Galactose:PEGamine coated gold nanoparticles adhere to filopodia and cause extrinsic apoptosis

Ultra-small gold nanoparticles, surface functionalised with a 50:50 ratio of a thiolated α-Galactose derivative and a thiolated hexaethylene glycol amine, are toxic to HSC-3 oral squamous carcinoma cells. Differences in nanoparticle toxicity were found to be related to synthesis duration, with 1 h reaction nanoparticles being less toxic than 5 h reaction nanoparticles. Ligand density decreased with longer reaction time, although size, charge and ligand ratio remained similar. The concentration of sodium borohydride in the reaction decreased logarithmically over 5 h but remained within a concentration range sufficient to desorb weakly-bound ligands, possibly explaining the observed gradual decrease in ligand density. Nanoparticle toxicity was abrogated by inhibition of either caspase 3/7 or caspase 8, but not by inhibition of caspase 9, consistent with extrinsic apoptosis. Electron microscopic analysis of cellular uptake demonstrated predominantly cytoplasmic localization. However, when energy-dependent transport was inhibited, by lowering the temperature to 4ºC, a remarkable adhesion of nanoparticles to filopodia was observed. Inhibition of filopodial assembly with a fascin inhibitor prevented nanoparticle adhesion to HSC-3 cells at 4ºC, while fascin inhibition at 37ºC resulted in less cytoplasmic uptake. More adhesion to HSC-3 filopodia was seen with the higher toxicity 5 h reaction time nanoparticles than with the 1 h nanoparticles. By including a further two cell types (HaCaT keratinocytes and hCMEC/D3 endothelial cells), a pattern of increasing toxicity with filopodial binding of 5 h reaction nanoparticles became apparent

Shape memory epoxy vitrimers based on DGEBA crosslinked with dicarboxylic acids and their blends with citric acid

Thermosetting polymers were synthesized from a commercial epoxy resin (diglycidyl ether of bisphenol A, DGEBA) and tricarboxylic (citric, CA) and different dicarboxylic (sebacic, SA and glutaric, GA) acids. Crosslinking of DGEBA-SA and DGEBA-GA systems was achieved using excess epoxy, which was homopolymerized after all the acid groups were consumed. It was found that the properties of the material depend on the diacid length and on the excess epoxy, and with the proper formulation, vitrimers with Tg values ranging from 51 °C to 62 °C, and a high rate of stress relaxation (less than 1 h at 160 °C to achieve 63% of relaxation) could be obtained. Notably, using a mixture of tri-functional CA with SA allowed a reduction in the epoxy excess while maintaining a high Tg value and faster stress relaxation. Three of the formulations were selected and their shape memory performance was studied. Good shape fixity and shape recovery ratios (>99%) were obtained, which indicate an overall good shape memory performance. These properties can be used to create different permanent and temporary shapes on a thermosetting polymer obtained from widely available and affordable raw materials.Fil: Altuna, Facundo Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Hoppe, Cristina Elena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Williams, Roberto Juan Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin

Nanomateriales creados en la Argentina

En los últimos años se han fabricado computadoras más rápidas, pantallas más delgadas, más brillantes y más livianas, motores más eficientes. Alcanza con mirar a nuestro alrededor para darnos cuenta de que nos encontramos rodeados por objetos que han cambiado nuestras vidas. Están hechos de gran diversidad de materiales, generados por técnicas basadas en avances del conocimiento de la física y la química de la materia. También se han puesto a punto en tiempos recientes nuevos métodos de diagnóstico y tratamiento de enfermedades, de recuperación de ambientes contaminados y de generación y almacenamiento de energía. Muchos de esos notables progresos tecnológicos han sido posibles gracias al desarrollo reciente de los nanomateriales. El objetivo de este artículo es discutir qué son y para qué sirven, y dar ejemplos de algunos que fueron elaborados en la Argentina para cumplir determinadas funciones.Fil: Hoppe, Cristina Elena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigación en Ciencia y Tecnología de Materiales (i); Argentina. Universidad Nacional de Mar del Plata. Facultad de Ingeniería; ArgentinaFil: Williams, Federico Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentin

Epoxy vitrimers: The effect of transesterification reactions on the network structure

Vitrimers are covalently crosslinked polymers that behave as conventional thermosets below the glass transition temperature (Tg) but can flow above a particular temperature, Tv > Tg, by bond exchange reactions. In epoxy vitrimers, transesterification reactions are responsible for their behavior at T > Tv that enables flow, thermoforming, recycling, self-healing and stress relaxation. A statistical analysis based on the fragment approach was performed to analyze the evolution of the network structure of epoxy vitrimers during transesterification reactions. An analytical solution was obtained for a formulation based on a diepoxide and a dicarboxylic acid. A numerical solution was derived for the reaction of a diepoxide with a tricarboxylic acid, as an example of the way to apply the model to polyfunctional monomers. As transesterification acts as a disproportionation reaction that converts two linear fragments (monoesters) into a terminal fragment (glycol) and a branching fragment (diester), its effect on network structure is to increase the concentration of crosslinks and pendant chains while leaving a sol fraction. Changes in the network structure of the epoxy vitrimer can take place after their synthesis, during their use at high temperatures, a fact that has to be considered in their technological applications.Fil: Altuna, Facundo Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Hoppe, Cristina Elena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Williams, Roberto Juan Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin

Elastomers obtained by crosslinking of α,ω-bis(glycidylether) poly(dimethylsiloxane) as versatile platforms for functional materials

