Tensioactive Agent Research Articles

Endoscope sampling and culturing methods

Contamination rates reported in the literature for patient-ready flexible endoscopes vary from 0.4% to 49%. Unfortunately, the comparison and interpretation of these results is almost impossible since several factors including sampling and culturing methods, target levels for contamination or definition of indicator microorganisms vary widely from one study to the other. The objective of this study was to compare the efficacy of six duodenoscope sampling and culturing methods by means of extraction efficacy comparison, while at the same time identifying key parameters that provide optimal microbial recovery.The duodenoscope sample extraction efficacy of each method was assessed using the repetitive recovery method described in ISO 11737-1: 2018. The results obtained indicated that the mean overall bioburden extraction efficacy varied from 1% for the Australian method to 39% for the French one. The lowest endoscope sample extraction efficacy was associated with the absence of any neutralizer, friction, or tensioactive agent and when only a small portion of the sampling solution collected was inoculated onto culture media.The efficacy of the sampling and culturing methods also varied according to the nature of microorganisms present in the endoscope, and the time between sampling and culturing.This study supports the need for a harmonized and standardized sampling and culturing method for flexible endoscopes.

Investigation of halotolerant marine Staphylococcus sp. CO100, as a promising hydrocarbon-degrading and biosurfactant-producing bacterium, under saline conditions

A halotolerant strain CO100 of Staphylococcus sp. was isolated from contaminated sediments taken from the fishing harbour of Sfax, Tunisia, as an efficient hydrocarbonoclastic candidate. Strain CO100 exhibited a high capacity to break down almost 72% of the aliphatic hydrocarbons contained in crude oil (1%, v/v), used as the sole carbon and energy source, after 20 days of culture, at 100 g/l NaCl, 37 °C and 180 rpm. The isolate CO100 displayed also its ability to grow on phenanthrene, fluoranthene and pyrene (100 mg/l), at 100 g/l NaCl. Moreover, the isolate CO100 showed a notable aptitude to synthesize an efficient tensioactive agent namely BS-CO100, on low-value substrates including residual frying oil and expired milk powder, thus reducing the high cost of biosurfactant production. The ESI/MS analysis designated that BS-CO100 belonged to lipopeptide class, in particular lichenysin and iturine members. Critical micelle concentrations of BS-CO100 were varying between 65 and 750 mg/l, depending on of the purity of the biosurfactant and the used carbon sources. BS-CO100 showed a high steadiness against a wide spectrum of pH (4.3–12), temperature (4–121 °C) and salinity (0–300 g/l NaCl), supporting its powerful tensioactive properties under various environmental conditions. Likewise, BS-CO100 exhibited no cytotoxic effect toward human HEK293 cells, at concentrations within 125 and 1000 μg/ml. Furthermore, the biosurfactant BS-CO100 exhibited remarkable anti-adhesive and anti-biofilm activities, being able to avoid and disrupt the biofilm formation by certain pathogenic microorganisms. In addition, BS-CO100 was found to have more potential to remove hydrocarbons from contaminated soils, compared to some chemical surfactants. In light of these promising findings, strain CO100, as well as its biosurfactant, could be successfully used in different biotechnological applications including the bioremediation of oil-polluted areas, even under saline conditions.

English

This study screened four Rhizopus species as biosurfactant producers using different markers. First of all, Rhizopus spp. UCP 1607 was identified as Rhizopus arrhizus by morphological and molecular methods. The production of biosurfactant/bioemulsifier was investigated by submerged fermentation using soybean post-frying oil (5% v/v) and sodium glutamate (1% w/v) medium. The primary markers’ hemolysis and parafilm M tests showed that R. arrhizus UCP1607 strain exhibited higher hemolytic activity (49 mm of clear zone) on sheep blood agar and a larger drop diameter (12 mm) on parafilm hydrophobic surface. The experimental results showed the most promising biosurfactant production by R. arrhizus UCP 1607 strain led to a reduction of surface tension (31.8 mN/m) and the diameter of the oil-spreading covered an area of 66.4 cm2. The strains Rhizopus microsporus var. chinensis UCP1296, R. microsporus var. microsporus UCP1304, and R. arrhizus UCP1607 were capable of forming stable emulsions corresponding to 91.7, 94.8, and 82.6%, respectively in crude oil. Key words: Tensio-active agent, bioemulsifier, screening of Rhizopus strains, submerged fermentation.

