Hexadecyltrimethylammonium Bromide Micelles Research Articles

Binary Mixed Micelles of Hexadecyltrimethylammonium Bromide–Sodium Deoxycholate and Dodecyltrimethylammonium Bromide–Sodium Deoxycholate: Thermodynamic Stabilization and Mixed Micelle Solubilization Capacity of Daidzein (Isoflavonoid)

Binary Mixed Micelles of Hexadecyltrimethylammonium Bromide–Sodium Deoxycholate and Dodecyltrimethylammonium Bromide–Sodium Deoxycholate: Thermodynamic Stabilization and Mixed Micelle Solubilization Capacity of Daidzein (Isoflavonoid)

Collection of Partition Coefficients in Hexadecyltrimethylammonium Bromide, Sodium Cholate, and Lithium Perfluorooctanesulfonate Micellar Solutions: Experimental Determination and Computational Predictions.

This study focuses on determining the partition coefficients (logP) of a diverse set of 63 molecules in three distinct micellar systems: hexadecyltrimethylammonium bromide (HTAB), sodium cholate (SC), and lithium perfluorooctanesulfonate (LPFOS). The experimental log p values were obtained through micellar electrokinetic chromatography (MEKC) experiments, conducted under controlled pH conditions. Then, Quantum Mechanics (QM) and machine learning approaches are proposed for the prediction of the partition coefficients in these three micellar systems. In the applied QM approach, the experimentally obtained partition coefficients were correlated with the calculated values for the case of the 15 solvent mixtures. Using Density Function Theory (DFT) with the B3LYP functional, we calculated the solvation free energies of 63 molecules in these 16 solvents. The combined data from the experimental partition coefficients in the three micellar formulations showed that the 1-propanol/water combination demonstrated the best agreement with the experimental partition coefficients for the SC and HTAB micelles. Moreover, we employed the SVM approach and k-means clustering based on the generation of the chemical descriptor space. The analysis revealed distinct partitioning patterns associated with specific characteristic features within each identified class. These results indicate the utility of the combined techniques when we want an efficient and quicker model for predicting partition coefficients in diverse micelles.

Physicochemical insights into the micellar delivery of doxycycline and minocycline to the carrier protein in aqueous environment

Physicochemical understanding of the micellar drug delivery is essential for designing efficient drug carrier molecules. An in-depth analysis of the partitioning mechanism of drugs in a quantitative manner and the effects of partitioning on the delivery of drugs through micellar media is a subject of enormous research. This paper focuses on the quantitative measurements of the binding of two antibiotic drugs from tetracycline family, doxycycline and minocycline with the carrier protein human serum albumin (HSA). The partitioning of both the drugs in the micellar system of hexadecyltrimethylammonium bromide (HTAB) and their delivery to HSA through this micellar system was also studied applying spectroscopy and calorimetry. A combination of fluorescence spectroscopy, isothermal titration calorimetry (ITC) and docking studies suggest that both the drugs bind close to Site I of HSA. The ITC results establish that the association of drugs with the protein occurs with an affinity of 103-104 M−1 and the binding is mainly entropy driven. The partitioning mechanisms have been evaluated in terms of the values of the changes in values of standard molar Gibbs free-energy, enthalpy, entropy, and partitioning stoichiometry. The thermodynamic signatures associated with the drug-HSA binding in the presence of HTAB micelles suggest that the partitioning of doxycycline/minocycline in the micelles of HTAB changes their interaction behavior with HSA. These findings provide deep understanding about the micellar drug delivery systems, thereby suggesting their potential applications in strategies for more effective therapeutics.

Structural Characterization of Silica and Amino-Silica Nanoparticles by Fourier Transform Infrared (FTIR) and Raman Spectroscopy

Mesoporous silica nanoparticles were synthesized via the sol-gel method using hexadecyltrimethylammonium bromide (CTAB) micelles as a template and a similar method was used for amino-silica nanoparticle synthesis. Compositional and structural analysis of materials involved Fourier transform infrared (FTIR) and Raman spectroscopies. A comparative study of the two spectra revealed the distinctive pattern for the samples, such as a strong peak from 1030 to 1050 cm−1 in the FTIR spectra, characteristic of Si–O–Si stretching vibration and the specific pattern of silica between 90 and 500 cm−1 and 2880 and 2980 cm−1 in the Raman spectra. A point of interest in this study was the control of CTAB removal during the second stage of synthesis that was highlighted in the FTIR spectra by decreasing intensity or disappearance of the peaks 2850 and 2930 cm−1 for - CH2 absorption. The presence of – NH2 groups in the amino-silica was evidenced by the changes from 1000 to 1500 cm−1 and the sharp band at 2900 cm−1 in the Raman spectra. The peaks at 1050, 1230, 1421, and 1464 cm−1 are present only in the spectra of the amino-silica as well as the higher and sharp band around 2900 cm−1, unlike the pattern in the spectra of silica without amino groups. The two spectroscopic methods offer valuable information concerning the structure of silica and amino-silica. Moreover, thermogravimetric analyses were confirmed these findings and the stability of silica nanoparticles in solution was investigated.

