Removal of nonionic surfactants from municipal wastewater using a constructed wetland with a horizontal subsurface flow was studied in 2009 and 2010. Extraction spectrophotometry with 3',3″,5',5″-tetrabromophenolphthalein ethyl ester and KCl served to determine the analyte concentrations. Triton(®) X-100 was used as a standard to express the nonionic-surfactant concentrations. Anionic and cationic surfactants were shown not to interfere during the determination. Nonionic surfactants were degraded (to products undeterminable by the method) with a high average efficiency that reached 98.1% in 2009 and 99.1% in 2010, respectively. The average concentration of nonionic surfactants at the inflow was 0.978 mg/l, while it was close to the limit of quantification at the outflow (0.014 mg/l). A significant fraction of nonionic surfactants (38.7%) was already degraded during the pretreatment, and only 14.0% of the nonionic surfactants remained in the interstitial H(2) O taken in the vegetation bed at a distance of 1 m from the inflow zone at a 50-cm depth. Nonionic surfactants were degraded both under aerobic and anaerobic conditions.
- MeSH
- Water Purification methods MeSH
- Wetlands MeSH
- Octoxynol isolation & purification MeSH
- Surface-Active Agents chemistry isolation & purification MeSH
- Environmental Restoration and Remediation methods MeSH
- Rhizosphere MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
The effect of ionic surfactants and manufacturing methods on the separation and distribution of multi-wall carbon nanotubes (CNTs) in a silicone matrix are investigated. The CNTs are dispersed in an aqueous solution of the anionic surfactant dodecylbenzene sulfonic acid (DBSA), the cationic surfactant cetyltrimethylammonium bromide (CTAB), and in a DBSA/CTAB surfactant mixture. Four types of CNT-based composites of various concentrations from 0 to 6 vol.% are prepared by simple mechanical mixing and sonication. The morphology, electrical and thermal conductivity of the CNT-based composites are analyzed. The incorporation of both neat and modified CNTs leads to an increase in electrical and thermal conductivity. The dependence of DC conductivity versus CNT concentration shows percolation behaviour with a percolation threshold of about 2 vol.% in composites with neat CNT. The modification of CNTs by DBSA increases the percolation threshold to 4 vol.% due to the isolation/separation of individual CNTs. This, in turn, results in a significant decrease in the complex permittivity of CNT–DBSA-based composites. In contrast to the percolation behaviour of DC conductivity, the concentration dependence of thermal conductivity exhibits a linear dependence, the thermal conductivity of composites with modified CNTs being lower than that of composites with neat CNTs. All these results provide evidence that the modification of CNTs by DBSA followed by sonication allows one to produce composites with high homogeneity.
- MeSH
- Benzenesulfonates chemistry MeSH
- Cetrimonium Compounds chemistry MeSH
- Electric Conductivity * MeSH
- Dielectric Spectroscopy MeSH
- Nanocomposites chemistry ultrastructure MeSH
- Nanotubes, Carbon chemistry ultrastructure MeSH
- Surface-Active Agents chemistry MeSH
- Silicone Elastomers chemistry MeSH
- Thermal Conductivity * MeSH
- Thermogravimetry MeSH
- Sonication MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
The liver of anurans play an important role in metabolism, including detoxification, the biotransformation of molecules, and the storage of metabolites. Surfactants are part of domestic and industrial effluents. The effects of linear alkylbenzene sulfonate (LAS) on anuran liver remain unknown, however, some studies have evaluated the effects of LAS on the skin, gills, heart, testes, and liver of fishes. Here, we tested the hypothesis that LAS is hepatotoxic, promoting morphometric alterations in hepatocytes along with inflammation in the tissue, altering hepatic catabolism. We evaluated the effects of a LAS concentration that is considered environmentally safe in Brazilian inland waters on the liver of Lithobates catesbeianus tadpoles, including studies on morphology, morphometry, immunology, and metabolism. LAS exposure promoted enlargement of liver sinusoids and vacuolization of hepatocytes. Exposure to LAS also increased the area of mast cells and melanomacrophages (MMs). Additionally, LAS exposure increased hemosiderin inside MMs, suggesting alterations in the catabolism and storage of iron. Hepatocyte size increased after exposure to LAS, suggesting cytotoxic effects. Integrative analyses (i.e., morphometric, metabolic, and immunological) demonstrated hepatotoxic effects of LAS. These types of studies are key to understanding the negative effects of these substances on tadpole health, as these liver alterations impair anuran homeostasis.
