Cetyltrimethylammonium Bromide Micelles Research Articles

Insights into the role of ionic surfactants on the morphology of gold and gold@silver nanoparticles

Cyanidin-3, 5-di-O-glycoside (anthocyanin) was extracted from the red rose flower petals in an aqueous media. Anthocyanin was used as reductant to the preparation of gold nanoparticles with cationic and anionic surfactants. UV–visible absorption spectroscope, transmission electron microscope, scanning electron microscope, and energy dispersive X-ray spectroscope were employed to determine absorption bands of anthocyanin, surface Plasmon resonance (SPR) band, and morphology of the gold and gold@silver nanoparticles. Anthocyanin exhibited two absorption peaks at 284 and 518 nm, and one shoulder at 328 nm in the UV–visible spectrum. The intensity of these peaks decreases with time after the addition of HAuCl4. The color and the position of SPR band of gold nanoparticles depend on the concentration of gold salt with and without cetyltrimethylammonium bromide (CTAB), and sodium dodecyl sulfate (SDS). The anionic and cationic head groups of SDS and CTAB micelles have significant impact of the morphology of gold nanoparticles. Seedless co-reduction method was used for the synthesis of gold@silver nanoparticles. TEM images clearly indicate the formation of bimetallic gold@silver core-shell nanoparticles. The antioxidant power of AuNPs and gold@silver nanoparticles were tested in terms of the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity as a function of different concentrations of nanoparticles.

Effect of CTAB premicelle and micelle formation on Bromophenol Blue spectra

AbstractThe interactions between surfactants and dyes in aqueous solutions are essential for gaining insights into dyeing processes across various industries and for driving advancements in chemical research. This paper investigates the interaction between the anionic dye bromophenol blue (BPB) and the cationic surfactant cetyltrimethylammonium bromide (CTAB) in aqueous solutions. It was observed that the absorbance value at the maximum absorption peak of BPB changes systematically with increasing CTAB concentration, revealing the critical premicelle concentration (cpc) and critical micelle concentration (cmc) of CTAB. Employing a micellization model and measuring the electric conductivity across different concentrations of CTAB, the micellization thermodynamic parameters of CTAB, both in the absence and presence of BPB, were determined. The findings indicate that the associative interaction between BPB and CTAB significantly influences the formation of CTAB micelles.

Kinetics and mechanism of methyl linoleate oxidation in cetyltrimethylammonium bromide micelles

Kinetics and mechanism of methyl linoleate oxidation in cetyltrimethylammonium bromide micelles

Surfactant-induced alterations in optoelectronic properties of perylene diimide dyes: modulating sensing responses in the aqueous environment.

The compartmentalization effect of microheterogeneous systems, like surfactant aggregates, showcases altered optoelectronic properties of a perylene diimide-based chromogenic dye (PDI-Ala) compared to bulk water. The relatively hydrophobic microenvironment, poor hydration, and exceptionally large local concentration of dye molecules in the confined environment affect their interaction with target analytes. This realization intrigued us to investigate if micellization can modify the sensing properties (selectivity, sensitivity, response kinetics, output signal, etc.) of the encapsulated dye molecules in the aqueous medium. Response comparisons of PDI-Ala to the ionic analyte (Fe3+) and biomolecule (heparin) in aqueous and surfactant-bound states highlighted significant variations. Fe3+ interaction exhibited a "turn-off" fluorescence response in a water medium, while surfactant-bound conditions triggered "turn-on" fluorescence, enhancing selectivity at the micelle-water interface. Conversely, the native probe showed no interaction with heparin in water but displayed a turn-on fluorescence response in cetyltrimethylammonium bromide (CTAB) micelles, indicating the transformation of a silent molecule into a turn-on fluorescence sensor. This study underscores the influence of micellar environments on dye molecules, altering the sensing responses and selectivity toward analytes, crucial for applications in understanding cellular pathways and toxicity mechanisms.

