Effect Of Sodium Dodecyl Sulfate Research Articles

Effect of sodium dodecyl sulfate (SDS) on the co-deposition and frictional behavior of carbon nanotube/nickel composite layer

In this paper, the effects of sodium dodecyl sulfate (SDS) concentrations in the electroplating solution on the morphology, nucleation rate, nucleation mode, and frictional behavior of the CNT/Ni composite layers were investigated. The results showed that the electrodeposition of Ni was in a three-dimensional nucleation/growth mode. In addition, the x-ray diffraction (XRD) of the deposited layers showed that adding SDS changed the preferred growth direction of Ni from (2 0 0) to the (2 2 0) crystallographic plane. When the carbon nanotube (CNT) content was 0.1 g l−1, and the SDS content was 0.05 g l−1, the deposition potential was the most negative, increasing the number of Ni nucleation sites on the electrode and resulting in the grain size refinement of the deposited layer. It also reduced the friction coefficient of the composite simultaneously.

A novel synchronous fluorescence spectrometry combined with fluorescence sensitization for the highly sensitive and simultaneous detection of enoxacin, ofloxacin and tetracycline hydrochloride residues in wastewater

The synergistic effect of sodium dodecyl sulfate (SDS) and Mg2+ could significantly enhance the fluorescence intensity of enoxacin (ENO) at λex/λem = 269.2 nm/385.6 nm, ofloxacin (OFL) at λex/λem = 290.8 nm/466.2 nm and tetracycline hydrochloride (TCH) at λex/λem = 372.6 nm/514.8 nm. Moreover, when the wavelength difference (Δλ) was chosen 135 nm, the synchronous fluorescence spectra of the three antibiotic complexes could be well separated and the interference of the samples matrix were eliminated primely. Therefore, only one synchronous fluorescence scan was needed to simultaneously determine the three antibiotics. Based on these facts, a synchronous fluorescence spectrometry combining fluorescence sensitization for highly sensitive and selective determination of ENO, OFL and TCH residues in wastewater was developed for the first time. The experimental results showed that the concentrations of ENO, OFL and TCH in the range of 0.5–550 ng mL−1, 1–1500 ng mL−1 and 10–5500 ng mL−1 showed a good linear relationship with fluorescence intensity. The limits of detection were 0.0599 ng mL−1, 0.115 ng mL−1 and 0.151 ng mL−1, respectively. The recoveries of the actual sample were 87.50%–99.99 %, 93.00%–98.50 % and 85.70%–98.42 %, respectively. Overall, the novel synchronous fluorescence spectrometry established in the experiment has the advantages of high sensitivity, good selectivity, fast detection speed and high accuracy. It has been successfully applied to the detection of residual amounts of ENO, OFL and TCH in wastewater with satisfactory results.

Electrode Imbibition and Surfactant Interactions with Vanadium Flow Battery Electrolytes

Redox flow batteries (RFB) are a critical technology for stationary grid-scale energy storage, with potential usage with intermittent power sources, such as wind and solar. RFBs are attractive for long-duration energy storage because the anolyte and catholyte are stored separately external to the electrochemical reactor. Separating the electrolytes and the electrochemical cell decouples energy and power densities, unlike batteries that store charge in the solid-state, such as Li-ion, Pb-acid, or Ni-Cd. A standard RFB chemistry is the all-vanadium redox flow battery (VRFB), which utilizes the four oxidation states of vanadium, with V2+, V3+, V4+, and V5+. Recently our group found that adding small amounts of sodium dodecyl sulfate (SDS) to a VFRB increased the kinetics of the V2+ to V3+oxidation.Furthermore, surfactants play essential roles in battery manufacturing and operation. Surfactants can change metal oxide crystal structure, inhibit dendrite growth, limit corrosion, and prevent nanoparticle agglomeration. Surfactants are never wholly removed during manufacturing and can be present during battery operation. Therefore, it is crucial to understand how surfactants impact battery performance and their effect on the materials.This talk describes SDS's equilibrium surface properties and adsorption characteristics at the liquid−air and liquid-solid interfaces, thus providing insights into the interactions of SDS with a VFRB electrolyte. Experiments focusing on the effects of sulfuric acid and vanadium ions on SDS's equilibrium surface tension and critical micelle concentration (CMC) were completed. The Szyszkowski equation is used to calculate SDS's adsorption parameters, such as interfacial surface excess, Γsz [mol/m2], the surface excess at the saturated interface, Γ∞ [mol/m2], the minimum molecular area in the adsorption layer at the saturated interface, Amin [nm2], and the Gibbs free energy of adsorption, ΔGads [kJ/mol]. Furthermore, an examination of the spontaneous imbibition of the VFRB electrolyte with SDS into a porous carbon electrode is presented. The microstructure of porous systems, interfacial tension, and fluid−solid interactions controls the capillary-driven flow and is vital in multiphase flow in porous media. Therefore, understanding SDS's effects on the VFRB electrolyte in an electrode is critical to understanding the electrochemical reactions and molecular interactions occurring.This work was supported as part of the Breakthrough Electrolytes for Energy Storage and Systems (BEES2), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award # DE-SC0019409.

