Interaction Of Sodium Dodecyl Sulfate Research Articles

A mechanistic study of the histone H1-DNA complex dissociation by sodium dodecyl sulfate

The effect of sodium dodecyl sulfate (SDS) on H1-DNA complex is studied by different methods. The histone H1 fluorescence emission increases on SDS addition. It is may be due to the transfer of the only tyrosine residue of H1 to a more hydrophobic environment. Circular dichroism (CD) shows an increase of 17.1% in α-helix content of H1 in the presence of SDS. The CD spectrum of DNA in the presence of SDS also indicates the transfer of DNA from the B-form to the A-form both in the absence and presence of H1. The isothermal titration calorimetric investigation indicates that H1–SDS and DNA–SDS interactions are both exothermic. Spectrophotometric study of the percent of precipitation of DNA by H1 has shown that the complex formation is highly cooperative and it is completely dissociates by SDS >0.5 mM. The results signify two important reasons for H1-DNA complex dissociation: (1) the addition of SDS reduces the ability of H1 to neutralize the negative charges of DNA, and (2) concurrently the hydrophobic chains of SDS induce the DNA conformational changes. Furthermore, the precipitation curve in the presence of lower concentrations of SDS (in the range of 0.25–0.5 mM) shows two domains. The calorimetric titration curve of DNA by H1 or the folded H1 (by 0.4 mM SDS) also reveal two domains. The results indicate that the C-terminal domain of intact H1 possibly is the first domain that is dissociated from DNA and then the separation of the globular domain occurs in the presence of SDS.

Interaction of sodium dodecyl sulfate with human native and cross-linked hemoglobins: a transient kinetic study

The interaction of sodium dodecyl sulfate (SDS) at a concentration range (0–515 μM) below the critical micelle concentration (CMC∼0.83 mM) with human native and cross-linked oxyhemoglobin (oxyHb) and methemoglobin (metHb) has been investigated by optical spectroscopy and stopped-flow transient kinetic measurements. It is observed that the interaction of SDS with human native and cross-linked oxyHb shows the disappearance of the bands of oxyHb at 541 and 576 nm and the appearance at 537 nm. The resultant spectra are characteristic of low spin (Fe 3+) hemichrome. Similarly SDS has been found to convert human native and cross-linked high spin (Fe 3+) metHb to low spin (Fe 3+) hemichrome. The interaction of SDS with oxyHb suggests a conformational change of the protein in the heme pocket, which may induce the binding of distal histidine to iron leading to the formation of superoxide radical. The formation of hemichrome from metHb is found to be concentration-dependent with SDS. The stopped flow transient kinetic measurements of the interaction of SDS with metHb show that at least four molecules of SDS interact with one molecule of metHb. The interaction of SDS with human cross-linked oxy and met hemoglobin shows results similar to those for human native oxy and met hemoglobin indicating that the covalent modification does not alter the interaction of SDS with cross-linked hemoglobin.

Thermodynamic Effects of Alcohol Additives on the Cooperative Binding of Sodium Dodecyl Sulfate to a Cationic Polymer

The binding isotherms for the interaction of sodium dodecyl sulfate (SDS) with poly(diallyldimethylammonium chloride) in aqueous solutions of 1,8-octanediol, 1,2-octanediol, or 1-butanol (BuOH) were determined by potentiometry, using a functional membrane responsive to anionic surfactants. Each alcohol caused the binding isotherm to shift to a lower SDS concentration. The magnitude of the effect was 1,2-octanediol > 1,8-octanediol ∼ BuOH. The binding isotherms were analyzed by a linear lattice model for cooperative binding. The effect of the alcohols was analyzed by thermodynamic treatment of mixtures based on the regular mixing model, and the interchange energies between alcohol and water (4.06 kT for 1,8-octanediol, 4.82 kT for 1,2-octanediol, and 3.63 kT for BuOH) and between alcohol and SDS (-1.21 kT for 1,8-octanediol, -3.52 kT for 1,2-octanediol, and -1.65 kT for BuOH) were estimated. The pronounced effect of 1,2-octanediol on the binding isotherms was ascribed to its instability in the water phase and its strong hydrophobic interaction with the SDS anion in the polyion domain. The effect of 1,8-octanediol was comparable to that of BuOH, but 1,8-octanediol was more unstable in both the water phase and the polyion domain by about kT In 2 compared to BuOH. This phenomenon can be attributed to the fact that binding of one 1,8-octanediol molecule structurally approximates the binding of two BuOH molecules.

