Critical Micelle Concentration Of Cetyltrimethylammonium Bromide Research Articles

In vitro solubilization of antibiotic drug sulfamethazine: An investigation on drug–micelle aggregate formation by spectroscopic and scattering techniques

AbstractMicellar solubilization has been used extensively for the dissolution of sparingly soluble drugs for effective drug delivery. Apart from improving the solubility and bioavailability, micelles can help reduce toxicity and improve permeability in the system. In this article, solubilization of a well‐known antibiotic, sulfamethazine (SMZ) upon micellization, is studied by employing various spectroscopic and scattering techniques like, ultraviolet–visible, fluorescence, small angle neutron scattering (SANS), and zeta potential (ZP) studies. The size(s) and charge(s) of the micelles were monitored by SANS and ZP. A positively charged/cationic surfactant, cetyl trimethyl ammonium bromide (CTAB) and a negatively charged/anionic surfactant, sodium dodecyl sulfate (SDS) are used for micelle formation. Regardless of the surfactant type, the solubility of SMZ increases linearly with the increase in the surfactant concentration, as a result of association between the drug and micelles. However, the solubility of SMZ is found to be better with CTAB than SDS. Upon interaction with SMZ, we observed that the critical micelle concentration of CTAB occurred at a lower concentration than that of SDS surfactant. As fitted in the ellipsoidal core–shell model, SANS results also show the formation of charged micelles. This comparative study can help us to select an appropriate medium for SMZ solubilization to improve selective drug delivery in biomedical applications.

Surface and associated studies between Coomassie brilliant blue G250 and CTAB in Aqueous Solution

The interaction of surfactant cetyltrimethylammonium bromide (CTAB) with anionic dye Coomassie brilliant blue G250 (CBBG250) in aqueous solution and its effect on the formation of CTAB micelles were studied by UV-Vis spectrophotometry and electrical conductivity methods. By establishing the micellar model and measuring the electrical conductivity of CTAB in CBBG250 aqueous solution, we get the values of the critical micelle concentration at different temperatures from 298.15K to 338.15K, which are essentially the same as the range of concentrations of regular change in absorbance. It suggests that the critical micelle concentration of CTAB in CBBG250 aqueous solution is larger than in aqueous solution because some surfactant molecules in micelles are associated with CBBG250 molecules.

Chiral Plasmonic Nanochains via the Self-Assembly of Gold Nanorods and Helical Glutathione Oligomers Facilitated by Cetyltrimethylammonium Bromide Micelles.

Gold nanorods are excellent anisotropic building blocks for plasmonic chiral nanostructures. The near-infrared plasmonic band of nanorods makes them highly desirable for biomedical applications such as chiral bioimaging and sensing, in which a strong circular dichroism (CD) signal is required. Chiral assemblies of gold nanorods induced by self-associating peptides are especially attractive for this purpose as they exhibit plasmonic-enhanced chiroptical activity. Here, we showed that the presence of cetyltrimethylammonium bromide (CTAB) micelles in a gold nanorod solution promoted the self-association of l-/d-glutathione (GSH) and significantly enhanced the chirality of the resulting plasmonic nanochains. Chiroptical signals for the ensemble in the presence of CTAB micelles were 20 times greater than those obtained below the critical micelle concentration of CTAB. The strong optical activity was attributed to the formation of helical GSH oligomers in the hydrophobic core of the CTAB micelles. The helical GSH oligomers led the nanorods to assemble in a chiral, end-to-end crossed fashion. The CD signal intensities were also proportional to the fraction of nanorods in the nanochains. In addition, finite-difference time-domain simulations agreed well with the experimental extinction and CD spectra. Our work demonstrated a substantial effect from the CTAB micelles on gold nanoparticle assemblies induced by biomolecules and showed the importance of size matching between the inorganic nanobuilding blocks and the chiral molecular templates (i.e., the GSH oligomers in the present case) in order to attain strong chiroptical activities.

