Sodium Dodecyl Sulfate Research Articles

Effect of sodium dodecyl sulphate on the rheological and carbon sequestration properties of cemented paste backfill with CO2 injection

Cemented paste backfill (CPB) is a technology that has a positive impact on both the environment and mining safety. In recent years, it has been widely applied and developed. To improve the carbon sequestration efficiency of CPB, air-entraining agent addition to CO2-injected CPB (CO2-CPB) has been proposed. However, the influence of air-entraining agents on the rheological and carbon sequestration properties of CO2-CPB has not been investigated to date. Therefore, sodium dodecyl sulphate (SDS), an air-entraining agent, was selected in this study, and the rheological and carbon sequestration properties of CO2-CPB added with SDS were comprehensively investigated. CO2-CPB samples with 0.0‰, 0.5‰, 1.0‰, and 1.5‰ SDS were prepared, and the rheological parameters (yield stress and viscosity) were tested after curing for 0, 0.25, 1, and 2 h. Gas content testing, microscopic analysis, and zeta potential measurements were performed. The results show that SDS addition decreased the yield stress and viscosity of CO2-CPB at 0–1 h; however, the yield stress and viscosity increased at 2 h. SDS addition significantly improved the carbon sequestration performance of CO2-CPB. The findings of this study have important implications for carbon sequestration development in CPB and solid waste utilisation.

Influence of Sodium Lauryl Sulfate Anionic Micelles on the Complex Equilibria of Divalent Metal Ions with Isoleucine Amino Acid

The main objective of the present investigation is the formation analysis of metal-ligand complexes of isoleucine with divalent calcium, magnesium and zinc metal ions in various concentrations of sodium dodecyl sulphate (0.0, 0.5, 1.0, 1.5, 2.0 and 2.5 percent w/v). To look into the impact of the concentration of negatively charged micelles, the parameters were changed and the possible chemical species of isoleucine that interact with the metal ions, are being studied. The experiment was performed using pH meter at 303 K using NaCl to keep ionic strength stable at 0.16 mol dm-3 in the presence of anionic surfactant sodium dodecyl sulphate (SDS). The determination of the correction factor was conducted via the computer program SCPHD. The computational software MINIQUAD75 is utilized to determine the stability constants of ligand-metal complexes through the analysis of titration data. Based on statistical features such as skewness, 2, kurtosis and crystallographic R-factor, the best fit to the complicated speciation was selected. The metal ions Ca (II), Mg (II) and Zn (II) formed complexes ML, ML2 and ML2H2 for Ca (II), Mg(II) and ML, ML2 and ML2H for Zn (II) through the complexation of isoleucine. In order to validate the accuracy of the final established model, deliberate defects were introduced into the relevant components.

Влияние катионоактивного, анионоактивного и неионогенного поверхностно-активных веществ на почвенные олигохеты Eisenia fetida andrey (Bouche, 1972)

Results of studying the main types of surfactants effect on earthworms Eisenia fetida andrey (Bouche, 1972) are presented. The worms were tested for survival and preference-avoidance behavioral reactions. Earthworms avoided sodium dodecyl sulfate (SDS) at 0.02 g/kg and above, cetyltrimethylammonium bromide – at 0.1 g/kg and above, and polysorbate 80 – at 30 mL/kg and above. The 100% mortality of earthworms occurred at 0.001, 0.01 and 0.02 g/kg of SDS on day 30, at 1 g/kg – on day 25, and at 1 g/kg – on day 2 of the experiment. Сetyltrimethylammonium bromide at 0.001 and 0.01 g/kg caused the 100% mortality of worms on day 30; at 0.1 g/kg – on day 25; at 0.5 g/kg – on day 5; and at 1.0 g/kg already on day 2 of the experiment. The 100% mortality of worms occurred at 0.1, 1 and 10 mL/kg of polysorbate 80 on day 30 of incubation; at 20 or 30 mL/kg – on day 20; at 50 mL/kg – on day 10 of experience. The following toxicity series (both in terms of g/L and in terms of g/mol) of the tested surfactants for earthworms was constructed on the basis of the results obtained (increasing toxicity): polysorbate 80 (non-ionic surfactant) < cetrimonium bromide (cationic surfactant) < sodium dodecyl sulfate (anion-active surfactant).

