Low Concentrations Of Cetyltrimethylammonium Bromide Research Articles

CTAB induced growth and shrinkage of Pluronics® P103 micelles: Experimental and theoretical rationale

This study offers an insight into the concentration influence of a cationic surfactant- cetyltrimethylammonium bromide (CTAB) having a 16-carbon long alkyl side chain that influences the self-assembly and micellization behaviour of a linear triblock copolymer based on ethylene oxide (EO) and propylene oxide (PO) Pluronic® P103 in aqueous solution. The work makes an exclusive use of a variety of methodologies, such as high sensitivity differential scanning calorimetry (HSDSC), phase behaviour study, dynamic light scattering (DLS), and small-angle neutron scattering (SANS). The investigation on the clouding behaviour demonstrates that the cloud point value of 5 %w/v P103, which is typically in the vicinity of 90 °C, rises up to more than 100 °C with the addition on of very low concentration of CTAB. The DLS technique predicted the change in hydrodynamic diameter (Dh) of micelles with temperature and in varying CTAB concentration. The SANS results inferred the morphological changes in the micelles. A comprehensive approach revealing the relationship between the molecular orbital energies of the tested P103 and CTAB were assessed by utilising the computational simulation method with the Gaussian 09 calculation window and Gauss View 5.0.9 software. The perception of CTAB-stabilized Pluronics® micelles is predicted to be much improved from the evaluated optimised descriptors. Additionally, our examined micellar system revealed the solubilization enhancement of a model hydrophobic dye orange-OT utilizing UV–vis spectroscopy.

Molecular mechanism of insulin aggregation in the presence of a cationic surfactant

Protein aggregation and amyloid fibrillation are connected with neurodegenerative disorders. Insulin, a small molecular weight protein related to type II diabetes, has been shown to self-assemble to form protein aggregates. In this work, we investigated the effects of cetyltrimethylammonium bromide (CTAB) of insulin on the in vitro aggregation process at pH 7.4 and 2.0. The aggregation tendency of insulin was measured using a variety of biophysical approaches, including turbidity measurements, light scattering, far UV-CD, ThT dye binding, and transmission electron microscopy. The turbidity results demonstrated that at pH 7.4, a low concentration of CTAB (30–180 μM) causes insulin aggregation but at higer concentration (>180 μM) aggregation was not seen. However, at pH 2.0, both low as well as high concentrations of CTAB were unable to promote insulin aggregation. The ThT dye binding and far-UV CD data suggest that aggregation induced by CTAB is not having an ordered structure. Insulin treated with higher concentrations (>180 μM) of CTAB, the insulin gained a secondary structure. The possible cause of inducing aggregation in insulin is electrostatic and hydrophobic interaction because insulin contains a net negative charge at pH 7.4 and no aggregation at pH 2.0 due to electrostatic repulsion.

Fluorescence Quenching of Carbazole by Selected Phenols in a Cationic Micellar System of Cetyltrimethyl Ammonium Bromide (CTAB).

A group of selected phenols i.e., picric acid, p-Nitrophenol, m-Nitrophenol, o-Nitrophenol, and phenol interactions were studied with a fluorescent probe carbazole in a micellar system of CTAB. CTAB concentration was optimized for maximum quenching of carbazole for each studied phenol. Interaction was studied in 0.02 and 0.1mol/dm3 CTAB. All the studied phenols resulted in the quenching of carbazole in both CTAB concentrations though lower CTAB concentration was found optimum for highest quenching of the probe carbazole. Carbazole fluorescence quenching with phenols were explained with the help of Stern-Volmer equation that produced the constants of Stern-Volmer ([Formula: see text]). [Formula: see text] shows the sensitiveness of the method for the studied phenol and were observed in the order picric acid > phenol > m-Nitrophenol > p-Nitrophenol > o-Nitrophenol. Detection threshold (DT) and quantification threshold (QT) were observed in the order 1.76 [Formula: see text] 10-7- 6.30 [Formula: see text] 10-7mol/dm3 and 5.898 [Formula: see text] 10-7-2.11 [Formula: see text] 10-6mol/dm3 respectively. The method is reproducible and is effective for the determination of studied phenols in the samples.

