Polyelectrolyte Multilayers Containing Triblock Copolymers of Different Charge Ratio

Multilayers formed by the sodium salt of poly(4-styrenesulfonate), PSS, and triblock copolymers of the form PDMAEMA−PCL−PDMAEMA (PDMAEMA corresponding to poly[2-(N,N-dimethylamino)ethyl methacrylate), and PCL to poly(ε-caprolactone) have been built by layer-by-layer self-assembly from the aqueous polyelectrolyte solutions. Two types of block copolymers have been used which differ on the type of the amino groups, either hydrochloride or quaternized. This leads to changes in the charge density of the chains for the same content of amino groups. The growth of the multilayers has been followed using dissipative quartz crystal microbalance and ellipsometry techniques. The results show that, independently of the conditions used in the assembling, the film thickness grows linearly with the number of layers. The comparison of the thickness values obtained from D-QCM and ellipsometry has allowed us to calculate the water content of the polymer film. The analysis of the D-QCM data also provides the shear modulus, whose values are typical of a rubber-like polymer system. The analysis of the mass adsorbed calculated by the ellipsometric measurements indicated that the nature of the charge compensation mechanism is extrinsic for all the studied systems, although the degree of extrinsic compensation is strongly dependent on the copolymer used and the concentration in solution. Finally, it was found that the adsorption kinetic of the layers is bimodal for all the films built. Even though the characteristic adsorption times depend on the specific copolymer used, no dependence on the number of layers has been found for a given multilayer.This work was supported in part by MICINN under grants FIS2009-14008-C02-01, by CAM under grant INTERFASES S05-MAT-227, and by ESA under grant MAPAO-00-052. E.G. was supported by a FPU fellowship from MICINN. The authors are grateful to the UIRC of the CAI of Spectroscopy of Complutense University for the use of the ellipsometer

Layer-by-Layer Materials for the Fabrication of Devices with Electrochemical Applications

The construction of nanostructured materials for their application in electrochemical processes, e.g., energy storage and conversion, or sensing, has undergone a spectacular development over the last decades as a consequence of their unique properties in comparison to those of their bulk counterparts, e.g., large surface area and facilitated charge/mass transport pathways. This has driven strong research on the optimization of nanostructured materials for the fabrication of electrochemical devices, which demands techniques allowing the assembly of hybrid materials with well-controlled structures and properties. The Layer-by-Layer (LbL) method is well suited for fulfilling the requirements associated with the fabrication of devices for electrochemical applications, enabling the fabrication of nanomaterials with tunable properties that can be exploited as candidates for their application in fuel cells, batteries, electrochromic devices, solar cells, and sensors. This review provides an updated discussion of some of the most recent advances on the application of the LbL method for the fabrication of nanomaterials that can be exploited in the design of novel electrochemical devices.Depto. de Química FísicaFac. de Ciencias QuímicasTRUEUnión Europea. Horizonte 2020Ministerio de Ciencia e Innovación (MICINN)pu

Development of an Environmentally Friendly Larvicidal Formulation Based on Essential Oil Compound Blend to Control Aedes aegypti Larvae: Correlations between Physicochemical Properties and Insecticidal Activity