Optimization of methylene blue dye degradation using heterogeneous Fenton-like reaction with Fe3O4 nanoparticles/PVDF macrospheres: A response surface methodology approach

Microplastics (MPs) are increasingly recognised for their significant impact on the environment and human health. Understanding MPs is crucial to grasp their widespread presence in various environmental areas. The unique properties of MPs, such as their small size, durability, and potential to adsorb and transport environmental pollutants, underscore the necessity of studying their characteristics. This study aims to investigate the physical and chemical characteristics of polypropylene microplastics (PPMPs) and address the dispersion stability issues associated with them. The PPMPs were characterised using scanning electron microscopy (SEM), revealing a surface structure marked by cracks, fractures, and a rough texture. The PPMPs were observed as irregularly shaped, white particles. Their size distribution spans from 14 to 96 µm, with a mean size of 50.00 µm. Fourier Transform Infrared Spectroscopy (FTIR) confirmed the presence of polypropylene functional groups, specifically identifying characteristic peaks at 2952-2846 cm-1 and 1456 -1376 cm-1, indicating C-H stretching and bending vibrations, respectively, with additional peaks suggesting degradation. The effect of different concentrations of sodium lauryl sulfate (SLS) on PPMPs dispersion indicated that 5% SLS led to superior dispersion of PPMPs, thereby addressing the stability issue. These findings provide comprehensive insights into the physical and chemical attributes of PPMPs and their dispersion stability, offering a foundation for informed environmental assessments and the development of effective mitigation strategies.

Insight into the physical and chemical attributes of polypropylene microplastics

Microplastics (MPs) are increasingly recognised for their significant impact on the environment and human health. Understanding MPs is crucial to grasp their widespread presence in various environmental areas. The unique properties of MPs, such as their small size, durability, and potential to adsorb and transport environmental pollutants, underscore the necessity of studying their characteristics. This study aims to investigate the physical and chemical characteristics of polypropylene microplastics (PPMPs) and address the dispersion stability issues associated with them. The PPMPs were characterised using scanning electron microscopy (SEM), revealing a surface structure marked by cracks, fractures, and a rough texture. The PPMPs were observed as irregularly shaped, white particles. Their size distribution spans from 14 to 96 µm, with a mean size of 50.00 µm. Fourier Transform Infrared Spectroscopy (FTIR) confirmed the presence of polypropylene functional groups, specifically identifying characteristic peaks at 2952-2846 cm-1 and 1456 -1376 cm-1, indicating C-H stretching and bending vibrations, respectively, with additional peaks suggesting degradation. The effect of different concentrations of sodium lauryl sulfate (SLS) on PPMPs dispersion indicated that 5% SLS led to superior dispersion of PPMPs, thereby addressing the stability issue. These findings provide comprehensive insights into the physical and chemical attributes of PPMPs and their dispersion stability, offering a foundation for informed environmental assessments and the development of effective mitigation strategies.

High‐Efficiency Separation of Near‐Zigzag Single‐Chirality Carbon Nanotubes by Gel Chromatography

High‐efficiency production of near‐zigzag single‐chirality single‐wall carbon nanotubes (SWCNTs) is of great importance for their property study and applications. The key to separate near‐zigzag single‐chirality SWCNTs by gel chromatography is to selectively adsorb them in the gel medium. In this study, by using a high surfactant ratio of sodium dodecyl sulfate and sodium cholate (≥4:1) to modulate the selective adsorption of distinct (n, m) SWCNTs in a gel column, a high enrichment of near‐zigzag SWCNTs adsorbed in the gel column is achieved, which usually have a low abundance in raw materials due to their low growth efficiency. Afterward, (7, 3), (8, 3), (8, 4), (9, 1), and (9, 2) single‐chirality SWCNTs are separated with small chiral angles less than 17° by following a stepwise elution for their selective desorption. This simple and efficient separation technique will promote the research and application of near‐zigzag SWCNTs.