Influence of Various Concentrations of Cetyltrimethylammonium Bromide on the Properties of Nickel Oxide Nanoparticles for Supercapacitor Application

In this paper, the impact of the crystallite sizes of nickel oxide nanoparticles (NiO NPs) on their efficiency for electrochemical capacitors (EC) has been investigated. NiO NPs were prepared without and with low and high concentrations (0.02[Formula: see text]M and 0.1[Formula: see text]M) of cetyltrimethylammonium bromide (CTAB) using the hydrothermal process that represent NiO, NiO-1, NiO-2, respectively. The crystallite size of NiO, NiO-1, NiO-2 NPs was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) analysis. The thermogravimetry/differential thermal analysis (TG/DTA) was used to investigate the thermal observation of as-prepared precursor to transform as NiO NPs. HRTEM revealed spherical seed-like morphologies, which consist of aggregated NiO-1 NPs with an average particle size of 9[Formula: see text]nm. The NiO-1 shows the large specific capacitance value of 168[Formula: see text]Fg[Formula: see text] at a current density of 0.5[Formula: see text]Ag[Formula: see text] compared with other NiO and NiO-2 NPs. The study suggests that the low concentration of surfactant CTAB of NiO NPs plays an important role in supercapacitor applications because of the smaller crystallite sizes of the materials as well as a large number of active sites for faradic reaction.

Truncated Triangular Silver Nanoparticles using low concentration of CTAB

Triangular silver nanoparticles have special properties which increase their importance in chemistry, biology, physical and medical applications. This work concerns with fabrication of truncated nanotriangles, using a simple chemical method. The seed mediated growth method that is usually used to synthesize nanorods, is modified to create nanotriangles. By using this modified method, we successfully obtained silver truncated nanotriangles by adding low concentration of cetyltrimethylammonium bromide (CTAB) into seed solution. UV-visible spectroscopy (UV-Vis) was used to characterize the surface plasmon resonance of the formed nanoparticles. Also, the geometrical properties of nanoparticles were characterized by transmission electron microscopy (TEM) and scanning tunneling microscopy (STM). The average edge length of truncated nanotriangle is affected by varying the amount of seed added to the growth solution; it varies from 56 nm up to 75 nm according to the amount of seed used. The degree of truncation (T) for the produced nanotriangle edges has been estimated. Furthermore, the effect of CTAB concentration as well as the speed in which NaBH4 is added to the seed solution on the formed nanoparticles was investigated.

Open-tubular admicellar electrochromatography of charged analytes

Fundamental studies on the separation of cationic and anionic analytes in open-tubular admicellar electrochromatography (OT-AMEC) using cetyltrimethylammonium bromide (CTAB) and fused silica capillaries are presented. OT-AMEC was compared with open-tubular admicellar liquid chromatography (OT-AMLC) by running the two methods using the same mobile phases. The mobile phases were buffered at pH ≥ 6 and contained a low concentration (above the critical surface aggregation concentration and below the critical micelle concentration) of CTAB. The stationary pseudophase of CTAB admicelles were formed at the solid surface and liquid interface inside the capillary by simply conditioning the capillary with the mobile phase. Separations were performed in a 30 cm (21.5 cm to UV detector) long and 50 μm inner diameter capillary, using low pressure (50 mbar) in OT-AMLC and high voltage (15 kV at negative polarity) in OT-AMEC. The appropriate equations for the experimental estimation of retention factor (k) values of analytes were discussed. For anionic analytes, k in OT-AMEC were carefully determined by considering the observed interaction between CTAB monomers and tested analytes. The calculated k for each analyte was found similar in OT-AMLC and OT-AMEC, although the mechanism of retention was not entirely different due to the contribution of electrophoresis in OT-AMEC. Studies on the addition of a typical (i.e., acetonitrile) and atypical modifier (i.e., nonyl-β-glucoside) into the mobile phase, and sample focusing with >10x improvement in peak height under isocratic conditions were also conducted.

Effect of cetyl-trimethyl-ammonium-bromide (CTAB) and bis (3-sulfopropyl) disulfide (SPS) on the through-silicon-via (TSV) copper filling

Through silicon via (TSV) is a key structure of three-dimensional (3-D) IC integration. However, the fabrication of TSV still faces the challenge of void-free copper filling. In this study, a new suppressor cetyl trimethyl ammonium bromide (CTAB) with a low molecular weight is used as a suppressor for the TSV copper filling. The effect of various CTAB concentrations on the TSV filing ratio are studied. It is observed that low concentrations of CTAB (0.1 g/L) can inhibit the copper deposition. However, this does not occur at higher concentrations (0.5 g/L). Possible inhibitor mechanisms of CTAB at different concentrations were proposed. As only CTAB cannot fill the TSV completely, bis (3-sulfopropyl) disulfide (SPS) was added to increase the deposition rate at the bottom of the TSV. Finally, a TSV filling ratio prediction model based on LSV curves is established to enhance the filling ratio, and consequently, optimized concentrations of CTAB and SPS were found to realize a complete TSV filling.

Influence of Cetyltrimethylammonium Bromide on Gold Nanocrystal Formation Studied by In Situ Liquid Cell Scanning Transmission Electron Microscopy

The synthesis of monodisperse size- and shape-controlled Au nanocrystals is often achieved with cetyltrimethylammonium bromide (CTAB) surfactant; however, its role in the growth of such tailored nanostructures is not well understood. To elucidate the formation mechanism(s) and evolution of the morphology of Au nanocrystals in the early growth stage, we present an in situ liquid-cell scanning transmission electron microscopy (STEM) investigation using electron beam-induced radiolytic species as the reductant. The resulting particle shape at a low beam dose rate is shown to be strongly influenced by the surfactant; the Au nanocrystal growth rate is suppressed by increasing the CTAB concentration. At a low CTAB concentration, the nanoparticles (NPs) follow a reaction-limited growth mechanism, while at high a CTAB concentration the NPs follow a diffusion-limited mechanism, as described by the Lifshitz–Slyozov–Wagner (LSW) model. Moreover, we investigate the temporal evolution of specific NP geometries. The am...

Flotation Performance of Low-rank Coal in the Presence of Cetyltrimethyl Ammonium Bromide

ABSTRACT The flotation enhancement mechanism and flotation kinetics of low-rank coal in the presence of cetyltrimethyl ammonium bromide (CTAB) were investigated. The contact angle of the coal sample increased by 46.07% and the attachment time between coal particles and a single air bubble decreased by 85.79% with increasing the concentrations of CTAB from 0 to 1 × 10–4 M. Low concentrations of CTAB enhanced the flotation performance of low-rank coal, and the concentrate yield significantly increased by up to 8.59 percentage points with increasing the concentrations of CTAB from 0 to 1 × 10–5 M at the cost of a lower increase in the ash content. However, the selectivity was reduced at high CTAB concentrations (5 × 10–5 M and 10–4 M). Six kinetic flotation models were employed to fit the flotation test data using the 1stOpt analysis software; the flotation rate constant (k), the maximum combustible recovery (ε ∞), the correlation coefficient (R 2) and the modified flotation rate constant (k m) were calculated. Most models showed that the modified rate constant and the maximum combustible recovery of low-rank coal increased with the increasing concentrations of CTAB.