The self-assembly of twinned boehmite nanosheets into porous 3D structures in ethanol–water mixtures

Surfactant molecules have high surface activity, and can therefore influence the self-assembly of nanomaterials. The self-assembly of twinned boehmite nanosheets into porous 3D superstructures will be greatly affected by the presence of surfactant monomer and micelles in various ethanol–water mixtures. It should be possible to influence the shape, thickness, and twinning of boehmite nanosheets by varying the concentration of the surfactant and ethanol in the synthesis mixture to obtain high porosity 3D superstructures. The critical micelle concentration (CMC) of cationic surfactant cetyl trimethylammonium bromide (CTAB) was determined in 0, 12.5, 25, 37.5, and 50 vol% ethanol–water mixtures. The effect of CTAB on boehmite particle morphology and superstructure formation during self-assembly was explored at the CMC, and at 20%, 15%, 10%, 5% below and above the CMC of CTAB in various ethanol–water mixtures. Boehmite nanosheets with controllable shape and thickness were successfully formed in various ethanol–water mixtures. Prior to micelle formation, the average thickness of nanosheets formed in 0 vol%, 25 vol%, and 50 vol% ethanol–water were 200 nm, 110 nm and 100 nm, respectively. Micelle formation reduced the availability of surfactant molecules for particle templating, broadening the nanosheet thickness distribution. Micelle formation was inhibited in 50 vol% ethanol–water due to the increase in Gibbs free energy needed to form micelles relative to the Gibbs free energy of micelles in 0 vol% or 25 vol% ethanol–water. The enthalpy-driven process gives greater control over the nanosheet thickness, producing particles with narrow thickness distributions. In general, the CMC represented the point at which control is lost over the thickness of the nanoplatelets; increasing the surfactant concentration above the CMC increased the thickness of the nanoplatelets. Particle twinning during crystal growth produced an interconnected 3D network of boehmite particles with high porosity (79–88%) and hydraulic permeability (62.4–809 mD). The addition of ethanol during synthesis increased the porosity and reduced the bulk density of the 3D superstructures by 8–11% and 26–28%, respectively, and yielded a ten-fold increase in the hydraulic permeability. The integrity of the porous 3D network was maintained upon calcination, suspension in water and deposition by filtration onto cellulose filter paper.

Interfacial Water Structure at Surfactant Concentrations below and above the Critical Micelle Concentration as Revealed by Sum Frequency Generation Vibrational Spectroscopy

Interfacial water in close proximity to an adsorbed surfactant layer plays an important role in many areas. Here, we systematically investigate the interfacial water structure at the adsorption layer of cetyltrimethylammonium bromide (CTAB) from low concentrations to its critical micelle concentration. Our sum frequency generation (SFG) spectroscopy results show that, with increasing CTAB concentration, the water SFG signals first increase, reaching maximum intensities at 0.1 mM, and then drop, whereas the ppp SFG signals of the terminal-methyl asymmetric stretch reach maximum intensities and saturate at 1 mM, which is the critical micelle concentration of CTAB. Our analysis reveals that the interfacial water layer adopts the most orderly arrangement when the interfacial potential of the adsorption layer reaches saturation and not at the surfactant concentration of adsorption saturation. Most importantly, our SFG data provide direct evidence for the antagonistic effects of the interfacial potential and thickness compression of the electrostatic field of the surfactant adsorption layer, leading to the strongest water SFG signals at 0.1 mM. Below 0.1 mM, the increased interfacial potential can have a pronounced effect on the increase of the overall dipole moment of the interfacial water layers. Above 0.1 mM, the decreased Debye screening length significantly reduces the water dipole moment. Finally, the newly proposed adsorption model cannot explain our SFG results.

Dissipative particle dynamics simulations of surfactant CTAB in ethanol/water Mixture

Dissipative particle dynamics is used to study the self-assembly and surface tension of a surfactant cetyl trimethylammonium bromide (CTAB) in ethanol/water mixture. With a simple spring and bead model, we investigate how ethanol influences the aggregation structure and the ability to reduce the surface tension of CTAB. It is not the surfactant total concentration, but the bulk concentration, that should be employed to describe the surfactant's properties accurately. The results show that ethanol may produce inhibition for micellar growth and enlarge the critical micelle concentration of CTAB. We further discuss the impact of the conservative international parameter between head and head (), which has a close relationship to counterions. It is found that the decrease of has the effect to enlarge the efficiency of CTAB.

