Binding Of Cetyltrimethylammonium Bromide Research Articles

Interaction and antibacterial activity of ciprofloxacin with choline based ionic liquid and CTAB: A comparative spectroscopic study

In this study, the complexation of potential chemo-therapeutic antibacterial drug, ciprofloxacin (CIP) with varying concentrations of surface active compounds (SACs) i.e., (N-(2-hydroxyethyl)-N,N-dimethyl-1-dodecanaminium bromide (12Cho.Br) and cetyltrimethylammonium bromide (CTAB) has been studied. Multispectroscopic techniques were exploited to carry out the study. The higher binding constant (Kb) value for CIP-CTAB than CIP-12Cho.Br obtained from fluorescence data revealed stronger binding of CTAB than 12Cho.Br, owing to the stronger hydrophobic-hydrophobic interaction betweeen CIP and CTAB compared to CIP and 12Cho.Br. The time resolve fluorescence decay shows changes in average lifetime (τavg) with the increasing concentration of 12Cho.Br and CTAB. The changes in τavg suggests that complex formation is taking place between CIP and 12Cho.Br / CTAB. Further, the formation of micelles by 12Cho.Br / CTAB and the effect of alkyl chain length was studied by dynamic light scattering (DLS) and zeta potential to confirm the drug complexation with 12Cho.Br and CTAB. The antibacterial activity has been performed for CIP and 12Cho.Br and CTAB. It was observed that in presence of lower concentrations of 12Cho.Br/ CTAB, the activity of the drug increased. The activity was also found cationic alkyl chain length dependent. Moreover, in-vitro cytotoxicity of CIP and its combinations with 12Cho.Br and CTAB was performed using MTT assay on HEK293 (Human embryonic kidney cells).

Binding of CTAB to Single Stranded DNA

Oligonucleotides will aggregate in the presence of a cationic surfactant in a similar way to DNA condensation, which occurs during the transportation of nucleic acids through the cell membrane. Aggregates formed from oligonucleotides of 20 to 100 bases in length in the presence of the surfactant, CTAB (cetyl trimethylammonium bromide) have been studied using UV spectroscopy and fluorescence polarization by titrating oligonucleotide solutions with CTAB. Results indicate that the onset of a signal change (optical density or polarization) occurs when the ratio of CTAB to DNA nucleotides reaches approximately 0.7. This ratio is consistent with previous literature studies and has been attributed to the formation of aggregates triggered by the presence of a surfactant such as CTAB. Measurements from UV spectroscopy showed a second onset occurring at a ratio of about 2 that may be attributed to aggregate precipitation. The saturation binding curves obtained using both techniques were sigmoidal in shape implying that the process is cooperative. A variety of models were explored to glean additional information on the binding including the association constant between CTAB and a DNA nucleotide, the Hill coefficient, and the number of CTAB molecules bound per nucleotide.

Internal charge transfer based ratiometric interaction of anionic surfactant with calf thymus DNA bound cationic surfactant: Study I

Cetyl trimethyl ammonium bromide (CTAB) binds calf thymus (ct-) DNA like anionic biopolymers electrostatically and established equilibrium both in the ground as well as in excited state in aqueous medium at pH 7. Anionic sodium dodecyl sulfate (SDS) does not show even hydrophobic interaction with ct-DNA at low concentration. On contrary, SDS can establish well defined equilibrium with DNA bound CTAB in ground state where the same CTAB–DNA isosbestic point reappears. First report of internal charge transfer (ICT) based binding of CTAB with ct-DNA as well as ICT based interaction of anionic SDS with DNA bound CTAB that shows dynamic quenching contribution also. The reappearance of anodic peak and slight increase in cathodic peak current with increasing concentration (at lower range) of anionic SDS, possibly reflect the release of CTAB from DNA bound CTAB by SDS.

