High Surfactant Research Articles

Pathophysiology of pulmonary hypertension in newborns: Therapeutic indications

Failure of the normal cardiopulmonary transition can lead to persistent pulmonary hypertension of the newborn. Some degree of pulmonary hypertension complicates the course of more than 10% of all neonates with respiratory failure. This review article discusses the vascular abnormalities associated with neonatal pulmonary hypertension. Common therapies including inhaled nitric oxide, high frequency ventilation, surfactant, and extracorporeal life support are included. Promising new treatment approaches like phosphodiesterase inhibition and cell-targeted therapies are presented.

Cationic Gemini Surfactant as a Corrosion Inhibitor and a Biocide for High Salinity Sulfidogenic Bacteria Originating from an Oil‐Field Water Tank

AbstractA novel cationic gemini surfactant (NCGS) was synthesized and characterized. The inhibitory effect of NCGS was evaluated on the basis of protecting a metal surface from the salinity (5.49 % NaCl) and the activity of environmental sulfidogenic bacteria which originated from an oil‐field water tank. Sulfidogenic bacterial activities were determined based on sulfide production, redox potential, changes in biofilm structures and constituents and metal corrosion rate calculations. At high surfactant concentrations, the sulfide production was completely inhibited as well as a considerable drop in the redox potential was observed in the reactor's bulk phase. A minimum inhibitory concentration of the NCGS was achieved at a concentration of 1 mM. The NCGS showed a high ability to inhibit a biofilm over the metal surface at a concentration of 0.1 mM. The lowest metal corrosion rate was detected at a concentration of 5 mM with a metal corrosion inhibition efficiency of 97 %. In addition the NCGS showed a nonspecific biocidal activity against Gram‐positive and Gram‐negative bacterial strains.

Pathophysiology of pulmonary hypertension in newborns: Therapeutic indications

Failure of the normal cardiopulmonary transition can lead to persistent pulmonary hypertension of the newborn. Some degree of pulmonary hypertension complicates the course of more than 10% of all neonates with respiratory failure. This review article discusses the vascular abnormalities associated with neonatal pulmonary hypertension. Common therapies including inhaled nitric oxide, high frequency ventilation, surfactant, and extracorporeal life support are included. Promising new treatment approaches like phosphodiesterase inhibition and cell-targeted therapies are presented.

Imidazolium-based ionic liquid-type surfactant as pseudostationary phase in micellar electrokinetic chromatography of highly hydrophilic urinary nucleosides

Ionic liquid (IL)-type surfactants have been shown to interact more strongly with polar compounds than traditionally used quaternary ammonium cationic surfactants. The aim of this study is to provide an alternative micellar electrokinetic chromatographic method (MEKC) for the analysis of urinary nucleosides in their ionic form at low surfactant concentration. This approach could overcome the use of high surfactant concentrations typically associated with the analysis of these highly hydrophilic metabolites as neutral species, which is frequently accompanied by high electric current, Joule heating and long analysis time. The investigated IL-type surfactant; 1-tetradecyl-3-methylimidazolium bromide (C14MImBr) is similar to the commonly employed cationic surfactant; tetradecyltrimethylammonium bromide (TTAB) but it provides a different separation selectivity. We employed C14MImBr micelles for the MEKC analysis of seven urinary nucleosides. The studied analytes possess a negative charge at pH 9.38 (exceptions are adenosine and cytidine which are neutral at this pH value). Borate imparts an additional negative charge to these compounds after complexation with the cis-diol functionality of the ribose unit, which in turn enables them to interact with the oppositely charged C14MImBr micelles via electrostatic (Coulomb) forces. The effect of the concentration of borate (the complexing, competing and buffering ion) on the effective electrophoretic mobilities and on the retention factors was investigated. The effective electrophoretic mobility data show that complexation between these nucleosides and borate occurs with high degree of complexation even at very low borate concentration (2.5mmolL−1 disodium tetraborate). In addition, we found that the retention factors are strongly dependent on the borate concentration being the highest when using the lowest borate concentration and they can be regulated by variation of either tetraborate concentration or the pH of the background electrolyte using only 20mmolL−1 C14MImBr. We confirmed also that the main mode of interaction between these analytes and the C14MImBr micelles is electrostatic interaction. Our experimental results reveal that the cationic surfactant C14MImBr exhibits superior selectivity and higher reproducibility relative to that of TTAB, which makes this surfactant a promising cationic surfactant for the MEKC separation of other hydrophilic polar analytes.

