Síntesis y caracterización de nanomateriales 0D, 1D Y 2D

Tesis doctoral inédita, leída en Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Química Inorgánica. Fecha de lectura: 13/09/2013La presente tesis, realizada en el grupo de nanomateriales del Departamento de Quimica Inrogánica de la Universidad Autónoma de Madrid, está enfocada al estudio de la síntesis y caracterización de nanomateriales 0D, 1D y 2D. La memoria está dividida en 4 capítulos y 2 apéndices. En el primer capítulo se hace una introducción a la nanotecnología y a los nanomateriales, campos en los que se engloba la investigación realizada. Además también se explican las distintas técnicas utilizadas para caracterizar las nanoestructuras. A continuación se abordan en los 3 siguientes capítulos (2, 3 y 4) los tres distintos tipos de nanomateriales en los que se ha desarrollado la investigación. El segundo capítulo está dedicado a las nanoestructuras 0D, concretamente virus y nanopartículas de cobalto. En el tercer capítulo son tratados los nanotubos de carbono. Y el cuarto capítulo trata sobre la obtención de polímeros orgánicos bidimensionales llevados a la nanoescala. Los capítulos 2, 3 y 4 se dividen en 4 secciones. En primer lugar una parte introductoria que intenta acercar al lector al nanomaterial en cuestión. En esta sección se explican las propiedades y características del material a estudiar y se realiza una revisión de los logros obtenidos por otros grupos de investigación. En la siguiente sección se muestran los objetivos propuestos en el inicio de la investigación, además de los retos que surgen durante el transcurso de la misma. La tercera sección es una discusión detallada de los resultados obtenidos. Finalmente, en la última sección se reúnen las principales conclusiones obtenidas. La parte experimental de todos los capítulos se ha agrupado en los apéndices A y B recogidos al final de esta memoria

Studies on bifunctional Fe(II)-triazole spin crossover nanoparticles: time-dependent luminescence, surface grafting and the effect of a silica shell and hydrostatic pressure on the magnetic properties

Pure and silica wrapped Fe(II)-triazole (FeHTrz) spin-crossover (SCO) nanoparticles have been prepared following a water-in-oil synthetic procedure. The size and shape can be tuned by controlling the Fe(II) and triazole concentrations in the aqueous phase. The magnetic properties of these nanoparticles are strongly affected by the presence of a silica shell embedding the nanostructured FeHTrz polymer. Whereas bare FeHTrz nanoparticles exhibit abrupt and cooperative spin transition with 24–35K-wide thermal hysteresis loops, for the silica derivates the hysteresis width increases up to 37–42 K. This probes the efficiency of the silica shell to promote interparticle interactions and enhance cooperativity effects. Tomographic studies of the FeHTrz@SiO2 nanoparticles reveal a core–shell structure with the pure FeHTrz polymer wrapped into a thin shell of pure silica. Taking advantage of the chemical properties of the silica shell, these hybrid nanoparticles were coated with a dansyl derivate fluorophore whose luminescence properties can be adjusted by the spin state of the SCO polymer. Time-dependent luminescence studies reveal the existence of a non-radiative energy transfer (Förster type) between the organic fluorophore and the Fe(II)-low spin ions. These nanoparticles have also been functionalized with thiol groups allowing them to be deposited onto a gold surface in a controlled manner

Synthesis of Non-Uniform Functionalized Amphiphilic Block Copolymers and Giant Vesicles in the Presence of the Belousov–Zhabotinsky Reaction

Giant vesicles with several-micrometer diameters were prepared by the self-assembly of an amphiphilic block copolymer in the presence of the Belousov–Zhabotinsky (BZ) reaction. The vesicle is composed of a non-uniform triblock copolymer synthesized by multi-step reactions in the presence of air at room temperature. The triblock copolymer contains poly(glycerol monomethacrylate) (PGMA) as the hydrophilic block copolymerized with tris(2,2′-bipyridyl)ruthenium(II) (Ru(bpy)3), which catalyzes the BZ reaction, and 2-hydroxypropyl methacrylate (HPMA) as the hydrophobic block. In this new approach, the radicals generated in the BZ reaction can activate a reversible addition-fragmentation chain transfer (RAFT) polymerization to self-assemble the polymer into vesicles with diameters of approximately 3 µm. X-ray photoelectron spectroscopy (XPS) measurements demonstrated that the PGMA-b-Ru(bpy)3-b-PHPMA triblock copolymer is brominated and increases the osmotic pressure inside the vesicle, leading to micrometer-sized features. The effect of solvent on the morphological transitions are also discussed briefly. This BZ strategy, offers a new perspective to prepare giant vesicles as a platform for promising applications in the areas of microencapsulation and catalyst support, due to their significant sizes and large microcavities

Formation of self-assembled monolayer of curcuminoid molecules on gold surfaces

We investigated the formation of self-assembled monolayers of two thiophene curcuminoid molecules, 2-thphCCM (1) and 3-thphCCM (2), on polycrystalline gold substrates prepared by immersion of the surfaces in a solution of the molecules during 24 h. The functionalized surfaces were studied by scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). Despite the fact that both molecules have the same composition and almost the same structure, these molecules exhibit different behavior on the gold surface, which can be explained by the different positions of the sulfur atoms in the terminal aromatic rings. In the case of molecule 1, the complete formation of a SAM can be observed after 24 h of immersion. In the case of molecule 2, the transition from flat-lying to upright configuration on the surface is still in process after 24 h of immersion. This is attributed to the fact that molecule 2 have the sulfur atoms more exposed than molecule 1.Fil: Berlanga, Isadora. Universidad de Chile; ChileFil: Etcheverry Berríos, Álvaro. Universidad de Chile; ChileFil: Mella, Andy. Universidad de Chile; ChileFil: Jullian, Domingo. Universidad de Chile; ChileFil: Gómez Andrade, Victoria Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Chile; ChileFil: Aliaga-Alcalde, Núria. Institució Catalana de Recerca i Estudis Avancats; España. Universitat Autònoma de Barcelona; EspañaFil: Fuenzalida, Victor. Universidad de Chile; ChileFil: Flores, Marcos. Universidad de Chile; ChileFil: Soler, Monica. Universidad de Chile; Chil

Gold Nanoparticles Mediate Improved Detection of beta-amyloid Aggregates by Fluorescence

The early detection of the amyloid beta peptide aggregates involved in Alzheimer's disease is crucial to test new potential treatments. In this research, we improved the detection of amyloid beta peptide aggregates in vitro and ex vivo by fluorescence combining the use of CRANAD-2 and gold nanorods (GNRs) by the surface enhancement fluorescence effect. We synthetized GNRs and modified their surface with HS-PEG-OMe and HS-PEG-COOH and functionalized them with the D1 peptide, which has the capability to selectively bind to amyloid beta peptide. For an in vitro detection of amyloid beta peptide, we co-incubated amyloid beta peptide aggregates with the probe CRANAD-2 and GNR-PEG-D1 observing an increase in the intensity of the fluorescence signal attributed to surface enhancement fluorescence. Furthermore, the surface enhancement fluorescence effect was observed in brain slices of transgenic mice with Alzheimer's disease co-incubated with CRANAD-2 and GNR-PEG-D1. An increase in the fluorescence signal was observed allowing the detection of aggregates that cannot be detected with the single use of CRANAD-2. Gold nanoparticles allowed an improvement in the detection of the amyloid aggregated by fluorescence in vitro and ex vivo.FONDAP 15130011 Comisión Nacional de Investigación Cientifica y Tecnológica (CONICYT) CONICYT FONDECYT 1161775 1170929 FONDEQUIP EQM17011