Polyoxyethylene Lauryl Ether Research Articles

Atomization Behavior of O/W Emulsion Droplets Made with Porous Glass Membranes

We conducted an experimental study of effects of dispersed oil droplet diameter on micro-explosion of oil-in-water (O/W) emulsion droplet during spheroid-type evaporation on a heated surface. The base fuel was n-dodecane, the surfactant was polyoxyethylene (6) lauryl ether. O/W emulsion was made with Shirasu Porous Glass (SPG) membrane, which is hydrophilic and has numerous and continuous pores, and then degassed. Also, the emulsion was stirred at low speed during the experiment. The hot surface temperature was 700 K, the initial droplet diameter was 1.95 mm, and the water content was 0.4. The pore diameter of the membrane was varied from 5 μm to 50 μm. The experiment of dropping the emulsion was conducted more than 30 times for each condition. The particle size distribution showed that the dispersed oil droplet diameter and its Sauter mean diameter decreased with the decrease of the membrane’s pore diameter. And as the pore diameter became smaller, the start time of phase separation was delayed. Total waiting time for disruptive microexplosion and its Weibull average increased with the decrease of the pore diameter. These results are considered to be due to the delay in the start time of phase separation as the dispersed oil droplet diameter decreases.

Improvement of water wettability of gray cotton fabric using electron beam irradiation and supercritical CO2 treatment

In this study, the effect of electron beam (EB) and supercritical carbon dioxide (scCO2) treatments on the hydrophilicity of gray cotton pile fabric were investigated. The immersion time, an indicator of the hydrophilicity, was 19 s for a combination of the pre-EB irradiation and the post-scCO2 extraction. In contrast, the values were 13,750–13,990 s after EB irradiation and 65 s post-scCO2 treatment. The addition of a small amount of methanol or polyoxyethylene lauryl ether in scCO2 decreased the immersion time to 4 s or 2 s, which is the water wettability required for a towel product. ATR-FTIR analysis suggested the complete removal of waxy impurities from the gray cotton pile fabric by the combination treatment of EB and scCO2. It was also observed from the FE-SEM images that the visual structure of parallel ridges and grooves covering gray cotton fibers disappeared on fibers with a lower immersion time than 19 s, which suggested dewaxing (the removal of wax). The study reveals that EB irradiation and scCO2 are alternative waterless methods for improving the wettability of gray cotton fabrics.

A real-time and in-situ monitoring of the molecular interactions between drug carrier polymers and a phospholipid membrane

The dynamic interactions between drug carrier molecules and a cell membrane can not be ignored in their clinical use. Here a simple, label-free and non-invasive approach, photo-voltage transient method, combined with the atomic force microscopy, dynamic giant unilamellar vesicle leakage assay and cytotoxicity method, was employed for a real-time monitoring of the interaction process. Two representative polymer molecules, polyoxyethylene (35) lauryl ether (Brij35) and polyvinylpyrrolidone (PVPk30), were taken as examples to interact with a phospholipid bilayer membrane in a low ionic strength and neutral pH condition. Brij35 demonstrated an adsorption-accumulation-permeabilization dominated process under the modulation of polymer concentration in the solution. In contrast, PVPk30 performed a dynamic balance between adsorption-desorption of the molecules and/or permeabilization-resealing of the membrane. Such difference explains the high and low cytotoxicity of them, respectively, in the living cell tests. Briefly, through combining the photo-voltage approach with conventional fluorescent microscopy method, this work demonstrates new ideas on the time and membrane actions of polymer surfactants which should be taken into account for their biomedical applications.