Micelle-mediated chemiluminescence of 6-aza-2-thiothymine-protected gold nanoclusters for carbazochrome sodium sulfonate detection

Chemiluminescence (CL) intensity of luminol-H2O2 system was dramatically enhanced by cetyltrimethylammonium bromide (CTAB) micelle-mediated 6-aza-2-thiothymine-protected gold nanoclusters (ATT-AuNCs). It is proved that spherical micelles of CTAB in aqueous solution improved the dispersity of ATT-AuNCs, thus enhancing their catalytic activity, which brought in the increased CL intensity of luminol-H2O2 system. Carbazochrome sodium sulfonate (CSS) with a hemostatic containing tetrahydroindole structure broke the spherical micelles and notably quenched the CL intensity of luminol-H2O2-CTAB-ATT AuNCs system. Based on these results, a simple, fast, and sensitive CL method has been developed for the detection of CSS with a linear range of 0.25–25 μM and a detection limit of 0.11 μM. The method has also been successfully applied to the determination of CSS in serum with satisfied recoveries in the range of 89.6 % to 103.7 %. This study not only provides an effective approach for CSS detection but also paves the way for AuNCs-based CL applications.

Synergistic effect of a fluorinated azobenzene for transforming spherical micelles into thread-like micelles with a disk-like cross-section

The free energy in solutions of amphiphilic molecules leads to the formation of supramolecular structures, often making spherical aggregates, worm-like micelles, vesicles, and lamellae. In this work, we add a fluorinated azobenzene, 4-(4-trifluoromethoxy phenyl azo) phenol (Azo-3F) to a solution mainly made of spherical and rodlike micelles of CetylTrimethylAmmonium Bromide (CTAB) and sodium salicylate (NaSal). These structures transform to disk-like micelles, which concatenate through hydrogen bridges to form long thread-like structures highly similar to worm-like micelle structures. This conclusion was reached after observing that NMR results suggest the formation of aggregates in solution with Azo-3F molecules inside them. Viscosity increases by three orders of magnitude at low shear rates when Azo-3F is added, and it shear-thins as the shear rate increases. The viscoelastic spectra show that the fluid changes from viscous to viscoelastic. Cole-Cole plots follow semicircles, typical of Maxwellian behavior below ∼ 35 °C. Cryo-TEM micrographs of the solution with Azo-3F show giant thread-like structures, and cross-sectional analysis of SAXS and WAXS profiles predict oblate ellipsoidal structures. In addition, MD simulations show that the disk-like micelles interact mainly through hydrogen bonds and electrostatics, forming micellar strings. These strings behave similarly to worm-like micelles, explaining why the solution behaves as a Maxwellian fluid at relatively low temperatures. Consequently, when some specific molecules are introduced in supramolecular structures, such as a spherical micelle, they can be transformed into disk-like micelles that assemble into thread-like micelles.

Effect of Substituents on Solubility, Medicinal, Absorption, Emission and Cationic/Anionic Detection Properties of Anthraquinone Derivatives.

Anthraquinones constitute an important class of compounds with wide applications. The solubility of derivatives at 298.15K was discussed in ethanol-water solution and at atmospheric pressure, the solubility of 1-amino-4-hydroxy-9,10-anthraquinone (AHAQ) in binary solvents (ethanol-water combinations) was determined. Colour strength and fastening properties depend upon the kind and position of a hydrophobic group connected to the phenoxy ring of Anthraquinone moiety. There is a continuing interest in the creation of novel anthraquinone derivatives with biological activities since they have demonstrated potential for treating multiple sclerosis. For this purpose, by utilizing voltammetric and absorption studies, interactions of various derivatives with calf thymus DNA (ct-DNA) and the cationic surfactant cetyltrimethylammoniumbromide (CTAB) were examined. Here prominent Hydrophobic interaction and electron transfer resulting in binding to CTAB micelles were observed. The polarity index of the media was assessed and associated with the electrochemical parameters. The medicinal behaviour of Anthraquinone derivatives was a result of electron transfer reactions with DNA. UV-Visible and fluorescence properties were due to the transitions between n* and π* orbitals. Large absorption band with low dichroic ratio was characteristic of various derivatives of Anthraquinone. Presence of -NH group proves various derivatives remarkable calorimetric and anionic sensors.

Super-enrichment of ultra-low concentration rhenium via synergistic co-flocculation precipitation using CTAB and ferric salt hydrolysis micelles