Free Energy of Interaction of Sodium Dodecyl Sulfate in Aqueous Solution with Carbon Black Surfaces

The free energy of the adsorption process of an ionic surfactant from aqueous solutions onto a set of carbon blacks in the range of low concentrations was evaluated using the model proposed by van Oss and co-workers. The obtained results indicated that the free energy of interaction between adsorbent and adsorbate through water results mainly from Lifshitz–van der Waals and electrostatic interactions, and its value showed a good correspondence with that previously found from a combination of the classical measurements of adsorption isotherms and the Langmuir model.

Electron spin resonance study of phosphatidyl choline vesicles using 5-doxyl stearic acid

Harshness and skin irritation are related to surfactant–skin lipid interactions. Delipidization of the stratum corneum is caused by surfactant penetration into extracellualar lipid bilayers; disrupting the lipid microstructure and thereby impairing skin barrier properties. The mechanisms of interactions of sodium dodecyl sulfate (SDS) with lipid as a model membrane are investigated in this work by studying the vesicle to micelle structural transition, which occurs during such interactions of the membrane. The optical density of the phosphatidyl choline liposome was found to increase upon the addition of up to 2 mM SDS and then to decrease gradually on further increase in SDS concentration. Electron spin resonance (ESR) spectrum of 5-doxyl stearic acid (5-DSA) in liposome before and after interaction with SDS solutions at different concentrations showed the rotational correlation time of 5-DSA to increase markedly, possibly due to the penetration of 5-DSA into the lipid bilayers. SDS addition decreased the rotational correlation time of 5-DSA until it attained a constant value above a certain SDS concentration suggesting complete solubilization of liposome and formation of mixed micelles. The ESR spectrum of 5-DSA inside SDS micelle was also seen to be quite different from that obtained after complete solubilization of liposome and, this also indicates the formation of mixed micelles.

A multitechnique approach in protein/surfactant interaction study: physicochemical aspects of sodium dodecyl sulfate in the presence of trypsin in aqueous medium.

Interaction of sodium dodecyl sulfate (SDS) with a globular protein, trypsin, has been physicochemically studied in aqueous medium in detail using tensiometric, conductometric, calorimetric, fluorimetric, viscometric, and circular dichroism techniques. The results indicate that SDS-trypsin aggregates start to form at a surfactant concentration higher than the critical micelle concentration of pure SDS micelle. In contrast, the counterion binding decreases in the presence of trypsin. The free energies and enthalpies of micellization, interfacial adsorption, and entropy of micellization associated with the interaction have also been calculated. The values show that the interaction phenomenon is entropy controlled and endothermic in nature. The increase in viscosity is observed for the system of SDS-trypsin cluster above the critical micelle concentration of SDS micelle only. The aggregation number and interface polarity decrease compared to the values of micelles without protein. Circular dichroism spectra show the high alpha-helical content and unfolded structure of trypsin in the presence of SDS due to strong electrostatic repulsion leading to a probable "necklace and bead" model in the case of biopolymer-surfactant complexes.

Interaction of Monodisperse Poly(N-isopropylacrylamide) Microgel Particles with Sodium Dodecyl Sulfate in Aqueous Solution

A thermodynamic analysis of ionic surfactant solutions in equilibrium with polymer solutions, polymer microgels, and macrogels is given. It is concluded that the surfactant binding isotherm cannot be exactly calculated only from the total and equilibrium surfactant concentrations. An additional trace probe electrolyte method is suggested for the determination of the binding isotherm. The interaction of sodium dodecyl sulfate with poly(N-isopropylacrylamide) microgel particles was investigated by dynamic light scattering, electrophoretic mobility, and surfactant binding isotherm measurements. The interaction of the surfactant with the microgel particles takes place in a two-step process. The surfactant binds above a critical surfactant concentration; then, after a plateau is reached a new binding step evolves in the isotherm. The hydrodynamic diameter of the particles also increases in a stepwise manner in correlation with the binding isotherm. The microgel−surfactant interaction is interpreted by means of...

Mechanism of mixed liposome solubilization in the presence of sodium dodecyl sulfate

Structural transformations of vesicles to micelles that take place during the interaction of sodium dodecyl sulfate (SDS) with individual and mixed vesicles of phosphatidyl choline (PC) and phosphatidic acid (PA), have been studied by monitoring changes in optical density and in the concentration of free SDS monomer in the respective systems. Incorporation of the surfactant monomers (SDS) in the bilayers was found to result in an initial increase in concentration of the mixed vesicles up to its saturation. Subsequently a progressive relaxation of these structures together with a simultaneous formation of mixed micelles was found to occur. The breakup of bilayer and the formation of mixed micelles were completely dependent on the structure of the individual phospholipid. The solubilization of the anionic phosphatidic acid vesicle was very fast in the presence of SDS, due to its simple structure and its compatibility with the SDS molecule. But solubilization of the zwitter ionic phosphatidyl choline vesicle was very complicated in the presence of SDS, possibly due to its complex structure and the zwitterionic nature. On the other hand, solubilization of the mixed vesicle (mixed liposome) and formation of mixed micelle was found to be relatively easier. This may be attributed to one of the phospholipid component preferentially coming out first through interaction with SDS, thereby making the overall system unstable and enhancing the micellization processes.

Fluorescence Probe Study of the Interaction Between Acrylic Acid-co-Ethyl Methacrylate Copolymers and Sodium Dodecylsulfate

The interaction between sodium dodecylsulfate (SDS) and acrylic acid (AA)–ethyl methacrylate (EMA) copolymers has been investigated using steady state fluorescence and conductimetric measurements to assess the effect of the polymer composition on the aggregation process. Micropolarity studies using the ratio between the emission intensities of the vibronic bands of pyrene (I1/I3) and the shift of the fluorescence emission of pyrene-3-carboxaldehyde show that the interaction of SDS with AA-EMA copolymers occurs at surfactant concentrations smaller than that observed for the pure surfactant in water and depends on the copolymer composition. The increase of ethyl methacrylate in the copolymers lowers the critical aggregation concentration (CAC) due to the larger hydrophobic character of the polymer backbone. The formation of aggregates on the macromolecule is induced mainly by hydrophobic interactions, but the process is also influenced by the ionic strength due to the counter-ions of the polyelectrolyte.

Investigation on the Interaction of Sodium Dodecyl Sulfate with Poly(Ethylene Oxide) by Electron Spin Resonance and UV Spectrum

Investigation on the Interaction of Sodium Dodecyl Sulfate with Poly(Ethylene Oxide) by Electron Spin Resonance and UV Spectrum

Binding of Sodium Dodecyl Sulfate (SDS) to the ABA Block Copolymer Pluronic F127 (EO97PO69EO97): F127 Aggregation Induced by SDS

It has been established that sodium dodecyl sulfate (SDS) binds to the micelles and monomers of the block copolymer F127. SDS binds to the monomeric unassociated F127 in the form of polymer/bound SDS micellar complexes. SDS binds to F127 micelles first forming mixed micelles, which dissociate into smaller mixed aggregates and then to single F127 unassociated monomers. A third interaction of SDS, which involves promotion of F127 micelles at concentrations up to 3 °C below the critical micellar temperature of pure F127, was identified and is investigated in the present work. The formation of such SDS-induced mixed micelles was monitored using differential scanning calorimetry, light scattering, isothermal titration calorimetry, and a SDS selective electrode for electromotive force measurements. These investigations have shown how the different binding and aggregation processes between SDS and F127 involving induced micellization, growth of mixed micelles, breakdown of mixed micelles, and binding of SDS to m...

Investigation of the association in water of sodium dodecyl sulfate with a positively charged copolymer based on N -isopropylacrylamide

The interactions of sodium dodecyl sulfate with a positively charged copolymer based on N-isopropylacrylamide (NIPAM) have been investigated in aqueous solution by turbidimetric and viscometric measurements. The copolymer contains mainly NIPAM and only 5 mol % of the charged comonomer [3-(methacryloylamino)propyl]-dimethyloctylammonium bromide. The polymer–surfactant complex is insoluble for mixture compositions near to the charge stoichiometry, while it exhibits lower critical solution temperature behavior for mixtures with an excess of polymer or surfactant. In the case of surfactant excess, the transition from an expanded coil to a globular state upon heating has been observed by viscometry.

Electrochemical Quartz Crystal Microbalance Study of Additive Effects in Pulsed Deposition of Cu‐Co Alloys

A rotating quartz crystal microbalance is employed to study the effects of the additives sodium dodecyl sulfate (SDS) and saccharin during the pulsed deposition of Cu‐Co alloys. SDS promotes Co displacement by Cu during pulse off‐times, while saccharin impedes this process. On‐time current efficiencies for pulsed deposition are lower than those during dc deposition, particularly for SDS‐only electrolytes. Off‐time areal mass increases in SDS‐only electrolytes are much larger than those expected from the displacement of Co by Cu and exhibit a square root dependence on the electrode rotation rate; other electrolytes do not display this behavior. Assuming these mass increases are due to SDS incorporation yields inclusion densities that are consistent with other metal/additive systems previously characterized in the literature. The interaction of SDS and saccharin during pulsed deposition is discussed. © 2000 The Electrochemical Society. All rights reserved.