Stability mechanism of viscoelastically enhanced surfactant air foam for low permeability reservoir

Polymer has been widely studied as an effective means to improve foam stability in reservoir exploitation. Nevertheless, the deployment of this technology in low-permeability reservoirs may prove challenging and could potentially result in formation damage. The innovation of this study is the utilization of viscoelastic surfactants to create enhanced air foam with wormlike micelles and three-dimensional network structures. This can result in a synergy between the properties of fluidity control and oil washing efficiency, thereby enhancing the strength of the foam. The supramolecular self-assembly property facilitates the injection of the foam into the formation while preserving its original structure and properties, thereby enhancing the stability of the foam and markedly improving the recovery of low permeability reservoirs. The viscoelastically enhanced air foam system is composed of the zwitterionic surfactant erucylamido propyl betaine (EHSB) and the anionic surfactant sodium dodecyl sulfate (SDS), which has been designated EHSB-SDS. The foam performance was evaluated using the Waring Blender method and rheological behavior, with foam fluid viscosity, initial foam volume (V0), half-life for drainage (td) and foam half-life (tf) serving as the evaluation indicators. The influence of temperature, salinity and oil content on foam performance is considered to explore the reservoir adaptability. The dynamic/micro stability, macro rheological properties, interfacial viscoelasticity and Zeta potential of the enhanced air foam system were further studied to clarify the stability mechanism of enhanced air foam system. The td, tf and composite index of EHSB-SDS is 56.6 min, 36 h and 648000 mL·min, respectively. The viscoelastic surfactants form wormlike micelles, which increase the foam solution viscosity. This results in a slow drainage speed and the rupture of the bubbles. The adsorption of surfactant at the gas/liquid interface results in an increase in surface activity, interfacial expansion modulus and zeta potential, which serves to enhance the strength of the liquid film and the electrostatic repulsion among bubbles. These three factors are primarily responsible for the stability of the foam. The research establishes a theoretical basis for the effective development of low permeability reservoirs and new foam flooding technology.

Antioxidant analysis of protein from fresh and dry leaf of Orthosiphon aristatus (Blume) Miq.

Orthosiphon aristatus (Blume) Miq. is a folklore plant consumed as brewed tea for various health benefits. The white variety of the plants leaf and stem are predominantly sold in the market in dried form, blooming as a natural herbal product. To date, no proteomics and antioxidant studies are available on the fresh and dried leaf protein extract of O. aristatus since most studies take an interest in the crude extracts of plants. Thereupon, this study focuses on the One-dimensional (1D) electrophoretic pattern of the fresh and dry leaf determined via sodium dodecyl-sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Additionally, antioxidant proteins are currently being focused on for their link to controlling disease through their potential to destroy free radicals that are present in excess. Hence, an antioxidant assay was conducted for the fresh and dry leaf protein extract using 2,2-Diphenyl-1-picrylhydrazyl (DPPH) free radical assay and ferric reducing antioxidant power (FRAP) assay. The electrophoretic pattern obtained resulted in approximately 16 and 10 bands for the fresh and dry leaves respectively. As for the antioxidant activity, the dry leaf had higher radical scavenging activity and higher reducing power compared to the fresh leaf. The findings obtained provides insight in to the protein content and antioxidant activity found in the protein extract of fresh and dry leaves of O. aristatus. Hence, further detailed study of the protein extracts could further unveil their therapeutic potential.