Effects of Sodium Bromide Salt and Temperature on the behaviour of Aqueous Solution of Cetyltrimethylammonium Bromide

The effects of sodium bromide(NaBr) salt and temperature on the aggregation behaviour of cetyltrimethylammonium bromide (CTAB) have been studied using conductivity data.Conductivity was observed to vary increasingly with both temperature and salt concentration. The critical micelle concentration (CMC) of CTAB decreased with increase in the concentration of NaBr but increased as temperature increased. For example,the CMCs of CTAB in 0.0 and 10.0mM solutionsof NaBr at 30 °C were 1.68 and 1.50 mMrespectively while those of the same concentrations at 35 °C were 1.84 and 1.63respectively.It wasalso found that both salt and temperature influenced the degree of micelle ionization as well as the free energy of micellization. Results also showedthat the stability of CTAB micelles was enhanced by adding NaBr molecules.These observations have been discussedin terms of the electrostatic repulsion of charged CTAB head group.

Kinetic investigations on alkaline fading of malachite green in the presence of micelles and reverse micelles

The kinetics of alkaline hydrolysis of malachite green (MG+) have been studied spectrophotometrically in the presence of cetyltrimethylammonium bromide (CTAB) under pseudo-first-order condition at buffered of pH11 and 298K. The rate increases slightly up to the critical micelle concentration of CTAB then increases rapidly for surface catalysis of the micelles. The reaction has also been studied in the water pools of the CTAB/1-butanol/heptane/water reverse micelles and found 4–8 times faster over its rate in aqueous phase but the rate decreases exponentially with its water pool (w) size. The CTAB micellar medium has been characterized using steady state emission spectroscopy and tensiometry at the reaction condition for better explanation of the experimental findings. The thermodynamic activation parameters for the hydrolysis reaction have also been determined for comparison of the kinetic behavior in different environments.

Micellar catalysis of oxidation of glycolic acid by N-bromophthalimide

Catalysis of oxidation of glycolic acid by N-bromophthalimide by micelles of cetyltrimethylammonium bromide (CTAB) at 318 K was investigated. The observed value of critical micelle concentration of CTAB in the presence of other components was lower than those reported in the literature. The oxidation reaction was strongly catalyzed by cationic micelles of CTAB. The reaction rate increased with CTAB concentration until the steady state was achieved. The reaction kinetics corresponded to first, fractional and inverse fiactional orders with respect to changes of concentration of reaction components. Effects of solvent, phthalimide, mercuric acetate, and potassium chloride on the reaction kinetics were also studied. The micelle-catalyzed oxidation reaction was shown to fit Arrhenius equation. The experimental data were rationalized in terms of Menger-Portnoy model considering a distribution of the reactants between the micellar and aqueous phases.

Interaction of 4-aminosalicylic acid and surfactants in aqueous solutions using UV-Vis spectra and steady-state fluorescence spectroscopy