Thermomagnetically Responsive γ‐Fe2O3@Wax@SiO2 Sub‐Micrometer Capsules

AbstractA three steps synthesis route is proposed to generate thermosensitive and magnetically responsive γ‐Fe2O3@Wax@SiO2 sub‐micrometer capsules with a paraffinic core and a solid and brittle shell. The process integrates Pickering‐based emulsions, inorganic and sol–gel chemistries to promote monodisperse in size wax droplets, γ‐Fe2O3 nanoparticles and mineralization of the wax/water interfaces. Hybrid capsules are obtained with an average size around 800 nm, representing the first example of sub‐micrometer capsules generated employing Pickering emulsions as templates. Cetyltrimethylammonium bromide (CTAB) cationic surfactant added during mineralization at concentrations between 0.17 and 1.0 wt% impacts the shell density. The shell density seems to improve its mechanical strength while affording a low wax expansion volume without breaking for CTAB concentrations above 1.0 wt%. At lower CTAB concentration (0.17 wt%), the silica shell becomes less bulky and cannot resist the wax dilatation induced by the solid‐to‐liquid phase transition imposed by hyperthermia. The magnetically induced heating provided by the internal magnetic moments is sufficient to melt the wax core, expanding its volume, inducing thereby the surrounding silica shell rupture. Such γ‐Fe2O3@Stearic Acid@Wax@SiO2 sub‐micrometer capsules allow a sustained wax release with time, whereby 20% of the wax is released after 50 min of alternating magnetic field treatment.

The effect of cetyltrimethylammonium bromide on the coefficient of thermal expansion and optical transmittance of poly(ether sulfone) film

Cetyltrimethylammonium bromide (CTAB) was used as a stabilizing agent for PES films, and its effect on the coefficient of thermal expansion (CTE) and optical transmittance (OT) of PES films was investigated. The CTE of PES film decreased with increasing CTAB concentration up to 0.5 wt%, because of the improved intermolecular interaction between polymer chains via CTAB molecules. When 0.5 wt% of CTAB was added to the PES film, the CTE of polymer film decreased from 66 to 50 ppm/°C without noticeable reduction in OT. At such a low CTAB concentration range (<0.5 wt%), the glass transition temperature (T g ) and tensile strength increased with CTAB. At high CTAB concentration above 0.5 wt%, however, it had a negative effect on the properties of PES film - CTE increased but T g and tensile strength decreased with it.

Conformational transition of κ-casein in micellar environment: Insight from the tryptophan fluorescence

Intrinsically disordered proteins (IDPs) are under intense analysis due to their structural flexibility and importance in biological functions. Minuscule modulation in the microenvironment induces significant conformational changes in IDPs, and these non-native conformations of the IDPs often induce aggregation and cause cell death. Changes in the membrane composition often change the microenvironment, which promote conformational change and aggregation of IDPs. κ-Casein, an important milk protein, belongs to the class of IDPs containing net negative charges. In this present work, we have studied the interaction of κ-casein with cetyltrimethyl ammonium bromide (CTAB), a positively charged surfactant, utilizing various steady state fluorescence, time-resolved fluorescence and circular dichroism spectroscopy. Our results clearly indicate that κ-casein undergoes at least two conformational transitions in presence of various concentrations of CTAB. The intrinsically disordered κ-casein assumes a partially folded conformation at lower concentration of CTAB, which adopts an unstructured conformation at higher concentration of CTAB. The partially folded conformation of κ-casein at a lower CTAB concentration might be induced by the favorable electrostatic interaction between the positively charged surfactant headgroup and net negative charges of the protein, whereas surfactant nature of CTAB is being pronounced at higher concentration of CTAB.