Oil in water (o/w) emulsions stabilized by an amphiphilic copolymer have been studied in relation to their potential insecticidal activity against Aedes aegypti mosquito larvae. These emulsions contain as oil phase different blends of two isomeric essential oil compounds, thymol and carvacrol. The results show that the addition of carvacrol facilitates the dispersion of the oil within the aqueous phase, with the stabilization and polydispersity of the emulsions being controlled by the change of the ratio between the copolymer concentration and that of the oil phase (Rcop/EOC). Emulsions containing pure essential oil compounds as oil phase do not present any significant difference on their larvicidal activity against mosquito larvae, with emulsions containing only thymol being slightly more effective than those containing only carvacrol as oil phase. Furthermore, the use of blendscontaining different weight fractions of thymol and carvacrol as oil phase results in formulations with an additive larvicidal activity in relation to those with the pure compounds. Despite the larvicidal activity of the emulsions, they do not provoke inhibition to the emergence of adult individuals in Aedes aegypti populations. The spreading and evaporation of the emulsions onto solid surface, which may be an important parameter for the performance of larvicidal formulations, was found to be dependent on the same parameters that govern the stability of the emulsions. This study helps on seeking new alternatives for the preparation of new eco-sustainable formulations against insect pest.Fil: Lucia, Alejandro. Universidad Nacional de Luján. Instituto de Ecología y Desarrollo Sustentable. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Ecología y Desarrollo Sustentable; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Agrarias y Forestales. Centro de Investigación de Sanidad Vegetal; ArgentinaFil: Girard, Clemence. École Nationale Supérieure de Chimie de Lille; FranciaFil: Fanucce, Micaela. Ministerio de Salud de la Nación; ArgentinaFil: Coviella, Carlos Eduardo. Universidad Nacional de Luján. Instituto de Ecología y Desarrollo Sustentable. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Ecología y Desarrollo Sustentable; ArgentinaFil: Rubio, Ramón G.. Universidad Complutense de Madrid. Facultad de Ciencias Químicas; EspañaFil: Ortega, Francisco. Universidad Complutense de Madrid. Facultad de Ciencias Químicas; EspañaFil: Guzmán, Eduardo. Universidad Complutense de Madrid. Facultad de Ciencias Químicas; Españ

Nanoemulsions based on thymol-eugenol mixtures: characterization, stability and larvicidal activity against Aedes aegypti

Dengue, Zika, chikungunya and yellow fever are the most important vector-borne diseases worldwide transmitted to humans by Aedes aegypti (L.) (Diptera Culicidae). Thus, the control of this vector is of vital importance in order to avoid epidemics in tropical and neo-tropical areas. To find new and effective larvicidal formulations for control programs against mosquito populations, aqueous dispersions containing thymol and eugenol were characterized and tested against Ae. aegypti larvae. The dispersion and stabilization of thymol and eugenol in water was possible using a triblock copolymer with two lateral blocks of poly(ethylene oxide) and a central block of poly(propylene oxide), the so-called poloxamer 407, which allows obtaining oil in water (o/w) emulsion. Dynamic Light Scattering (DLS) points out that emulsions containing eugenol were in most cases monodisperse with an average apparent hydrodynamic diameter of the droplets in the 20-25 nm without destabilization after 28 months from their preparation, which plays a key role for the potential application of the studied formulations. On the other side, those emulsions containing only thymol as oilphase had higher polydispersity, suggesting a central role of eugenol in the dispersion of thymol in water. Furthermore, the combined effect of thymol and eugenol against Ae. aegypti larvae was evaluated. The nanoemulsion containing thymol as main component of the oil phase (100%) showed the lowest LC50 and the introduction of eugenol to the nanoemulsions facilitated the dispersion andstability of thymol in water, even though reducing the effectiveness of the emulsions. The findings on the larvicidal effects of the combined application of the monoterpenes tested could be considered a promising contribution to the development of botanicalderived larvicidal formulations against mosquitos.Fil: Lucia, Alejandro. Universidad Nacional de Luján. Instituto de Ecología y Desarrollo Sustentable. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Ecología y Desarrollo Sustentable; ArgentinaFil: Toloza, Ariel Ceferino. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Investigación y Desarrollo Estratégico para la Defensa. Ministerio de Defensa. Unidad de Investigación y Desarrollo Estratégico para la Defensa; ArgentinaFil: Fanucce, Micaela. Dirección Nacional de Instituto de Investigación.Administración Nacional de Laboratorios e Institutos de Salud "Dr. Carlos G. Malbrán"; ArgentinaFil: Fernandez Peña, Laura. Universidad Complutense de Madrid. Facultad de Ciencias Químicas; EspañaFil: Ortega, Francisco. Universidad Complutense de Madrid. Facultad de Ciencias Químicas; EspañaFil: Rubio, Ramón G.. Universidad Complutense de Madrid. Facultad de Ciencias Químicas; EspañaFil: Coviella, Carlos Eduardo. Universidad Nacional de Luján. Instituto de Ecología y Desarrollo Sustentable. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Ecología y Desarrollo Sustentable; ArgentinaFil: Guzmán, Eduardo. Universidad Complutense de Madrid. Facultad de Ciencias Químicas; Españ

