Two-Dimensional Titanium Dioxide-Surfactant Photoactive Supramolecular Networks: Synthesis, Properties, and Applications for the Conversion of Light Energy.

The desire to harness solar energy to address current global environmental problems led us to investigate two-dimensional (2D) core-shell hybrid photocatalysts in the form of a 2D-TiO2-surfactant, mainly composed of fatty acids. The bulk products, prepared by two slightly different methods, consist of stacked host-guest hybrid sheets held together by van der Waals forces between alkyl carboxylate moieties, favoring the synergistic conjugation of the photophysical properties of the core and the hydrophobicity of the self-assembled surfactant monolayer of the shell. X-ray diffraction and the vibrational characteristics of the products revealed the influence of synthesis strategies on two types of supramolecular aggregates that differ in the core chemical structure, guest conformers of alkyl surfactant tails and type, and the bilayer and monolayer of the structure of nanocomposites. The singular ability of the TiO2 core to anchor carboxylate leads to commensurate hybrids, in contrast to both layered clay and layered double-hydroxide-based ion exchangers which have been previously reported, making them potentially interesting for modeling the role of fatty acids and lipids in bio-systems. The optical properties and photocatalytic activity of the products, mainly in composites with smaller bandgap semiconductors, are qualitatively similar to those of nanostructured TiO2 but improve their photoresponse due to bandgap shifts and the extreme aspect-ratio characteristics of two-dimensional TiO2 confinement. These results could be seen as a proof-of-concept of the potential of these materials to create custom-designed 2D-TiO2-surfactant supramolecular photocatalysts.

Concomitant Antihyperalgesic and Antitumor Effects of Gabapentin in a Murine Cancer Pain Model.

Cancer pain may be the consequence of physical nerve compression by a growing tumor. We employed a murine model to study whether gabapentin was able to regulate tumor growth, in addition to controlling hyperalgesic symptoms. A fluorescent melanoma cell line (B16-BL6/Zs green) was inoculated into the proximity of the sciatic nerve in male C57BL/6 mice. The tumor gradually compressed the nerve, causing hypersensitivity. Tumor growth was characterized via in vivo imaging techniques. Every other day, gabapentin (100 mg/Kg) or saline was IP administered to each animal. In the therapeutic protocol, gabapentin was administered once the tumor had induced increased nociception. In the preventive protocol, gabapentin was administered before the appearance of the positive signs. Additionally, in vitro experiments were performed to determine gabapentin's effects on cell-line proliferation, the secretion of the chemokine CCL2, and calcium influx. In the therapeutically treated animals, baseline responses to noxious stimuli were recovered, and tumors were significantly reduced. Similarly, gabapentin reduced tumor growth during the preventive treatment, but a relapse was noticed when the administration stopped. Gabapentin also inhibited cell proliferation, the secretion of CCL2, and calcium influx. These results suggest that gabapentin might represent a multivalent strategy to control cancer-associated events in painful tumors.

ZnO nucleation into trititanate nanotubes by ALD equipment techniques, a new way to functionalize layered metal oxides.

In this contribution, we explore the potential of atomic layer deposition (ALD) techniques for developing new semiconductor metal oxide composites. Specifically, we investigate the functionalization of multi-wall trititanate nanotubes, H2Ti3O7 NTs (sample T1) with zinc oxide employing two different ALD approaches: vapor phase metalation (VPM) using diethylzinc (Zn(C2H5)2, DEZ) as a unique ALD precursor, and multiple pulsed vapor phase infiltration (MPI) using DEZ and water as precursors. We obtained two different types of tubular H2Ti3O7 species containing ZnO in their structures. Multi-wall trititanate nanotubes with ZnO intercalated inside the tube wall sheets were the main products from the VPM infiltration (sample T2). On the other hand, MPI (sample T3) principally leads to single-wall nanotubes with a ZnO hierarchical bi-modal functionalization, thin film coating, and surface decorated with ZnO particles. The products were mainly characterized by electron microscopy, energy dispersive X-ray, powder X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. An initial evaluation of the optical characteristics of the products demonstrated that they behaved as semiconductors. The IR study revealed the role of water, endogenous and/or exogenous, in determining the structure and properties of the products. The results confirm that ALD is a versatile tool, promising for developing tailor-made semiconductor materials.

Dolor y malestar: un ejemplo experimental de interacción neuro-inmune / Pain and sickness: an experimental example of neuro-immune interaction

Bajo la definición de malestar general se agrupan una constelación de signos y síntomas tales como fiebre, disminución de la actividad, pérdida del apetito, disminución de la libido, trastornos del sueño y modificaciones en el umbral del dolor, entre otros. Estas manifestaciones son necesarias para hacer frente a procesos infecciosos y son iniciadas por el sistema inmunitario y controladas por el sistema nervioso, por lo que representan un ejemplo ideal de interacción entre ambos componentes. En el presente estudio se analizaron los cambios conductuales inducidos en el umbral del dolor luego de la administración i.p. de lipopolisacárido (LPS), una endotoxina que forma parte de la pared de bacterias gram negativas. Adicionalmente, se determinaron los cambios que ocurren en los patrones de descarga de dos poblaciones de neuronas de la formación reticular bulbar, las células “off” y “on”, luego de la administración de la endotoxina. Estas células aparentemente constituyen los brazos ejecutores del sistema de modulación endógena del dolor. Los resultados obtenidos indican que dependiendo de la dosis de LPS empleada (100 o 200 μg/kg) se pueden activar diferentes mecanismos de modulación, que a su vez parecen depender de las dos poblaciones de neuronas bulbares. La dosis de 100 μg/kg de LPS produjo antinocicepción, la cual estuvo asociada a incrementos en la actividad de las células “off” y a la disminución de la actividad de las “on”. La dosis de 200 μg/kg de LPS produjo hiperalgesia, la cual se acompañó de una disminución de la actividad de las celulas off”y un aumento en la actividad de las células on.

The definition of sickness/illness behavior involves a constellation of signs and symptoms such as fever, decrease of physical activity, anorexia, decrease of libido, insomnia and changes of the pain threshold, among others. These manifestations are necessary to face infectious processes and are apparently initiated and controlled by the immune and the nervous system, so that they represent an ideal example of interaction between both components. In the present study the behavioral changes in the pain threshold induced by the i.p. administration of lipopolysaccharide, an endotoxin derived from gram-negative bacterial cell walls, were analyzed. Additionally, changes in the discharge pattern of two neuronal populations of the medullary reticular formation, the off- and on-cells, which apparently act as the executory arm of the endogenous pain modulatory system were determined after endotoxin administration. The results indicate that depending on the LPS dose (100 or 200 μg/kg) different modulatory mechanisms might be activated, which in turn seem to be the consequence of the activation of the two different classes of medullary neurons. Antinociception was produced after administration of 100 μg/kg of LPS. That was associated to an increase of the off-cell firing and a reduction of the on-cell activity. Hyperalgesia was produced after administration of 200 μg/kg of LPS. That effect was accompanied by an inhibition of the off-cell activity and an increase of the on-cell firing. These findings suggest that changes of the pain threshold that occur during sickness/illness involve the differential participation of the two control options of the endogenous pain modulatory system and of specialized mechanisms of communication between the immune and the nervous system.