Influence of nanopesticide surface chemistry on adsorption to plant cuticle and wax layer: The role of zeta potential and wetting

Nanopesticidal adsorption on plant surfaces is a critical determinant of their application efficacy, persistence, and ecological impact. In this study, we systematically investigate the impact of surface chemistry on the attachment of nanopesticides for seven different nanocarriers: ethyl lauroyl arginate (ELA, cationic), cocamidopropyl betaine (CAPB, zwitterionic), tween 80 (TW80, nonionic), β-cyclodextrin (βCD), sodium dodecyl sulfate (SDS, anionic), whey protein isolate (WPI), and poloxamer 407 (PXL, nonionic). Azadirachtin from neem seed extract was employed as a model pesticide active ingredient. The nanopesticides were characterized using dynamic light scattering, UV–visible spectroscopy, static contact angle (SCA, θ), and zeta (ζ) potential measurements. Pepper leaves (ζ = −11.6 mV) and candelilla wax (ζ = −2.6 mV) films were utilized to analyze the effect of nanocarrier chemical composition on nanopesticide adsorption. Fluorescence microscopy was utilized to quantify the adsorption of nanopesticides (with fluorophore tagging) on the substrates. It was found that the choice of nanocarrier significantly influenced the adsorption behavior. Nanopesticides with ELA corona, which was cationic with a zeta potential of ∼+19 mV and θ of ∼ 61°, exhibited the highest affinity towards the leaf cuticle and wax substrates, attributed to favorable electrostatic interactions forces. Conversely, nanopesticides with SDS (ζ = −48 mV; θ = 45°), WPI (ζ = −24 mV; θ = 54°), and PXL (ζ = −31 mV; θ = 64°) corona demonstrated the least adsorption. These findings indicate a weak correlation between the wetting behavior of nanopesticide suspensions and nanopesticide adsorption on plant and wax surfaces, as well as a strong correlation between nanopesticide zeta potential and nanopesticide adsorption. These findings heuristically recommend that aqueous cationic and zwitterionic nanocarriers for pesticides provide superior adsorption characteristics on pepper leaves and candelilla wax surfaces. Aqueous macromolecular carriers such as PXL and WPI have performed less effectively in adherence compared to shorter chain amphiphiles with similar zeta potential and wetting characteristics, indicating that the steric and osmotic chain effects of hydrophilic macromolecules hinder the adsorption relative to shorter chains.

Solvent-induced modulation of sensitivity and selectivity in the self-assembly of tetracationic cyclophanes with cholesterol sulphate, sodium dodecyl sulfate, and sodium dodecyl benzene sulfonate: Observations of significant shifts

Cyclophane CP-1 demonstrates markedly distinct sensitivities toward Cholesterol sulfate (CH-S), Sodium Dodecyl Sulfate (SDS), and Sodium Dodecyl Benzene Sulfonate (SDBS) when the solvent is shifted minimally from a 95 % to a 98 % HEPES-DMSO mixture. In a 98:2 HEPES-DMSO mixture, CP-1 engages in highly selective self-assembly with CH-S, which is characterized by aggregation-induced emission enhancement (AIEE) in contrast to other steroidal sulfates such as pregnenolone sulfate (PRG-S), dehydroisoandrosterone sulfate (DIAND-S), taurocholic acid (TACH-S), and the surfactants SDS and SDBS. This assembly results in an approximate 40-fold increase in fluorescence intensity with three equivalents of CH-S and allows for the detection of concentrations as low as 200 nM under physiological conditions. Dynamic light scattering (DLS) studies illustrate the aggregation of CP-1 and CH-S, with the zeta potential of each shifting from negative values to nearly zero in a 1:2 CP-1:CH-S mixture, indicating self-assembly. This aggregation behavior is reversible, as demonstrated by a corresponding decrease and then increase in fluorescence intensity with temperature variations from 25 °C to 70 °C and back to 25 °C. Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) analyses show that CP-1 forms aggregates ranging from 100 to 180 nm, which increase to 150–250 nm upon interaction with CH-S. In a 95:5 HEPES-DMSO mixture, CP-1 exhibits a stronger AIEE response with SDS and SDBS compared to CH-S. Cyclophane CP-2, when dissolved in binary DMSO-water mixtures with water content exceeding 80 %, shows similar AIEE phenomena and undergoes selective fluorescence quenching with SDS and only a 50 % increase in fluorescence intensity with CH-S, irrespective of the HEPES concentration (95 % or 98 %).

The Interaction Of Homodimer Styrylcyanine Dyes With Sodium Dodecyl Sulfate And Triton X-100.

Solubilization of the styrylcyanine dye Sbt ((E)-2-(4-(dimethylamino)styryl)-3-methylbenzo[d]thiazol-3-ium iodide) and its homodimers Dbt-5 and Dbt-10 in aqueous solution of sodium dodecyl sulfate and Triton X-100 has been studied by steady state and picosecond time-resolved fluorescence spectroscopy. At low concentration of sodium dodecyl sulfate in solution, between Sbt, Dbt-5 dyes molecules and surfactant ion pairs are formed followed by the formation non-luminescent H-aggregates. The nature of the interaction between molecules of dyes and surfactants has been revealed. The binding constants Ks of the dyes to the surfactants, free energy changes (ΔG0), the number of dye molecules (n) included in a single micelle and photophysical parameters have been determined. The degree of solubilization of dyes in micellar solution of Triton X-100 is higher as compared to sodium dodecyl sulfate and depends on the molecular weight and size of both dye molecules and micelles.

The Effect of Different Surfactants and Polyelectrolytes on Nano-Vesiculation of Artificial and Cellular Membranes.

Nano- and micro-sized vesicular and colloidal structures mediate cell-cell communication. They are important players in the physiology of plants, animals, and humans, and are a subject of increasing interest. We investigated the effect of three surfactants, N-cetylpyridinium chloride (CPC), sodium dodecyl sulfate (SDS), and Triton X-100 (TX100), and two anionic polyelectrolytes, sodium polystyrene sulfonate (NaPSS) and sodium polymethacrylate (NaPMA), on nanoliposomes. In addition, the effect of SDS and TX100 on selected biological membranes (erythrocytes and microalgae) was investigated. The liposomes were produced by extrusion and evaluated by microcalorimetry and light scattering, based on the total intensity of the scattered light (Itot), hydrodynamic radius (Rh), radius of gyration (Rg), shape parameter p (=Rh/Rg,0), and polydispersity index. The EPs shed from erythrocytes and microalgae Dunaliella tertiolecta and Phaeodactylum tricornutum were visualized by scanning electron microscopy (SEM) and analyzed by flow cytometry (FCM). The Rh and Itot values in POPC liposome suspensions with added CPC, SDS, and TX100 were roughly constant up to the respective critical micelle concentrations (CMCs) of the surfactants. At higher compound concentrations, Itot dropped towards zero, whereas Rh increased to values higher than in pure POPC suspensions (Rh ≈ 60-70 nm), indicating the disintegration of liposomes and formation of larger particles, i.e., various POPC-S aggregates. Nanoliposomes were stable upon the addition of NaPSS and NaPMA, as indicated by the constant Rh and Itot values. The interaction of CPC, SDS, or TX100 with liposomes was exothermic, while there were no measurable heat effects with NaPSS or NaPMA. The SDS and TX100 increased the number density of EPs several-fold in erythrocyte suspensions and up to 30-fold in the conditioned media of Dunaliella tertiolecta at the expense of the number density of cells, which decreased to less than 5% in erythrocytes and several-fold in Dunaliella tertiolecta. The SDS and TX100 did not affect the number density of the microalgae Phaeodactylum tricornutum, while the number density of EPs was lower in the conditioned media than in the control, but increased several-fold in a concentration-dependent manner. Our results indicate that amphiphilic molecules need to be organized in nanosized particles to match the local curvature of the membrane for facilitated uptake. To pursue this hypothesis, other surfactants and biological membranes should be studied in the future for more general conclusions.

Angiosome-Guided Perfusion Decellularization of Fasciocutaneous Flaps.

Tissue engineering based on whole-organ perfusion decellularization has successfully generated small-animal organs, including the heart and limbs. Herein, we aimed to use angiosome-guided perfusion decellularization to develop an acellular fasciocutaneous flap matrix with an intact vascular network. Abdominal flaps of rats were harvested, and the vascular pedicle (iliac artery and vein) was dissected and injected with methylene blue to identify the angiosome region and determine the flap dimension for harvesting. To decellularize flaps, the iliac artery was perfused sequentially with 1% sodium dodecyl sulfate (SDS), deionized water, and 1% Triton-X100. Gross morphology, histology, and DNA quantity of flaps were then obtained. Flaps were also subjected to glycosaminoglycan (GAG) and hydroxyproline content assays and computed tomography angiography. Histological assessment indicated that cellular content was completely removed in all flap layers following a 10-hour perfusion in SDS. DNA quantification confirmed 81% DNA removal. Based on biochemical assays, decellularized flaps had hydroxyproline content comparable with that of native flaps, although significantly fewer GAGs (p = 0.0019). Histology and computed tomography angiography illustrated the integrity and perfusability of the vascular system. The proposed angiosome-guided perfusion decellularization protocol could effectively remove cellular content from rat fasciocutaneous flaps and preserve the integrity of innate vascular networks.

EFFICIENT COPPER EXTRACTION FROM CHALCOPYRITE USING THE «GLYCOLIC ACID – ETHYLENE GLYCOL – SODIUM LAURYL SULFATE» SYSTEM

This research explores a sustainable and efficient method for extracting copper from chalcopyrite, utilizing an innovative leaching system composed of glycolic acid, ethylene glycol, and sodium lauryl sulfate (SLS). The optimal conditions identified were 1,0 M glycolic acid, 20% (v/v) ethylene glycol, 0,8% (w/v) SLS, and a temperature of 75°C, achieving up to 85% copper recovery. Glycolic acid plays a dual role, promoting the breakdown of the chalcopyrite structure and stabilizing copper ions in the solution. SLS improves the leaching efficiency by disrupting the passivating sulfur layer, allowing for better solution penetration. Additionally, ethylene glycol prevents the precipitation of sulfur, further enhancing the process. The combination of these components creates a synergistic effect that improves copper recovery while minimizing environmental impact. The findings suggest that this leaching system could serve as a sustainable and efficient alternative to the traditional pyrometallurgical methods, offering potential applications in industrial copper recovery processes.

Assessing the Effects of Surgical Irrigation Solutions on Human Neutrophil Interactions with Nascent Staphylococcus aureus Biofilms.

Staphylococcus aureus (S. aureus) is the leading cause of surgical site infections (SSIs) and is capable of biofilm growth on implanted foreign devices. The use of surgical irrigation solutions has become a common strategy to combat bacterial contamination events that occur during surgery. Despite their antimicrobial activity, SSI rates remain consistent, suggesting that low-level contamination persists. In these cases, circulating neutrophils must traffic from the blood to contamination sites to aid in bacterial clearance. The influence of irrigation solutions on neutrophils' ability to engage with bacteria has not been explored. The effects of three commonly used irrigation solutions: Xperience (sodium lauryl sulfate), Irrisept (chlorhexidine gluconate), and Betadine® (povidone-iodine) on nascent S. aureus biofilms alone and in the presence of human neutrophils were assessed at manufactured and diluted concentrations. All three solutions, at a 10% dilution, inhibited bacterial growth as demonstrated by culture assays and confocal video microscopy of bacterial aggregate formation. The effects of 10% dilutions of each of these solutions on neutrophil membrane integrity (by flow cytometry and propidium iodide staining) and motility (by confocal video microscopy of neutrophil track length) were investigated with differing outcomes for each irrigation solution. At this concentration only Irrisept preserved neutrophil membrane integrity and motility. Together, this study examines an overlooked aspect of surgical irrigation solutions by investigating their impact on innate immunity and highlights the feasibility of formulations wherein solution effectiveness is complemented by neutrophil function to reduce risks of infection.