Detergent induced structural perturbations in peanut agglutinin: insights from spectroscopic and molecular dynamic simulation studies

The three dimensional structure of a protein is very important for its structure. Studies relating to protein structure have been numerous and the effect of denaturants on proteins can help understand the process of protein folding and misfolding. Detergents are important denaturants and play important roles in various fields. Here we explored the effect of sodium dodecyl sulphate (SDS) and cetyltrimethylammonium bromide (CTAB) on the structure of peanut agglutinin (PNA). The protein was purified from its natural source and impact of SDS and CTAB was studied by circular dichroism, intrinsic fluorescence, 8-anilino-1-napthalenesulfonic acid, molecular docking and molecular dynamics simulation. Pure peanut agglutinin showed a trough at 220 nm and positive ellipticity peak at 195 nm, specific for lectins. Results from the experimental and simulation studies suggest how oppositely charged detergents can interact differently and lead to varied structural perturbations in PNA. Both the surfactants induce all α protein-like circular dichroism in the protein, above its critical micelle concentrations, with significant change in accessible surface area that became more hydrophobic upon the treatment. Major interactions between the surfactants and protein, resulting in PNA conformational rearrangement, are electrostatic and van der Waals interactions. However, CTAB, a cationic surfactant, has similar effects as anionic surfactant (SDS) but at significantly very low concentration. Though the effects followed same pattern in both the surfactant treatment, i.e. above respective CMC, the surfactants were inducing all α protein-like conformation in PNA. Communicated by Ramaswamy H. Sarma

Effect of sodium dodecyl sulfate on preferential degradation of naphthalene by thermally activated persulfate: Implications for soil flushing solution reuse

Various flushing solutions that contain hydrophobic organic compounds and surfactants are generated during surfactant-enhanced soil flushing processes. How to effectively remove the target pollutants while minimizing the degradation of surfactants for reuse of the flushing solutions has become a major problem. A series of batch experiments were conducted to investigate the preferential degradation mechanisms of naphthalene by sodium dodecyl sulfate (SDS) as well as the effect of SDS concentration on the degradation efficiency using a competitive kinetic method. In addition, the effects of persulfate (PS) dosage, temperature, and pH on the degradation efficiency of naphthalene were also studied, and a prediction model based on response surface methodology (RSM) was built to optimize the preferential degradation of naphthalene. One-dimensional column flushing experiments were performed to evaluate the feasibility of reusing soil flushing solutions at the predicted PS dosage. Results show that: (i) SDS inhibited naphthalene degradation owing to competitive oxidation and micellar protection, with a decreasing degradation rate constant as SDS concentration increased. However, naphthalene was still degraded by reactive oxygen species (ROS) at a higher rate than SDS, indicating the preferential degradation of naphthalene. When the concentration of SDS increased from 5 to 10 times of critical micelle concentration (CMC; 8.2 mM), the ratio for rate constants of naphthalene to SDS (kNAP/kSDS) decreased significantly from 31.61 to 3.38, illustrating the obvious effect of SDS concentration on preferential degradation of naphthalene; (ii) The formation of single-chambered vesicles with a higher thermodynamic stability was observed at 10 CMC, compared to the spherical micelles formed at 5 CMC. The accessibility of naphthalene to ROS was greatly reduced at 10 CMC, resulting in a significant reduction in kNAP/kSDS value. Moreover, the method in which ROS attacked naphthalene in surfactant micelles varied with SDS concentration, which also impacted the preferential degradation of naphthalene; (iii) Under the optimal PS dosage predicted by the RSM model, a good reusability of SDS was observed in the soil flushing solutions after thermally activated PS oxidation, with a significant reduction on the toxic risk of soil after flushing.