Nano-network with dual temperature and pH responsiveness based on copolymers of 2-hydroxyethyl methacrylate with 3,9-divinyl-2,4,8,10-tetraoxaspiro[5.5]-undecane

This study refers to the synthesis of a nano-network with dual temperature and pH responsiveness based on the 2-hydroxyethyl methacrylate (HEMA) copolymers with a comonomer with spiroacetal moiety and crosslinking capacity, namely 3,9-divinyl-2,4,8,10-tetraoxaspiro[5.5]-undecane (U). The copolymers were synthesized by radical emulsion polymerization, using 4,4′-azobis(cyanopentanoic acid) as initiator, in the presence of sodium lauryl sulfate as tensioactive agent and poly(vinyl alcohol) as protective colloid. Three copolymer variants were taken into study resulted from the different ratio between the comonomers (HEMA/U), which was about 98/2, 95/5, and 90/10, respectively. The copolymers were characterized by FTIR and thermal analysis. The copolymers sensitivity was evidenced by studying the evolution of the hydrodynamic radius and zeta potential of the polymeric particles as a function of pH. Thus, the particles size increases with the comonomer amount, from 193 nm in case of the homopolymer up to 253 nm for the copolymer with maximum content of the comonomer (10%). The increase of the particle hydrodynamic radius with the growth of temperature was also put into evidence.

Economic Optimized Medium for Tensio-Active Agent Production by Candida sphaerica UCP0995 and Application in the Removal of Hydrophobic Contaminant from Sand

Statistical experimental designs and response surface methodology were employed to optimize the concentrations of agroindustrial residues as soybean oil (SORR) from refinery, and corn steep liquor (CSL) from corn industry, for tensio-active agent produced by Candida sphaerica UCP 0995. Three 22 full factorial design were applied sequentially to investigate the effects of the concentrations and interactions of soybean oil refinery residue and corn steep liquor on the surface tension of free-cell culture broth for 144 h. Two 22 central composite designs and response surface methodology were adopted to derive a statistical model to measure the effect of SORR and CSL on the surface tension of the free-cell culture broth for 144 h. The regression equation obtained from the experimental data using a central composite design was solved, and by analyzing the response surface contour plots, the optimal concentrations of the constituents of the medium were determined: 8.63% v/v (≅9% v/v) of SORR and 8.80% v/v (≅9% v/v) CSL. The minimum surface tension predicted and experimentally confirmed was 25.25 mN/m. The new biosurfactant, denominated Lunasan, recovered 95% of motor oil adsorbed in a sand sample, thus showing great potential for use in bioremediation processes, especially in the petroleum industry.

Preparation of samples for alpha-spectrometry by direct evaporation of extracted species

Because of the energy loss of α-particles by self-absorption, α-spectrometry requires thin, uniform, and nearly weightless samples. Several methods exist for sample preparation, e.g., electrodeposition or co-precipitation. Unfortunately, the methods yielding the best energy resolution are not always quantitative and are usually relatively demanding and time-consuming. This fact makes application of α-spectrometry for screening tests with radiotracers complicated. For its simplicity and fastness, the possibility to prepare samples for α-spectrometry by direct evaporation of simple aliquots of aqueous or organic solutions and the influence of the presence of volatile organic diluent or tensioactive agent was investigated. Also, the influence of coating the samples with Mylar film was evaluated. The sample preparation techniques were compared based on the counting efficiency and energy resolution achieved. The performance of the selected method was tested on assessment of the efficiency of americium extraction by BTBP (bis-triazine-bipyridine) extractant.

Experimental design for the production of tensio-active agent by Candida lipolytica

The strategy of optimization using sequential factorial design was employed to enhance the tensio-active emulsifying agent produced by Candida lipolytica using soybean oil refinery residue as substrate. A full factorial design was used to evaluate the impact of three fermentation factors-amounts of refinery residue, glutamic acid and yeast extract. This allowed exclusion of the yeast extract. Full factorials designs were then sequentially used to optimize the levels of the residue and glutamic acid. The surface tension value was finally reduced to 25.29 mN/m. The maximum emulsifier activity using different substrates was within 40 h of cultivation. The surface tension of the cell-free broth containing the biosurfactant remained very stable during exposure to a wide range of pH (2-12), temperatures (0-120 degrees C) and salinity (2-10% NaCl). The combination of an industrial waste and a cheap substrate therefore seems to be very promising for the low-cost production of potent biosurfactant.