Binding of Sodium Dodecyl Sulfate to Some Polyethyleneimines and Their Ethoxylated Derivatives at Different pH Values. Electromotive Force and Microcalorimetry Studies

Electromotive force and isothermal titration microcalorimetry measurements have been carried out to study the interactions of sodium dodecyl sulfate (SDS) with polyethyleneimines (PEI's) and some ethoxylated PEI's at different pH's. In all cases the polymers show a remarkable affinity toward SDS. The SDS concentration at the onset of binding decreases with decreasing pH. At low pH's phase separation similar to that observed for strong polyelectrolyte/oppositely charged surfactant systems occurs presumably as a consequence of the protonation of the N atoms in the polymer to form a polycation. The SDS range over which phase separation occurs decreases as the size of the ethoxylated chains increases, and for the polymer with the longest ethoxylated chain no precipitation occurs. In many cases where phase separation occurs, as more SDS is added the polymer/surfactant complex often resolubilizes and binding proceeds until the polymer becomes saturated with bound SDS. For any given polymer at this limiting stage in the binding, the number of surfactant molecules bound per mole of polymer is independent of pH. In addition both the charged and uncharged N atoms as well as the pendant ethoxylated chains make significant contributions to the binding process.

Interaction of sodium dodecyl sulfate with polyelectrolyte complexes derived from diazoresin and sulfonate-containing polymers

The sulfonate-containing polyelectrolytes (SPE) from sulfonation of polystyrene (PS) and copolymerization of 3-sulfo-propyl methacrylate, potassium salt (SPMS) with styrene (S) were prepared. Photosensitive polyelectrolyte complexes (PEC DR ) derived from SPE and diazoresin (DR), which does not dissolve in water or organic solvent due to its ionic crosslinking structure, dissolves in aqueous solution of sodium dodecyl sulfate (SDS) due to the dissociation of PEC DR and the hydrophobic interaction between SDS and the polymer chain. The photosensitive behavior and thermostability of the PEC DR were investigated, and it was found that the thermostability of PEC DR increases dramatically in SDS aqueous solution. It was proposed that the higher thermostability of PEC DR in SDS aqueous solution is due to an aggregation of SDS molecules around the diazonium group of the PEC DR which protects the-N 2 + group of the DR from attack by the nucleophiles. The image-forming behavior of PEC DR by ultraviolet (UV) light was examined and considered to be different from other PECs. It was concluded that the photoimaging behavior of PEC DR is based on a reaction in which an ionic bond converts to a covalent bond.

Interaction of sodium dodecyl sulfate with polyelectrolyte complexes derived from diazoresin and sulfonate‐containing polymers

The sulfonate-containing polyelectrolytes (SPE) from sulfonation of polystyrene (PS) and copolymerization of 3-sulfo-propyl methacrylate, potassium salt (SPMS) with styrene (S) were prepared. Photosensitive polyelectrolyte complexes (PECDR) derived from SPE and diazoresin (DR), which does not dissolve in water or organic solvent due to its ionic crosslinking structure, dissolves in aqueous solution of sodium dodecyl sulfate (SDS) due to the dissociation of PECDR and the hydrophobic interaction between SDS and the polymer chain. The photosensitive behavior and thermostability of the PECDR were investigated, and it was found that the thermostability of PECDR increases dramatically in SDS aqueous solution. It was proposed that the higher thermostability of PECDR in SDS aqueous solution is due to an aggregation of SDS molecules around the diazonium group of the PECDR, which protects the N group of the DR from attack by the nucleophiles. The image-forming behavior of PECDR by ultraviolet (UV) light was examined and considered to be different from other PECs. It was concluded that the photoimaging behavior of PECDR is based on a reaction in which an ionic bond converts to a covalent bond. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2601–2606, 1999

Solubilization of Liposomes by Sodium Dodecyl Sulfate: New Mechanism Based on the Direct Formation of Mixed Micelles