- MeSH
- Alkanesulfonic Acids * toxicity MeSH
- Larva MeSH
- Chemical and Drug Induced Liver Injury * MeSH
- Surface-Active Agents toxicity MeSH
- Rana catesbeiana MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Geographicals
- Brazil MeSH
Surfactant protein B (SP-B) is essential in transferring surface-active phospholipids from membrane-based surfactant complexes into the alveolar air-liquid interface. This allows maintaining the mechanical stability of the surfactant film under high pressure at the end of expiration; therefore, SP-B is crucial in lung function. Despite its necessity, the structure and the mechanism of lipid transfer by SP-B have remained poorly characterized. Earlier, we proposed higher-order oligomerization of SP-B into ring-like supramolecular assemblies. In the present work, we used coarse-grained molecular dynamics simulations to elucidate how the ring-like oligomeric structure of SP-B determines its membrane binding and lipid transfer. In particular, we explored how SP-B interacts with specific surfactant lipids, and how consequently SP-B reorganizes its lipid environment to modulate the pulmonary surfactant structure and function. Based on these studies, there are specific lipid-protein interactions leading to perturbation and reorganization of pulmonary surfactant layers. Especially, we found compelling evidence that anionic phospholipids and cholesterol are needed or even crucial in the membrane binding and lipid transfer function of SP-B. Also, on the basis of the simulations, larger oligomers of SP-B catalyze lipid transfer between adjacent surfactant layers. Better understanding of the molecular mechanism of SP-B will help in the design of therapeutic SP-B-based preparations and novel treatments for fatal respiratory complications, such as the acute respiratory distress syndrome.
- MeSH
- Phospholipids chemistry MeSH
- Protein Conformation MeSH
- Lipid Bilayers chemistry metabolism MeSH
- Models, Molecular MeSH
- Protein Multimerization MeSH
- Pulmonary Surfactants chemistry MeSH
- Pulmonary Surfactant-Associated Protein B chemistry metabolism MeSH
- Molecular Dynamics Simulation MeSH
- Binding Sites MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Mitochondria-targeting peptides represent an emergent tool for cancer inhibition. Here supramolecular assemblies of novel amphiphilic cell-penetrating peptides for targeting cancer cell mitochondria are reported. The employed strategy aims at amplifying the apoptotic stimuli by weakening the mitochondrial VDAC1 (voltage-dependent anion channel-1)-hexokinase-II (HK-II) interaction. Peptide engineering is performed with the N-terminus of the HK-II protein, which binds to VDAC1. First, a designed positively charged segment (pKV) is anchored to the specific 15 amino acid sequence (MIASHLLAYFFTELN) to yield a cell-penetrating peptide (pHK-pKV). Second, a lipid chain (Pal) is conjugated to the N-terminus of pHK-pKV in order to enhance the intracellular delivery of the HK-II scaffold. The self-assembly properties of these two synthetic peptides are investigated by synchrotron small-angle X-ray scattering (BioSAXS) and cryogenic transmission electron (cryo-TEM) imaging, which evidence the formation of nanoassemblies of ellipsoid-like shapes. Circular dichroism (CD) spectroscopy demonstrates the induction of partial α-helical structures in the amphiphilic peptides. Confocal microscopy reveals the specific mitochondrial location of Pal-pHK-pKV assemblies in human non-small cell lung cancer (NSCLC) A549 cells. The cytotoxicity and apoptotic studies indicate the enhanced bioactivity of Pal-pHK-pKV self-assembled reservoirs, which cause massive A549 cell death with regard to pHK-pKV. Of significance, Pal-pHK-pKV treatment of non-cancerous NCM460 cells resulted in substantially lower cytotoxicity. The results demonstrate the potential of self-assembled lipo-peptide (HK-II-derived) conjugates as a promising strategy in cancer therapy.
- MeSH
- Cell Death drug effects MeSH
- A549 Cells MeSH
- Hexokinase metabolism MeSH
- Drug Delivery Systems methods MeSH
- Humans MeSH
- Lipids chemistry MeSH
- Lipopeptides chemical synthesis therapeutic use MeSH
- Mitochondria metabolism MeSH
- Lung Neoplasms drug therapy pathology MeSH
- Voltage-Dependent Anion Channel 1 metabolism MeSH
- Cell-Penetrating Peptides chemical synthesis metabolism MeSH
- Surface-Active Agents metabolism MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
The values of CMC (critical micellar concentration) for buffered surfactant solutions used in separation methods in analytical chemistry, especially in micellar electrokinetic capillary chromatography, were studied by conductivity, surface tension and viscosity measurements. The study involved solutions of representative anionic (SDS), cationic (CTAB), and non-ionic (TX100, GX080) surfactants. The data measured for aqueous solutions were in good agreement with the published data. The data for buffer solutions confirmed theoretical presumptions ? the CMC values decreased with increasing ionic strength of the solutions. In contrast, viscoelastic properties of the solutions of surfactants were not significantly influenced by the ionic strength or pH of the solutions.
Degradation of anionic and nonionic surfactants in a constructed wetland with horizontal subsurface flow was studied using high performance liquid chromatography and extraction spectrophotometry. The ratio of individual homologues of linear alkylbenzene sulfonates (LAS) and the efficiency of their removal were studied. Tridecyl-, dodecyl-, undecyl-, and decylbenzene sulfonates were removed with efficiencies of 92.9%, 84.3%, 64.7%, and 41.1%, respectively. These differences are due to sequential shortening of the alkyl chain in homologues during degradation (the higher homologue can provide the lower one). The formation of sulfophenyl carboxylic acids during ω-oxidation of the alkyl chain followed by successive α- and/or β-oxidation is also a possible mechanism for removal of LAS. Solid phase extraction using Chromabond® HR-P columns was used for preconcentration of the analytes prior to their determination by HPLC. Methylene blue active compounds were determined using extraction spectrophotometry. The average efficiency of their removal was 84.9% in this case. The efficiency of nonionic surfactant removal (98.2%) was significantly higher in comparison to that for anionic surfactants. The concentration of the endocrine disruptor nonylphenol (a product of nonylphenol polyethoxylate surfactant degradation) determined in the profile of the wetland was beneath the limit of detection (0.4 μg/L). The average outflow concentrations of anionic and nonionic surfactants determined by spectrophotometry were 0.54 and 0.021 mg/L, respectively. The average outflow concentrations of decyl- and tridecylbenzene sulfonates determined by HPLC were 0.195 and 0.015 mg/L. Efficiencies of 86.4% and 92.2% were obtained for removal of organic compounds as indicated by chemical and biochemical oxygen demand (COD(Cr) and BOD(5)). These results demonstrate the suitability of the constructed wetland for degrading surface-active compounds.
In this study, culture supernatnats of Bacillus subtilis T-1 growing on brewery effluents and molasses was used for silver nanoparticles (Ag-NPs) synthesis. The biosurfactant production of B. subtilis T-1 was confirmed by the detection of genes in the genome and by the identification of the product in the supernatants. The genes for synthesis of surfactin (sfp, srfAA) and iturin (ituC) were noted by PCR reactions. Also, in examined culture supernatants the presence of C13, C14 and C15 surfactin homologues with the sodiated molecules [M + Na](+) at m/z 1030, 1044 and 1058 was confirmed using LC/MS/MS analysis. The formation of NPs in the culture supernatants was confirmed by UV-vis spectroscopy. The dynamic light scattering measurements and transmission electron microscopy images showed the nanometric sizes of the biosynthesised Ag-NPs which ranged from several nm to several tens of nm depending on the used culture supernatant. Biological properties of Ag-NPs were evaluated by binding of Ag-NPs with DNA isolated from the Escherichia coli ATCC 25922 and B. subtilis ATCC 6633. Biogenic Ag-NPs were actively bound to DNA in increased concentration which could be the one important mode of antibacterial action of the Ag-NPs.
- MeSH
- Bacillus subtilis genetics growth & development metabolism MeSH
- Peptides, Cyclic genetics isolation & purification metabolism MeSH
- Metal Nanoparticles chemistry MeSH
- Lipopeptides genetics isolation & purification metabolism MeSH
- Molasses microbiology MeSH
- Surface-Active Agents chemistry isolation & purification metabolism MeSH
- Industrial Waste * MeSH
- Silver chemistry metabolism MeSH
- Tandem Mass Spectrometry MeSH
- Microscopy, Electron, Transmission MeSH
- Particle Size MeSH
- Agriculture MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