Anisotropic Overgrowth of Palladium on Gold Nanorods in the Presence of Salicylic Acid Family Additives

We explored the use of salicylic acid (SA) and its derivatives 5-formylsalicylic acid (FSA) and 5-sulfosalicylic acid (SSA) as organic additives to cetyltrimethylammonium bromide (CTAB) in synthesizing gold nanorods (AuNRs) followed by palladium (Pd) capping at the ends of AuNRs. In the AuNR synthesis step, SA family additives in the presence of low concentration of CTAB (50 mM) serve as both the prereducing agent and the cofactor in nanorod growth. At an optimum additive/CTAB ratio (0.1–0.2), AuNRs grow to the longest length. At low additive concentrations, the gold seeds do not grow. At high concentrations, the longitudinal growth of AuNRs is disrupted because the excessive additive disturbs the ligand structure, leading to more isotropic growth. In the Pd overgrowth step, Pd starts to grow from both ends for AuNRs synthesized at optimum additive/CTAB ratios. Feeding more Pd grows the particles into a core–shell structure, possibly because there lacks a tight ligand layer on Pd that favors the longitudinal growth. For AuNRs synthesized at high additive/CTAB ratios, Pd growth loses preference, showing randomized Pd nucleation on AuNR surface. Finally, the palladium-end-capped–AuNRs’ catalytic activity was tested using the resazurin reduction reaction. This study shows a new way to produce controllable deposition of Pd on AuNRs.

Role of anionic and cationic surfactants on the structural and dielectric properties of ZrO2 nanoparticles

In the present paper, we report the synthesis of Cetyltrimethylammonium Bromide (CTAB) and Sodium dodecyl sulfate (SDS) assisted Zirconia (ZrO2) nanoparticles by co-precipitation method. The effect of surfactant concentration on the structural and dielectric properties has been extensively studied. X-ray diffraction studies reveal the formation of tetragonal phase in the ZrO2 nanoparticles prepared by lower CTAB concentration. However, for higher concentration of CTAB some traces of monoclinic phase appeared along with tetragonal phase. SDS assisted nanoparticles shows crystalline tetragonal phase with lower concentration of SDS and amorphous nature with higher concentrations of SDS. FTIR results show the presence of Zr–O symmetrical stretching vibrations at tetrahedral site. The dielectric properties of all samples have been studied from 10Hz to 1MHz, revealing the low value of dielectric constant with CTAB and very high value with SDS as compared to bare ZrO2 nanoparticles. The dielectric behaviour of the bare and surfactant assisted nanoparticles has been correlated with the phase transition, size of nanoparticles and the nature of surfactants.

Signal enhancement of cetyltrimethylammonium bromide as a highly-sensitive sensing strategy for tetrabromobisphenol A

It is quite important to monitor tetrabromobisphenol A (TBBPA) in environmental samples due to its wide existence and high toxicity. Herein, a highly-sensitive electrochemical method was developed for the determination of TBBPA based on the strong signal enhancement effects of cetyltrimethylammonium bromide (CTAB). In pH7.5 phosphate buffer, an irreversible oxidation peak with low height is observed for TBBPA on the surface of a carbon paste electrode (CPE), and the oxidation wave is improved greatly after addition of a low concentration of CTAB. The great peak current enlargements indicate that CTAB exhibits remarkable enhancement effects toward TBBPA oxidation. The enhancement mechanism of CTAB was investigated using electrochemical impedance spectroscopy and chronocoulometry. It is found that the existence of CTAB obviously increases the accumulation efficiency of TBBPA and facilitates its electron transfer. The linear range of this new sensing system is from 2.5 to 800nM, and the detection limit is 0.99nM. It was used in water sample analysis, and the recovery value was over the range from 95.74% to 102.6%.

Cetyltrimethylammonium bromide (CTAB) promote amyloid fibril formation in carbohydrate binding protein (concanavalin A) at physiological pH

Low concentration of CTAB provoked cross β-sheet formation whereas high concentrations of CTAB direct to alpha helix induction in Con A.