Super-enrichment and recovery of associated Rhenium (Re) in sandstone-type uranium deposits is challenging due to its sparse distribution and ultra-low contents in raw ores. Conventional industrial processes are extremely difficult to achieve economic recovery of Re with a concentration below 0.1 mg/L from in-situ leaching solutions of sandstone-type uranium deposits. This study proposes a novel approach for achieving super-enrichment ultra-low concentration of Re using a synergistic co-flocculation precipitation system composed of cetyltrimethylammonium-bromide (CTAB) and ferric salt (FeCl3) hydrolysis micelles. Experimental results reveal that the enriched content of Re in the co-flocculation precipitates is as high as 503 g/t, nearly 3353 times higher than that in the in-situ leaching solutions. The synergistic precipitation percentage of Re can reach more than 60%, which is larger than the sum of using CTAB micellar flocculation (30.16%) and FeCl3 hydrolysis micellar flocculation (5.43%) separately. Furthermore, the synergistic co-flocculation and precipitation mechanism of Re is examined by SEM, turbidity, Fourier transform infrared spectroscopy, Zeta potential analysis, and DTF calculations. Results demonstrate that the ReO4- anions first form ion associations with CTA+ cations through electrostatic force, which are subsequently captured to forms insoluble co-flocculating precipitate via weak intermolecular hydrogen bond force between Fe(OH)3 and ReO4-, which promotes the super-enrichment of the ultra-low concentration Re. In summary, this process presents great potential for the efficient recovery Re from a large amounts of sandstone-type uranium deposits leaching solution, and provides new insights into the enhancement mechanism of synergistic co-flocculation precipitation.

Surfactant micellar induced aggregation control of an anionic fluorescent dye in Langmuir-Blodgett film

This work reports the formation of stable Langmuir monolayer of an anionic water soluble fluorescent dye 5(6)-carboxyfluorescein (abbreviated as CFS) by electrostatic interaction with a cationic monolayer. Formation of non-fluorescent H-dimeric sites of CFS molecules in Langmuir monolayer and Langmuir Blodgett films has been controlled by using cationic surfactant micelles of cetyltrimethylammonium bromide (CTAB). Thus the film can act as efficient fluorescence marker. Langmuir monolayer has been investigated by Surface Pressure versus Area per molecule (π-A) isotherm and in situ Brewster Angle Microscope (BAM) studies. Mono and multilayered Langmuir Blodgett films were characterized by using UV–vis absorption and steady state fluorescence spectroscopy.

Enhancement of Fluorescence Mediated by Silver Nanoparticles: Implications for Cell Imaging.

In this study, we report the surface enhanced fluorescence (SEF) of a biologically important organic dye, fluorescein (FL), by silver nanoparticles (Ag NPs) in an aqueous medium and its implications for human cell imaging. The as-synthesized Ag NPs were characterized by dynamic light scattering (DLS), zeta potential, transmission electron microscopy (TEM), and UV-vis absorption spectroscopic studies. The interaction and aggregation of FL dye with Ag NPs and a cationic surfactant, namely, cetyltrimethylammonium bromide (CTAB), were explored by UV-vis absorption and steady-state and time-resolved fluorescence spectroscopic methods. The distance-dependent fluorescence enhancement of FL due to Ag NPs in the solution was also theoretically correlated by three-dimensional finite-difference time-domain (3D-FDTD) simulation. The plasmonic coupling between neighboring NPs facilitated the augmentation of the local electric field, thereby producing various "hotspots" that influence the overall fluorescence of the emitter. J-type aggregates of FL in the presence of the CTAB micelles and Ag NP mixed solution were confirmed by electronic spectroscopy. The density functional theoretical (DFT) study revealed the electronic energy levels associated with different forms of FL dye in the aqueous solution. Most interestingly, the Ag NP/FL mixed system used in fluorescence imaging of human lung fibroblast cells (WI 38 cell line) showed a significantly stronger green fluorescence signal compared to that of FL after an incubation period of only 3 h. This study confirms that the Ag NP mediated SEF phenomenon of the FL dye is also manifested in the intracellular medium of human cells giving a brighter and more intense fluorescence image. The cell viability test after exposure to the Ag NP/FL mixed system was confirmed by the MTT assay method. The proposed study may have an implication as an alternate approach for human cell imaging with higher resolution and more contrast.

Quantitative Analysis of Drug Supersaturation Region by Temperature-Variable Nuclear Magnetic Resonance Measurements, Part 2: Effects of Solubilizer