A Supramolecular Amphiphile Based on Calix[4]resorcinarene and Cationic Surfactant for Controlled Self-Assembly

A novel supramolecular system based on calix[4]resorcinarene sulfonatoalkylated at the lower rim and piperidine-methylated at the upper rim and the cationic surfactant hexadecyl-1-azonia-4-azobicyclo[2.2.2]octane bromide was investigated by methods of NMR, tensiometry, conductometry, potentiometry, dynamic light scattering, X-ray powder diffraction, and spectral probe techniques. Both types of molecules were found to self-associate in aqueous solution, with aggregates of different morphology formed. Importantly, a supramolecular amphiphilic binary system with controlled structure and binding behavior could be fabricated. At high surfactant concentration, the formation of its own aggregates takes place. In the systems with the excess of cyclophane the supramolecular amphiphiles are formed, which, in turn, self-assemble in particles with a large hydrophobic core. Thereby the structure of supramolecular species is determined by relative fractions of components and, hence, could be selectively controlled. The...

Highly ordered and surfactant-free PtxRuy bimetallic nanocomposites synthesized by electrostatic self assembly for methanol oxidation reaction

Positively charged Ru nanoparticles (∼1.0nm, zeta potential=+6.6mV) induced by hydrated protons and negatively charged Pt nanoparticles (∼2.2nm, zeta potential=−4.2mV) by NO3− are synthesized separately. Without use of any high molecular weight surfactants, oppositely charged surfactant-free Ru and Pt colloids display sustained stability. Highly ordered PtxRuy nanocomposites are electrostatically self assembled when the oppositely charged Ru and Pt colloids were mixed at room temperature. CO stripping voltammograms of PtxRuy/C show that the CO stripping peak and the on-set oxidation potential are highly dependent on Pt/Ru ratio, which is most probably due to the different interstitial space between Pt and Ru in the self-assembled patterns. The mass-normalized activity of Pt3Ru1/C for methanol oxidation reaction is found to be 112% higher relative to that of PtRu/C catalyst from E-TEK.

Association of sodium dodecyl sulfate in aqueous solutions according to chemical shifts in 1H NMR spectra

Proton chemical shifts of different atomic groups in sodium dodecyl sulfate (SDS) have been studied by 1H NMR spectroscopy as functions of surfactant concentration in aqueous solutions. Three surfactant concentration ranges of the chemical shifts have been revealed. The first range corresponds to the premicellar solutions, the second one is in the vicinity of critical micelle concentration (CMC1), and the third range corresponds to high surfactant concentrations, at which intermicellar interactions play a significant role. The parameters of SDS association (CMC1 and CMC2) determined based on the concentration dependences of the chemical shifts are in satisfactory agreement with the data available from the literature. The concept of critical dimerization concentration (CDC) has been introduced for the first concentration range. The values of CDC and dimerization constant K 2 (210 × 60 dm3/mol) have been estimated within the framework of the two-state model.

Adsorption layer properties of alkyltrimethylammonium bromides at interfaces between water and different alkanes

We measured the interfacial tensions of aqueous solutions against different oil phases using drop profile analysis tensiometry (PAT-1, Sinterface Technologies, Germany) for decyl- and dodecyltrimethylammonium bromide (C10TAB and C12TAB) in phosphate buffer (10mM, pH7). The following alkanes were used as oil phases: hexane, heptane, octane, nonane, decane, dodecane and tetradecane. The obtained equilibrium interfacial tension isotherms were fitted by the Frumkin Ionic Compressibility model (FIC). The surfactants adsorb at the water/oil interface in competition with the oil molecules. At high surfactant surface coverage this competitive adsorption is manifested in two ways. First, for short chain surfactants, the oil molecules are embedded into the adsorption layer. Second, for long chain surfactants, the short alkane chains of the oil molecules are squeezed out from the adsorption layer due to strong mutual interaction between surfactants’ chains.

Effects of Various Co-Surfactants and Oils on Microemulsion Formation in Decylglucoside System

Decylglucoside is a non-ionic, non-toxic, biodegradable surfactant. This work aimed to establish composition where stable microemulsions could form using hydrophilic lipophilic deviation (HLD) concept to optimise the formulations. Scanning for suitable ratios of surfactant and co-surfactant was carried out by altering the surfactant/co-surfactant (S/CoS) ratios with two co-surfactants and seven different oils in order to find the optimum formulations. From the optimal S/CoS ratios, pseudo-ternary phase diagrams by dilution were subsequently performed, leading to obtain microemulsion zones. The zones of microemulsions could be observed in the systems composed of decylglucoside/sorbitan monooleate/isopropyl myristate/water at the 0.10/0.90 and 0.20/0.80 S/CoS ratios and decylglucoside/sorbitan monooleate /isopropyl palmitate/water at the 0.10/0.90, 0.15/0.85 and 0.20/0.80 S/CoS ratios. The microemulsion zones of two systems were similar and found at high surfactant concentrations. However, the studied decylglucoside microemulsion systems were interesting in drug and cosmetic applications because it consisted of non-ionic surfactant and co-surfactant, resulting low toxic products.

Formation of Dynamic Soluble Surfactant-induced Amyloid β Peptide Aggregation Intermediates

Intermediate amyloidogenic states along the amyloid β peptide (Aβ) aggregation pathway have been shown to be linked to neurotoxicity. To shed more light on the different structures that may arise during Aβ aggregation, we here investigate surfactant-induced Aβ aggregation. This process leads to co-aggregates featuring a β-structure motif that is characteristic for mature amyloid-like structures. Surfactants induce secondary structure in Aβ in a concentration-dependent manner, from predominantly random coil at low surfactant concentration, via β-structure to the fully formed α-helical state at high surfactant concentration. The β-rich state is the most aggregation-prone as monitored by thioflavin T fluorescence. Small angle x-ray scattering reveals initial globular structures of surfactant-Aβ co-aggregated oligomers and formation of elongated fibrils during a slow aggregation process. Alongside this slow (minutes to hours time scale) fibrillation process, much faster dynamic exchange (k(ex) ∼1100 s(-1)) takes place between free and co-aggregate-bound peptide. The two hydrophobic segments of the peptide are directly involved in the chemical exchange and interact with the hydrophobic part of the co-aggregates. Our findings suggest a model for surfactant-induced aggregation where free peptide and surfactant initially co-aggregate to dynamic globular oligomers and eventually form elongated fibrils. When interacting with β-structure promoting substances, such as surfactants, Aβ is kinetically driven toward an aggregation-prone state.

Production and characterization of a trehalolipid biosurfactant produced by the novel marine bacterium Rhodococcus sp., strain PML026

The aim of this study was to evaluate biosurfactant production by a novel marine Rhodococcus sp., strain PML026 and characterize the chemical nature and properties of the biosurfactant. A novel marine bacterium (Rhodococcus species; strain PML026) was shown to produce biosurfactant in the presence of hydrophobic substrate (sunflower oil). Biosurfactant production (identified as a trehalolipid) was monitored in whole-batch cultures (oil layer and aqueous phase), aqueous phase (no oil layer) and filtered (0·2μm) aqueous phase (no oil or cells; extracellular) and was shown to be closely associated with growth/biomass production. Extracellular trehalolipid levels increased postonset of stationary growth phase. Purified trehalolipid was able to reduce the surface tension of water to 29mN m(-1) at Critical Micellar Concentration (CMC) of c. 250mgl(-1) and produced emulsions that were stable to a wide range of conditions (pH 2-10, temperatures of 20-100°C and NaCl concentrations of 5-25% w/v). Separate chemical analyses of the intact trehalolipid and its constituents demonstrated the compound was in fact a mixture of homologues (>1180MW) consisting of a trehalose moiety esterified to a series of straight chain and hydroxylated fatty acids. The trehalolipid biosurfactant produced by the novel marine strain Rhodococcus sp. PML026 was characterized and exhibited high surfactant activity under a wide range of conditions. Strain PML026 of Rhodococcus sp. is a potential candidate for bioremediation or biosurfactant production for various applications.