Selection of antibacterial aptamers against Pseudomonas plecoglossicida and analysis on their potential binding proteins

Pseudomonas plecoglossicida is one of the main pathogens causing visceral white spot disease of the large yellow croaker (Pseudosciaena crocea). Although antibiotics are used to control P. plecoglossicida infections, the long-term and large-scale use of antibiotics can lead to the development of drug-resistant bacteria as well as environmental pollution. Therefore, it is necessary to develop novel antibacterial agents to treat P. plecoglossicida infections. In this study, we first developed a two-step-centrifugation method to isolate live and dead P. plecoglossicida cells. Subsequently, we used the Systematic Evolution of Ligands by Exponential Enrichment (SELEX) screening based on inhibition rate to directly isolate antibacterial aptamers from the random library without post-processing. We isolated five antibacterial aptamers, namely B1, B2, B4, B8, and B109, which showed good inhibitory effects against P. plecoglossicida. Among these, B4 showed the highest inhibitory effect (62.40 ± 4.17 %). Further analysis revealed no positive correlation between the inhibitory effect of aptamers and their affinities with the target bacterium. The B4- and B109-binding proteins were isolated from P. plecoglossicida by magnetic separation and sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE). Mass spectrometry analysis revealed that the 26 kDa ribosomal protein L2 was the probable B4-binding protein, while the 26 kDa ribosomal protein S3 and 75 kDa ribosomal protein S1 or succinate dehydrogenase flavoprotein subunit were the probable B109-binding proteins. Structural and subcellular localization analyses of these potential B4- and B109-binding proteins were also conducted. Our findings suggest that the inhibitory activity of the antibacterial aptamers against P. plecoglossicida may be mediated via their interaction with the ribosomal proteins, which can interfere with the protein synthesis process in the bacterium, affecting its growth. These findings provide the scientific basis for the development of functional antibacterial aptamers and the elucidation of their mechanisms of action.

Monolayer instability of ionic surfactants at the water/air interface due to biosurfactant molecules: A molecular dynamic approach

The decomposition of monolayers prepared with anionic surfactants, sodium dodecyl sulfate (SDS), or cationic ones, dodecyltrimethylammonium bromide (DTAB), at the water/air interface was studied when biosurfactants (surfactin) are added to the films. Molecular dynamics simulations were carried out for monolayers with a fixed number of SDS or DTAB molecules and a different amount of biosurfactants to form SDS/surfactin and DTAB/surfactin mixtures. It is found that the presence of the biosurfactant modifies interfacial and structural properties of the ionic monolayers at the interface; the DTAB monolayer is distorted even for a few surfactin molecules, whereas the SDS monolayer remains steady up to a given amount of biosurfactant. In both monolayers the surface tension decreases with the number of biosurfactants, however while for the DTAB/surfactin the values seem to fluctuate, for the SDS/surfactin mixture the values decay linearly, with a discontinuity for a given surfactin concentration. The linear behaviour of the surface tension for the SDS/surfactin allows us to evaluate free energies for the monolayers and a two-dimensional equation of state. The structure of the monolayers was analyzed in terms of density profiles, order parameters, thickness of the interfaces and the data show that the DTAB/surfactin is more distorted than the SDS/surfactin by the presence of few surfactin molecules. The results indicate that SDS surfactants are more likely to form longer lasting films with fewer surfactin molecules than DTAB.

Structural and dynamics characterization of the Zika virus NS2B using nuclear magnetic resonance and RosettaMP: A challenge for transmembrane protein studies

Zika virus (ZIKV) is an emergent flavivirus that represents a global public health concern due to its association with severe neurological disorders. NS2B is a multifunctional viral membrane protein primarily used to regulate viral protease activity and is crucial for virus replication, making it an appealing target for antiviral drugs. This study presents the structural elucidation of full-length ZIKV NS2B in sodium dodecyl sulfate (SDS) micelles using solution nuclear magnetic resonance experimental data and RosettaMP. The protein structure has four transmembrane α-helices, two amphipathic α-helices, and a β-hairpin in the hydrophilic region. NS2B presented secondary and tertiary stability in different concentrations of SDS. Furthermore, we studied the dynamics of NS2B in SDS micelles through relaxation parameters and paramagnetic relaxation enhancement experiments. The findings were consistent with the structural calculations. Our work will be essential in understanding the role of NS2B in viral replication and screening for inhibitors against ZIKV.

Monitoring the process of interfacial polymerization for fabrication of polyamide reverse osmosis membrane via molecular simulation based on π-π interaction between surfactant and monomer

Accurate regulation of the interfacial polymerization (IP) process is prerequisite for preparation of thin film composite reverse osmosis (RO) membranes with ideal polyamide (PA) layers, and surfactant assembly-regulated IP (SARIP) is proved to be an effective approach. However, mechanism in molecular level for modulation of IP based on surfactants is still inadequate. Here, sodium dodecylbenzene sulphonate (SDBS) and sodium dodecyl sulfate (SDS) have been chosen as surfactants to make comparison of the IP process based on π-π interaction between surfactant and monomer via molecular simulation. As illustrated by Molecular Dynamics (MD) simulations, surfactants enlarge the width of the miscible zone, increase the diffusion rate together with the relative concentration of MPD in the miscible zone, as well as regulate the position of IP reaction towards the aqueous phase. Compared to SDS, SDBS makes the diffusion of MPD in good order, thus avoiding the severe variation in structure and morphology on PA layer. As calculated by DFT, higher interaction energy between the phenyl group of MPD and SDBS based on the π-π interaction is achieved, leading to uniform distribution of MPD close to the phenyl group of SDBS instead of escaping violently into miscible zone. Thus, strong consistency between the position of IP reaction and the height of the phenyl group in SDBS is emerged, which further explains the intrinsic reason for the variation of the IP position and the modulation of the PA microstructure. The mechanism for IP regulation based on SARIP at molecular level is finally proposed via molecular simulation, providing new idea for the preparation of high-performance RO membranes.

Template-Assisted Electrodeposited Copper Nanostructres for Selective Detection of Hydrogen Peroxide.

In this study, we demonstrate the electrodeposition of copper nanoparticles (NPs) on pencil graphite electrodes (PGEs) utilizing sodium dodecyl sulphate (SDS) as a soft template. The utilization of the surfactant had an impact on both the physical arrangement and electrochemical characteristics of the modified electrodes. The prepared Cu-SDS/PGE electrodes had hierarchical dendritic structures of copper NPs, thereby increasing the surface area and electrochemical catalytic activity in comparison with Cu/PGE electrodes. The Cu-SDS/PGE electrode showed excellent catalytic activity in reducing hydrogen peroxide, resulting in the sensitive and selective detection of hydrogen peroxide. The electrode exhibited a good sensitivity of 21.42 µA/µM/cm2, a lower limit of detection 0.35, and a response time of less than 2 s over a wide range spanning 1 µM to 1 mM of hydrogen peroxide concentrations. The electrodes were also highly selective for H2O2 with minimal interference from other analytes even at concentrations higher than that of H2O2. The approach offers the benefit of electrode preparation in just 5 min, followed by analysis in 10 min, and enables for the quantitative determination of hydrogen peroxide within 30 min. This can be achieved utilizing a newly prepared, cost-effective electrode without the need for complex procedures.