Polymorphisms in the selenoprotein S gene: lack of association with autoimmune inflammatory diseases

<p>Abstract</p> <p>Background</p> <p>Selenoprotein S (SelS) protects the functional integrity of the endoplasmic reticulum against the deleterious effects of metabolic stress. <it>SEPS1/SelS </it>polymorphisms have been involved in the increased release of pro-inflammatory cytokines interleukin (IL)-1β, tumor necrosis factor (TNF)-α and IL-6 in macrophages. We aimed at investigating the role of the <it>SEPS1 </it>variants previously associated with higher plasma levels of these cytokines and of the <it>SEPS1 </it>haplotypes in the susceptibility to develop immune-mediated diseases characterized by an inflammatory component.</p> <p>Results</p> <p>Six polymorphisms distributed through the <it>SEPS1 </it>gene (rs11327127, rs28665122, rs4965814, rs12917258, rs4965373 and rs2101171) were genotyped in more than two thousand patients suffering from type 1 diabetes, rheumatoid arthritis or inflammatory bowel diseases and 550 healthy controls included in the case-control study.</p> <p>Conclusion</p> <p>Lack of association of <it>SEPS1 </it>polymorphisms or haplotypes precludes a major role of this gene increasing predisposition to these inflammatory diseases.</p

Influence of the molecular architecture on the secondary relaxations of Poly(styrene-co-methylmethacrylate) copolymers

The processes of adsorption of grafted copolymers onto negatively charged surfaces were studied using a dissipative quartz crystal microbalance (D-QCM) and ellipsometry. The control parameters in the study of the adsorption are the existence or absence on the molecular architecture of grafted polyethyleneglycol (PEG) chains with different lengths and the chemical nature of the main chain, poly(allylamine) (PAH) or poly(L-lysine) (PLL). It was found out that the adsorption kinetics of the polymers showed a complex behavior. The total adsorbed amount depends on the architecture of the polymer chains (length of the PEG chains), on the polymer concentration and on the chemical nature of the main chain. The comparison of the thicknesses of the adsorbed layers obtained from D-QCM and from ellipsometry allowed calculation of the water content of the layers that is intimately related to the grafting length. The analysis of D-QCM results also provides information about the shear modulus of the layers, whose values have been found to be typical of a rubber-like polymer system. It is shown that the adsorption of polymers with a charged backbone is not driven exclusively by the electrostatic interactions, but the entropic contributions as a result of the trapping of water in the layer structure are of fundamental importance

PRL-3 is essentially overexpressed in primary colorectal tumours and associates with tumour aggressiveness

Phosphatase PRL-3 has been involved in different types of cancer, especially in metastases from colorectal carcinoma (CRC). In this study, we explored both isoforms of PRL-3 as a biomarker to predict the recurrence of stage IIIB-C CRC. Overexpression of PRL-3 was investigated in primary human colorectal tumours (n=20) and hepatic metastases (n=36) xenografted in nude mice, samples characterised by absence of human non-tumoral cells, showing a high degree of expression in metastases (P=0.001). In 27 cases of matched normal colonic mucosa/primary tumour/hepatic metastases, PRL-3 overexpression occurs in primary tumours vs normal mucosa (P=0.001) and in hepatic metastases vs primary tumours (P=0.045). Besides, our results in a series of 80 stage IIIB-C CRC primary tumours showed that high levels of PRL-3 were an independent predictor of metastasis (P<0.0001; OR: 9.791) in multivariate analysis of a binary logistic regression and that PRL-3 expression tightly correlates with parameters of bad outcome. Moreover, PRL-3 expression associated with poor outcome in univariate (P<0.0001) and multivariate Cox models (hazard ratio: 3.322, 95%, confidence interval: 1.405-7.852, P=0.006). In conclusion, PRL-3 is a good marker of aggressiveness of locally advanced CRS and a promising predictor of distant metastases. Nevertheless, for prognosis purposes, it is imperative to validate the cutoff value of PRL-3 expression in a larger and consecutive series and adjuvant setting