Intelligent hydrophilic nanoparticles fabricated via alkaline hydrolysis of crosslinked polyacrylonitrile nanoparticles

Crosslinked polyacrylonitrile (PAN) nanolatex, with an average hydrodynamic diameter of 84 nm and a polydispersity index of 0.06, was successfully synthesized at a high monomer concentration and low surfactant content via a modified emulsion polymerization. Three measurements were adopted to control the nucleation and growth processes. Taking advantage of the chemical activity of nitrile groups, intelligent hydrophilic polymeric nanoparticles were fabricated via simple alkaline hydrolysis treatment of the crosslinked PAN nanolatex. Dynamic light scattering, electrophoretic light scattering, FT-IR spectroscopy, elemental analysis, and TEM observations were used to monitor the changes in the composition, structure, and morphology of the nanoparticles during the hydrolysis process. The sizes, chemical composition, morphology, and pH-responsive behavior of the intelligent hydrophilic nanoparticles could be adjusted by simply changing the hydrolysis time. As the hydrolysis was prolonged, the following nanoparticles could be obtained, crosslinked PAN nanoparticles with hydrophilic surfaces, amphiphilic nanoparticles with a hydrophobic PAN core and a hydrophilic polymeric shell composed of acrylamide and acrylic acid units, or carboxylic polyacrylamide nanoparticles. These modified nanoparticles all display good hydrophilicity, good biocompatibility, pH-sensitivity, as well as carboxyl functional groups, and thus are ideal candidates for various biomedical applications.

Adsorption of organic pollutants by surfactant modified zeolite as controlled by surfactant chain length

Surfactant modified zeolites are promising for decontamination of organic pollutants from water. However, the influence of chain length of surfactants on decontamination process has not been clarified to our knowledge. In this study, a natural zeolite was modified with surfactants of varying chain length (from one carbon to 22 carbons) and the adsorption of organic contaminants, including anionic (sodium form of humic acid), ionizable (phenol, p-chlorophenol and bisphenol A), and non-ionizable compounds (naphthalene) was investigated. Results showed that the amount of surfactant loaded increased with increasing chain length. Measurement of FTIR spectroscopy indicated that the surfactant chains adopted a more disordered conformation as the chain length decreases. In general, the adsorption of the organic pollutants increases as the chain length increases. We noted that long chain length, high surfactant coverage, and ordered chain conformation are driving forces for the retention of organic chemicals. The pH dependency of adsorption suggested that negatively charged groups of anionic or ionizable organic solutes interacted with positively charged head of surfactant. Furthermore, adsorption increased with increasing kow value for organic pollutants, indicating that hydrophobic interaction of the benzene ring(s) of organic compounds with the carbon chain of surfactant contributes to adsorption.

Early-Season Weed Control Using Herbicides with Adjuvants in Direct-Seeded Onion

Early-season weed competition may cause substantial yield losses in onion. Oxyfluorfen and bromoxynil are POST herbicide options for weed control once onion has developed two leaves, which often takes 4 to 6 wk. Multiple applications of oxyfluorfen at 35 and 18 g ai ha−1and bromoxynil at 35 and 18 g ae ha−1with adjuvants were evaluated for onion safety and weed control under controlled greenhouse conditions. Oxyfluorfen at 35 g ha−1plus organosilicone surfactant caused 42% onion injury at 12 d after three sequential applications. Onion treated with bromoxynil at 18 g ha−1plus high surfactant oil concentrate had lower fresh weight (0.7 g) compared to methylated seed oil (MSO) (1.2 g) or petroleum oil concentrate (POC) (1.3 g) at the same bromoxynil rate. The addition of nonionic surfactant to bromoxynil, averaged across bromoxynil rates, provided 17 and 39% control of redroot pigweed and common lambsquarters, respectively. Redroot pigweed control with oxyfluorfen at 35 or 18 g ha−1plus any tested adjuvant was excellent (≥ 93%). Results suggested the use of POC or MSO with either oxyfluorfen or bromoxynil for subsequent field trials because of similar common lambsquarters and redroot pigweed control and onion safety.