This study utilized temperature-variable nuclear magnetic resonance (NMR) spectroscopy to investigate the effects of a solubilizing agent on the ketoprofen (KTP) supersaturation region. Quantitative NMR analysis showed that the solubilizing agent cetyltrimethylammonium bromide (CTAB) increased both the crystalline and amorphous solubilities of KTP, shifting the KTP supersaturation region to a higher KTP concentration range. The amorphous solubility of KTP was found to be independent of the enantiomeric composition of KTP, even in the presence of CTAB. However, the supersaturation region of the S-enantiomer of KTP (s-KTP) in CTAB solutions was smaller than that of the racemic form of KTP (rac-KTP), likely because of the higher crystalline solubility of s-KTP. When KTP formed a KTP-rich phase via liquid-liquid phase separation from KTP-supersaturated solutions, CTAB was observed to be distributed into the KTP-rich phase, decreasing the chemical potential of KTP and the maximum thermodynamic activity of KTP in the aqueous phase. Additionally, the incorporation of CTAB into the KTP-rich phase diminished the solubilization effect of CTAB micelles in the aqueous phase, narrowing the KTP supersaturation region to a greater extent at higher KTP dose concentrations. Furthermore, the upper-temperature limit of the supersaturated dissolvable region of KTP was lowered in the presence of CTAB, which was rationalized by the melting point depression of the KTP crystal upon mixing with CTAB. The findings of this study highlight the importance of considering the molecular-level impact of solubilizing agents on the drug supersaturation region to fully exploit the potential benefits of supersaturated formulations.

Tuning of distinguished fluorescent responses to methylmercury and Hg2+ ions: Selective detection of methylmercury over Hg2+ ions by fluorescent sensor using micelle system

Although CH3Hg+ is highly toxic, reversible fluorescent sensors for detecting CH3Hg+ over Hg2+ are rare. In this study, we synthesized a reversible fluorescent sensor (1) based on tryptophan amino acid and 6-membered cyclic amine as an electron-donating unit of the fluorophore for turn-on monitoring of Hg2+ in H2O and developed a fluorescent sensing method for selective sensing CH3Hg+ over Hg2+ using 1 and the micelles with a different surface charge. 1 in triton X-100 (TX-100) micelles differentiated between CH3Hg+ and Hg2+ by fluorescent response types (turn-on vs red-shifted emission), whereas 1 in cetyltrimethylammonium bromide (CTAB) micelles detected only CH3Hg+ among 16 metal ions by turn-on response. 1 in the micelles exhibited remarkable detection ability for CH3Hg+ such as ultrafast response (<30 s), high sensitivity and/or selectivity for CH3Hg+, low detection limits (107 nM), and large enhancement of the fluorescence. We proposed the plausible binding mode of 1 in the micelles for selective sensing CH3Hg+ based on fluorescence and NMR and IR study. The 6-membered cyclic amine group of the fluorophore part of 1 might play a critical role to distinguish between CH3Hg+ and Hg2+ by fluorescent response types in TX-100 micelles. 1 detected sensitively Hg2+ and CH3Hg+ in live cells through significant enhancement of green and red fluorescence. 1 with and without the micelles successfully quantified CH3Hg+ and Hg2+ in groundwater and tap water. The combination of the sensor with the micelles provided a selective detection of CH3Hg+ over Hg2+ or distinguished between CH3Hg+ and Hg2+ by fluorescent response types.

Surfactant Assisted One-Pot Method for Preparation of Polyethylene-Clay Nanocomposites (PECN) and Study of their Viscoelastic Behaviour

This work demonstrates a one-pot soft template-assisted technique for developing polyethylene clay nanocomposite (PECN) using cetyltrimethylammonium bromide (CTAB) micelle as structure directing agent. Linear and shear viscosities of the composite were studied in the oscillatory and rotational modes. The effect of clay content, temperature and gallery space on the storage modulus and steady-state viscosities were analyzed. The composite exhibited enhanced storage modulus over the pristine polymer, confirming strong interaction between the clay platelet and polymer molecules. The prepared PECN showed superior thermal stability, phase transition temperature, flame retardancy and mechanical properties as compared to the conventional composite. Morphological studies using SEM and TEM also confirmed the formation of the nanocomposite. This one step surfactant-assisted emulsion method offers a broad scope in designing polymer clay nanocomposites with exciting properties and consequent applications.

How Micelles Influence the Optical Limiting Properties of Zinc Porphyrins and J-Aggregates for Picosecond Pulse Trains

In this work, we studied nonlinear dynamics and optical limiting (OL) effects of pulse trains in zinc porphyrins meso-tetrakis methylpyridiniumyl (Zn2+TMPyP) and meso-tetrakis sulfonatophenyl (Zn2+TPPS) and porphyrin J-aggregates. The environments of zinc porphyrins were selected as aqueous solutions and micelles of sodium dodecyl sulfate (SDS) and cetyltrimethyl ammonium bromide (CTAB). Our numerical results show that both Zn2+TMPyP and Zn2+TPPS are good optical limiters in all solutions. Zn2+TPPS in aqueous solutions shows the best OL effect. Micelles of SDS and CTAB produced less OL effects than the aqueous solutions. The main reason lies in the first excited singlet state and intersystem crossing depending on the electronic structures in different environments.