The interactions of 4-aminosalicylic acid (4-ASA) and surfactants in aqueous solutions were investigated by using UV-Vis spectra and steady-state fluorescence spectroscopy. The results showed that the strongest peak at UV-vis spectra of 4-ASA aqueous solution in the presence of cationic surfactant and cetyltrimethyl ammonium bromide (CTAB) appeared at 206 nm and took a red shift from 206 nm to 221 nm with the increase of 4-ASA concentrations from 0.8×10−5 to 4.4×10−4 mol/L. Similarly, the strongest peak at UV-vis spectra of 4-ASA aqueous solution in the presence of nonionic surfactant and polyvinylpyrrolidone (PVP) appeared at 206 nm and took a red shift from 206 nm to 219 nm with the increase of 4-ASA concentrations from 0.8×10−5 to 4.4×10−4 mol/L. However, the similar phenomena did not appeared in the presence of anion surfactant, sodium dodecyl sulfate (SDS), the UV-vis spectra of 4-ASA aqueous solution remained the same peak position and the peak value increased with the 4-ASA concentration increase. The results could be attributed to the electrostatic attraction between 4-ASA and CTAB or PVP, as well as the electrostatic repulsion between 4-ASA and SDS. Furthermore, the value of critical micelle concentration (CMC) of surfactants in the presence of 4-ASA was determined with Fluorescence method. The first and second CMC of CTAB was 1.2× 10−4 M and 2.4×10−4 M, respectively. The first and second CMC of PVP was 1.2×10−4 M and 2.8×10−4 M. SDS realized the multiple micellizations to form multiple CMC.

Conductometry and Thermodynamic Study of Micellization of Cetyltrimethylammonium Bromide in Mixed Solvents Containing Dilute Electrolyte Solutions

Abstract The critical micelle concentration (CMC) of Cetyltrimethyl ammonium bromide (CTAB) was determined conductometrically in binary mixtures of water + cosolvent at various temperatures and at low concentrations of sodium chloride, ranging from 0.0 to 2.4 × 10−2 M. Dimethylsulfoxide (DMSO) and acetonitrile (AN) were used as cosolvents added to water. The ability of NaCl to lower the CMC of CTAB in water was inhibited by DMSO and AN. Thermodynamic parameters of micellization ΔHo m, ΔSo m, and ΔGo m were evaluated according to the pseudo-phase model. The contribution of DMSO and AN in the micellization process of CTAB in aqueous electrolyte solutions were discussed in terms of the observed thermodynamic properties.

Physicochemical Studies on the Interfacial and Micellization Behavior of CTAB in Aqueous Polyethylene Glycol Media

AbstractInterfacial and micellization behavior of cetyltrimethylammonium bromide (CTAB) have been studied in aqueous polyethylene glycol (PEG) mixed solvent systems of varying concentrations and molar mass. Interfacial behavior of CTAB was investigated by the equilibrium surface tension method. Conductance studies of surfactant solutions under different condition helped in determining the critical micelle concentration (CMC) and degree of dissociation of CTAB micelles. In addition, the limiting molar conductivity of surfactant and micellar species were evaluated from the differential plots. The CMC of CTAB was found to increase with increasing PEG concentration as well as its molar mass, although, the process of interfacial adsorption and micellization was found to be spontaneous, as evidenced by negative free energy change. The viscosity of CTAB micelles in aqueous‐PEG mixtures was found to increase with the increase in PEG concentration and molar mass. Dynamic light scattering measurements revealed a size enhancement effect contributed by the PEG oligomers. An increase in the CMC of CTAB and the subsequent presence of a higher number of ionic species in their dissociated form was further established by an overall increase in the zeta potential value in the presence of PEG oligomers. It is proposed that the PEG could wrap around the micelles through their conformational changes. Results also suggest that PEG oligomers could give solvophobic effect which enhances the CMC of CTAB compared to that in pure water.

Spectroscopic analysis of naphtholazobenzimidazole in organised solution

Micelle–water partition coefficient (Kx ) of naphtholazobenzimidazole dye (NAB) in aqueous solutions of cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulphate (SDS) has been determined spectrophotometerically. Changes in absorption patterns of dye caused by surfactants and solvents were quantified in terms of dye–surfactant ratio (n D/n S) and solvent water partition coefficients (P), respectively. Multiple residence sites have been suggested for dye molecules within micelles, based on shifts in azo-hydrazone tautomeric equilibrium. Micelle–water partition coefficients were used to evaluate the influence of dye on critical micelle concentration of CTAB and SDS. At same micelle concentration, M, the relative solubility of NAB was greater in cationic surfactant CTAB than in anionic surfactant SDS.