Hollow organosilica nanospheres prepared through surface hydrophobic layer protected selective etching

In this study, a facile and effective surface hydrophobic layer protected selective etching strategy has been adopted to fabricate organic functionalized hollow silica nanospheres (OHSNSs). Our experiments demonstrated that the morphology and structure of OHSNSs were greatly affected by the types of organosilanes and concentrations of cetyltrimethylammonium bromide (CTAB) as pore-making agent. At low concentration of CTAB (1.9mg/mL−1), it was found that the protective effect of the hydrophobic layer of 3-thiocyanatopropyltriethoxysilane (TCPTES) was so strong that can be endured long time etching (8h), leading to the formation of hollow core and organic porous shell structure. And yet, the protective effect of the hydrophobic layer of vinyltriethoxysilane (VTES) was too weak to withstand alkali etching, resulting in preferentially etched of the outer vinyl protection shell. Whereas, at a higher concentration of CTAB (2.5mg/mL−1), for TCPTES, the irregular and capsules-like spheres were obtained. In contrast, for VTES, porous core/solid shell structures with shell thickness of 16nm were generated. In addition, no particles were observed when the CTAB concentration was above 2.5mg/mL−1.

Voltammetric Ciprofloxacin Sensor Based on Carbon Paste Electrodes Modified with Mesoporous Carbon with Enhancement Effect Using CTAB

The voltammetric behavior of Ciprofloxacin (CIP) was investigated in different buffer solutions using cyclic voltammetry. It exhibited a single irreversible anodic peak with shift in peak potential with pH value which indicates proton dependent reaction. In a pH 4.0 phthalate buffer, a poorly defined oxidation peak current (ip) is observed using carbon paste (CP) electrode for the determination of CIP using linear sweep adsorptive stripping voltammetric method (LS-AdASV). However, in the presence of low concentration of Cetyltrimethylammonium bromide (CTAB), ip enhancement occurs. Moreover, the usage of mesoporous carbon-modified carbon paste (MC/CP) electrode exhibits a significant enhancement in the ip. The enhancement of the ip of CIP at MC/CP electrode in the presence of CTAB [1.0 × 10−4 M], was ascribed to two factors: (1) CTAB facilitates electron transfer of CIP; and (2) the high surface area of MC, which accumulates adsorptive CIP on the MC/CP electrode surface. All experimental parameters, were optimized for the determination of CIP. LS-AdASV method is observed to possess the following good qualities: high sensitivity (detection limit is 1.5 × 10−9 M), wide linearity (5.0 × 10−9–2.0 × 10−5 M), rapid response, low cost and simplicity. In conclusion, this method was employed to successfully detect CIP in pharmaceutical formulation and human serum.

Quantitative Separation of Graphene Oxide Nanoribbon by Froth Flotation

Froth flotation was employed for quantitative separation of graphene oxide nanoribbon (GONR) from its solution. The effects of GONR concentration, pH, and cetyltrimethyl ammonium bromide (CTAB) concentration on GONR separation were studied through a Box–Behnken experimental design method. F value of 176.47, coefficient of determination of 0.9969, adjusted R2 of 0.9912, and coefficient of variation of 4.09%, explored by means of analysis of variance, implied the satisfactory adjustment of the obtained quadratic model. The results indicated that low GONR and high CTAB concentration at low pH were ideal for maximum separation by flotation.

Inhibitory action of quaternary ammonium bromide on mild steel and synergistic effect with other halide ions in 0.5 M H2SO4

The corrosion inhibition of mild steel in 0.5M H2SO4 solution has been investigated using electrochemical methods, X-ray diffraction (XRD) and scanning electron microscope (SEM). The adsorption and inhibition action of acid corrosion of mild steel using cetyltrimethylammonium bromide (CTABr) and different halides (NaCl, NaBr and NaI) has shown synergetic effect. The results showed that the protection efficiency (P%) has high values at considerable high concentration of CTABr. However, in the presence of the different halides, the P increases dramatically at low concentration of CTABr. Physisorption was proposed from the the values of ΔGads0. The synergism parameter (Sθ) is found to be greater than unity indicating that the enhanced P% caused by the addition of the halides to the CTABr is due to a co-operative adsorption of both species. Corrosion products phases and surface morphology were studied using X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively.