Solutions Of Cetyltrimethylammonium Bromide Research Articles

The antimicrobial and antiadhesion activities of micellar solutions of surfactin, CTAB and CPCl with terpinen-4-ol: applications to control oral pathogens.

The oral pathogen Streptococcus mutans is involved in tooth decay by a process that initiates with biofilm adhesion and caries development. The presence of other microbes such as Candida albicans may worsen the demineralization process. Since both microbes are virulent to the host and will proliferate under specific host immune deficiencies and systemic diseases, it is important to study antimicrobial substances and their effects on both pathogens. There are several antiseptic agents used to reduce plaque biofilm and its outcome (dental caries and/or periodontal disease). However, some of these have undesired effects. In the current study we investigated the antimicrobial and anti-adhesion properties of micellar solutions of surfactants and the plant natural product terpinen-4-ol (TP). The results revealed an increase in antimicrobial properties of the synthetic surfactants, cetylpyridinium chloride (CPC) and cetyltrimethylammonium bromide (CTAB), when mixed with TP. In addition, although surfactin, a biosurfactant, has little antimicrobial activity, it was demonstrated that it enhanced the effect of TP both as antimicrobial and anti-adhesion compound. Surfactin and the synthetic surfactants promote the antimicrobial activity of TP against S. mutans, the causal agent of tooth decay, suggesting specificity for membrane interactions that may be facilitated by surfactants. This is the first report on the successful use of surfactin in association with TP to inhibit the growth and adhesion of microbial pathogens. Surfactin has other beneficial properties besides being biodegradable, it has antiviral and anti-mycoplasma activities in addition to adjuvant properties and encapsulating capacity at low concentration.

SYNTHESIS AND CATALYTIC ACTIVITY OF BRANCHED GOLD NANOPARTICLES IN AQUEOUS MEDIUM

In this article, a simple method for the preparation of multi–branched gold nanoparticles from an aqueous solution of silver seeds, cetyl-trimethylammonium bromide (CTAB), HAuCl4, and Pluronic F–127 was described. It was found that morphologies and sizes of gold nanostructures (AuNPs) depended strongly on such experimental parameters as concentrations of Pluronic F–127 and Au3+. The products were characterized by transmission electron microscopy (TEM). Interestingly, the multi – branched AuNPs were found to serve as an effective catalyst for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) in the presence of NaBH4. Kinetic data have been obtained from monitoring the concentrations of 4-NP and BH4‒ by UV‒vis spectroscopy.

Influence of Pulsed Electromagnetic Fields on Positional and Orientational Ordering in Aqueous Solutions of Cetyltrimethylammonium Bromide (CTAB)

Influence of Pulsed Electromagnetic Fields on Positional and Orientational Ordering in Aqueous Solutions of Cetyltrimethylammonium Bromide (CTAB)

Investigation on the interfacial behavior of aqueous solutions of cetyltrimethyl ammonium bromide in the presence of polyethylene glycols

The surface tensions of aqueous cetyltrimethyl ammonium bromide and four polyethylene glycols were measured experimentally at the temperature of 298.15 K and the pressure of 1 atm. Then the surface tensions of aqueous (cetyltrimethyl ammonium bromide + polyethylene glycols) were measured at different concentrations. These measurements were conducted with the pendant drop method. The surface tensions of these aqueous solutions were described by using the equality of chemical potentials at the interface and bulk liquid. The calculated results showed a good agreement with experimental measurements, so the model was successfully applied to aqueous cetyltrimethyl ammonium bromide, polyethylene glycols, and their mixtures. Moreover, the surface coverage, molar surface area, and surface-to-solution distributions were determined by this model. The values of critical micelle concentration were obtained through surface tension measurements for each aqueous solution. The presence of polyethylene glycols increased the values of the critical micelle concentration and decreased the surface coverages of cetyltrimethyl ammonium bromide.

One-Stage Synthesis of Gold Hydrosol with Nanoparticles of Desired Shape

The effect of borohydride concentration on the synthesis of gold nanoparticles in solutions of chloroauric acid, cetyltrimethylammonium bromide, and ascorbic acid in the absence of seeds has been studied systematically. Variations in the concentration of NaBH4 allow one to obtain particles of different sizes and shapes. A method has been developed for the one-stage synthesis of large pentagonal gold rods (the average length and thickness are 550 ± 135 and 71.2 ± 11.6 nm, respectively) with a high yield using borohydride in an ultra-low (≤5 × 10–8 mol/L) concentration. The resulting particles have been characterized using optical spectroscopy, scanning and transmission electron microscopy (including high-resolution technique), and electron diffraction.

Effect of surfactant materials to nanoparticles formation under pulsed plasma conditions and their antibacterial properties

Pulsed plasma between two Zn rods submerged into aqueous solution of cetyl trimethylammonium bromide (CTAB) and sodium dodecyl sulphate (SDS) surfactants resulted in formation of pure ZnO nanorods, while the pulsed plasma between two Zn rods in water without surfactant yielded a mixture of ZnO and Zn nanoparticles. Carbon coated ZnO nanorods with about 20 nm thickness and 150 nm length were synthesized by this method using different surfactant materials such as CTAB and SDS. Cu nanoparticles of about 10 nm in size were also synthesized by the pulsed plasma in aqueous solution of 0.2% gelatine as surfactant material. Surfactant materials served as protective and stabilizing agent and induced formation of smaller sized particles with larger surface area, which in turn inhibited excellent antibacterial activity for Escherichia coli (E.coli). Silver nanoparticles stabilized by SDS exhibited much higher antibacterial activity against E.coli than that of without surfactant.

Crown-Containing Phthalocyanines are Potential Sensibilizers for Photodynamic Therapy. Synthesis, Properties and Role of Non-Covalent Interactions

Phthalocyanines (Pc) and their supramolecular aggregates are widely used in molecular electronics, chemical sensors, and catalysis, as well as in biology and medicine, including photodynamic therapy (PDT). One of the possibilities of preventing Pc aggregation in an aqueous medium is using surfactants: with their molecules are self-organized various supramolecular complexes. This results in formation of the required microheterogeneous Pc environment compatible with the biological medium. The monomolecular state of Pc in an aqueous medium is especially important for their use as sensitizers in fluorescence diagnostics and PDT. We have summarized here the results of investigations of distinctive features of the supramolecular aggregation of octa-[(4′-benzo-15-crown-5)oxy]phthalocyaninates (Mcr8Pc) and tetra-[(4′-benzo-15-crown-5)oxy]phthalocyaninates (Mcr4Pc) in electrolytic solutions and solutions of synthetic cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS), sodium dodecylbenzenesulfonate (SDBS). Biocompatible surfactants such as carboxymethylcellulose sodium salt (Na-CMC) and sodium deoxycholate (SDC) were also studied. Using the electron absorption spectra it has been shown that formation of Mсr8Pc monomers in micellar solutions of SDC is affected by both increased surfactant concentration and by changes in the ionic strength of solution after sodium chloride is added. The effect of the chemical structure of the biocompatible anionic surfactant on monomerization of crown_containing phthalocyanines has been identified; this fact opens new possibilities for using this family of compounds for fluorescent diagnosis and PDT.

Effect of CTAB Concentration on Foam Properties and Discussion Based on Liquid Content and Bubble Size in the Foam

Surfactants known as frothers are widely used in froth flotation to produce small bubbles and stabilize the froth, meanwhile, froth stability plays an important role in determining the product grade and recovery achieved from a mineral flotation process, and therefore it is of great significance to study the effect of surfactant on foam properties. However, foam properties, especially foam stability concerning liquid content of foam and evolution of bubble size, in flotation has received little attention. In this study, we intensively investigated the foamability and foam stability of different concentration cetyltrimethylammonium bromide (CTAB) solutions. Experiments were carried out using a commercially available instrument, Foam Scan, which determined simultaneously the foaming time, foam volume, the liquid content of foam and bubble size distribution. Particularly, the evolution of bubble size can be allowed to determine at a regular time interval. The results showed that as an increase in CTAB concentration, the foamability continuously increased till reached a constant at a critical micelle concentration (CMC), however, the foam stability initially increased and then presented a little decrease when the tested concentrations were larger than its CMC. An argument based on foam drainage, bubble coalescence and coarsening processes is proposed to account for the effect of CTAB concentration foam properties.