Prevalidation of in vitro continuous flow exposure systems as alternatives to in vivo inhalation safety evaluation experimentations: Outcome from MAAPHRI-PCRD5 research program

Diesel engine emission aerosol-induced toxicity patterns were compared using both in vitro (organotypic cultures of lung tissue) and in vivo experimentations mimicking the inhalation situation with continuous aerosol flow exposure designs. Using liquid media resuspended diesel particles, we show that toxic response pattern is influenced by the presence of tensioactive agent in the medium which alter particle-borne pollutant bioavailability. Using continuous aerosol exposure in vitro, we show that with high sulfur fuel (300 ppm) in the absence of oxidation catalysis, particulate matter was the main toxic component triggering DNA damage and systemic inflammation, while a very limited oxidant stress was evidenced. In contrast, with ultra-low sulfur fuel in the presence of strong diesel oxidation catalysis, the specific role of particulate matter is no longer evidenced and the gas phase then becomes the major component triggering strong oxidant stress, increased NO 2 being the most probable trigger. In vivo, plasma tumor necrosis factor alpha (TNFalpha), lung superoxide dismutase (SOD), catalase and glutathione peroxidase (GPx) activity levels varied in agreement with in vitro observations. Diesel emission treatment with oxycat provokes a marked systemic oxidant stress. Again NO 2 proved to account for a major part of these impacts. In conclusion, similar anti-oxidant responses were observed in in vitro and in vivo experiments after diesel emission aerosol continuous flow exposures. The lung slice organotypic culture model-exposed complex aerosol appears to be a very valuable alternative to in vivo inhalation toxicology experimentations in rodents.

Magnetic composite based on vinylic template

AbstractThis article presents the achievement of a magnetic composite having a vinylic polymeric structure as matrix based on a styrene/methyl methacrylate/2,3‐epoxypropyl methacrylate. The synthesis of the copolymers performed through an emulsion polymerization process was realized in the presence of potassium persulfate as radical initiator and sodium lauryl sulfate as anionic tensioactive agent. To have a network capable for a better coupling of the ferrite, the vinylic polymeric structure was crosslinked with a diamino‐compound. The magnetic composite obtainment was confirmed by the IR, DSC, and thermogravimetric analysis, as well as by optic and electronic microscopy, and also by the determination of the magnetic susceptibility of the products. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Micellar Electrokinetic Capillary Chromatography of 1,4-Benzodiazepine Derivates and their Degradation Products

The aim of this work is to elaborate a fast and reliable capillary electrophoresis method, for the separation of 1,4-benzodiazepine (BZD) derivates and their degradation products in acidic medium and in UV light. Because BZDs are neutral, hydrophobic compounds, the most efficient method proved to be micellar elektrokinetic capillary chromatography (MECC). For the separation we used a sodium tetraborate buffer with tensioactive agent (sodium dodecyl sulphate - SDS) and an organic modifier (methanol). We also optimized the analytical conditions, and studied the effects of the SDS and methanol concentrations and buffer pH on the determination efficiency.

Magnetic composites obtainment based on styrene polymers

AbstractThree styrene‐based matrices for hybrid composites with ferrite have been obtained by emulsion polymerization in the presence of a tensioactive system: sodium n‐dodecylbenzene sulfate (C12H25C6H4SO3Na) as anionic agent and poly(oxyethylene) nonylphenyl ether [C9H19C6H4(OCH2CH2)30OH] as nonionic tensioactive agent. The system assures the steadiness of the emulsion during the reaction and the stability of the latices. The surfactants act as a protective colloid component and thickening agents determining an optimum viscosity and conditions for the further catching of the inorganic oxide with magnetic properties. The obtained polystyrene and styrene copolymers with acrylamide and methacrylamide were analyzed by elemental analysis, IR spectroscopy, DSC, and their viscosity data have been characterized. The size as well as the magnetic properties of composites were also appreciated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4133–4141, 2006

Shaping and cleaning the root canal system: A scanning electron microscopic evaluation of a new instrumentation and irrigation technique

The purpose of the present scanning electron microscopic study was to investigate the efficacy of a combination of EDTA, NaOCl, and surface-active irrigating solutions during and after root canal preparation with ProFile nickel-titanium rotary instruments. Thirty canals were divided into three groups, instrumented and irrigated as follows: 5% NaOCl and a final flush with 17% EDTA were used for group A; group B specimens were irrigated using 17% EDTA, followed 15 s later by 1% TRITON X-100 (tensioactive agent) and then by 5% NaOCl; and group C specimens were irrigated with the same combination, but once shaping procedures were completed the irrigating sequence was repeated three times. After scanning electron microscopic evaluation, group C specimens exhibited the most effective debridement of the root canals. Results showed that tensioactive agent contributed to enhanced debridement. Cleaning was significantly improved once shaping procedures were completed.