Understanding the partitioning of polyamines in micelles and delivery to the carrier protein: Thermodynamic approach

Micelle-based drug delivery system is widely used to solubilize and carry a varied range of drugs to the target cells. It selectively delivers drugs to the site of action and hence increases drug bioavailability and reduces the side effects of the drug. In the current work, we have studied the partitioning of two polyamines spermidine and spermine in hexadecyltrimethylammonium bromide (HTAB) micelles followed by their delivery to the carrier protein human serum albumin (HSA) using a combination of spectroscopy and calorimetry. The thermodynamic parameters for the partitioning of the polyamines with the micelles provide information about the nature of interactions of the polyamines with HTAB micelles and monomers. The ITC and docking results suggest that the polyamines sequentially bind with HSA with the values of binding constants in the range of 105 to 102. The binding of these polyamines with HSA gets slightly altered when delivered through HTAB micelles. Fluorescence and CD measurements suggest that the binding of these polyamines does not affect HSA conformation significantly. The results will help in understanding the mechanism of drug partitioning in micellar structures which is essential for developing guidelines to design effective drug delivery systems.

Dissociation of the DCF-Hb complex in presence of cationic micelles: A spectroscopic and computational approach

Diclofenac sodium (DCF) is a derivative of phenyl acetic acid and a model representative of the family of non-steroidal anti-inflammatory drugs (NSAIDs). It is extensively consumed for treating inflammation and degenerative disorders like rheumatoid arthritis. The micelles or aggregates of surfactants have ability to solubilize poorly soluble drugs thereby increasing bioavailability of the drugs. Thus, in the current study we have shown a systematic approach for the association of diclofenac with haemoglobin and deintercalation of DCF from hemoglobin (Hb) by hexadecyltrimethylammonium bromide (CTAB) micelles by using various spectroscopic techniques. The fluorescence and UV–visible spectral results revealed that DCF interacts with CTAB micelles and resides in its hydrophobic core. Thus, steady fluorescence and UV–visible measurements provides a strong sign for the relocation of DCF molecules from the hemoglobin interior to the micellar interface of CTAB above cmc. The CD results hinted that CTAB micelles do not disturb the structure of hemoglobin, which further supported that CTAB micelles can be applied as a reliable delivery vehicle for DCF. The present study may be significant for the discovery of improved micelle-based vehicles to the delivery of non-steroidal anti-inflammatory drugs in their targeted site.

Cationic Surfactant Modified 3D COF and Its Application in the Adsorption of UV Filters and Alkylphenols from Food Packaging Material Migrants.

Hexadecyl trimethylammonium bromide (CTAB) micelles were applied in the synthesis of covalent organic frameworks (COFs) for the first time to achieve the synthesis of 3D COF from 2D materials. Benzidine, one raw material for COF, was enclosed in the CTAB micelles because of the hydrophobic effect, and thus the target COF, which can be formed immediately with the aid of p-toluenesulfonic acid, grew in a micelle guided 3D form. The synthesized 3D COF showed a flower-like structure, whereas the COF synthesized without CTAB showed a smooth structure. The diameter of the 3D COFs showed direct correlations with CTAB concentrations. Moreover, the CTAB modified COF also showed a dramatically improved fluorescence property in comparison with that of normal COFs. The synthesized 3D COF showed good adsorption performance for UV filters and alkylphenols with recoveries ranged from 90.2% to 99.8%, and it also showed good fluorescence response for Pb2+. The utility of CTAB modified COF was verified in the enrichment of UV filters and alkylphenols from food packaging material migrants.

Binding ability of sodium valproate with cationic surfactants and effect on micellization: calorimetric, surface tension, light scattering and spectroscopic approach

The interactions of surfactant molecules with biologically active pharmaceutical ingredients remain an important area of research due to the necessity to improve drug delivery and solubilization systems. In the present study, the various interactions present between a hydrophilic drug sodium valproate (SV) and cationic surfactants, viz. dodecyltrimethylammonium bromide (DTAB), tetradecyltrimethylammonium bromide (TTAB), hexadecyltrimethylammonium bromide (HTAB) and cetylpyridinium chloride (CPC), in aqueous media have been explored by using various techniques. The partitioning of SV in the micelles of respective surfactants has been studied by using isothermal titration calorimeter (ITC), and various parameters like binding/partitioning constant (K), enthalpy, entropy, free energy and stoichiometry of binding have been determined in post-micellar regions. The outcomes reveal that CPC binds strongly to the SV as it provides more hydrophobic interactions, and the positive values of enthalpy (ΔrH) are overcome by higher positive value of entropy (ΔrS) which makes the overall process thermodynamically favorable. The binding parameters obtained for TTAB, HTAB and CPC are further compared with the double-tailed surfactants, i.e., didodecyldimethylammonium bromide (DDAB) and dihexadecyldimethylammonium bromide (DHDAB). In addition, the effect of SV on the micellization behavior of TTAB, HTAB and CPC was also studied using ITC and surface tension measurements, and various thermodynamic and interfacial parameters have been derived. Dynamic light scattering and proton (1H) NMR studies have been performed to determine the locus of SV molecules within micelles of HTAB, TTAB and CPC.

X-ray absorption fine structure spectroscopy and photoluminescence study of multifunctional europium (III)-doped hydroxyapatite in the presence of cationic surfactant medium

Europium-doped hydroxyapatite has attracted considerable scientific attention to smart drug delivery scaffold applications because of its biocompatible and traceable luminescence features. In this sense, to investigated the europium incorporation mechanism and photoluminescence properties in the presence of surfactant organic molecules the europium doped-hydroxyapatite samples were synthesized via co-precipitation with hexadecyl trimethylammonium bromide (CTAB) micelles mediated approach. Results of the X-ray absorption spectroscopy techniques (XANES and EXAFS) showed that Eu3+ ions were incorporated preferentially at the Ca (1) site with local charge compensating via oxygen interstitial ion for samples calcined under air at 450 °C/4 h °C. Europium(III) luminescence analysis suggested that Ca site symmetry became distorted in CTAB medium.

Effect of Urea on the Thermodynamics of Hexadecyltrimethylammonium Bromide Micelle Formation in Aqueous Solutions

The effect of urea on the thermodynamics of hexadecyltrimethylammonium bromide (CTAB) micelle formation in aqueous urea solutions was studied by isothermal titration microcalorimetry. The thermodynamic functions of ΔH, ΔG, and ΔS of CTAB micelle formation were calculated. The critical micelle concentrations (CMC) were determined. The addition of urea to the solution decreased the micelle formation entropy. This was attributed to the “lowering” of the structural temperature of the solution, which led to an increased number of hydrogen bonds and structure formation of water.

Facile synthesis and in vitro bioactivity of radial mesoporous bioactive glasses

This paper reports a facile method for fabricating radial mesoporous bioactive glasses (RMBGs) using Hexadecyl trimethyl ammonium bromide (CTAB) micelle as the reaction center. The radial structure was formed with the extension of precursor dissolved in the hydrophobic solvent (cyclohexane) which gathered in the internal part of the CTAB micelle. The morphology, structure and in vitro bioactivity of RMBGs were investigated by various methods. The results indicate that the CTAB micelle could restrict the precursor-dissolved cyclohexane and was in favor of preparing the RMBGs with radial mesoporous structure, high specific surface area and good apatite-forming ability. The obtained RMBGs with the novel structure and properties may have potential application in drug delivery and hard tissue regeneration.

Synthesis of Highly Crystalline Beta/MCM-41 Composites by Controllable Assembly of Tailorable Nano Proto-Zeolitic Building Blocks

Hierarchical Beta/MCM-41 composites have been synthesized by kinetically controlling the assembly process of nano-building blocks around hexadecyl trimethyl ammonium bromide (CTAB) micelles. Composites with different microzeolitic–mesoporous properties were prepared from three typical beta zeolite precursors. Without disturbing the intrinsic acidity of the zeolites, the obtained composites exhibited improved catalytic performance in n-decane cracking.

Formose reaction accelerated in aerosol-OT reverse micelles.

The formose reaction in reverse micelles of aerosol-OT (AOT), triton X-100 (TX), and hexadecyltrimethylammonium bromide (CTAB) was investigated. Time–conversion data have indicated that the interfacial water layer of AOT reverse micelles is a medium that accelerates formation of glycolaldehyde in the formose reaction. The 13C NMR spectra for the products of the formose reaction using formaldehyde-13C as starting material are indicative of the formation of ethylene glycol as a major product.

Stability of trianionic curcumin enhanced by gemini alkyl O-Glucosides and alkyl trimethyl ammonium halides mixed micelles

Improved capability to inhibit degradation of trianionic curcumin has been realized in this study. The interaction between trianionic curcumin (Cur3−) and gemini dodecyl or tetradecyl O-glucoside micelles, tetradecyltrimethylammonium chloride (TTAC) or hexadecyltrimethylammonium bromide (CTAB) micelles as well as gemini alkyl O-glucosides (AGs)/alkyl trimethyl ammonium halides mixed micelles have been characterized. It is demonstrated that Cur3− cannot be incorporated into gemini AGs micelles since the lack of electrostatic attraction and degraded as rapidly as in aqueous phase. Cur3− tend to reside at palisade layer − water interface of TTAC or CTAB micelles due to the strong electrostatic interaction while moderate electrostatic interaction allows Cur3− to locate more deeply in the palisade layer of mixed micelles. Additionally, mixed micelles tend to form a more compact and hydrophobic palisade layer than pure TTAC and CTAB ones. These factors bring about enhanced fluorescence intensity and blue − shift of emission maxima, improved fluorescence anisotropy and quantum yield, as well as reduced decay rate of Cur3− in mixed micelles than in pure TTAC and CTAB ones.

Phosphate Diester Cleavage Promoted by the Metallomicelles of Ce(III) Complexes of Aza-Crown Ether with Different Numbers of Nitrogen Atoms

The design of artificial hydrolase has attracted extensive attention due to their scientific significance and potential application in the field of gene medicine and molecular biology. This work reports the catalytic activation of two aza-crown ether Ce(III) complexes and their metallomicelles as artificial hydrolase in bis(4-nitrophenyl) phosphate ester (BNPP) hydrolysis. The chemical composition of two complexes was determined by the fluorescence spectra and the mole ratio method for electronic absorption spectra. The bonding effect of BNPP and solubilizing effect of the complexes were proved by a method of fluorescence spectroscopy. The catalytic activity of different catalytic systems in BNPP hydrolysis was measured with UV-vis spectrophotometric method. These catalytic systems showed high catalytic activity for promoting BNPP hydrolysis at the almost physiological conditions. BNPP hydrolysis rate in these catalytic system is about 107- to 109-fold faster than that of the BNPP spontaneous hydrolysis in aqueous solution at the same conditions. The metallomicelle systems exhibited higher catalytic activity compared with the complex solution systems in BNPP hydrolysis, and hexadecyltrimethyl ammonium bromide micelle provides a useful catalytic environment for reaction. The acid effect of the catalytic system is ascribed to the formation of metal-bound hydroxide serving as a better kind of nucleophile.

A New Insight into Growth Mechanism and Kinetics of Mesoporous Silica Nanoparticles by in Situ Small Angle X-ray Scattering.

The growth mechanism and kinetics of mesoporous silica nanoparticles (MSNs) were investigated for the first time by using a synchrotron time-resolved small-angle X-ray scattering (SAXS) analysis. The synchrotron SAXS offers unsurpassed time resolution and the ability to detect structural changes of nanometer sized objects, which are beneficial for the understanding of the growth mechanism of small MSNs (∼20 nm). The Porod invariant was used to quantify the conversion of tetraethyl orthosilicate (TEOS) in silica during MSN formation, and the growth kinetics were investigated at different solution pH and temperature through calculating the scattering invariant as a function of reaction time. The growth of MSNs was found to be accelerated at high temperature and high pH, resulting in a higher rate of silica formation. Modeling SAXS data of micelles, where a well-defined electrostatic interaction is assumed, determines the size and shape of hexadecyltrimethylammonium bromide (CTAB) micelles before and after the addition of TEOS. The results suggested that the micelle size increases and the micelle shape changes from ellipsoid to spherical, which might be attributed to the solubilization of TEOS in the hydrophobic core of CTAB micelles. A new "swelling-shrinking" mechanism is proposed. The mechanism provides new insights into understanding MSN growth for the formation of functional mesoporous materials exhibiting controlled morphologies. The SAXS analyses were correlated to the structure of CTAB micelles and chemical reaction of TEOS. This study has provided critical information to an understanding of the growth kinetics and mechanism of MSNs.