Association Behavior of 3,4-Dihydroxy-9,10-dioxo-2-anthracenesulfonic Acid Sodium Salt in Cationic Surfactant Medium Under Different pH Conditions

Ultraviolet (UV)-visible behavior of 3,4-dihydroxy-9,10-dioxo-2-anthracenesulfonic acid sodium salt (ARS) has been studied at pH 4.0, aqueous medium, and at pH 10.0. The effects of cetyl trimethylammoniumbromide (CTAB) on the UV-visible spectra of ARS have been evaluated qualitatively as well as quantitatively in the different concentration regions of CTAB. The shift in the UV-visible spectrum of ARS, due to CTAB, at its low concentration is comparable to the shift shown by the same at pH 10.0. In acidic and basic pH, effect of CTAB is significantly lowered on the UV-visible spectra than ARS in the purely aqueous medium. In aqueous and basic medium, lower values of partition and binding constant are obtained compared to the one obtained in acidic medium. Conductivity studies show that increasing dye concentrations have no effect on its partitioning behavior nevertheless critical micelle concentration of CTAB is lowered.

Interaction of Azo Dye with Cationic Surfactant Under Different pH Conditions

AbstractThe aggregation induced by Alizarin Yellow R (AYR) in the cationic surfactant, cetyltrimethylammonium bromide (CTAB), was investigated by measuring their UV–visible absorption spectra. Conductance measurements as a function of surfactant concentration below and above the critical micelle concentration (CMC) were studied. CTAB aggregation takes place at the concentration far below its normal CMC in the presence of AYR. Both hydrophobic and electrostatic interactions affect the aggregation process in aqueous solution. The dye effect on the CMC of CTAB was noted by a specific conductivity method as well. AYR–CTAB binding constant (Ks) and water–micelle partition co‐efficient (Kx) were quantified with the help of mathematical models employed to determine the partitioning of organic additives in the micellar phase. The number of dye molecules per micelle was estimated at particular CTAB concentrations above CMC, during this study.

Organization of amphiphiles: Part X: Studies on the interaction between polyoxyethylated (30) octylphenol and cetyltrimethylammonium bromide in aqueous solution

The solution behavior of the mixture of cetyltrimethylammonium bromide (CTAB) and polyoxyethylene (30) octylphenol (OP-30) has been investigated by measuring the conductance, fluorescence intensity, surface tension and absorbance of the surfactant mixtures. A strong interaction between the two surfactants is indicated from each of the measurements. The critical micelle concentration of CTAB is found to increase with increase in the amount of OP-30 in the mixture. This delaying in micellization of CTAB has been attributed to the diminution of its effective hydrophobicity due to interaction with monomers or micelles of OP-30. Below CMC of OP-30, the monomeric concentration of CTAB decreases due to the formation of a hydrophobic complex between OP-30 and CTAB. Above CMC of OP-30, CTAB monomers get solubilized into micellar core of OP-30 in 1:1 stoichiometric ratio. Micropolarity and the aggregation numbers of the mixed systems have been determined from fluorescence studies. The thermodynamics of micelle formation of CTAB coupled with fluorescence studies of the mixtures indicates that the complex grows in size with increase of OP-30 concentration till the micelle of latter is formed at higher concentrations. The treatment of theoretical model to the interaction of OP-30 and CTAB yields a positive interaction parameter showing antagonism behavior. A schematic model of interaction of OP-30 with CTAB below and above its CMC has been suggested.

Self-assembly of cetyl trimethylammonium bromide in ethanol-water mixtures

The critical micelle concentration (CMC) of cetyl trimethylammonium bromide (CTAB) in both water and ethanol-water-mixed solvent was determined using steady-state fluorescence techniques in order to investigate the effect of the self-assembling properties of the surfactant on the template synthesis of porous inorganic materials. Results indicated that the CMC increased with the increase of ethanol concentration in the mixed solvent. The CMC of CTAB is 0.0009 mol/L in water, while it is 0.24 mol/L in ethanol. Furthermore, the dissipative particle dynamics (DPD) was adopted to simulate the aggregation of CTAB in water and ethanol/water mixtures, and the energy difference was calculated for the surfactant tail groups after mixing with the solvent. The simulation results reflected a regularity similar to the experimental data, i.e., tail groups of CTAB interacted more strongly with ethanol than with groups of CTAB interacted more strongly with ethanol than with water, which elucidates the reason that the micelle is difficult to form in ethanol.