Elastomers with an interesting set of properties were synthesized by crosslinking α,ω-bis(glycidylether)poly(dimethylsiloxane,PDMS), using two different strategies. The first one was the anionic homopolymerization of terminal epoxy groups initiated by 4-dimethylaminopyridine (DMAP); the second strategy was the crosslinking with a polyoxypropylenediamine (Jeffamine D2000). Reaction conditions were selected to achieve complete conversion of epoxy groups. Resulting soft elastomers (PDMS-Homop and PDMS-D2000) were transparent materials with gel fractions higher 95%. PDMS-D2000 exhibited an outstanding damping capacity (maximum tan δ > 2) in a temperature range located between −50 °C and −75 °C, assigned to a high viscous dissipation during the relaxation of polyoxypropylene blocks. PDMS-Homop showed also good damping properties in a broader low-temperature range. A significant property of both elastomers was the capacity to re-organize their nanostructures, as shown by SAXS spectra and contact angle measurements, in response to the hydrophilic or hydrophobic nature of the liquid in contact. Hydroxyl groups present in the chemical structure of PDMS-D2000 could be used as reducing agents for the in situ generation of gold nanoparticles from an infused Au(III) compound. The synthesis was also performed using a sacrificial template to provide macroporosity to the resulting materials. These macroporous elastomers were used to remove organic components from water. Magnetic nanoparticles were infused and stabilized inside the macroporous structure to allow magnetic separation of the materials after use.Fil: Gonzalez, Jimena Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Hoppe, Cristina Elena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Williams, Roberto Juan Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin

Extrapulmonary Tuberculosis among Somalis in Minnesota1

To analyze extrapulmonary tuberculosis in Somalis living in Minnesota, we reviewed surveillance and public health case management data on tuberculosis cases in ethnic Somalis in Minnesota from 1993 through 2003. The presence of these recent immigrants substantially affects the local epidemiology and clinical manifestation of tuberculosis

Cannabidiol (CBD) Skincare on Instagram

Background: Cannabidiol (CBD), a non-psychoactive component of cannabis, has emerged as a popular ingredient in skincare products. However, there is limited evidence on the benefits, efficacy, and safety of CBD for skincare. Despite this, CBD is widely endorsed on social media, specifically Instagram. With more than one billion active users and a heavy presence of “influencers”, Instagram is powerful source of health and beauty information. Purpose: This study uses content analysis to examine how CBD skincare products are portrayed on Instagram. Methods: In 2019, using the search terms “CBD skincare” and “CBD skin”, researchers sampled every third post from the top 1000 posts to collect 205 relevant posts. A codebook was developed, pilot tested, and used to code posts. Results: Of the sample, the majority (77%) positively portrayed CBD skincare with appearance-related claims including moisturizing (31%), inflammation reduction (14%), and acne prevention (11%). Twenty-two percent of posts claimed that CBD skincare product performed better than other commercial products. There were high levels of engagement with posts having an average of 66 comments and more than 1500 likes and half of the posts (51%) mentioned a product was gifted to the Instagram influencer – in other words, they were given the product or paid in exchange for sharing. Conclusions: Social media is a powerful source of health information. Instagram portrays CBD as an effective skincare option, however, there is evidence of unsupported claims being shared

Remote actuation of epoxy nanocomposites with functional properties

Las redes epoxi son una familia de compuestos con uso extensivo en aplicaciones tales comorecubrimientos, adhesivos y materiales compuestos avanzados. Exhiben diferentes propiedadesfuncionales tales como la capacidad de modificar su forma en respuesta a estímulos externos (epoxi conmemoria de forma o SME por sus siglas en inglés), o su capacidad para intercambiar segmentos en suestructura química cuando se calientan a temperaturas superiores a la temperatura crítica (vitrímerosepoxi o EV). Los vitrímeros constituyen uno de los descubrimientos más importantes en el campo de lospolímeros de los últimos años. Se comportan de diferente manera según se varíe la temperatura porencima o debajo de la temperatura crítica. Por encima de la misma pueden fluir e intercambiar segmentosde cadenas elásticas sin modificar la densidad de entrecruzamiento.Epoxy networks are one of the most important families of thermosetting polymers with an extensive use as adhesives, coatings and matrices of advanced composites. In recent years, smart materials based on epoxy formulations were developed. They exhibit different functional properties such as the capacity of modifying their shapes in response to an external stimulus (shape-memory epoxies, SME) or the capacity of interchanging segments of their chemical structures when heated above a critical temperature (epoxy vitrimers, EV). Vitrimers are one of the most important recent discoveries in the field of polymers. They behave as conventional thermosets below the critical temperature but they can flow at higher temperatures interchanging segments of elastic chains while keeping a constant crosslink density. This enables their self-healing, recycling and welding as well as the relaxation of strained chains. SME and EV are activated by adequate heating/cooling cycles. Incorporation of specific nanoparticles (NPs) capable of converting IR or visible light radiation into heat (photothermal effect) makes it possible the remote actuation of these smart materials. Similarly, incorporation of magnetic NPs can be used to produce the remote heating by exposure to an alternating magnetic field (magnetic hyperthermia). The photothermal effect provides also the possibility of local heating and, therefore, a local response (e.g., localized shape recovery or the self-healing of a localized area). Besides, the synthesis of smart epoxy nanocomposites requires the appropriate functionalization of NPs to produce their uniform dispersion in the epoxy matrix. In this article, we review recent selected papers dealing with the development of EV and SME nanocomposites that can be remotely activated.Fil: Altuna, Facundo Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Puig, Julieta. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Hoppe, Cristina Elena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Williams, Roberto Juan Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin