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Vesicular nanostructures composed of oleic acid and phosphatidylcholine:Effect of pH and molar ratio

K. Talló, V. Moner, M. De Cabo, M. Cócera, O. López

Chemistry and Physics of Lipids 213 (2018) 96–101

Phospholipids and fatty acids are the main building blocks of biological membranes. Oleic acid is a monounsaturated omega-9 fatty acid commonly found in many natural sources. Its characteristic kinked structure grants this molecule with a great number of biological properties. To better understand the role that this kind of fatty acids play into phospholipid membranes, nanostructured systems formed with hydrogenated soy phosphatidylcholine and oleic acid were studied in this work by means of cryo-electron microscopy, dynamic light scattering and differential scanning calorimetry. Differences concerning size, morphology and phase behavior were found when those systems were prepared at different conditions of pH and molar ratio between both compounds. Broadly, it was seen how alkaline mediums and high proportions of oleic acid reduced the size of the structures and increased the fluidity of the membranes. The ease of preparation of these lipid systems, and the response to pH suggests a future use of these systems as model membranes or delivery systems.

 

Chromonic self-assemblies in a series of dialkyl-thiacarbocyanine dyes and generalization of a facile route for the synthesis of fluorescent nanostructured silica fibers

Magana, J.R., Solans, C., Salonen, L.M., Carbó-Argibay, E., Gallo, J., Tiddy, G.J.T., Rodríguez-Abreu, C.

 Journal of the Taiwan Institute of Chemical Engineers, 2018

 In the search for new chromonic liquid crystals, we have explored the self-assembly behavior in water of a series of high-purity dialkylthiacarbocyanine dyes with different alkyl chain lengths and acetate as counterion. The dimer model was used to fit the UV–vis spectra and estimate the dissociation energy between molecules, which increases with the alkyl chain length suggesting that not only aromatic p–p interactions but also entropic/steric effects contribute to the aggregation process. NMR spectra suggest the existence of aromatic stacking interactions within the aggregates. At high concentrations, the dyes form nematic and hexagonal chromonic liquid crystals (CLC) in water within a limited range of alkyl chain lengths (ethyl to butyl); for longer lengths (pentyl) no liquid crystals were observed because of insufficient dye solubility. From small angle X-ray scattering patterns, it can be inferred that dye aggregates have cylindrical morphology with a multimolecular cross-section. The dye aggregates template the formation of silica nanofibers synthetized via sol–gel method in alkaline media. After removing excess dye, the silica/dye nanofibers showed high fluorescence emission with superb photochemical stability. The present report demonstrates a generalized route for the wet synthesis of nanostructured silica nanofibers with tunable optical properties.

 

Analysis of the neurotoxic effects of neuropathic organophosphorus compounds in adult zebrafish

Melissa Faria, Inmaculada Fuertes, Eva Prats, Jose Luis Abad, Francesc Padrós, Cristian Gomez-Canela, Josefina Casas, Jorge Estevez, Eugenio Vilanova, Benjamin Piña & Demetrio Raldúa

Scientific Reports volume 8, Article number: 4844 (2018)

 Inhibition and aging of neuropathy target esterase (NTE) by exposure to neuropathic organophosphorus compounds (OPs) can result in OP-induced delayed neuropathy (OPIDN). In the present study we aimed to build a model of OPIDN in adult zebrafish. First, inhibition and aging of zebrafish NTE activity were characterized in the brain by using the prototypic neuropathic compounds cresyl saligenin phosphate (CBDP) and diisopropylphosphorofluoridate (DFP). Our results show that, as in other animal models, zebrafish NTE is inhibited and aged by both neuropathic OPs. Then, a neuropathic concentration inhibiting NTE activity by at least 70% for at least 24 h was selected for each compound to analyze changes in phosphatidylcholines (PCs), lysophosphatidylcholines (LPCs) and glycerolphosphocholine (GPC) profiles. In spite to the strong inhibition of the NTE activity found for both compounds, only a mild increase in the LPCs level was found after 48 h of the exposure to DFP, and no effect were observed by CBDP. Moreover, histopathological evaluation and motor function outcome analyses failed to find any neurological abnormalities in the exposed fish. Thus, our results strongly suggest that zebrafish is not a suitable species for the development of an experimental model of human OPIDN.

 

Fluorescent microarray for multiplexed quantification of environmental contaminants in seawater samples

Sanchis, A., Salvador, J.-P., Campbell, K., Elliott, C.T., Shelver, W.L., Li, Q.X., Marco, M.-P.

Talanta, 184, pp. 499-506. 2018

 The development of a fluorescent multiplexed microarray platform able to detect and quantify a wide variety of pollutants in seawater is reported. The microarray platform has been manufactured by spotting 6 different bioconjugate competitors and it uses a cocktail of 6 monoclonal or polyclonal antibodies raised against important families of chemical pollutants such as triazine biocide (i.e. Irgarol 1051®), sulfonamide and chloramphenicol antibiotics, polybrominated diphenyl ether flame-retardant (PBDE, i.e. BDE-47), hormone (17ß-estradiol), and algae toxin (domoic acid). These contaminants were selected as model analytes, however, the platform developed has the potential to detect a broader group of compounds based on the cross-reactivity of the immunoreagents used. The microarray chip is able to simultaneously determine these families of contaminants directly in seawater samples reaching limits of detection close to the levels found in contaminated areas (Irgarol 1051®, 0.19?±?0,06?µg?L-1; sulfapyridine, 0.17?±?0.07?µg?L-1; chloramphenicol, 0.11?±?0.03?µg?L-1; BDE-47, 2.71?±?1.13?µg?L-1; 17ß-estradiol, 0.94?±?0.30?µg?L-1 and domoic acid, 1.71?±?0.30?µg?L-1). Performance of the multiplexed microarray chip was assessed by measuring 38 blind spiked seawater samples containing either one of these contaminants or mixtures of them. The accuracy found was very good and the coefficient of variation was

 

Direct coupling of detergent purified human mGlu5 receptor to the heterotrimeric G proteins Gq and Gs

Chady Nasrallah, Karine Rottier, Romain Marcellin, Vincent Compan, Joan Font, Amadeu Llebaria, Jean-Philippe Pin, Jean-Louis Banères & Guillaume Lebon

 Scientific Reports volume 8, Article number: 4407 (2018)

 The metabotropic glutamate (mGlu) receptors are class C G protein-coupled receptors (GPCRs) that modulate synaptic activity and plasticity throughout the mammalian brain. Signal transduction is initiated by glutamate binding to the venus flytrap domains (VFT), which initiates a conformational change that is transmitted to the conserved heptahelical domains (7TM) and results ultimately in the activation of intracellular G proteins. While both mGlu1 and mGlu5 activate Gαq G-proteins, they also increase intracellular cAMP concentration through an unknown mechanism. To study directly the G protein coupling properties of the human mGlu5 receptor homodimer, we purified the full-length receptor, which required careful optimisation of the expression, N-glycosylation and purification. We successfully purified functional mGlu5 that activated the heterotrimeric G protein Gq. The high-affinity agonist-PAM VU0424465 also activated the purified receptor in the absence of an orthosteric agonist. In addition, it was found that purified mGlu5 was capable of activating the G protein Gs either upon stimulation with VU0424465 or glutamate, although the later induced a much weaker response. Our findings provide important mechanistic insights into mGlu5 G protein-dependent activity and selectivity.

 

Cationic ionene as an n-dopant agent of poly(3,4-ethylenedioxythiophene)

Saborio, M. C.; Bertran, O.; Lanzalaco, S.; Häring, M.; Díaz, D. D.; Estrany, Francesc; Aleman, C.

Phys. Chem. Chem. Phys. 2018

We report the reduction of poly(3,4-ethylenedioxythiophene) (PEDOT) films with a cationic 1,4-diazabicyclo[2.2.2]octane-based ionene bearing N,N'-(meta-phenylene)dibenzamide linkages (mPI). Our main goal is to obtain n-doped PEDOT using a polymeric dopant agent rather than small conventional tetramethylammonium (TMA), as is usual. This has been achieved using a three-step process, which has been individually optimized: (1) preparation of p-doped (oxidized) PEDOT at a constant potential of +1.40 V in acetonitrile with LiClO4 as the electrolyte; (2) dedoping of oxidized PEDOT using a fixed potential of -1.30 V in water; and (3) redoping of dedoped PEDOT applying a reduction potential of -1.10 V in water with mPI. The resulting films display the globular appearance typically observed for PEDOT, with mPI being structured in separated phases forming nanospheres or ultrathin sheets. This organization, which has been supported by atomistic molecular dynamics simulations, resembles the nanosegregated phase distribution observed for PEDOT p-doped with poly(styrenesulfonate). Furthermore, the doping level achieved using mPI as the doping agent is comparable to that achieved using TMA, even though ionene provides distinctive properties to the conducting polymer. For example, films redoped with mPI exhibit much more hydrophilicity than the oxidized ones, whereas films redoped with TMA are hydrophobic. Similarly, films redoped with mPI exhibit the highest thermal stability, while those redoped with TMA show thermal stability that is intermediate between those of the latter and the dedoped PEDOT. Overall, the incorporation of an mPI polycation as the n-dopant into PEDOT has important advantages for modulating the properties of this emblematic conducting polymer.

 

Formaldehyde scavengers for cleaner production: A case study focused on the leather industry

Marsal, A., Cuadros, S., Ollé, L., Bacardit, A., Manich, A.M., Font, J.