Comparison of the safety profiles of PLA 50 and Me.PEG-PLA 50 nanoparticles after single dose intravenous administration to rat

We compared the safety profiles of two types of nanoparticles intravenously administered to rats, prepared from PLA 50 and Me.PEG-PLA 50 by emulsification/solvent evaporation using cholate as tensioactive agent. With PLA 50/Cholate nanoparticles, no signs of toxicity were noted at 75 mg kg −1. At higher doses, 220 and 440 mg kg −1, marked toxicity (mortality and marked clinical signs) was observed with dose-related hematological changes (decrease of thrombocytes count, increase of Prothrombine Time and Activated Partial Thromboplastin Time) and biochemical changes (increase of aminotransferases activities). All changes were transient and disappeared on Day 9. With Me.PEG-PLA 50/Cholate nanoparticles, no lethality and no clinical changes were observed after intravenous administration of Me.PEG-PLA 50/Cholate even at high dose, up to 440 mg kg −1. The improved safety profile of Me.PEG-PLA 50/Cholate nanoparticles as compared to PLA 50/Cholate nanoparticles suggests that the steric repulsion owing to the high density of Me.PEG chains on the nanoparticles surface prevents the coagulation cascade and associated toxicity.

Penetration ability of different irrigants into dentinal tubules

Dentinal tubules of human root canal walls were infected with a known bacterial isolate. The teeth were divided into two groups and the root canals instrumentated. Different types of canal irrigant were used for each group. In group A, 5% NaOCl was followed by a 10% EDTA rinse and neutralized with a final physiological solution rinse. In Group B, 10% EDTA, a tensioactive agent (TRITON), and 5% NaOCl were used in sequence, with a final physiological solution rinse to neutralize the action of the agents used. Histological examination of group A specimens showed a residual area of infection extending from the canal lumen to a mean depth of 300 microns. Histological examination of group B specimens showed an infection-free area of tubules to a mean depth of 130 microns. Below this was an infected area of variable extent. In some group B sections, no infection was found.

Enhanced oily sludge biodegradation by a tensio-active agent isolated from Pseudomonas aeruginosa USB-CS1

The biodegradation of an oily sludge is facilitated by a microbial tensio-active agent isolated from Pseudomonas aeruginosa USB-CS1. The optimal oil-in-water dispersion conditions are as follows: pH 6.5, temperature 30 °C, agitation 150 rev/min. The total hydrocarbon content shows that the biodegradation of the oily substrate mediated by the biosurfactant or by the biosurfactant–P. aeruginosa USB-CS1 complex is significantly higher after 30 days of incubation than that in other experimental conditions, by a mean of 70%. Substrate fractionation by column chromatography reveals that, if biosurfactant is present, saturated and aromatic compounds are more susceptible to microbial degradation than they are in other biodegradation systems by an average of 55% and 40% respectively. These results suggest that the stimulatory effects of the biosurfactant on the biodegradation of the oily substrate are limited over time by the loss of surface activity of the biosurfactant after 30 days of incubation.

Analysis of molybdenite bioleaching by Thiobacillus ferrooxidans in the absence of iron (II)

Thiobacillus ferrooxidans attachment on MoS2 and Mo dissolution are increased by the addition of the tensioactive agent Tween 80 in absence of iron(II), which suggests that the poor bioleaching of MoS2 is caused by its hydrophobic character. Additionally, inhibition ofThiobacillus ferrooxidans growth by the presence of MoO42− and the effect of variable amounts of Tween 80 on bacteria growth and on MoS2 bioleaching are considered in this paper. Data confirm the need of bacterial attachment to insoluble substrate for bioleaching by the direct mechanism.