An integrated value chain to iron-containing mine tailings capitalization by a combined process of magnetic separation, microwave digestion and microemulsion – assisted extraction

The recovery of metals from tailing ponds or dumps is a priority as they remained stored on large areas around the mining operations and represent an aggressive pollution source of natural water bodies. The paper objective is to develop a combined process for iron-containing mine tailings capitalization associates the benefits of magnetic separation to reduce the iron content, microwave digestion for metals forms solubilization from solid matrix and microemulsion for their extraction, concentration, and recycling from the digested sample. The magnetic separation of ferromagnetic fraction, with over 50 % iron, leads to an improved extraction efficiency. The optimum digestion procedure uses aqua regia, hydrogen peroxide (30 % H2O2) and microwaves. The microemulsion extraction using Brij 30 (polyoxyethylene (4) lauryl ether) as surfactant, ethyl acetate:butyl acetate (1:1, v/v) as oil phase and acidic metal solutions as aqueous phase, and also NaSCN (0.1 M) as carrier agent, performed at room temperature and atmospheric pressure, reveals that excellent recovery performance for iron (98.3 %), lead (98.5 %), zinc (93.0 %) can be obtained. In addition, copper (63.0 %) is recovered quite efficiently. The maximum microemulsion loading capacity in terms of mass of total metal ions/L was 351 mg/L and was achieved by two successive extractions. It has been demonstrated that by two successive extractions, the loading capacity is mainly represented by iron content. The results obtained demonstrate that the three combined procedures involving magnetic separation, microwave digestion and microemulsion assisted extraction ccontributes to the reduction of mine waste deposits and, consequently, the environmental pollution with heavy metals.

Synthesis and characterization of surfactant assisted hydroxyapatite powder using microemulsion method

Hydroxyapatite (HAP), which is chemically represented as (Ca10(PO4)6(OH)2), is one of the main inorganic material of vertebrate bone and teeth. The bioceramic material is used as a substitute for deficient bone tissue because of its similarities to crystallographic and chemical composition of teeth and bone. HAP is extensively used in various biomedical applications because of its excellent properties, such as bioactivity, non-toxicity, biocompatibility, non-immunogenicity and osteoconductivity. In this work, hydroxyapatite powder was synthesized using polyoxyethylene lauryl ether (Briji-35) as a surfactant and dimethyl sulfoxide as a primary surfactant through microemulsion method. The obtained products were characterized by FTIR, XRD and SEM. The result indicated that, the Briji-35 played an important role for the formation of nano-hydroxyapatite particle with good crystallinity and particles with uniform morphology besides controlling the particle size of nano-HAP. The biomedical application studies of the as-synthesised material are yet to be studied.

Influence of Carbon Nanotube-Pretreatment on the Properties of Polydimethylsiloxane/Carbon Nanotube-Nanocomposites

Incorporating nanofillers into elastomers leads to composites with an enormous potential regarding their properties. Unfortunately, nanofillers tend to form agglomerates inhibiting adequate filler dispersion. Therefore, different carbon nanotube (CNT) pretreatment methods were analyzed in this study to enhance the filler dispersion in polydimethylsiloxane (PDMS)/CNT-composites. By pre-dispersing CNTs in solvents an increase in electrical conductivity could be observed within the sequence of tetrahydrofuran (THF) > acetone > chloroform. Optimization of the pre-dispersion step results in an AC conductivity of 3.2 × 10−4 S/cm at 1 Hz and 0.5 wt.% of CNTs and the electrical percolation threshold is decreased to 0.1 wt.% of CNTs. Optimum parameters imply the use of an ultrasonic finger for 60 min in THF. However, solvent residues cause a softening effect deteriorating the mechanical performance of these composites. Concerning the pretreatment of CNTs by physical functionalization, the use of surfactants (sodium dodecylbenzenesulfonate (SDBS) and polyoxyethylene lauryl ether (“Brij35”)) leads to no improvement, neither in electrical conductivity nor in mechanical properties. Chemical functionalization enhances the compatibility of PDMS and CNT but damages the carbon nanotubes due to the oxidation process so that the improvement in conductivity and reinforcement is superimposed by the CNT damage even for mild oxidation conditions.

Predicting Pharmacokinetic Properties of Potential Anticancer Agents via Their Chromatographic Behavior on Different Reversed Phase Materials.