Micelle anchored in situ synthesis of V2O3nanoflakes@C composites for supercapacitors

A micelle-anchoring method has been developed for the in situ synthesis of V2O3 nanoflakes@C core–shell composites as the electrode materials in supercapacitors. Hexadecyltrimethylammonium bromide (CTAB) micelles assembled to solubilize activated carbon and anchor vanadate ions of the precursor, NH4VO3, onto the carbon surface. During drying and calcination, CTAB and NH4VO3 decompose to produce V2O5, which is carbon-thermally reduced to V2O3in situ. In the as-obtained composites, monodisperse V2O3 nanoflakes stand edge-on the carbon surface, forming a carbon core with a shell layer of edge-on standing V2O3 nanoflakes. Because of the increased electric conductivity and high specific surface area, V2O3 nanoflakes@C composites exhibit a specific capacitance of 205 F g−1 at 0.05 A g−1 over a potential range of −0.4 to 0.6 V, which surpasses those of their individual counterparts (67 F g−1 and 159 F g−1 at 0.05 A g−1 for activated carbon and bulk V2O3, respectively). The composites also showed good cycling stability due to structure support of the inner carbon cores. The proposed method provides a novel strategy to synthesize composites of transition-metal oxides with improved electrochemical performance for applications in supercapacitors.

Time-Resolved Electron Paramagnetic Resonance Investigation on the Quenching Reaction of Photo-Induced Excited Triplet Vitamin K3 by Antioxidant Vitamin C in Homogeneous and Micelle Solutions

The reaction mechanism and dynamics of the quenching of the excited triplet of vitamin by vitamin C was studied in both homogenous ethylene glycol-H2O plus hexadecyltrimethylammonium bromide, aerosol OT, sodium dodecyl sulfate, and Triton X-100 micelle solutions by time-resolved electronic paramagnetic resonance. The photolysis of vitamin K3 in EG-H2O solution led to the chemically induced dynamic electron polarization (CIDEP) of the vitamin K3 neutral radical VK3H• and ethylene glycol ketyl radical, which showed that a hydrogen atom abstraction reaction of with the solvent ethylene glycol occurred. The triplet mechanism was the primary mechanism underlying the generation of CIDEP, suggesting that quickly reacted with ethylene glycol before spin-lattice relaxation. During the photolysis of vitamin K3 and vitamin C in ethylene glycol-H2O solution, abstracted hydrogen atoms not only from the solvent ethylene glycol but also from a vitamin C monoanion. The stronger CIDEP signal of the vitamin C monoanion radical indicated that can be rapidly quenched by vitamin C. In hexadecyltrimethylammonium bromide (aerosol OT, sodium dodecyl sulfate)/ethylene glycol-H2O micelle solutions, lipid-soluble needed to diffuse around the micelle surface to react with the water-soluble vitamin C. The spin-lattice relaxation of the parent resulted in weaker CIDEP of the reaction-generated radicals. Furthermore, the attraction between the positive charge layer of the hexadecyltrimethylammonium bromide micelle and vitamin C monoanion made the quenching reaction of by vitamin C rapid, whereas the repulsion between the negative charge layer of aerosol OT (sodium dodecyl sulfate) micelle and vitamin C monoanion made the quenching reaction slow. For Triton X-100 micelle, the coexistence of vitamin K3 and vitamin C in the same polyethylene glycol shell resulted in the fastest quenching reaction and strong CIDEP of the monoanion radical.

Effects of surfactant concentration on formation of high-aspect-ratio gold nanorods

The effects of surfactant concentration in a growth solution on the elongation of gold nanorods were examined. Gold nanorods were synthesized in solutions with different concentrations of hexadecyltrimethylammonium bromide (HTAB): 100, 200, 300, 400, 500, and 600mM. The nanorods grown in a solution with higher surfactant concentrations were longer (aspect ratio ∼30) than those grown in that with lower concentrations (aspect ratio <10). The self-assembled surfactant structures in the solutions were analyzed using viscosity measurement and small-angle X-ray scattering. These results showed a decrease in the inter-micellar distance with increasing surfactant concentration. Taking the chemical equilibrium for the complex formation between Au ions and HTAB micelles into account, we found that the free Au ion concentration decreases accompanied with the increase in the surfactant concentration. This decrease in the free Au ion concentration suppresses undesirable secondary nucleation of gold crystals in a growth solution, resulting in gold nanorod elongation.

Control of the Long-axis Length of Gold Nanorods through Temperature Variation

Abstract The effect of temperature on the growth of the long axis of gold nanorods is studied. The length of the nanorods decreases gradually with an increase in the growth temperature. By considering the chemical equilibrium between hexadecyltrimethylammonium bromide (HTAB) micelles and Au ions, we suggest that the secondary nucleation of seeds in a growth solution affects the long-axis length. In addition, small-angle X-ray scattering suggests that the equilibrium self-assembled structure of surfactant molecules does not affect the long-axis length in the present system.