Spectroscopic study on the interaction of Bacillus subtilis α-amylase with cetyltrimethylammonium bromide

The interaction between α ‐amylase from Bacillus subtilis and cetyltrimethylammonium bromide (CTAB) has been investigated at various temperature conditions using fluorescence and circular dichroism (CD) spectroscopic methods. Fluorescence data revealed that the fluorescence quenching of α ‐amylase by CTAB is the result of complex formation between CTAB and α ‐amylase. The thermodynamic analysis on the binding interaction data shows that the interactions are strongly exothermic (Δ H°=−17.92 kJ mol −1) accompanied with increase in entropy (Δ S° between 109 to 135 J mol −1 K −1). Thus the binding of CTAB to α-amylase is both enthalpic and entropic driven, which represent the predominate role of both electrostatic and hydrophobic interactions in complex formation process. The values of 2.17×10 −3 M −1 and 1.30 have been obtained from associative binding constant ( K a) and stoichiometry of binding number ( n), from analysis of fluorescence data, respectively. Circular dichroism spectra showed the substantial conformational changes in secondary structure of α ‐amylase due to binding of CTAB, which represents the complete destruction of both secondary and tertiary structure of α-amylase by CTAB.

Photochemical synthesis of shape-selective palladium nanocubes in aqueous solution

We have developed a seedless, citrateless one-step synthetic process for the formation of shape controlled monodisperse Pd nanoparticles (NPs) in 4 h of UV-photoirradiation. The synthesis was done in cetyl trimethylammonium bromide (CTAB) surfactant media in the presence of ascorbic acid as a reducing agent. The size and shape of the particles can be tuned easily by varying the molar ratio of the CTAB with the Pd salt and by controlling the UV-photoirradiation time. The preferential binding of CTAB to the (100) facets of Pd leads to the formation of Pd nanorods and nanocubes. The approach developed here would reduce the use of seed particles and tri-sodium citrate for the fast synthesis of faceted Pd NPs. The synthesized particles were found to be stable for at least 3 months under ambient conditions at room temperature. This newly developed process might find potential applications in the formation of other materials like Au, Ag, and CdS NPs and applicable in surface enhanced Raman scattering, and different catalysis reactions. We have developed a seedless, citrateless one-step synthetic process for the formation of shape controlled monodisperse Pd nanoparticles (NPs) in 4 h of UV-photoirradiation. The synthesis was done in cetyl trimethylammonium bromide (CTAB) surfactant media in the presence of ascorbic acid as a reducing agent. The size and shape of the particles can be tuned easily by varying the molar ratio of the CTAB with the Pd salt and by controlling the UV-photoirradiation time. The preferential binding of CTAB to the (100) facets of Pd leads to the formation of Pd nanorods and nanocubes. The approach developed here would reduce the use of seed particles and tri-sodium citrate for the fast synthesis of faceted Pd NPs. The synthesized particles were found to be stable for at least 3 months under ambient conditions at room temperature. This newly developed process might find potential applications in the formation of other materials like Au, Ag, and CdS NPs and applicable in surface enhanced Raman scattering, and different catalysis reactions.

Biopolymer–surfactant interaction: 3: Kinetics of binding of cetyltrimethyl ammonium bromide to deoxyribonucleic acid

By using a surfactant ion-selective membrane electrode, the kinetics of binding of cetyltrimethyl ammonium bromide with deoxyribonucleic acid (DNA) were studied. The binding followed first-order kinetics and appeared to occur in three stages for native DNA. Denatured DNA (caused by heat, acid and alkali) exhibited two-stage first-order kinetics. The multi-stage rate constants followed the order k 1> k 2> k 3 or k 1> k 2; they were energetically well separated. The three-stage kinetics at ionic strength μ=0.05 was reduced to a two-stage one at μ=0.001. The enthalpies of activation of all three stages were low whereas the entropy values were reasonably high, and varied in a narrow range. The Δ H ‡< TΔ S ‡ manifestation suggested the kinetic process to be essentially entropy controlled. An isokinetic enthalpy–entropy compensation phenomenon was observed.

Biopolymer–surfactant interactions: 5: Equilibrium studies on the binding of cetyltrimethyl ammonium bromide and sodium dodecyl sulfate with bovine serum albumin, β-lactoglobulin, hemoglobin, gelatin, lysozyme and deoxyribonucleic acid

The equilibrium binding of cetyltrimethyl ammonium bromide (CTAB) with bovine serum albumin, β-lactoglobulin, hemoglobin, lysozyme, gelatin and deoxyribonucleic acid, and of sodium dodecyl sulfate (SDS) with lysozyme, has been studied by an electrometric method mainly with variation of pH and ionic strength. The reversibility of the interaction has been established by studying the association and dissociation processes. The isotherms obtained are of the co-operative type; DNA, β-lactoglobulin and bovine serum albumin have shown strong binding of CTAB; the binding of SDS with lysozyme is also fairly strong and greater than that of CTAB. Ionic strength and pH influence the interaction process. The free energies of binding are distinctly of two categories. The low and high free energies (Δ G I° and Δ G II°) correspond to normal and co-operative binding processes respectively, their difference being identified with the free energy of co-operative association.

Thermodynamics of the Binding of a Cationic Lipid to DNA

The binding of cationic lipids to DNA induces the condensation of complexes of the lipid and polyelectrolyte. This paper presents data on the binding of the simple cationic lipid cetyltrimethylammonium bromide (CTAB) to DNA prior to the condensation process. The complete thermodynamics of the binding of CTAB to both helical and single strand DNA are evaluated with use of isothermal titration calorimetery data and analysis of UV melting transitions. The binding to the helical form involves a two-step process: first, binding to an isolated phosphate site on the DNA strand with a binding constant of 1.5 × 103 M-1, and second, a highly cooperative binding event that seems to involve hydrophobic intereactions between hydrocarbon chains of the bound CTAB. The cooperativity parameter is 56, leading to a cooperative binding constant of 8.7 × 104 M-1. The enthalpies of the two binding events on the helix sites are resolved: −20 kJ/mol for the isolated site and +3.3 kJ/mol for contiguous sites. Binding to the sin...

Biopolymer-surfactant interaction: 4. Kinetics of binding of cetyltrimethyl ammonium bromide with gelatin, hemoglobin, beta-lactoglobulin and lysozyme.

The binding of CTAB with the proteins, gelatin, hemoglobin, beta-lactoglobulin and lysozyme follow first order kinetics and occurs either in two or three distinct stages. The number of stages depends on the overall configuration of the biopolymers. The denatured protein, gelatin has shown three-stage kinetics under all conditions, whereas the native proteins, hemoglobin, beta-lactoglobulin and lysozyme have exhibited two stage kinetics. Heat treated lysozyme in 8 mol dm-3 urea medium has also shown a two-stage kinetics. On the basis of non interacting binding sites on the proteins and independent sequential binding, the rates of reaction have been observed to increase with temperature and follow the trend k1 >> k2 > k3. The interaction of CTA+ with the proteins is both electrostatic and hydrophobic. Hemoglobin has shown maximum reaction rate whereas, beta-lactoglobulin has shown a minimum. The activation parameters for the kinetic process have exhibited almost non-variant delta G++ and delta H++ < T delta S++. The formation of activation complex in the Eyring model is entropy controlled so also the overall kinetics. An isokinetic entropy-enthalpy compensation phenomenon has been observed for the respective kinetic stages.

Biopolymer–surfactant interaction. I. Kinetics of binding of cetyltrimethyl ammonium bromide with carboxymethyl cellulose (Na Salt)

AbstractThe kinetics of binding of the cationic surfactant cetyltrimethyl ammonium bromide with the Na salt of carboxymethyl cellulose was studied by the electrometric method using cetyltrimetlyl ammonium+ (CTA+) ion‐selective polyvinyl chloride membrane electrode. The binding process followed the first‐order kinetics and occurred in three stages. Its affinity increased with increasing CTA bromide concentration and decreased with ionic strength. The activation process comprised moderate E and ΔH≠ and negative ΔS≠ for all three stages with a ΔH≠ &lt; TδS≠ trend proving it to be entropy controlled. The ΔG≠ values followed the trend ΔG &lt; ΔG &lt; ΔG (in accordance with k1 &gt; k2 &gt; k3). The enthalpies (ΔH≠) and entropies (ΔS≠) of activation followed a systematic and interdependent trend. The multiple‐stage binding kinetics is grossly comparable with the kinetics of binding of proteins to solid surfaces. © 1995 John Wiley &amp; Sons, Inc.

Physicochemical behaviour of the sodium salt of carboxymethylcellulose in dye, salt and surfactant environments

AbstractThe interactions of the polyelectrolyte carboxymethylcellulose (sodium salt) with salts, dyes and surfactants have been studied by viscometry, conductometry, spectrophotometry and membrane potential measurements. The compact conformation of the polyelectrolyte has been realized in all the environments. The average radius of gyration, s̄, and the intrinsic viscosity, [η], decline with increasing concentration of the additives. This and the narrow pseudoternary single‐phase zones for both the carboxymethylcellulose (sodium salt)/CTAB (cetyltrimethylammonium bromide)Systematic name: hexadecyltrimethylamounium bromide. / Triton X‐100 (α‐alkylphenyl‐ω‐hydroxypoly(oxyethylene))/water and the carboxymethylcellulose (sodium salt)/CTAB/Tween 20 (poly(oxyethylene)sorbitan monolaurate)/water system suggest instability of the polymer in presence of the additives. The spectral results indicate dye aggregation (stacking) on the flexible polymer chain. The binding of CTAB with the polyelectrolyte is Langmuirian in absence of KCl and strongly co‐operative in its presence. Thermodynamic parameters have been evaluated in the light of both Langmuir and Scatchard equations. Considering water and polymer to be in separate phases, the free energy of transfer of CTAB from the aqueous to the polymer phase has been calculated.

Electric birefringence and emf measurements on polymer/surfactant complexes

Electromotive force measurements with a surfactant-sensitive electrode and transient electric birefringence measurements have been carried out to study the interaction between the cationic surfactant cetyltrimethylammonium bromide (CTAB) and the neutral copolymer poly (vinyl alcohol-co-vinyl acetate) (PVAA). The results show that binding of CTAB on the polymer starts abruptly at a critical surfactant concentration c 1 far below the c.m.c. of CTAB. The uptake of surfactant ions by the neutral polymer is accompanied by a dramatic increase of the Kerr constant B. With increasing CTAB concentration, the Kerr constant approaches a saturation value which increases linearly with the polymer concentration. The relaxation of the electric birefringence after removal of the electric field had to be fitted with two time constants τ 1 and τ 2. The relaxation times showed, in contrast to the Kerr constants, no significant variation with polymer or surfactant concentration, which implies that no expansion of the macromolecular coil due to binding takes place. It seems that the long relaxation time τ 2 corresponds to the overall rotational motion of the whole macromolecular coil. The critical association concentration c 1 is, in a large polymer concentration range, nearly independent of the polymer concentration. However, c 1 is markedly depressed, as expected, by addition of NaCl. A linear relationship between the logarithm of the critical concentrations c 1 and the c.m.c. and the logarithm of the counter-ion concentration was found with a smaller slope for c 1. It was concluded that in the CTAB concentration range studied two different association processes take place which differ with respect to their cooperativity: a first non- or only slightly cooperative association process after binding starts, followed by a second highly cooperative association process. The nature of the two different processes is discussed.

Activity of lipase in water-in-oil microemulsions

The lipase-catalysed hydrolysis rates of several nitrophenyl alkanoate esters of varying alkyl chain length (C4–C16) have been measured both in aqueous solution and in water-in-oil (w/o) microemulsions (which are known to contain discrete droplets). Lipase retains its activity in w/o microemulsions of water, heptane and sodium bis-2-ethylhexyl sulphosuccinate (AOT); the observed rates are consistent with the intrinsic activity of the enzyme (i.e. kcat/Km) being the same as in water. However, the observed conversion rates for C4 and C6 substrates are slower in the microemulsion system because of substrate partitioning to the oil-continuous phase, which results in a reduced concentration in the aqueous pseudophase. This conclusion is reached by comparing lipase and non-enzymic-(i.e. buffer) catalysed rates in both solution media. Again for the C4 and C6 substrate, partition coefficients for the substrates in the limit of high molar ratio of H2O:AOT, as determined from the kinetic results, show good agreement with measured values in heptane + water mixtures. This suggests that lipase functions effectively in the water pseudophase of the microemulsion. Lipase in the microemulsion can also catalyse the hydrolysis of longer chain alkanoates (up to C16). It can be inferred from the kinetics that such substrates partition to the interface where the lipase must also be active. In the case of AOT microemulsions, the pH profile of enzyme activity is not significantly altered compared with bulk water. The lipase retains > 60% activity in the microemulsion after incubation at 35 °C for 6 days. In w/o microemulsions of water, heptane, chloroform and cetyltrimethylammonium bromide (CTAB), the observed hydrolysis rates are significantly reduced and the intrinsic activity is reduced by a factor of twenty as compared with the AOT system. This is thought to be caused by inhibitory binding of CTAB to the protein.

Interaction of cationic detergents, cetyl- and dodecyl-trimethylammonium bromides, with lysozyme.

Binding of lysozyme with cetyltrimethylammonium bromide (CTAB) and dodecyl-trimethylammonium bromide (DTAB) at various detergent concentrations and pH was studied at 25 degrees C by equilibrium dialysis technique. In the case of CTAB, binding isotherms at pH 5.0, 7.0, and 9.0 show cooperative binding at all the concentrations of the detergent and the binding ratios increase with pH. Cooperative binding is also shown by DTAB at all the concentrations and pH, but the binding ratios are lower compared to CTAB. The Gibb's free energy change calculated on the basis of Wyman's binding potential concept increases with pH, indicating increased binding strength of CTAB at higher pH. The UV difference spectra of CTAB and DTAB with lysozyme and its model compounds such as L-Trp, L-Tyr X HCI and L-Phe show two peaks at 297 nm and 250 nm at pH 9.0 indicating the possible involvement of tryptophans as the binding sites along with the carboxylate anion or the phenolic group of a tyrosine on lysozyme. The effect of higher ionic strength on the binding of CTAB with lysozyme at pH 9.0 is evidenced by lower binding ratios and decreased intensities of the UV difference bands, thus indicating the involvement of electrostatic interactions. However, the hydrophobic interactions between the detergents and the aromatic amino acid residues in lysozyme contribute more to the binding strength. The binding of these cationic detergents by lysozyme induces conformational changes in the enzyme. They are followed by the circular dichroism (CD) technique which shows a decrease in the aromatic bands in the 320-250 nm region.(ABSTRACT TRUNCATED AT 250 WORDS)

The binding of CTAB, a cationic surfactant, to the rat erythrocyte membrane.

The adsorption of CTAB (cetyltrimethylammonium bromide) to the rat erythrocyte membrane was studied by determining the electrophoretic mobility of erythrocytes treated with CTAB and by SDS polyacrylamide electrophoresis of membrane proteins from erythrocytes treated with 14C-CTAB. At low concentrations of CTAB there was only a small reduction in the electrophoretic mobility of the erythrocytes. At lytic concentrations the electrophoretic mobility of the erythrocytes was markedly reduced. Alterations at the cell surface were found to be a more likely reason for the reduction in the electrophoretic mobility than interactions between the surfactant and charged groups at the cell surface. Very small amounts of radioactivity were found to be associated with the protein and sialoglycoprotein bands of the polyacrylamide gels. It is suggested that the adsorption of CTAB to the rat erythrocyte membrane does not involve electrostatic interactions between the surfactant and negatively charged groups of the sialoglycoproteins and that membrane proteins do not play a major role in the lytic events.