The vesicle-to-micelle structural transitions that occurred in the interaction of sodium dodecyl sulfate with phosphatidylcholine vesicles were studied at the equilibrium by means of dynamic light scattering (at different scattering angles) and freeze–fracture electron microscopy techniques. The incorporation of surfactant monomers in the bilayers resulted in an initial contraction of the mixed vesicles formed up to their saturation (size reduction of about 10%). Then, a progressive relaxation of these structures (growth from 170 to 225 nm) and a simultaneous formation of mixed micelles (particles of about 6 nm) occurred. Hence, in this interval “relaxed mixed vesicles” and mixed micelles coexisted in different proportions without formation of intermediate complex aggregates (bimodal size distribution curves). Freeze–fracture electron microscopy showed a direct formation of mixed micelles within the bilayer and their subsequent separation from the vesicle surface without formation of complex intermediate aggregates. This simple process progressed up to the complete vesicle solubilization.

Study of the interaction between poly( N-ethyl-4-vinylpyridium bromide) and surfactants in aqueous solution

The interaction between cationic poly( N-ethyl-4-vinylpyridium bromide) (PEVPB) and SDS (sodium dodecyl sulfate) was investigated. It is proved that the polymer-bound micelles of SDS are formed below the CMC of SDS in pure water through fluorescence spectroscopy using pyrene as a probe. Also, it has been found that the PEVPB–SDS interaction depends on what type of confirmation of SDS is added into polymer solution: molecules or micelles. The two systems of PEVPB–SDS molecules and PEVPB–SDS micelles are studied by the measurements of reduced viscosity, fluorescence spectroscopy, conductivity and turbidity.

Interaction of sodium dodecyl sulfate with stratum corneum lipid liposomes: influence of the level of cholesteryl sulfate on this process

The role played by the cholesteryl sulfate (Chol-sulf) in the interactions of sodium dodecyl sulfate (SDS) with liposomes formed by stratum corneum (SC) lipids was studied. We determined the surfactant to lipid molar ratios (Re) and the bilayer/aqueous phase partition coefficients ( K) of this interaction varying the proportion of Chol-sulf in liposomes, the relative proportions of the others lipids remaining constant. These parameters were determined at sublytic level by monitoring the changes in the fluorescence intensity of liposomes due to the 5(6)-carboxyfluorescein (CF) released from the interior of vesicles. The fact that the free surfactant concentration was always lower than that of its CMC indicates that permeability changes were mainly ruled by the action of surfactant monomers. The SDS ability to produce permeability changes on SC liposomes and its affinity with these bilayers decreased as the proportion of Chol-sulf in bilayers increased up to a minimum was reached for a Chol-sulf proportion of 10–15%. Hence, slightly higher and lower Chol-sulf proportions than that existing in the SC (about 10%) led to a fall and to a rise in the SDS activity on these liposomes, respectively. Furthermore, the resistance of SC liposomes to be solubilized by SDS (via mixed micelles formation) showed a maximum for a Chol-sulf proportion of 15%. These effects may be related to the reported dependencies of the level of Chol-sulf on the abnormalities in the skin barrier function and on the SC intercellular cohesion.

Binding of sodium dodecylsulfate to poly( N-isopropylacrylamide) microgels at different temperatures

The binding of sodium dodecylsulfate (SDS) to poly ( N-isopropylacrylamide), (PNIPAM) microgels at different temperatures (below and above the transition temperature from swollen to shrunken particles, T s) has been investigated by fluorescence probe methods complemented with surface tension and dynamic light scattering measurements. Pyrene and 1-anilinonaphthalene-8-sulfonate (ANS) were employed as fluorescence probes. At 21°C, the association of the surfactant with the particles occurs at a critical aggregation concentration (cac). Values obtained were (cac)=1 mM form surface tension data and (cac)≅0.75 mM from the dependence of the fine structure of pyrene fluorescence spectra with SDS addition. The binding isotherm derived from surface tension data at 21°C is highly cooperative, implying that the binding takes place with formation of surfactant aggregates. At 42°C (a temperature above T s), the (cac) shifts to 1.7 mM indicating that the interaction of SDS with shrunken PNIPAM microgels is weaker than with the swollen species. The microenvironment sensed by pyrene probe in both, the SDS aggregates formed onto PNIPAM swollen (21°C) and shrunken (42°C) species is less polar than that corresponding to SDS micelles in pure water. The T s of the particles and the effect of SDS on it can be determined from the temperature dependence of ANS fluorescence intensity or emission band position. At temperatures higher than T s, coulombic repulsion effects (probably due to the higher charge density of the collapsed particles) are evidenced by the fluorescence behaviour of both probes employed.