Role of ionic surfactants on the activation of K2S2O8 for the advanced oxidation processes

Effects of cetyltrimethylammonium bromide (CTAB) and sodium dodecylsulfate were studied to elucidate the persulfate based in-situ chemical oxidation of subsurface contamination. Advanced oxidation processes (AOP) utilizing Fenton’s like reagent was investigated for the degradation of acid orange 7 (AO7) with and without ionic surfactants. The new findings are that the CTAB and SDS retarding the S2O82− activation to some extent. The kinetics of S2O82− assisted decomposition of AO7 were performed under different reaction parameters such as [S2O82−], [Fe2+], [AO7], pH, and temperature. The rate constants (kψ) were decreased markedly in presence of both surfactants. CTAB showed the most potential deactivation than that of SDS. The stability of both surfactants were determined in presence of S2O82−, and no drastic changes was observed in the critical micellar concentration (CMC). The columbic attraction and repulsion between the reactants (S2O82−, and AO7) with ionic head groups of CTAB and SDS are responsible to deactivating the S2O82− decomposition. AO7 and S2O82−, respectively, solubilized and transferred from bulk phase to micellar surface through electrostatic interactions, which may contribute to the inhibitory role of CTAB micelles in the AOP of AO7. Finally the role of surfactants in the Fenton’s like oxidation of AO7 based on the micellar-pseudo phase model was proposed and discussed.

Nanoporous electrode with stable polydimethylsiloxane coating for direct electrochemical analysis of bisphenol A in complex wine media

Direct electrochemical analysis of bisphenol A (BPA) in alcoholic drinks without proper sample preparation is a major challenge. The current work reports a nanoporous electrode design with ultrathin polydimethylsiloxane (PDMS) coating grafted on the top of an indium tin oxide (ITO) electrode with silica nanochannels membrane and cetyltrimethylammonium bromide micelles (SNCM), using a facile contact heating step. The proposed PDMS@SNCM/ITO electrode was subjected to direct ultra-trace detection of BPA in the linear range of 1.0–100.0 µM and detection limit of 0.23 µM, under optimized pH 8 and an accumulation time of 9.0 min. The analytical utility of the proposed method was checked in real wine samples for BPA detection with successful recovery percentages in the range from 95.20 ± 8.53 to 96.22 ± 10.00. The intrinsic hydrophobic features, exceptional stability, and sensitivity of the proposed electrode show potential for food safety surveillance in complex food matrices.

Light Responsiveness and Assembly of Arylazopyrazole-Based Surfactants in Neat and Mixed CTAB Micelles.

The self-assembly of an arylazopyrazole-based photosurfactant (PS), based on cetyltrimethylammonium bromide (CTAB), and its mixed micelle formation with CTAB in aqueous solution was investigated by small angle neutron and X-ray scattering (SANS/SAXS) and UV-vis absorption spectroscopy. Upon UV light exposure, PS photoisomerizes from E-PS (trans) to Z-PS (cis), which transforms oblate ellipsoidal micelles into smaller, spherical micelles with larger shell thickness. Doping PS with CTAB resulted in mixed micelle formation at all stoichiometries and conditions investigated; employing selectively deuterated PS, a monotonic variation in scattering length density and dimensions of the micellar core and shell is observed for all contrasts. The concentration- and irradiance-dependence of the E to Z configurational transition was established in both neat and mixed micelles. A liposome dye release assay establishes the enhanced efficacy of photosurfactants at membrane disruption, with E-PS exhibiting a 4-fold and Z-PS a 10-fold increase in fluorescence signal with respect to pure CTAB. Our findings pave the way for external triggering and modulation of the wide range of CTAB-based biomedical and material applications.