Behavior of vitamin E acetate delivery systems under simulated gastrointestinal conditions: Lipid digestion and bioaccessibility of low-energy nanoemulsions

Colloidal delivery systems are needed to incorporate oil-soluble vitamins into aqueous-based foods and beverage products. In this study, we encapsulated vitamin E acetate into oil-in-water nanoemulsions produced using either a low-energy method (Emulsion Phase Inversion, EPI) or a high energy method (microfluidization). Oil-in-water nanoemulsions (d<200nm) could be produced using both low- and high-energy methods from a non-ionic surfactant (Tween 80) and medium chain triglycerides (MCTs). The influence of surfactant-to-oil ratio (SOR) on lipid digestion and vitamin bioaccessibility of EPI nanoemulsions was determined using a gastrointestinal tract (GIT) model that simulated the mouth, stomach, and small intestine. There were increases in the size and negative charge of the oil droplets after passage through the GIT, which was attributed to droplet coalescence and changes in interfacial composition. The rate and extent of lipid digestion decreased with increasing surfactant concentration, but the bioaccessibility of vitamin E acetate was high in all of the samples (>95%). No appreciable influence of the preparation method (low-energy versus high-energy) on lipid digestion and vitamin bioaccessibility was observed. The major advantage of the EPI method for forming nanoemulsions is that no expensive equipment is required, but relatively high surfactant concentrations are needed compared to microfluidization.

Study of Surfactant (Benzyldimethylhexadecylammonium Chloride) Effect on Selected Properties of Hydrogels

Abstract This paper aims to provide analysis of the influences of concentration changes of the surfactant – benzyldimethylhexadecylammonium chloride in hydrogels on their liberation, rheological, association and solubility properties. The hydrogels contained constant amounts of the gel-creating basis (polymer chitosan – 2.5 % w/w), the drug (chlorhexidine dihydrochloride – 0.1 % w/w) and the surfactant, which was used as an enhancer (0.005 – 0.05 % w/w). The highest value of the released drug corresponded to the highest surfactant concentration in the hydrogel. Critical micelle concentration and thermodynamic parameters, molar Gibbs energy, enthalpy and entropy of micellization were calculated. A linear increase of the surfactant amounts in hydrogels caused a non-linear increase of the cloud point. The appearance of the surfactant's associates in hydrogels influenced both their liberation and rheological properties.

Sucrose Stearate-Enriched Lipid Matrix Tablets of Etodolac: Modulation of Drug Release, Diffusional Modeling and Structure Elucidation Studies

Etodolac is a non-steroidal anti-inflammatory drug having an elimination half-life of 7 h; oral doses are given every 6-8 h. The aim of current work was the development of controlled-release etodolac lipid matrix tablets. The variables influencing design of these tablets (L1-L28) by the hot fusion method were investigated including; (1) lipid type (stearic acid, cetyl alcohol, cetostearyl alcohol, Imwitor® 900K, Precirol® ATO 5 and Compritol® ATO 888), (2) drug/lipid ratio (1:0.25 and 1:0.50, respectively), (3) filler type (lactose, Avicel® PH101 and their physical mixtures; 2:1, 1:1, and 1:2, respectively), (4) surfactant's HLB (5 and 11), and (5) drug/surfactant ratio (20:1 and 10:1, respectively). Statistical analysis and kinetic modeling of drug release data were evaluated. The inner matrix of the tablet was visualized via scanning electron microscopy (SEM). An inverse correlation was observed between the drug/lipid ratio and the drug release rate. Precirol®- and Compritol®-containing formulae showed more retarded drug release rates. Lactose/Avicel® physical mixture (1:1) was considered as a filler of choice where it minimized the burst effect observed with Avicel®-free formulae. The higher surfactant's HLB, the higher drug release rate. The similarity factor (f(2)) between the drug release profiles revealed similarity within the investigated drug/surfactant ratios. Sucrose stearate D1805®-based matrix (L21) succeeded in delivering more than 90% of etodolac over 12 h, following anomalous (non-Fickian) controlled-release kinetics. SEM micrographs confirmed pore formation, within the latter matrix, upon contact with dissolution medium.