The Quantitative Structure-Activity Relationship (QSAR) methodology was used to predict biological properties, i.e., the blood–brain distribution (log BB), fraction unbounded in the brain (fu,brain), water-skin permeation (log Kp), binding to human plasma proteins (log Ka,HSA), and intestinal permeability (Caco-2), for three classes of fused azaisocytosine-containing congeners that were considered and tested as promising drug candidates. The compounds were characterized by lipophilic, structural, and electronic descriptors, i.e., chromatographic retention, topological polar surface area, polarizability, and molecular weight. Different reversed-phase liquid chromatography techniques were used to determine the chromatographic lipophilicity of the compounds that were tested, i.e., micellar liquid chromatography (MLC) with the ODS-2 column and polyoxyethylene lauryl ether (Brij 35) as the effluent component, an immobilized artificial membrane (IAM) chromatography with phosphatidylcholine column (IAM.PC.DD2) and chromatography with end-capped octadecylsilyl (ODS) column using aqueous solutions of acetonitrile as the mobile phases. Using multiple linear regression, we derived the statistically significant quantitative structure-activity relationships. All these QSAR equations were validated and were found to be very good. The investigations highlight the significance and possibilities of liquid chromatographic techniques with three different reversed-phase materials and QSARs methods in predicting the pharmacokinetic properties of our important organic compounds and reducing unethical animal testing.

Water-free dewaxing of grey cotton fabric using supercritical carbon dioxide

Grey cotton shows low water wettability owing to contamination of the fibre surface with hydrophobic non-cellulosic impurities, such as waxes. This study investigated the efficiency of supercritical carbon dioxide (scCO2) water-free treatment for dewaxing grey cotton pile fabric to improve its hydrophilicity. The wettability of the virgin grey fabric was initially 14,400 s, and this value increased to 10,800 s upon treatment in pure scCO2 compared to 1200 in scCO2 containing acetone. The addition of polyoxyethylene lauryl ether to scCO2 containing acetone dramatically enhanced the water wettability to 6 s. Fourier-transform infrared (FT-IR) analysis of the change in the surface chemical composition of the fabric suggested the removal of wax by treatment in scCO2 containing acetone and polyoxyethylene lauryl ether. The study revealed that scCO2 is an alternative waterless method for improving the wettability of grey cotton fabrics.

A detailed morphology investigation on the effects of mixed anionic and nonionic surfactants on methane hydrate formation and dissociation

Foam generation from the presence of sodium dodecyl sulfate (SDS) as a kinetic promoter in methane hydrate formation can be potentially reduced by using mixed surfactants. Mixtures of SDS with nonionic surfactants were proposed to solve this problem. Polyoxyethylene (n) lauryl ether (EO3 and EO5) and alkyl poly glycol ether (APG) were chosen to mix with SDS in different concentrations at 8 MPa and 4 °C in the quiescent system for both kinetics and morphology studies. The result showed that the addition of EO3 resulted in the slight increase for the induction time but no change in the formation rate. Adding EO5 showed the stochastic phenomenon on hydrate formation kinetics. In the presence of APG, the induction time increased up to ten times and lowered the hydrate formation rate compared to only 0.25 wt% SDS. The methane uptakes were about the same with all conditions. The morphology showed similar hydrate formation and dissociation patterns with all investigated solutions. Interestingly, the mixture of nonionic surfactants with SDS decreased the foam formation compared with the system with only SDS. The addition EO3 showed the gradual decrease in the foam height with the higher concentration of EO3. Adding the highest EO5 concentration showed the optimum foam reduction compared with all conditions. Moreover, the presence of APG showed the similar effects of foam reduction with EO5.

Effects of ferric ion on the photo-treatment of nonionic surfactant Brij35 washing waste containing 2,2′,4,4′-tetrabromodiphenyl ether

The effects of ferric iron on the photo-treatment of simulated BDE-47 (2,2′,4,4′- tetrabromodiphenyl ether)-Brij35 (Polyoxyethylene lauryl ether) washing waste were studied to evaluate the influences of ferric iron on BDE-47 removal and Brij35 recovery. The results show that Fe3+ accelerated BDE-47 degradation at lower concentrations (<0.5 mM) but attenuated it at higher concentrations (0.5–5 mM) and that Brij35 loss was increased with increasing Fe3+. These results likely are caused by changes in the rate of •OH production due to the ferric ion, association of Fe3+ and electron transfer from Brij35, and light attenuation at high concentration. The BDE-47 and Brij35 had different degradation rates at different pH values and at different dissolved oxygen concentrations. The BDE-47 products were identified by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS). The results indicated that BDE-47 transformed into mainly lower-brominated products, a few bromodibenzofurans, some rearrangement products, and some hydroxylated polybrominated diphenyl ethers. A series of Brij35 oxidization products were detected by ultra-performance liquid chromatography-high resolution mass spectrometry (UPLC-HRMS), including hydroxylation products, carboxylation products, and some hydrophilic chain-breaking products. Brij35 was mainly oxidized by Fe3+ and/or reactive oxygen species (ROS) with the final products of CO2 and H2O. The iron ions apparently cycled from ferric to ferrous ions in the micelles such that the Fe3+-Brij35 complex dominated the main redox reaction, leading to both BDE-47 and Brij35 degradation. It appears that in any applied soil washing system, the ferric ions in the washing waste need to be removed because of the adverse effects on BDE-47 removal and eluate reuse.

Effect of the benzene ring of the dispersant on the rheological characteristics of coal-water slurry: Experiments and theoretical calculations

In this study, low-rank coal-water slurry (LCWS) was prepared using polyoxyethylene dodecylphenol ether (PDPE) and polyoxyethylene lauryl ether (PLE), respectively. A combination of experiments and simulations was used to investigate the pulping properties and microscopic mechanism of the LCWS samples prepared using the two agents, so as to explore the influence of benzene ring on the performance of dispersant. The results of the LCWS preparation experiments revealed that the pulp-forming performance of PDPE exceeded that of PLE. When LCWS concentration is 62%, 64%, and 66%, the apparent viscosity corresponding to PDPE is 247.80, 504.17, and 653.10 mPa·s, and the apparent viscosity corresponding to PLE is 548.10, 1470.61, and 1549.98 mPa·s, respectively. The C1000 (When the apparent viscosity is 1000 mPa·s, the corresponding concentration of LCWS is defined as C1000) values of PDPE and PLE are 67.60% and 62.95%, respectively. In addition to the van der Waals forces and hydrogen bonds between the PDPE and/or PLE molecules and coal, the benzene rings of PDPE present π-π stacking effect with the aromatic rings of coal. That could facilitate and strengthen the adsorption of PDPE on coal, which would be conducive to further improving the dispersion of coal particles. The two dispersants have no significant difference in effect on the pyrolysis of LCWS. The simulation results indicated that the times for PDPE and PLE molecules to reach flat adsorption state on coal are approximately 290 and 565 ps, respectively. The self-diffusion coefficient (D) of the PDPE and PLE on coal is 3.16 × 10−6 and 6.57 × 10−6 m2/s, respectively, and their interaction energies with coal are 785.71 and 648.60 kcal/mol, respectively. The results of the simulation calculations demonstrated that PDPE adsorbed on coal easier than PLE, and its binding is more stable than that of PLE owing to the π-π stacking effect, which is conducive to uniform dispersion of coal in solution. The simulation results confirmed the experimental results.

Studying on the properties of Mixed Surfactant Systems

The Anionic-nonionic Gemini Surfactant oxalamide polyoxyethylene lauryl ether (7) succinate sodium sulfonate (OPLES-7) was synthesized. It was mixed with the dodecyl glucoside in different ratios to enhance application performance. The mixed critical micelle concentration (CMC) of the binary surfactant systems was determined by surface tension measurement. Critical micelle concentration of mixed system is 0.141mmol ⋅ L−1 when the molar fraction of OPLES-7 to dodecyl glucoside 1:1. The influence of NaCl on surface properties of the mixed system was also studied. The surface activity was enhanced with the increase of NaCl concentration.