Heat-induced morphological transformation of gold nanodumbbells in ionic surfactant solutions

The thermal stability of gold nanodumbbells (NDs) is studied in aqueous solution of ionic surfactants. It is found in aqueous solution of cetyltrimethylammonium bromide that the blue-shift of longitudinal surface plasmon resonance band of gold NDs occurs at 75 °C and the new gold nanorods (NRs) with shortened aspect ratio are formed at the same time. The aspect ratio of the generated gold NRs gradually decreases and finally approaches ∼1.7 after repeated processing. Similarly, the same results are also obtained in aqueous solution of sodium dodecyl sulfate at room temperature. Mechanism is proposed for the shape transformation of gold NDs.

Stabilization of spherical nanoparticles of iron(III) hydroxides in aqueous solution by wormlike micelles

HypothesisThe low Ksp value of Fe(OH)3 (3 × 10−38 at 298 K) explain the immediate coagulation when the pH of a solution of Fe(III) is adjusted to 7. However, stable dispersions of Fe(OH)3 can be formed when the pH is adjusted to 7 in the presence of wormlike micelles formed by cetyltrimethylammonium bromide and sodium salicylate. The formation of a structure containing Fe(OH)3 nanoparticles decorating wormlike micelles is responsible for the high stability of the dispersions. ExperimentsFe(OH)3 nanoparticles were obtained by increasing the pH of solutions of cetyltrimethylammonium bromide and Fe(III), previously complexed with salicylate at pH 3. The interaction between nanoparticles and the chains of wormlike micelles was investigated by DLS, SAXS, TEM and Cryo-TEM. FindingsDLS revealed higher scattering contrast and slower diffusion for wormlike micelles in the presence of nanoparticles. These results were interpreted as the decoration of the chains of wormlike micelles by nanoparticles of Fe(OH)3. A pearl-necklace model was successfully used to adjust SAXS curves, revealing nanoparticles with ∼3 nm of diameter, spaced ∼2 nm apart along the string. This result agrees with TEM and Cryo-TEM images. The formed structure prevents the coagulation of nanoparticles, assuring high stability to the dispersion.

FT-IR spectroscopic and micellization studies of cetyltrimethylammonium bromide in aqueous and aqueous solution of ionic liquid (1-butyl-3-methylimidazolium bromide) at different temperatures

The electrical conductivity and infrared spectroscopic measurement of aqueous solutions of cetyltrimethylammonium bromide (CTAB), cationic surfactant, with imidazolium based ionic liquid 1- butyl-3 methyl imidazolium bromide [C4mim] [Br] were determined at different weight percentages and temperatures. The temperature dependence of critical micelle concentration (cmc) obtained from conductivity measurements at different temperatures (298.15, 303.15, and 308.15) K has been used to calculate various thermodynamic parameters of micellization like standard enthalpy of micellization (ΔHm0), standard free energy of micellization (ΔGm0), and standard entropy of micellization (ΔSm0), and the obtained parameters are further used to understand the effect of ionic liquid on surfactant. The influence of ionic liquid 1-butyl-3-methylimidazolium Bromide [C4mim][Br] on the micellization process of the cetyltrimethylammonium bromide (CTAB) is discussed.

Experimental and modeling study of the surface tension and interface of aqueous solutions of alcohols, cetyltrimethylammonium bromide (CTAB) and their mixtures

In this study, the experimental surface tensions were measured for aqueous solutions of cetyltrimethyl ammonium bromide, 1-propanol, 2-propanol, and 1-butanol with a pendant drop apparatus. The temperature and pressure of all experiments were 298.15K and 1bar, respectively. Subsequently, a model based on the equality of the chemical potential of components at the interface and the bulk liquid was used. The results of this part showed that the surface tensions were reproduced well. The average absolute deviation percent of surface tension was 1.11. Then the surface tensions of (cetyltrimethylammonium bromide+alcohols) aqueous mixtures were measured at different concentrations. Moreover, the critical micelle concentrations of the applied systems were determined. The present model was used for aqueous mixtures of (cetyltrimethylammonium bromide+alcohols). The average absolute deviation percent of surface tension was 2.72, so the model successfully predicted the surface tension for aqueous solutions of (cetyltrimethylammonium bromide+alcohols). Furthermore, the results of the model proved that the presence of alcohols decreased the surface coverage of cetyltrimethylammonium bromide and increased the values of the critical micelle concentration.

Accelerating Gold Nanorod Synthesis with Nanomolar Concentrations of Poly(vinylpyrrolidone).

A novel modification for the seedless synthesis of gold nanorods (AuNRs) has been developed. Nanomolar concentrations of 10 kDa poly(vinylpyrrolidone) (PVP) can be introduced to a growth solution containing 25, 50, or 100 mM cetyltrimethylammonium bromide (CTAB) to significantly reduce the dimensions of AuNRs. We found that PVP accelerates the growth rate of AuNRs by more than two times that of nanorods grown in 50 and 100 mM CTAB solutions. Additionally, there is a time-dependent effect of adding PVP to the nanorod growth solution that can be utilized to tune their aspect ratio. Because the concentration of PVP is far below the concentration of HAuCl4 in the reaction mixture, PVP primarily functions not as a reducing agent, but as a capping or templating ligand to stabilize the growing nanorods. Our reproducible protocol enables the synthesis of AuNRs in high yield with tunable sizes: 45 × 6.7, 28 × 5.5, and 12 × 4.5 nm for 100, 50, and 25 mM CTAB, respectively. We estimated the number of PVP chains per nanorod in growth solutions to be around 30, which suggests that the effect on the aspect ratio is caused by a direct interaction between the AuNR surface and the PVP.

Effects of CTAB concentration on the quality of graphene oxide nanosheets produced by green laser ablation

In this study the influence of the concentration level of cetyl trimethyl ammonium bromide (CTAB) as the ablation environmental medium on the characteristics of graphene oxide nanosheets, produced by laser ablation method has been surveyed. The second harmonic of a Q-switched Nd:YAG laser at 532 nm wavelength and 7 ns pulse width and 0.5 J/cm2 fluence was used to irradiate a graphite plate in CTAB solution. The produced samples were characterized by field emission scanning electron microscopy (FE-SEM), UV–Vis–NIR absorption spectroscopy, transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), Raman and photoluminescence (PL) spectroscopy. Raman results exhibit that the 0.04 M concentration of CTAB is the optimum concentration for producing high-quality graphene oxide nanosheets. The experimental results suggest that the amount of defects and the number of graphene oxide layers can be changed with adjusting the concentration level of CTAB in suspensions. This paper can be beneficial guidance to produce of high-quality graphene oxide nanosheets.

Particle Velocities near and along the Electrode during Electrophoretic Deposition: Influence of Surfactant Counter-Ions

Research into the micro-nanostructured coatings process has made a variety of new applications available. Electrophoretic deposition (EPD) is an efficient and attractive technique to produce coated materials. Therefore the understanding of the formation and growth mechanism of the coating process continues to be investigated. In this study, a home-made EPD laminar flow cell was used for in-situ investigation of the particle velocity and deposition of micronic particles on a cathode. Monodisperse polystyrene latex particles were functionalized with cationic surfactants: cetyltrimethyl ammonium bromide (CTAB) or cetyltrimethyl ammonium chloride (CTAC). The tangential velocity of the particles when they migrated to the electrode, the approach angle and the tangential velocity along the electrode were measured under a DC electric field. From the values of the velocities, the particle-electrode distance was evaluated in CTAB and CTAC solutions. The electrophoretic velocity was calculated from the electrophoretic mobility of the particles and the electric field applied to the particles. All these parameters depend on the type of surfactant counter-ions and influence the growth of the coating. Dense structures were obtained in CTAB solution while open structures were observed in CTAC solution.

Aggregation of Carbocyanine Dyes in Choline Chloride-Based Deep Eutectic Solvents in the Presence of an Aqueous Base.

Deep eutectic solvents (DESs) have shown potential as novel media to support molecular aggregation. The self-aggregation behavior of two common and popular carbocyanine dyes, 5,5',6,6'-tetrachloro-1,1'-diethyl-3,3'-di(4-sulfobutyl)-benzimidazole carbocyanine (TDBC) and 5,5'-dichloro-3,3'-di(3-sulfopropyl)-9-methyl-benzothiacarbo cyanine (DMTC), is investigated within DES-based systems under ambient conditions. Although TDBC is known to form J-aggregates in basic aqueous solution, DMTC forms H-aggregates under similar conditions. The DESs used, glyceline and reline, are composed of salt choline chloride and two vastly different H-bond donors, glycerol and urea, respectively, in 1:2 mol ratios. Both DESs in the presence of base are found to support J-aggregates of TDBC. These fluorescent J-aggregates are characterized by small Stokes' shifts and subnanosecond fluorescence lifetimes. Under similar conditions, DMTC forms fluorescent H-aggregates along with J-aggregates within the two DES-based systems. The addition of cationic surfactant cetyltrimethylammonium bromide (CTAB) below its critical micelle concentration (cmc) to a TDBC solution of aqueous base-added glyceline shows the prominent presence of J-aggregates, and increasing the CTAB concentration to above cmc results in the disruption of J-aggregates and the formation of unprecedented H-aggregates. DMTC exclusively forms H-aggregates within a CTAB solution of aqueous base-added glyceline irrespective of the surfactant concentration. Anionic surfactant, sodium dodecylsulfate (SDS), present below its cmc within aqueous base-added DESs supports J-aggregation by TDBC; for similar SDS addition, DMTC forms H-aggregates within the glyceline-based system whereas both H- and J-aggregates exist within the reline-based system. A comparison of the carbocyanine dye behavior in various aqueous base-added DES systems to that in aqueous basic media reveals contrasting aggregation tendencies and/or efficiencies. Surfactants as additives are demonstrated to control and modulate carbocyanine dye self-aggregation within DES-based media. The unique nature of DESs as alternate media toward affecting cyanine dye aggregation is highlighted.

IFT and friccohesity study of formulation, wetting, dewetting of liquid systems using oscosurvismeter

Interfacial tension (IFT, mN/m) of pepsin with water and aqueous FeCl3 solution at 20 to 63G were studied along with a mutual wettability of water and isobutyl alcohol (IBA) with sodium and ammonium acetates at 298.15K. The Gauss doses and four H atoms of CH3COONH4 have decreased the IFT contrary to CH3COONa. FeCl3 has catalysed interfacial activities of pepsin in aqueous solution with its manifold unfolding resulting a larger surface area (1/τ=cm2/mol). Internal structures and surface areas of pepsin with weaker cohesive forces were analysed with SEM and Survismeter on exposure of electromagnetic dose of 63G induced by 2.5A current. Dewetting of Azadirachta indica (neem) oil with 0.001 to 0.015mol/L aqueous cetyltrimethylammonium bromide (CTAB) solutions was studied for reducing size of oil globules from <70μm to <100nm. Friccohesity a fundamental physicochemical property as a function of cohesive forces and spreading or frictional forces has resolved a closely placed interaction mechanism of water+(melamine-formaldehyde-polyvinylpyrrolidone=MFP) polymer resin mixtures. The focus has been on interacting molecular activities of magnetic field+FeCl3 on pepsin unfolding, acetate salts and surfactants to estimate water and IBA mutual solubilization, friccohesity of aqueous MFP resin. Stabilizing effect of pi-conjugation with a less mutual solubilization of benzene with water as compared to cyclohexane has produced higher IFT values. EDTA>borax>ninhydrin for 0.02 to 0.03mol/kg and borax>EDTA>ninhydrin orders for 0.04 to 0.08mol/kg substantiate a role of O atom due to its placement in chosen molecules.

Concentration, salt and temperature dependence of strain hardening of step shear in CTAB/NaSal surfactant solutions

By measuring stress relaxation following a step strain, we find that strain hardening is prevalent over a temperature range of 15–25 °C for a solution of cetyl trimethylammonium bromide (CTAB) with the added hydrotrope sodium salicylate (NaSal) at hydrotrope-to-surfactant concentration ratios (CS/CD) between 0.5 and 3.0. The extent of strain hardening upon nonlinear deformation varies nonmonotonically as a function of salt-to-surfactant ratio for different temperatures. As the strain amplitude is progressively increased, a transition from strain hardening to softening or linear response is observed at strains that are dependent on temperature and concentration. Strain hardening was also found in CTAB when using sodium 3-Hydroxy-2-naphthoate as a hydrotrope with CTAB, but solutions of anionic sodium lauryl sulfate surfactants in salt with no hydrotrope showed no strain hardening, indicating that the hydrotrope is critical to obtaining strain hardening in step strains. The results indicate a stress relaxation mechanism that is more complex than that of simple disentanglement and micelle breakage and rejoining, possibly involving strain-induced associations between micelles facilitated by hydrotropes that may act as linkers.

Development of Intracrystalline Mesoporosity in Zeolites through Surfactant-Templating

Novel insights into the surfactant-templating process leading to the formation of tailored intracrystalline mesoporosity in USY zeolite are presented in the light of the changes in the textural, morphological, and chemical properties of this zeolite produced during its treatment in a basic solution of cetyltrimethylammonium bromide (CTAB). The inability of analogous surfactants with bulkier heads to produce mesoporosity suggests that individual CTAB molecules can actually enter the zeolite through its microporosity. Once inside, the surfactant molecules self-assemble to produce the micelles responsible for the formation of mesoporosity causing the expansion of the zeolite crystals, as evidenced by He pycnometry measurements. The analysis of ultramicrotomed samples by transmission electron microscopy evidenced the formation of uniform intracrystalline mesoporosity throughout the entire crystals. In order to investigate an alternative method, namely, the dissolution and reassembly of zeolites, this was perf...

Micellar Solution as Green Extractive Solvent for Determination of Content of Quercetin as Natural Antioxidant in Oil Samples

We used water-contained surfactant-based vortex-assisted microextraction (WSVAME) as a green extraction method followed by high-performance liquid chromatography (HPLC) to determine the content of quercetin as natural antioxidant in different oil samples. During the WSVAME procedure, micellar solution of cationic surfactant cetyltrimethylammonium bromide (CTAB) was injected into oil samples in a conical-bottom glass tube to form cloudy solution. The dispersion process was accelerated by vortex mixing. After extraction and phase separation by centrifugation, the lower sediment phase was directly analyzed by HPLC. Optimization of extraction factors such as the volume and concentration of extraction solvent (aqueous solution of CTAB), percentage of acetic acid added to the oil sample, and vortex time was carried out using the chemometrics approach. Under the optimum condition (30 μL of 0.15 mol L−1 CTAB solution and vortex time of 1 min) the calibration curve was linear in the range of 0.1–100.0 μg mL−1 for hazelnut, olive, and coconut oil and 0.1–120.0 μg mL−1 for almond and grapeseed oil, with correlation coefficient (R 2) greater than 0.996. The limits of detection were 0.01–0.06 μg mL−1.