Aggregates of cationic calix[4]arenes in aqueous solution as media for governing protolytic equilibrium, fluorescence, and kinetics

Many water-soluble ionic calixarenes readily form micelle-like aggregates in aqueous solution. Presently, it is firmly proved that such aggregates tend to shift the state of the acid-base equilibrium of indicator dyes just in the same manner as cationic surfactant micelles do. In this paper, we further the corresponding studies and report the peculiarities of several kinds of solvatochromic effects, fluorescence, acid-base equilibrium and kinetic processes in aqueous solutions of four cationic amphiphilic calix[4]arenes bearing hydrophilic choline groups at the upper rim: 5,11,17,23-tetra(N,N-dimethyl-N-hydroxyethylammonium)methylene-25,26,27,28-tetraalkyl-oxycalix[4]arene tetrachlorides. n-Propyl, n-hexyl, n-octyl, and n-dodecyl were used as alkyls, and the calixarenes were designated as of Cn-C4A-Ch, where n = 3, 6, 8, and 12, respectively. The principal colloidal properties, i.e., particle size and electrophoretic mobility of aggregates were characterized via dynamic light scattering. In parallel, the results were compared with those obtained in the presence of micelles of the common cationic surfactant cetyltrimethylammonium bromide and of large-sized aggregates of the calix[6]arene with six methoxy groups at the lower rim. As tools, molecular probes of triphenylmethine and fluorescein series, as well as the solvatochromic Reichardt’s dye were used. The obtained block of data sheds light upon the properties of calixarene aggregates as tools for governing chemical processes.

Inhibition of phenolic compounds from entering condensed freshwater by surfactant-modified evaporators during solar-driven seawater desalination

Seawater desalination based on air–water interfacial solar heating is considered to be one of the effective methods to solve the freshwater shortage crisis in islands. However, the high temperature of the air–water interface unavoidably makes volatile organic compounds (VOCs) such as phenolic compounds volatilize into the condensed freshwater, resulting in freshwater pollution. In this work, solar evaporators with different photothermal materials such as carbon black, MoS2 and carbon nanotubes were modified with cetyl trimethyl ammonium bromide (CTAB) and were applied for both solar evaporation and inhibition of phenolic compounds from entering condensed freshwater. The distillation rates (RD) of 10 phenolic compounds could be significantly reduced. For example, the RD value of phenol was reduced from 77% to 4.6%, which was mainly due to the electrostatic force between the quaternary ammonium group of CTAB and phenol, the binding effect of CTAB micelle on phenol, as well as the hydrogen bond between phenol and air-laid cloth in the evaporator. In addition, the phenolic compounds with the boiling point above 230 °C have RD values all below 10%, while the RD values of phenolic compounds with the boiling point below 230 °C are significantly correlated with n-octanol/water partition coefficient (logKow) values with a correlation coefficient R2 of 0.915. This work demonstrates that the CTAB-modified solar evaporators can be used for clean condensed freshwater production during solar-driven seawater desalination.

Unusual Correlation between the Apparent Amorphous Solubility of a Drug and Solubilizer Concentration Revealed by NMR Analysis.

Herein, we investigated the effect of the solubilizers, cetyltrimethylammonium bromide (CTAB) and amino methacrylate copolymer (Eudragit E PO, EUD-E), on the apparent amorphous solubility of ketoprofen (KTP) and free KTP concentrations in an aqueous phase when a KTP-rich phase was generated by liquid-liquid phase separation. Quantitative analysis by solution nuclear magnetic resonance (NMR) revealed that the apparent amorphous solubility of KTP increased with increasing EUD-E concentrations by the solubilization of KTP into the EUD-E micelles; this was reminiscent of the improvement in the apparent crystalline solubility of KTP observed when EUD-E was added. In contrast, the apparent amorphous solubility of KTP decreased with increasing CTAB concentrations, although the solubilizing ability of CTAB was stronger than that of EUD-E when the KTP-rich phase was absent. NMR analysis revealed that CTAB was distributed into the KTP-rich phase to a relatively large extent. This resulted in a significant reduction of the chemical potential of KTP in the KTP-rich phase in the CTAB solution. Thus, the maximum free KTP concentration in the aqueous phase was reduced more significantly in the CTAB solution than in the EUD-E solution. Moreover, the solubilization effect of KTP by the CTAB micelles in the aqueous phase was drastically diminished due to the distribution of CTAB into the KTP-rich phase. As a result, the apparent amorphous solubility of KTP reached a minimum at a CTAB concentration of 200 μg/mL. A further increase in the CTAB concentration resulted in an improvement in the apparent amorphous solubility of KTP due to the solubilization effect of CTAB remaining in the aqueous phase. The present study highlights the impact of solubilizer selection on the apparent amorphous solubility and attainable supersaturation of the drug, which should be considered during the development of supersaturating formulations to obtain preferable oral absorption.