Colloidal sol of UO2 nanoparticles supported by multi-lamellar vesicles of carboxylate based surfactant

Producing compact monoliths of mesoporous uranium oxide that are free from surface active components and able to be wet by highly radioactive solutions is of great interest for future nuclear technologies. In this direction, metastable colloidal sols of UO2 using U(IV) as precursor and carboxylic surfactants (Polyoxyethylene(9) oleyl ether carboxylic acid C16/18:1E9COOH and Polyoxyethylene(10) lauryl ether carboxylic acid C12E10COOH) have been successfully prepared by indirect precipitation for 6 ≤ pH ≤ 8 with a molar ratio between uranium and surfactant U/S < 0.3. The self-assembly of this colloidal system results in micelles and U(IV) species partitioned as different forms: U-C16/18:1E9COOH/U-C12E10COOH complexes forming multi-lamellar vesicles with interdigitated bilayers, UO2 nanocrystallites (nc-UO2) within the vesicles and nc-UO2 forming aggregates attached on the surface of the vesicles with a relative proportion of 61 %:28 %:11 %. We showed that using an amphiphilic molecule having carboxylic head group, U(IV) species can be complexed and form multi-lamellar vesicles as supporting gel. The competition between the U(IV) species complexation by surfactant molecules and their hydrolysis prevents the rapid condensation of U (OH)4-nn+ (1 ≤n≤4) and makes the colloidal sol-gel process controllable. The principle shown here that results in partitioning the uranium into molecules, nanoparticles and aggregates could be useful in the design of molecularly dispersed Uranium and Plutonium coming from sol-gel chemistry.

Eco-friendly anticorrosion for carbon steel in artificial seawater: Effect of the ethylene oxide number of polyoxyethylene lauryl ether on its inhibition behaviour combining experimental and theoretical perspectives

An environmental and cost-effective surfactant, polyoxyethylene lauryl ether with different numbers of ethylene oxide groups, was investigated as a corrosion inhibitor for carbon steel in artificial seawater by combining experimental and theoretical methods. All the anticorrosion experimental results from different techniques were in good agreement, which showed that polyoxyethylene lauryl ethers have outstanding anticorrosion properties for steel in seawater and that their performance improves with increasing ethylene oxide. SEM-EDS and FTIR spectroscopy confirmed that the inhibition behaviour arose from the formation of an adsorbed layer on the steel surface that repelled chloride corrosion. The Monte Carlo simulation and quantum calculation results further clarified the effect of ethylene oxide groups on the inhibition mechanism.

Incorporation of Nonyl 3,4-Dihydroxybenzoate Into Nanostructured Lipid Systems: Effective Alternative for Maintaining Anti-Dermatophytic and Antibiofilm Activities and Reducing Toxicity at High Concentrations.

Dermatophytosis is the most common mycosis worldwide, affecting approximately 20 to 25% of the population, regardless of gender, race, color, and age. Most antifungal agents used for the treatment of dermatophytosis belong to the azole and allylamine classes. Dermatophytes are reported to be resistant to most commercial drugs, especially microbial biofilms, in addition to their considerable toxicity. It should be emphasized the importance of looking for new molecules with reduced toxicity, as well as new targets and mechanisms of action. This work aims to incorporate nonyl 3,4-dihydroxybenzoate, a potent fungicide compound against planktonic cells and dermatophyte biofilms in nanostructured lipid systems (NLS), in order to reduce toxicity in high concentrations, improve its solubility and maintain its effectiveness. The compound was incorporated into NLS constituted by cholesterol, mixture of polyoxyethylene (23) lauryl ether (Brij®98) and soybean phosphatidylcholine (Epikuron® 200)], 2: 1 ratio and PBS (phosphate-buffered saline). The characterization of the incorporation was performed. Susceptibility tests were conducted according to document M38-A2 by CLSI (2008). The toxicity of the NLS compound was evaluated in HaCaT cell lines by the sulforhodamine B method and in alternative models Caenorhabditis elegans and zebrafish. Finally, its efficacy was evaluated against the mature Trichophyton rubrum and Trichophyton mentagrophytes biofilms. NLS and nonyl 3,4-dihydroxybenzoate loaded into NLS displayed sizes ranging from 137.8 ± 1.815 to 167.9 ± 4.070 nm; the polydispersity index (PDI) varying from 0.331 ± 0.020 to 0.377 ± 0.004 and zeta potential ranging from −1.46 ± 0.157 to −4.63 ± 0.398 mV, respectively. Polarized light microscopy results confirmed the formation of NLS of the microemulsion type. Nonyl incorporated into NLS showed minimum inhibitory concentration (MIC) values, ranging from 2 to 15.6 mg/L. The toxicity tests presented cell viability higher than 80% in all tested concentrations, as well as, a significantly increased of the survival of Caenorhabditis elegans and zebrafish models. Anti-biofilm tests proved the efficacy of the incorporation. These findings contribute significantly to the search for new antifungals and allow the systemic administration of the compound, since the incorporation can increase the solubility of non-polar compounds, improve bioavailability, effectiveness and reduce toxicity.

Effects of Conventional Surfactants on the Activity of Designed Antimicrobial Peptide.

In this article, the interaction between a designed antimicrobial peptide (AMP) G(IIKK)3I-NH2 (G3) and four typical conventional surfactants (sodium dodecyl sulfonate (SDS), hexadecyl trimethyl ammonium bromide (C16TAB), polyoxyethylene (23) lauryl ether (C12EO23), and tetradecyldimethylamine oxide (C14DMAO)) has been studied through surface tension measurement and circular dichroism (CD) spectroscopy. The antimicrobial activities of AMP/surfactant mixtures have also been studied with Gram-negative Escherichia coli, Gram-positive Staphylococcus aureus, and the fungus Candida albicans. The cytotoxicity of the AMP/surfactant mixtures has also been assessed with NIH 3T3 and human skin fibroblast (HSF) cells. The surface tension data showed that the AMP/SDS mixture was much more surface-active than SDS alone. CD results showed that G3 conformation changed from random coil, to β-sheet, and then to α-helix with increasing SDS concentration, showing a range of structural transformation driven by the different interactions with SDS. The antimicrobial activity of G3 to Gram-negative and Gram-positive bacteria decreased in the presence of SDS due to the strong interaction of electrostatic attraction between the peptide and the surfactant. The interactions between G3 and C16TAB, C12EO23, and C14DMAO were much weaker than SDS. As a result, the surface tension of surfactants with G3 did not change much, neither did the secondary structures of G3. The antimicrobial activities of G3 were little affected in the presence of C12EO23, slightly improved by C14DMAO, and clearly enhanced by cationic surfactant C16TAB due to its strong cationic and antimicrobial nature, consistent with their surface physical activities as binary mixtures. Although AMP G3 did not show activity to fungus, the mixtures of AMP/C16TAB and AMP/C14DMAO could kill C. albicans at high surfactant concentrations. The mixtures had rather high cytotoxicity to NIH 3T3 and HSF cells although G3 is nontoxic to cells. Cationic AMPs can be formulated with nonionic, cationic, and zwitterionic surfactants during product development, but care must be taken when AMPs are formulated with anionic surfactants, as the strong electrostatic interaction may undermine their antimicrobial activity.

Study of Structure of Water Droplets of Nonionic Polyoxyethylene (4) Lauryl Ether Reverse Micelles in the Presence of Sodium Cholate

Abstract The microenvironment of water droplets of nonionic polyoxyethylene (4) lauryl ether reverse micelles was investigated with infrared and ultraviolet-visible spectroscopy, also by viscosity and dynamic light scattering measurements in the presence of biological surfactant sodium cholate as additive. Influence of concentrations of polyoxyethylene (4) lauryl ether and sodium cholate on the microstructure of mixed reverse micelles was studied. Influence of sodium cholate as additive on the ratio of free, bound and trapped water fractions was studied via deconvolution of the O-H stretching vibrational absorption spectra in the region of 3 000–3 800 cm−1 into three subpeaks with a Monte Carlo method. Several characteristic parameters of reverse microemulsions were calculated on the basis of measurements of their kinematic viscosity. A different influence of concentration of sodium cholate on the binding constant and association degree of optical probes (o-nitroaniline and methyl orange respectively) to ethylene oxide groups of nonionic surfactant was observed. It was found that the bound water fraction, the binding constants and association degrees, the relative density of water pockets, etc. change their values passing through an extremum under the influence of sodium cholate.