Structural investigations on Quinone Methides for understanding their properties in confined media

Encapsulation of 4−[(4′-hydroxy−3′,5′-dimethylphenyl)(aryl)-methylene]−2,6−dimethyl-cyclohexa−2,5−dienones (when aryl=4−hydroxyphenyl 1, 4−methoxyphenyl 2, 2,3,4-trimethoxy phenyl 3) by β-cyclodextrin is studied. The compound 2 is selectively encapsulated by β-cyclodextrin. The result is rationalised by analysing the structural parameters from the crystal structure of 1–3. The visible spectra of the compounds 2 and 3 at pH 9.0 show red shifts on the absorption maxima upon addition of cetyltrimethylammonium bromide (CTAB). For example, addition of a solution of CTAB to aqueous ethanolic solution of 2 at pH 9 causes shift of the absorption at 578–593 nm (Δλmax=15 nm). The advantage of this observation is taken to use 2 and 3 to determine the critical micelle concentration of CTAB in basic medium.

Effect of cationic micellar aggregates on the kinetics of oxidation of aminoalcohols by N-bromosuccinimide in alkaline medium

The kinetics of oxidation of some aminoalcohols (AA), viz. ethanolamine, diethanolamine, and triethanolamine, by N-bromosuccinimide (NBS) in alkaline medium has been investigated in the absence as well as in the presence of cetyltrimethylammonium bromide (CTAB), a cationic surfactant. The reaction always followed a first-order dependence of rate on NBS, while the order in each AA and alkali was found to decrease from unity to zero at higher [AA] and [OH −], respectively. The reaction is strongly catalyzed by CTAB even before the critical micelle concentration (CMC) of CTAB. However, the observed rate constants attained constancy at higher [CTAB] (>CMC of CTAB). The premicellar kinetics has been rationalized in the light of the Piszkiewicz positive cooperativity model [J. Am. Chem. Soc. 99 (1977) 1550]. The binding constants between the reactants and the surfactant have also been evaluated using the Raghvan and Srinivasan model [Proc. Ind. Acad. Sci. 98 (1987) 199], which is applicable to bimolecular micellar catalyzed reaction and predicts constancy in the observed rate constant at higher [surfactant]. The binding constants obtained by both the models are in good agreement.

Adsolubilization and Stability Characteristics of Hydrocarbon Aggregates Chemically Bonded to Porous Silica

The desorption of surfactant may be a problem in the development of admicellar catalysis for organic synthesis or for wastewater cleanup. The formation of hydrocarbon aggregates chemically bonded to mineral oxide surfaces has been investigated to solve this problem. In this study, octadecyltrichlorosilane (ODS) was chemically bonded with silanol groups of a silica surface. The adsolubilization capabilities and stability of the bonded ODS were then studied and compared to those of physically adsorbed aggregates of cetyltrimethylammonium bromide (CTAB). The adsorption of ODS increases with increasing ODS concentration in the bulk phase and reaches a constant value when the equilibrium ODS concentration is higher than 17 000 μM. The maximum ODS adsorption of 340 μmol/g is slightly higher than that of CTAB (300 μmol/g). The critical micelle concentration of CTAB is approximately 3000 μM. The adsolubilization of two organic substrates, trichloroethylene (TCE) and phenol, was also measured. The adsolubilization of TCE was similar in CTAB and bonded ODS, while the phenol adsolubilized to a greater extent in CTAB than in ODS. The bonded ODS was stable under agitation up to 310 rpm and temperatures below 40 °C. The pH value has very little effect on ODS debonding. The rate of oxidation of ODS by ozone increases with increasing ozone concentration, but pH has no effect on ODS oxidation.