Influence des ions metalliques liberes par un charbon actif sur l'adsorption de micropolluants organiques. Le role des ions calcium

Recent studies concerning the removal, by activated carbon adsorption, of natural organics or micropollutants found in water supplies, have focused attention on the ionic composition of the treated water. Many workers have demonstrated that both the ionic composition and the salt concentration affect the ability of activated carbon to remove humic substances (Randtke and Jepsen, 1982; Weber et al., 1983; Lafrance and Mazet, 1985) or organic micropollutants (Lafrance et al., 1983; Souabi et al., 1986) from solution. In particular, calcium ions have been shown to significantly increase the adsorption of organics onto activated carbon (Lafrance et al., 1983; Weber et al., 1983). Although calcium salt residues have been found on the surface of commercial activated carbon (Lafrance and Mazet, 1986), no studies have considered the effects of this cation on the adsorption of organics in batch equilibrium experiments. The purpose of the present study is to quantify the effect of calcium ion concentration on the adsorptive capacity of a powdered activated carbon (PAC) for an anionic tensio-active agent: sodium lauryl sulfate. In one series of experiments, measurements of sorption kinetics of lauryl sulfate were made using a PAC treated in three ways: (1) untreated PAC; (2) PAC washed with distilled water before use; and (3) PAC washed with HCl 1N before use. Our results (Fig. 3) show that washing the PAC before conducting an adsorption study diminishes the effectiveness of the carbon in removing lauryl sulfate. These results may be related to the surface ionic content of the PAC, especially the calcium content: the untreated PAC may contain 50 μmol Ca 2+ g −1 of carbon (Fig. 4). The PAC washed with distilled water releases 42 μmol Ca 2+ g −1 of carbon, and the PAC washed with HCl 1N releases 75 μmol Ca 2+ g −1 of carbon (Table 1). In a second series of batch experiments, the effect of micromolar concentrations of Ca 2+ on the adsorptive capacities of the PAC (treated with HCl) for lauryl sulfate was studied. Decreasing the molar ratio [lauryl sulfate]/[Ca 2+] causes an increase in the removal of the lauryl sulfate (isotherms on Figs 5 and 7, and Langmuir equilibrium parameters on Fig. 8). The influence of the order of mixing, of the adsorbates lauryl sulfate and Ca 2+ with the PAC (Table 3), is shown by the sorption kinetic curves in Fig. 6. Results indicate that the residual concentration of lauryl sulfate in solution is not affected by the order of mixing adsorbates and PAC when the molar ratio [lauryl sulfate]/[Ca 2+] is 1.0. Such results support the assumption that calciums ions specifically interact with the carbon surface in order to increase the adsorption of lauryl sulfate. The electrostatic interactions between PAC and Ca 2+, which are probably responsible for an increase in adsorption of lauryl sulfate, are examined by zeta potential measurements of the PAC. Whereas micromolar concentrations of lauryl sulfate causes a marked increase in the negative surface charges of the PAC (Figs 9 and 10), calcium ion induces a rapid neutralization of this zeta potential (Figs 10 and 11). Such neutralization of the negative functional groups of both lauryl sulfate molecules and the PAC surface is strongly related to the increase of the maximum adsorption capacity (Γ ∞) of the PAC for lauryl sulfate (Fig. 11). Batch adsorption experiments using this PAC can lead to different measures of the efficiency of the carbon for the adsorption of some organics, depending on the treatment of the PAC before and use on the release of the ionic content of the PAC. The particular role of calcium ion in the adsorption of lauryl sulfate indicates, that the carbon efficiency in removing anionic compounds can be significantly improved by the addition of micromolar quantities of salt in solution.

STRUCTURE AMD VISCDMETRIC BEHAVIOR OF GEL PHASES IN QUATERNARY SYSTEMS CONTAINING ANIONIC SURFACTANTS

ABSTRACT The homogeneous viscous phases which form by mixing sodium dodecylsulphate, butanol, toluene and water in different proportions have been characterized through viscometric measurements and optical techniques. Abrupt increases in viscosity observed in some regions of the phase diagram have been correlated to the formation of birefringent phases which exhibit non-newtonian behavior. These highly swollen mesophases are shown to be of the lamellar type by the characteristic optical textures displayed under polarizing microscope. An addition of NaCl salt to the systems, upon decreasing the solubility of the surfactant in water, tends to destroy the organized structure and give rise to a diphasic system (Winsor II). Similarly, a rise in temperature increases the relative affinity of the tensio-active agent for water, producing a transition from the lamellar phase to an isotropic newtonian phase through a two-phase coexistence region.

Solubilization of monoamine oxidase in rat liver mitochondria

The monoamineoxidase of the mitochondria of rat liver may be dissolved up to 50% of the initial activity by treatment with a tensioactive agent followed by ultracentrifugation. The best experimental conditions are obtained with 0.2% of sodium laurylsulphate (pH 7) during 1 h at + 2°C.