Synergistic effect of sodium dodecyl sulfate (SDS) and oleic acid (OA) on gelation and lubrication performance

In this paper, it was found that with the addition of sodium dodecyl sulfate (SDS, a hydrophilic surfactant) and oleic acid (OA, a lipophilic surfactant) in a solvent with a proper composition ratio, a stable gel could be obtained via a simple ultrasonic treatment. The synergistic gelation of OA–SDS was verified in a series of solvents with different polarities, such as white oil (WO), LB-2000, n-hexane, polyalphaolefin (PAO10), and deionized water. The Fourier transform infrared (FTIR) analysis confirms that the gelation of OA–SDS is highly related to the ion exchange reaction between them. However, the xerogel of OA–SDS gelator in deionized water and WO (OSW) exhibited remarkably different morphologies, indicating that the gelation is based on different molecular assembly processes, which is governed by the orientation of the two surfactant molecules in liquid media. Further characterizations of OSW gel presented that the synergistic effect between OA and SDS not only existed in gelation, but also in enhancing the mechanical and thermal stability of WO, and endowing the OSW gel with reliable friction reduction and antiwear performances under variable working conditions. Subsequently, the lubrication mechanism was proposed based on rheological analysis and the morphological and compositional analysis of wear surfaces. This study provides a novel idea for the molecular design of lubricating gelators with wide adaptability to solvent polarity and working conditions.

Emulsion Polymerisation of Poly(Methyl Methacrylate)-Grafted-Graphene Oxide (PMMA-GO): Effect of Surfactant Concentration on Colloidal Stabilization

Graphene oxide (GO) exhibits a wide range of outstanding mechanical, electrical, and physical characteristics, and it is of substantial interest to impart such qualities onto polymeric materials such as poly (methyl methacrylate) PMMA for wider specialized functionalization. The attention of this work is on the development of emulsion polymerization procedure to prepare PMMA-GO nanocomposite and the effect of sodium dodecyl sulphate (SDS) surfactant dosages incorporated during the polymerization, on the effect of PMMA surface interactions in oil. The grafting efficiency is quantified using the Fourier-transform infrared spectroscopy (FTIR), and the effect of surfactant concentration on PMMA-GO stability is examined using UV-Visible spectroscopy, zeta potential and particle size analyses using the Malvern Zetasizer. The surfactant free emulsion has a better stabilization in terms of zeta potential analysis compared to emulsion of PMMA-GO with 0.32, and 0.4 wt. % of SDS. The polymerized PMMA-GO can be used as a model system to alter wax crystallization at low temperatures in oil and gas industries.

Biophysical assessment of amantadine and SDS surfactant mixture onto boron nitride nanotube: a molecular dynamics investigation.

The aggregation and adsorption of amantadine and sodium dodecyl sulfate on the boron nitride nanotubes in aqueous system were investigated, employing the classical molecular dynamics method. The aqueous system containing amantadine and sodium dodecyl sulfate was investigated by self-diffusion of the molecules, with particular emphasis on their center of mass mean square displacement. The radial distribution function and dipole moment measurement were used to analyze the water effect on the aggregation and molecular interaction between amantadine and sodium dodecyl sulfate in the complex. In turn, the amantadine molecules are able to develop water monolayers at the aqueous solution but show no noticeable aggregated adsorption in the fluid. In contrast, sodium dodecyl sulfate self-aggregation on the boron nitride nanotube efficiently occurs, and so the effect of sodium dodecyl sulfate on aggregated adsorption of amantadine was studied. Our results show that in the presence of sodium dodecyl sulfate at critical micelle concentration, its effect on the aggregation of amantadine was enhanced onto boron nitride nanotube compared to just pure sodium dodecyl sulfate or amantadine on boron nitride nanotube. Our simulations show a remarkable restructuring and enhanced orientation of the water molecules around sodium dodecyl sulfate and amantadine adsorbed on boron nitride nanotube. All molecular dynamics simulations were done using NAMD-2.9 package with CHARMM-36 force field. The nanotube PDB file was made by VMD with (12, 12) indexes. The nanotube atoms were considered to be fixed and periodic during the simulation process, and the ends did not cap with hydrogens. The initial PDB file of components was saved from ChemOffice software, and the webservers to obtain the charge and topology files were Reddb and Swiss Param webservers. The VMD software was used for structural visualizations and graphical analysis.

Effects of the anionactive surfactant sodium dodecyl sulfate on the adhesion of cells of the strain <i>Micrococcus luteus</i> 1-i to the surface of carbon materials

The adhesion of microorganisms on various surfaces plays a crucial role in many biotechnological processes. A widespread component of wastewater is the anion-active surfactant sodium dodecyl sulfate (SDS). Surfactants have a significant influence on all interfacial reactions, including those occurring in microbial fuel-cell technology. The work set out to study the effect of sodium dodecyl sulfate on the sorption of cells of the Micrococcus luteus 1 strain (which has electrogenic activity in microbial fuel cells) on the surface of various carbon-containing electrode materials used in biological fuel cell technology: 1) carbon tissue; 2) carbon felt; 3) crushed graphite contact trolleybus inserts (summer); 4) birch activated carbon. Using spectrophotometry and microscopy methods, the presence of sodium dodecyl sulfate in the concentration range of 10–200 mg/l was shown to increase the sorption of Micrococcus luteus 1-i cells on the surfaces of the tested carbon materials under experimental conditions. The maximum increase in sorption during 2 hours of exposure was detected when 100 mg/l of this surfactant was applied: for birch activated carbon – 21%; for carbon fabric – 26%; for carbon felt relative to the control (without surfactant) – 24%. The results demonstrate a sufficiently effective adhesion of Micrococcus luteus 1-i cells to various carbon materials, including in the presence of fairly high concentrations of sodium dodecyl sulfate, confirming the prospects of this strain for use in various types of microbial fuel cells.

Reinterpret the heterogeneous reaction of α-Fe2O3 and NO2 with 2D-COS: The role of SDS, UV and SO2

Heterogeneous reaction of mineral aerosols and atmospheric polluting gases play an important role in atmospheric chemistry. In this study, the reactions of NO2 with or without SO2 mixture gas on the surface of α-Fe2O3 particles under dry conditions were studied. The effects of sodium dodecyl sulfate (SDS) and the heterogeneous reaction under both dark and UV irradiation conditions were investigated. The infrared spectrum analyzed by the two-dimensional correlation spectroscopy (2D-COS) was used to obtain the products formation sequences. The results showed that UV irradiation can promote the production of nitrate. The 2D-COS analysis indicated SDS changed the sequence order of nitrate and nitrite species during reactions. In oxidation conditions, the final product of heterogeneous reaction of NO2 and α-Fe2O3 was monodentate nitrate. Only the heterogenous reaction of NO2 and α-Fe2O3 containing SDS (FOS) without UV light, the final product was bidentate nitrate. SDS was the catalysis agent supply and photoresist to the system. With surface active compounds, the environmental lifetime of heterogeneous reactions between trace gases and aerosols extends. Surfactants, ultraviolet light, and the types of gases involved in the reaction all have complex effects on the aerosol aging process. This study provided a reference for subsequent heterogeneous reaction studies and the formation of aerosols.

Reducing the assemblies of amyloid-beta multimers by sodium dodecyl sulfate surfactant at concentrations lower than critical micelle concentration: molecular dynamics simulation exploration

Amyloid-β peptide, the predominant proteinaceous component of senile plaques, is responsible for the incidence of Alzheimer's disease (AD), an age-associated neurodegenerative disorder. Specifically, the amyloid-β(1-42) (Aβ1-42) isoform, known for its high toxicity, is the predominant biomarker for the preliminary diagnosis of AD. The aggregation of the Aβ1-42 peptides can be affected by the components of the cellular medium through changing their structures and molecular interactions. In this study, we investigated the effect of sodium dodecyl sulfate (SDS) at much lower concentrations than the critical micelle concentration (CMC) on Aβ1-42 aggregation. For this purpose, we studied mono-, di-, tri- and tetramers of Aβ1-42 peptide in two different concentrations of SDS molecules (10 and 40 molecules) using a 300 ns molecular dynamics simulation for each system. The distance between the center of mass (COM) of Aβ1-42 peptides confirms that an increase in the number of SDS molecules decreases their aggregation probability due to greater interaction with SDS molecules. Besides, the less compactness parameter reveals the reduced aggregation probability of Aβ1-42 peptides. Based on the energetic FEL landscapes, SDS molecules with the concentration closer to the CMC are an effective inhibitory agent to prevent the formation of Aβ1-42 fibrils. Also, the aggregation direction of the peptide pairs can be predicted by determining the direction of the accumulation-deterrent forces. Communicated by Ramaswamy H. Sarma

Experimental study on the effects of ultrasonic excitation on pore structure of water-bearing coal

Coal seam water injection is one of the main coal mine dust control measures. To study the effects of ultrasonic excitation on the pore structure of water-bearing coal in depth, ultrasonic excitation experiments were conducted with varied variables including ultrasonic excitation time, ultrasonic power, and fluid pressure on coal. The effects of sodium dodecyl sulfate (SDS) treatment and ultrasonic excitation were also compared. The coal samples treated under different conditions are characterized by low-temperature nitrogen adsorption and scanning electron microscopy (SEM) respectively for the quantitative analysis of pore volume and specific surface area and qualitative analysis of surface pore and fracture structure. The results show that ultrasonic excitation can significantly increase the pore volume and specific surface area of coal and damages the inner wall surfaces of the pore to different extents, making the pore inner surfaces rougher. However, the effect of ultrasonic excitation becomes weaker after the pore volume increases to a certain extent, resulting in more uniform pore size and volume distributions. Ultrasonic excitation time affects the pores with smaller size more significantly, and there is a time threshold effect. The volume and specific surface area of large pores and fractures show limited responses (or increases) to as the excitation time increased. The energy is mainly used for the fracturing and expanding the pores with smaller size. The effect of ultrasonic excitation on pore expansion is more obvious under the fluid pressures lower than 4 MPa. High fluid pressures weaken the fracturing and expanding effect of ultrasonic excitation on the pore structure of water-bearing coal. The ultrasonic power threshold effect is also observed. Once exceeding a certain value, further increasing the ultrasonic power does not dramatically affect the pore structure of water-containing coal. Ultrasonic excitation can enlarge the primary pores and fracture and generate secondary pores and fracture in coal. In contrast, the 0.85% SDS treatment is only able to clean the primary small pores, and no new pore structures are formed.

Effect of Sodium Dodecyl Sulfate on Stability of MXene Aqueous Dispersion.

MXenes suffer from severe oxidation and progressive degradation in aqueous media due to its poor chemical stability. Herein, sodium dodecyl sulfate (SDS) is employed as an efficient protectant for long-term storage of Ti3 C2 Tx -MXene aqueous dispersion. Experimental data support SDS's capability to protect oxidation-prone sites on Ti3 C2 Tx nanosheets, providing extended colloidal stability of up to 213 days. Concentration-dependent anti-oxidation effect articulates that 1.5mgmL-1 is deemed as an ideal SDS dose for Ti3 C2 Tx to achieve optimal oxidation-resistance in aqueous solution. Additionally, a chroma strategy is developed to instantly and precisely measure the oxidation degree of Ti3 C2 Tx . Adsorption-driven anti-oxidation efficacy of SDS is further confirmed by optimized conformations with interaction energies of SDS on termination-free and surface-defective Ti3 C2 Tx through multiscale simulations. This proposed route is a step forward in broadening the horizons of experimental and theoretical investigations of MXenes with promising implications for long-term storage and reliable applications.

Molecular interaction of lysozyme with therapeutic drug azithromycin: Effect of sodium dodecyl sulfate on binding profile

This paper describes an inclusive biophysical study elucidating the interaction of therapeutic drug azithromycin (Azith) with hen egg white lysozyme (HEWL). Spectroscopic and computational tools have been employed to study the interaction of Azith with HEWL at pH 7.4. The fluorescence quenching constant values (Ksv) exhibited a decrease with the increase in temperature which revealed the occurrence of static quenching mechanism between Azith and HEWL. The thermodynamic data demonstrated that hydrophobic interactions were predominantly involved in the Azith-HEWL interaction. The negative value of standard Gibbs free energy (ΔG°) stated that the Azith-HEWL complex formed via spontaneous molecular interactions. The effect of sodium dodecyl sulfate (SDS) surfactant monomers on the binding propensity of Azith with HEWL was insignificant at lower concentrations however the binding significantly decreased at increased concentrations of the former. Far-UV CD data revealed alteration in the secondary structure of HEWL in the presence of Azith and the overall HEWL conformation changed. Molecular docking results revealed that the binding of Azith with HEWL takes place through hydrophobic interactions and hydrogen bonds.

Micellar liquid chromatography as a sustainable tool to quantify three statins in oral solid dosage forms

A method based on micellar liquid chromatography has been developed to determine rosuvastatin, lovastatin and simvastatin in oral solid dosage forms. Samples were solved in mobile phase up to the target concentration, filtered and directly injected. The three statins were resolved in 30 min, using an aqueous solution of 0.10 M sodium dodecyl sulfate – 7.0% 1-butanol, buffered at pH 3 with 0.01 M phosphate salt as mobile phase, running under isocratic mode at 1 mL/min through a C18 column. Detection was at 240 nm. The effect of sodium dodecyl sulfate on elution strength was more important than that of the organic solvent. The procedure was successfully validated by the guidelines of the International Council for Harmonization in terms of: specificity, linearity (r2 > 0.990), calibration range (1.5 - 15 mg/L for rosuvastatin, 0.5–10 mg/L for lovastatin and simvastatin), limit of detection (0.4, 0.2 and 0.15 mg/L for rosuvastatin, lovastatin and simvastatin, respectively), trueness (98.8–101.7%), precision (<2.7%), carry-over effect, robustness, and stability. Values were inside the acceptance criteria of the Methods, Method Verification and Validation, Food and Drug Administration-Office of Regulatory Affairs, thus ensuring the reliability of the results. The main feature was the low proportion of organic solvent used, thus making the procedure sustainable and green. Besides, it was easy-to-conduct and with high sample-throughput, and then useful for routine analysis in pharmaceutical quality control. Finally, it was applied to commercial pharmaceutical preparations.

Effects of SDS surface-active agents on hydrodynamics and oxygen mass transfer in a square bubble column reactor: Experimental and CFD modeling study

This work examined experimentally and numerically the effects of sodium dodecyl sulfate (SDS) surfactant agent on mass transfer coefficients kLaL and kL in a high-aspect square bubble column reactor. To this end, SDS aqueous solutions at concentrations between 5 ppm and 30 ppm were prepared. Superficial gas velocity was varied from 0.74 cm.s−1 to 9.44 cm.s−1 covering all flow regimes to analyze the interaction between different phases and the effect of liquid surface tension on gas-liquid interfaces. Experimental data indicated that the presence of the SDS in the liquid phase augmented the overall gas holdup up to 25% at a constant gas velocity (Ug = 7.3 cm.s−1) in the transition regime, which is due to the role of SDS in bubble interactions. The impact of SDS addition on the mass transfer is twofold. Firstly, it reduced kL because the SDS molecules migrate towards the bubble-liquid interface thanks to the lower O2 diffusivity in water, thus hindering the O2 transfer from one phase to the other. Secondly, it increased aL owing to the inhibition of bubbles coalescence and, therefore, the lower mean bubble size. Among these two effects, the latter is prevailing, which led to an increase in kLaL in contaminated systems. In the second part of this work, a population balance model (PBM) was coupled with a computational fluid dynamics (CFD) model based on large-eddy simulation (LES) to analyze the effect of both tap water and SDS contaminated systems on the breakage phenomena, local flow pattern, and the resulting hydrodynamics and mass transfer features in the reactor. Ultimately, experiments and numerical simulations agreed well in terms of global gas holdup and kLaL coefficient. In particular, the transition points in the case of the SDS media (except for foam formation) provided the model with adequate PBM definitions for the dispersed phase.

Effects of sodium dodecyl sulfate and solution chemistry on retention and transport of biogenic nano-hydroxyapatite in saturated porous media

Effects of sodium dodecyl sulfate and solution chemistry on retention and transport of biogenic nano-hydroxyapatite in saturated porous media

Effects of Sodium Dodecyl Sulfate on the Enzyme Catalysis and Conformation of a Recombinant γ-Glutamyltranspeptidase from Bacillus licheniformis.

The study of interactions between proteins and surfactants is of relevance in a diverse range of applications including food, enzymatic detergent formulation, and drug delivery. In spite of sodium dodecyl sulfate(SDS)-induced unfolding has been studied in detail at the protein level, deciphering the conformation-activity relationship of a recombinant γ-glutamyltranspeptidase (BlrGGT) from Bacillus licheniformis remains important to understand how the transpeptidase activity is related to its conformation. In this study, we examined the enzyme catalysis and conformational transition of BlrGGT in the presence of SDS. Enzymatic assays showed that the transpeptidase activity of BlrGGT was greatly affected by SDS in a concentration-dependent manner with approximately 90% inactivation at 6mM. Native polyacrylamide gel electrophoresis of SDS-treated samples clearly revealed that the heterodimeric enzyme was apparently dissociated into two different subunits at concentrations above 2mM. The study of enzyme kinetics showed that SDS can act as a mixed-type inhibitor to reduce the catalytic efficiency of BlrGGT. Moreover, the t1/2 value of the enzyme at 55°C was greatly reduced from 495.1min to 7.4min in the presence of 1mM SDS. The I3/I1 ratio ofpyreneexcimerfluorescence emission changed around 3.7mMSDSin the absence ofBlrGGT and the inflection point of enzyme samples was reduced to less than 2.7mM. The Far-UV CD spectrum of the native enzyme had two negative peaks at 208 and 222nm, respectively; however, both negative peaks increased in magnitude with increasing SDS concentration and reached maximal values at above 4.0mM. Theintrinsic fluorescence spectraof tryptophan further demonstrated that the SDS-induced enzyme conformational transition occurred at approximately 5.1mM. Tween 20 significantly suppressed the interaction of BlrGGT with SDS by forming mixed micelles at a molar ratio of 1.0. Taken together, this study definitely promotes our better understanding of the relationship between the conformation and catalysis of BlrGGT.

A Study on Unsubstituted Cu(II) Phthalocyanine and Bovine Serum Albumin Bioconjugation

The ground state electronic and fluorescence spectra of unsubstituted copper (II) phthalocyanine (CuPc) have been studied in the presence of bovine serum albumin (BSA) in water as a solvent. The effect of sodium dodecyl sulfate (SDS) on the solution properties of CuPc: BSA bioconjugate has also been investigated. FT-IR, UV-Vis, and fluorescence analysis have been carried to evaluate the BSA: CuPc bioconjugation. The optimum bioconjugate ratio of BSA: CuPc has been studied via UV-Vis and fluorescence spectral techniques. The collaborative effect of SDS with BSA on the aggregation of CuPc suspension has also been studied in terms of UV-Vis, fluorescence, and FT–IR analysis.

Quercetin displacement caused by sodium dodecyl sulphate on inclusion complex quercetin-beta cyclodextrin in an acid environment

The global formation constants of two inclusion complexes formed from quercetin (QH5) and beta-cyclodextrin (βCD) in ClO4- 0.1 M pH 4.7 were calculated with the support of Stability Quotients from Absorbance Data (SQUAD), in addition, the effect of sodium dodecyl sulphate (SDS) on these complexes was studied. The molar ratios of the inclusion complexes formed QH5-βCD were 1:1 and 1:2 with log β values of 2.06 ± 0.22 and 3.69 ± 0.13 M−1 respectively. With measurements of surface tension and fluorescence, the critical micellar concentration (CMC) value of the SDS was calculated in the absence and presence of βCD resulting in an increase with the concentration of βCD, as a consequence of the formation of an inclusion complex βCD-SDS with log K of 3.589 ± 0.059 M−1. From the fluorescence results, the breakdown of the complex Q-βCD is inferred due to the interaction with the SDS causing its inclusion in the βCD cavity and displacement of the QH5. Finally, with the UV–vis spectrophotometric data it is shown that the formation of a ternary complex does not take place, as stated in some studies.