Surfactant Pretreatment Is Superior to Treatment after Reperfusion for Lung Ischemia-Reperfusion Injury

Purpose Lung ischemia-reperfusion injury (LIRI) is a risk factor for development of primary graft dysfunction after lung transplantation. Treatment with surfactant ameliorates LIRI, but the optimal timing and surfactant dose are unknown. We compared the efficacy of surfactant treatment before ischemia with treatment at and 24 hours after reperfusion. Methods and Materials Male Sprague-Dawley rats (n=98) were randomized to receive intratracheally administered porcine surfactant in high (200 mg/kg) or low dose (50 mg/kg) either 1 hour before ischemia, at the start of reperfusion, or 24 hours after reperfusion. Sham-operated and untreated LIRI animals served as controls. LIRI was induced by clamping the bronchus, pulmonary artery and veins of the left lung for 150 minutes. After 72 hours, arterial oxygenation, pulmonary compliance, inflammatory cells in broncho-alveolar-lavage fluid and histological pulmonary injury were assessed. Results LIRI caused hypoxemia, impaired lung compliance, diffuse alveolar damage, inflammation consisting of granulocytes, macrophage and lymphocytes, and upregulation of MHCII+ on antigen presenting cells. Pretreatment with 200 mg/kg surfactant improved survival and lung function, averted fibroproliferation, and reduced diffuse alveolar damage and infiltration of T-cells in the ischemic lung. Surfactant treatment after reperfusion resulted in a mortality rate comparable to untreated LIRI and had no effect on pulmonary function, independent of the dose. Low dose surfactant reduced inflammation independent of the time of application, but the effect on lung function was less pronounced. Conclusions Pretreatment with high dose surfactant is superior to low dose treatment. Surfactant pretreatment is superior to treatment directly-, or 24 hours after reperfusion.

New self-nanoemulsifying drug delivery system (SNEDDS) with amphiphilic diblock copolymer methoxy poly (ethylene glycol)-block-poly (ϵ-caprolactone)

The objective of the study is to prepare a new self-nanoemulsifying drug delivery system (SNEDDS) with amphiphilic diblock copolymers methoxy poly (ethylene glycol)-block-poly (ϵ-caprolactone) (MPEG-b-PCL) and to investigate the effect of MPEG-b-PCL on the characteristics of SNEDDS. MPEG-b-PCL was synthesized and characterized by 1H-NMR, IR and GPC. Various ratios of MPEG-b-PCL copolymers and Tween 80 were used as emulsifier to prepare the new SNEDDS. SNEDDS with high oil and low surfactant content forms a semi-solid gel at room temperature, which could be effectively sealed in soft or hard capsules. The mean droplet size of SNEDDS-generated nanoemulsions significantly decreased after the addition of diblock polymer and increased with increase of PCL chain in MPEG-b-PCL. The drug Coenzyme Q10 (CoQ10) was chosen as the model compound in this study due to its insolubility in water. CoQ10 from SNEDDS was rapidly dissolved regardless of the fluid condition.

Factors affecting the viscosity of sodium hypochlorite and their effect on irrigant flow

To assess the influence of concentration, temperature and surfactant addition to a sodium hypochlorite solution on its dynamic viscosity and to calculate the corresponding Reynolds number to determine the corresponding flow regimen. The dynamic viscosity of the irrigant was assessed using a rotational viscometer. Sodium hypochlorite with concentrations ranging from 0.6% to 9.6% was tested at 37 and 22 °C. A wide range of concentrations of three different surfactants was mixed in 2.4% sodium hypochlorite for viscosity measurements. The Reynolds number was calculated under each condition. Data were analysed using two-way anova. There was a significant influence of sodium hypochlorite concentration (P < 0.001) and temperature (P < 0.001) on dynamic viscosity: the latter significantly increased with sodium hypochlorite concentration and decreased with temperature. A significant influence of surfactant concentration on dynamic viscosity (P < 0.001) occurred, especially for high surfactant concentrations: 6.25% for benzalkonium chloride, 15% for Tween 80 and 6.25% for Triton X-100. Reynolds number values calculated for a given flow rate (0.14 mL s(-1)), and root canal diameter (sizes 45 and 70) clearly qualified the irrigant flow regimen as laminar. Dynamic viscosity increased with sodium hypochlorite and surfactant concentration but decreased with temperature. Under clinical conditions, all viscosities measured led to laminar flow. The transition between laminar and turbulent flow may be reached by modifying different parameters at the same time: increasing flow rate and temperature whilst decreasing irrigant viscosity by adding surfactants with a high value of critical micellar concentration.