A Mixed Micellar Liquid Chromatography with Direct Injection for Rapid Analysis of Eight Sulfonamides in Milk

In this work, an isocratic mixed micellar liquid chromatography method was first applied to the separation of eight sulfonamides in milk. Mixed anionic and nonionic surfactants were used as mobile phase additives. Because proteins in the milk can be dissolved by the micelles, the milk samples can be directly injected into the chromatographic system after being simply diluted 10 times with 0.1 M sodium dodecyl sulfate solution. Besides, three-phase equilibrium theory was firstly used to explain the retention mechanism of sulfonamides in the mixed micellar liquid chromatography. The optimized mobile phase was an aqueous solution (0.04 M sodium dodecyl sulfate and 0.01 M polyoxyethylene lauryl ether) containing 20 mM NaH2PO4 with 10% (v/v) of n-propanol at pH 3.0. The separation was performed on a Venusil XBP C18 column (250 × 4.6 mm, i.d., 5 μm). The proposed mixed micellar liquid chromatography method was validated in terms of linear ranges (20–2500 μg/L), limit of detections (1.9–8.0 μg/L), limit of quantitations (6.1–27 μg/L), recoveries (84–105%), intra- and inter-precisions (RSD < 6.0%, RSD < 9.3%). The established method, which is rapid, low-cost, and environmentally friendly, provides an alternative way for rapid separation of sulfonamides within 15 min, and it does not require the complex gradient elution.

Modulation of Antimicrobial Peptide Conformation and Aggregation by Terminal Lipidation and Surfactants.

The function and properties of peptide-based materials depend not only on the amino acid sequence but also on the molecular conformations. In this paper, we chose a series of peptides Gm(XXKK)nX-NH2 (m = 0, 3; n = 2, 3; X = I, L, and V) as the model molecules and studied the conformation regulation through N-terminus lipidation and their formulation with surfactants. The structural and morphological transition of peptide self-assemblies have also been investigated via transmission electron microscopy, atomic force microscopy, circular dichroism spectroscopy, and small-angle neutron scattering. With the terminal alkylation, the molecular conformation changed from random coil to β-sheet or α-helix. The antimicrobial activities of alkylated peptide were different. C16-G3(IIKK)3I-NH2 showed antimicrobial activity against Streptococcus mutans, while C16-(IIKK)2I-NH2 and C16-G3(IIKK)2I-NH2 did not kill the bacteria. The surfactant sodium dodecyl sulfonate could rapidly induce the self-assemblies of alkylated peptides (C16-(IIKK)2I-NH2, C16-G3(IIKK)2I-NH2, C16-G3(VVKK)2V-NH2) from nanofibers to micelles, along with the conformation changing from β-sheet to α-helix. The cationic surfactant hexadecyl trimethyl ammonium bromide made the lipopeptide nanofibers thinner, and nonionic surfactant polyoxyethylene (23) lauryl ether (C12EO23) induced the nanofibers much more intensively. Both the activity and the conformation of the α-helical peptide could be modulated by lipidation. Then, the self-assembled morphologies of alkylated peptides could also be further regulated with surfactants through hydrophobic, electrostatic, and hydrogen-bonding interactions. These results provided useful strategies to regulate the molecular conformations in peptide-based material functionalization.

Micellar and Interfacial Behavior of Mixed Systems Containing Anionic-nonionic Gemini Surfactant

The Anionic-nonionic Gemini Surfactant oxalamide polyoxyethylene lauryl ether(9)succinate sodium sulfonate(OPLES-9) was synthesized. It was mixed with the anionic surfactant sodium lauryl sulfate(SDS) and the nonionic surfactant dodecanol polyoxyethylene(9) ether (AEO9) respectively in different ratios to enhance application performance. The experimental results showed that the surface performance of the mixed systems was more superior to the relevant single surfactants. The mixed critical micelle concentration (CMC) of the binary surfactant systems was determined by surface tension measurement. Critical micelle concentration of mixed system reached the minimum 0.146mmol·L−1 when the molar fraction of OPLES-9 to SDS was 1:1. Critical micelle concentration of OPLES-9/AEO9 mixed system reached the minimum 0.259mmol·L−1 when the molar fraction of OPLES-9 to AEO9 was 0.9:1.