergism in all mole fractions of SDS with [BSC14-C6-14CSB] and [BSC16-C6-16CSB] at all temperatures. The Rubinghs regular solution theory (RST) was employed to evaluate micellar mole fraction, X1, ideal micellar mole fraction, Xideal, interaction parameter (β), activity coefficients (f1, and f2) for both mixed micelles systems and Gibbs excess free energy (GE). The GE values are negative for entire mole fraction range suggesting the formation of stable mixed micelles. In addition to this, other thermodynamic parameters like Gibbs free energy change of micellization (ΔGmic), enthalpy change of micellization (ΔHmic) and entropy change of micellization (ΔSmic) were evaluated. Also, the aggregation number (Nagg) in micelles was calculated using pyrene probe fluorescence measurement. The binding constant, dielectric constant and micropolarity of mixed systems of SDS + [BSC14-C6-14CSB] and SDS + [BSC16-C6-16CSB] binary mixtures were obtained from the ratio of peak strength (I1/I3) from the pyrene probe fluorescence emission spectra.

Conductometric and molecular dynamics studies of the aggregation behavior of sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB) in aqueous and electrolytes solution

Herein, we have studied the mixed micellization of Cetyltrimethylammonium bromide (CTAB) and Sodium dodecyl sulfate (SDS), in aqueous/various salts medium at several temperatures (298.15–318.15 K) by conductivity measurement method. The extent of interaction between CTAB and SDS was assessed from the values of ideal critical micelle concentration (cmcid) as well as experimental cmc. In attendance of salts, cmc values are obviously decreased from the corresponding values in aqueous medium. The magnitudes of micellar mole fraction of CTAB (X1) and activity coefficients of CTAB & SDS (f1 &f2) were estimated based on different theoretical model and outcome disclose the effective involvement of CTAB in the mixed micellization. The executed values of both interaction parameters (β) and excess free energy of micellization were negative signifying the attractive interaction and stability of mixed micelles respectively. The executed negative values of Gibbs free energy change of micellization, ∆Gom illustrate the spontaneous micellization of individual/mixed surfactant system. The other thermodynamic parameters ΔHom (enthalpy change), and ∆Som (entropy change) were also calculated from the conventional standard equations. Molecular level interactions are disclosed by molecular dynamics (MD) simulation which showed that salts promote more interactions between the surfactants.

Experimental and theoretical investigation of micellization behavior of sodium dodecyl sulfate with cetyltrimethylammonium bromide in aqueous/urea solution at various temperatures

Mixed micelle formation behavior of cationic surfactant-cetyltrimethylammonium bromide (CTAB) and anionic surfactant sodium dodecyl sulfate (SDS) in aqueous as well as in urea medium from 303.15 K to 323.15 K at 5 K interval was carried out by conductometric method. The differences between the experimental values of critical micelle concentrations (cmc) and ideal critical micelle concentrations (cmcid) illustrate the interaction between the amphiphiles studied. The values of micellar mole fraction ( $$\text{X}_1^{Rub}$$ (Rubingh), $$\text{X}_1^{M}$$ (Motomura), $$\text{X}_1^{Rod}$$ (Rodenas) and $$\text{X}_1^{id}$$ (ideal) of surfactant CTAB determined by different proposed models and outcome indicate high involvement of CTAB in SDS-CTAB mixed micellization, which enhance by means of the augment of mole fraction of CTAB. The negative value of interaction parameter (β) showed an attractive interaction involving CTAB and SDS. Activity coefficients were less than unity in all case, which also reveals the presence of interaction between CTAB & SDS. The negative $$\Delta{\text{G}}_m^0$$ values imply the spontaneous mixed micellization phenomenon. The attained values of $$\Delta{\text{H}}_m^0$$ were positive at inferior temperature, while negative at superior temperature. The negative $$\Delta{\text{H}}_m^0$$ values in urea (NH2CONH2) medium illustrate exothermic micellization process. The magnitudes of $$\Delta{\text{S}}_m^0$$ were positive in almost all cases. The excess free energy of mixed micelle formation (ΔGex) was found to be negative, which indicates the stability of mixed micelle as compared to the individual’s components micelles.

Stereocomplexed micelle formation through enantiomeric PLA-based Y-shaped copolymer for targeted drug delivery

In this study, a novel stereocomplexed micelle system was prepared from the self-assembly of enantiomeric PLA-based Y-shaped copolymers, i.e. folic acid-adamantane/β-cyclodextrin-b-[poly(D-lactide)]2 (FA-AD/CD-b-(PDLA)2) and poly(2-dimethylaminoethyl methacrylate)-b-[poly(L-lactide)]2 (PDMAEMA-b-(PLLA)2) in aqueous solution. The newly designed Y-shaped copolymer FA-AD/CD-b-(PDLA)2 was prepared by a combination of “click” reaction and host guest interaction between FA-AD and CD-b-(PDLA)2. In addition, enantiomeric Y-shaped PDMAEMA-b-(PLLA)2 copolymer was synthesized through ring-opening polymerization (ROP) of L-lactide using three-head initiator with bromo and –OH at distal ends, followed by atom transfer radical polymerization (ATRP) of DMAEMA to obtain the desired macromolecular architecture. The resultant copolymers and their intermediates were characterized by 1H nuclear magnetic resonance (1H NMR) and gel permeation chromatography (GPC) techniques. Due to the strong stereocomplexation interaction, FA-AD/CD-b-(PDLA)2 and PDMAEMA-b-(PLLA)2 mixture could self-assemble into stable mixed micelles in aqueous solution. Further, the stereocomplexed micelles exhibited excellent biocompatibility as revealed in the cytotoxicity assay. Together with the intrinsic biodegradability of PLA, it is envisioned that the stereocomplexed micelles developed in this study can be used as a promising nanocarrier for targeting drug delivery.

Conductometric Probe Analysis of the Effect of Benzyldimethylhexadecylammonium Chloride on the Micellization Behavior of Dodecyltrimethylammonium Bromide in Aqueous/Urea Solution: Investigation of Concentration and Temperature Effect

AbstractSurfactant mixtures are used in many different industrial formulations. In this study, the mixed micelle formation behavior of 2 different cationic surfactants, namely dodecyltrimethylammonium bromide (DTAB) and benzyldimethylhexadecylammonium chloride (BDHAC), in the absence and presence of urea at various temperatures (298.15–318.15 K) was studied using the conductometric method. The attractive interaction between DTAB and BDHAC was estimated from the values of critical micelle concentration (CMC) and the CMC for ideal mixing (CMCid). Urea increases the CMC value as a result of the enrichment in the surface charge of the micelles/mixed micelles. The values of micellar mole fraction (X1Rub [Rubingh], X1M [Motomura], X1Rod [Rodenas]) and ideal micellar (X1id) of surfactant BDHAC were obtained by different models and are shown to exhibit the high contribution or effective involvement of BDHAC in mixed micelles and increase with increasing BDHAC mole fraction (α1). Activity coefficients (f1 and f2) were also evaluated from the relevant formula given in the literature. The negative values of the interaction parameters (β) show the attractive interaction among the studied components. Excess Gibbs free energy (∆Gex) of micellization revealed that the stability of mixed micelles is higher in aqueous solution than in urea solution. The thermodynamic parameters, namely the Gibbs free energy change, enthalpy change, and entropy change (∆Gom, ΔHom, and ∆Som, respectively), were also calculated from the conventional standard equations.

Binary mixed micellar systems of PEO-PPO-PEO block copolymers for lamotrigine solubilization: a comparative study with hydrophobic and hydrophilic copolymer

Polyethyelene oxide-polypropylene oxide-polyethyelene oxide, PEO-PPO-PEO triblock copolymers, Pluronics® are considered to be the best nanocarrier for hydrophobic substances on account of their wonderful solubilization power over other ionic and non-ionic surfactants. In the present manuscript, the Pluronic® binary mixtures (two systems, F127/P123 and F127/L35) as micellar nanocarriers for solubilization of lamotrigine (LTG) drug were investigated through UV-Visible spectroscopy, dynamic light scattering (DLS) and small angle neutron scattering (SANS) analysis. Both the binary systems form stable mixed micelles had low CMC in water. The CMC of binary systems, F127/P123 was located in the middle of the CMC of each copolymer, but it was slightly increased in the F127/L35 mixed systems. Results of DLS and SANS data were proven the spherical shape of micelles for both the binary systems with less than 30-nm diameter in sizes. Not much but mixed micelle became slightly larger after solubilizing of LTG drug. The solubilization capacity (SCP) of the binary systems was monitored using UV-Visible spectroscopy. The F127/P123 system shows relatively high solubilization capacity (SCP) due to a more hydrophobic system as copolymers with similar PPO block lengths. The F127/L35 system has been given the low SCP because of hydrophilic nature of L35. The micellar water partition coefficient (P) and Gibbs free energy changes (ΔG°) of solubilized LTG drug were also evaluated from a thermodynamics viewpoint. In conclusion, these binary micellar systems may be considered as the effective nanocarriers for LTG drug and F127/P123 mixed micelles proven better than the F127/L35 system for LTG drug.

Synergistic Interaction between Nonionic Octylphenol Polyoxyethylene Ethers and Effect of Hydrophilic Chain

AbstractThe micellization of binary mixture composed of nonionic octylphenol polyoxyethylene ether (OP‐n, n is the average number of oxyethylene unit) and its homologues, as well as the effect of hydrophilic chain were investigated. The tensiometry was adopted to determine the critical micelle concentration of binary surfactant mixture. According to the regular solution theory, some thermodynamic models were used to predict the parameters of micellization and the thermodynamic parameters. For all the three binary mixtures of nonionic/nonionic surfactants, each of which shows a nonideal mixing and can behave synergistically in aqueous solution. For both the mixture of OP‐10/OP‐7 and the mixture of OP‐10/OP‐4, the positive deviation of the mole fraction of surfactant in mixed micelle from its ideal value coexists with the negative deviation in the entire range of compositions in aqueous solution, while for the mixture of OP‐7/OP‐4, it only shows a positive deviation. Thermodynamic data indicate that for all the three binary surfactant mixtures, the process of micellization is entropically spontaneous, and the change of hydrophilic chain results in the difference in the stability of mixed micelle. The results can be explained by the steric effect, the hydrogen bonding and the hydration. The work helps with understanding the interaction between molecules and properties for some industrial products constituted by nonionic surfactant and its homologues.

Effect of anionic surfactant and temperature on micellization behavior of promethazine hydrochloride drug in absence and presence of urea

The interaction between promethazine hydrochloride (PMH) drug and sodium dodecyl sulfate (NaDS) have been carried out conductometrically at various temperatures and concentration to examine the monomeric as well as micellar phases of aqueous solutions of mixed systems in absence and attendance of urea (NH2CONH2). PMH is belonged to the group of drugs called phenothiazines and is employed to care for allergy symptoms. Urea increases the cmc value because of enhancement in the surface charge of the micelles/mixed micelles. Relevant parameters were evaluated using the various theoretical models for binary mixed systems. The values of micellar mole fraction (X1m) and the ideal micellar mole fraction (X1id) were found to higher than the corresponding mole fraction (α1) of surfactant. The micellar interaction parameters (β), were determined from the critical micelle concentration (cmc) values using the approach of Rubingh's regular solution theory. Clint's model was also used to explain the nonideal behavior of the systems. In presence of urea the interaction between the studied components decreases. The evaluated excess free energy (ΔGexRub) explains the more stability of mixed micelles in comparison to micelles of the pure component; the stability decreases in attendance of urea. Also, activity coefficients (f1 and f2) are always less than unity suggesting non-ideality in the mixed solution. The ΔG0m for all studied systems were found out to be negative i.e., micellization processes are energetically favourable.

Comparison of bile salt/phosphatidylcholine mixed micelles in solubilization to sterols and stability.

Androst-3β,5α,6β-triol (Triol) is a promising neuroprotective agent, but its poor solubility restricts its development into parenteral preparations. In this study, Triol is significantly solubilized by bile salt/phosphatidylcholine mixed micelles (BS/PC-MM). All BS/PC-MM systems are tested to remarkably improve the drug solubility with various stabilities after drug loading. Among them, the sodium glycocholate (SGC)/egg phosphatidylcholine (EPC) system with 2:1 ratio in weight and the total concentration of SGC and EPC of 100 mg/mL is proved to produce stable mixed micelles with high drug loading. It is found that the stability of drug-loaded mixed micelles is quite different, which might be related to the change in critical micelle concentration (CMC) after incorporating drugs. SGC/EPC and SGC/soya phosphatidylcholine (SPC) remain transparent under accelerated conditions and manifest a decreased CMC (dropping from 0.105 to 0.056 mg/mL and from 0.067 to 0.024 mg/mL, respectively). In contrast, swine bile acid-sodium salt (SBA-Na)/PC and sodium deoxycholate (SDC)/PC are accompanied by drug precipitation and reached the maximum CMC on the first and the third days, respectively. Interestingly, the variation of CMC under accelerated testing conditions highly matches the drug-precipitating event in the primary stability experiment. In brief, the bile salt/phosphatidylcholine system exists as a potential strategy of improving sterol drug solubility. CMC variation under accelerated testing conditions might be a simple and easy method to predict the stability of drug-loaded mixed micelles.