Journal of Cleaner Production, 186, pp. 45-56. 2018

 Due to its carcinogenic character, the presence of formaldehyde in leather continues to be a subject of great concern. By using formaldehyde scavengers, it is possible to reduce the formaldehyde content in leather. In this work, the potential ability of three different compounds (ethylene urea, pyrogallol and gallic acid) to reduce the formaldehyde content in splits leathers treated with formaldehyde resins (melamine-formaldehyde and dicyandiamide-formaldehyde) is assessed. This capacity is compared with that of a fourth scavenger (hydroxylamine sulphate) already used in tanneries. The evolution of the formaldehyde content with time is also considered, as well as the potential coadjuvant effect of other compounds such as mimosa extract and an acid dye (Acid Black 234). Hydroxylamine sulphate initially showed the highest ability to reduce formaldehyde content. However, after a certain time, this ability proved to be inferior to the ability of other compounds due to the reversibility of the reaction between hydroxylamine and formaldehyde. Pyrogallol showed a higher ability than gallic acid when used in the final wash of leather processing. However, the treatment with pyrogallol results in a darkening of the leather; this darkening limits its use. Gallic acid may be a good alternative to formic acid as the final fixing agent in leather processing when the presence of formaldehyde in leathers is suspected. The use of gallic acid in the final wash or as a fixing agent fulfils the formaldehyde content limit (65–75?mg/kg) of the major brands in leather goods in direct contact with the skin. The addition of 2% of gallic acid in the final wash of leather processing resulted in formaldehyde content reductions that varied from 65% to 85%. However, further experiments are required to assess the influence of gallic acid on the fastness properties and the coloration acquired by the treated leathers. The joint effect of gallic acid in the final wash or as a fixing agent and mimosa extract as a retanning agent in formaldehyde content reduction is even enhanced by subsequently using a dye with amino groups in its chemical structure. Reducing the formaldehyde content by using scavengers can contribute to the achievement of a cleaner production in those sectors (leather, textile, wood) that use formaldehyde resins.

 

Glucose-nucleobase pairs within DNA: Impact of hydrophobicity, alternative linking unit and DNA polymerase nucleotide insertion studies

Vengut-Climent, E., Peñalver, P., Lucas, R., Gómez-Pinto, I., Aviñó, A., Muro-Pastor, A.M., Galbis, E., De Paz, M.V., Fonseca Guerra, C., Bickelhaupt, F.M., Eritja, R., González, C., Morales, J.C.

Chemical Science, 9 (14), pp. 3544-3554. 2018

Recently, we studied glucose-nucleobase pairs, a binding motif found in aminoglycoside–RNA recognition. DNA duplexes with glucose as a nucleobase were able to hybridize and were selective for purines. They were less stable than natural DNA but still fit well on regular B-DNA. These results opened up the possible use of glucose as a non-aromatic DNA base mimic. Here, we have studied the incorporation and thermal stability of glucose with different types of anchoring units and alternative apolar sugar-nucleobase pairs. When we explored butanetriol instead of glycerol as a wider anchoring unit, we did not gain duplex thermal stability. This result confirmed the necessity of a more conformationally restricted linker to increase the overall duplex stability. Permethylated glucose-nucleobase pairs showed similar stability to glucoside-nucleobase pairs but no selectivity for a specific nucleobase, possibly due to the absence of hydrogen bonds between them. The three-dimensional structure of the duplex solved by NMR located both, the hydrophobic permethylated glucose and the nucleobase, inside the DNA helix as in the case of glucose-nucleobase pairs. Quantum chemical calculations on glucose-nucleobase pairs indicate that the attachment of the sugar to the DNA skeleton through the OH1 or OH4 positions yields the highest binding energies. Moreover, glucose was very selective for guanine when attached through OH1 or OH4 to the DNA. Finally, we examined DNA polymerase insertion of nucleotides in front of the saccharide unit. KF- polymerase from E. coli inserted A and G opposite glc and 6dglc with low efficiency but notable selectivity. It is even capable of extending the new pair although its efficiency depended on the DNA sequence. In contrast, Bst 2.0, SIII and BIOTAQ™ DNA polymerases seem to display a loop-out mechanism possibly due to the flexible glycerol linker used instead of deoxyribose.

 

Influence of process variables in a continuous treatment of non-sterile hospital wastewater by Trametes versicolor and novel method for inoculum production

Mir-Tutusaus, J.A., Caminal, G., Sarrà, M.

 Journal of Environmental Management, 212, pp. 415-423, 2018

 Micropollutants such as pharmaceutical active compounds, present at high concentration in hospital wastewater (HWW), pose both environmental and human health challenges. Fungal reactors can effectively remove such contaminants and produce non-toxic effluents, but their ability to operate for a long period of time is yet to be demonstrated in real hospital wastewater. Several process variables need to be studied beforehand. Here, variables: pellet size, aeration and carbon-to-nitrogen ratio are studied in continuous operations with real HWW. Moreover, a novel strategy for inoculum production that could reduce economical and operational costs is proposed and tested. Optimum pellet size was found to be 2?mm and an aeration of 0.8?L?min-1 was needed to maintain fungal viability. The carbon-to-nitrogen ratio of 7.5 was selected and the pellet production time was reduced from 6 to 3 days. The novel low-cost inoculum preparation produced pellets with the same characteristics as the traditionally prepared ones.

 
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