Nano-estructuras tridimensionales funcionales (alúmina 3D y redes de nanohilos interconectados en las 3 direcciones del espacio)

Tesis inédita de la Universidad Complutense de Madrid, Facultad de Ciencias Físicas, leída el 09-03-2022This Thesis has been focused on the development of functional nanostructures for a variety of applications, from structural coloring to magnetic nanostructures with tailored properties and highly efficient thermoelectric metamaterials. In all cases, the fabrication of such nanostructures has been based on two processes: aluminum anodization and electrochemical growth. Both are chemical processes, which need no vacuum and that are well known at the industrial level. The results that are presented in this manuscript represent the state of the art of both techniques, which is well endorsed by the publications that have resulted from it.In brief, the main objective pursued in this Ph.D. Thesis has been to prove the versatility of a recent kind of alumina membranes, consisting of longitudinal pores that are transversely perforated by smaller pore channels, in the development of future nanotechnology applications. These 3D-Anodic alumina templates (3D AAO) have been studied by themselves, but also used as templates to grow different materials and tune their properties...Este trabajo de tesis se centra en el desarrollo de nanoestructuras funcionales interconectadas para diversas aplicaciones, desde la obtención de color estructural a la fabricación de metamateriales magnéticos con propiedades modificadas, así como metamateriales termoeléctricos de alta eficiencia. En todos estos casos, la fabricación de estas nanoestructuras se ha basado en dos procesos: anodización de aluminio y crecimiento electroquímico. Ambos son procesos químicos que no requieren de vacío y que son muy conocidos a nivel industrial. Los resultados que se presentan en este manuscrito muestran el estado del arte en ambas técnicas, lo que queda patente por las publicaciones científicas a las que este trabajo ha dado lugar. Brevemente, el objetivo principal de esta Tesis ha sido probar la versatilidad de un tipo de membranas de alúmina desarrolladas recientemente para el desarrollo de futuras aplicaciones nanotecnológicas. Estas membranas consisten en poros longitudinales que están unidos por poros transversales más pequeños que forman canales que los conectan. Estas membranas de alúmina tridimensionales (3D-AAO, del inglés 3D Anodic Aluminum Oxide) se han estudiado, por un lado, como plataformas para la generación de dispositivos en sí mismas, y, por otro lado, como plantillas para crecer en su estructura porosa distintos materiales y nanoestructurarlos, modificando de este modo sus propiedades...Fac. de Ciencias FísicasTRUEunpu

Antibacterial activity of a chitosan-PVA-Ag+-Tobermorite composite for periodontal repair

A polymer-mineral composite was prepared by solvent casting a mixture of chitosan, poly(vinyl alcohol), and Ag+-exchanged tobermorite in dilute acetic acid and characterised by scanning electron microscopy and Fourier transform infrared spectroscopy. The in vitro bioactivity of the CPTAg membrane was confirmed by the formation of hydroxyapatite on its surface in simulated body fluid. The alkaline dissolution products of the tobermorite lattice buffered the acidic breakdown products of the chitosan polymer and the presence of silver ions resulted in marked antimicrobial action against S. aureus, P. aeruginosa, and E. coli. The in vitro cytocompatibility of the CPTAg membrane was confirmed using MG63 osteosarcoma cells. The findings of this preliminary study have indicated that chitosan-poly(vinyl alcohol)-Ag+-tobermorite composites may be suitable materials for guided tissue regeneration applications

Effect of calcium precursor on the bioactivity and biocompatibility of sol-gel-derived glasses

This study investigated the impact of different calcium reagents on the morphology, composition, bioactivity and biocompatibility of two-component (CaO-SiO2) glasses produced by the Stöber process with respect to their potential application in guided tissue regeneration (GTR) membranes for periodontal repair. The properties of the binary glasses were compared with those of pure silica Stöber particles. The direct addition of calcium chloride (CC), calcium nitrate (CN), calcium methoxide (CM) or calcium ethoxide (CE) at 5 mol % with respect to tetraethyl orthosilicate in the reagent mixture gave rise to textured, micron-sized aggregates rather than monodispersed ~500 nm spheres obtained from the pure silica Stöber synthesis. The broadening of the Si-O-Si band at ~1100 cm-1 in the infrared spectra of the calcium-doped glasses indicated that the silicate network was depolymerised by the incorporation of Ca2+ ions and energy dispersive X-ray analysis revealed that, in all cases, the Ca:Si ratios were significantly lower than the nominal value of 0.05. The distribution of Ca2+ ions was also found to be highly inhomogeneous in the methoxide-derived glass. All samples released soluble silica species on exposure to simulated body fluid, although only calcium-doped glasses exhibited in vitro bioactivity via the formation of hydroxyapatite. The biocompatibilities of model chitosan-glass GTR membranes were assessed using human MG63 osteosarcoma cells and were found to be of the order: CN < pure silica ~ CC << CM ~ CE. Calcium nitrate is the most commonly reported precursor for the sol-gel synthesis of bioactive glasses; however, the incomplete removal of nitrate ions during washing compromised the cytocompatibility of the resulting glass. The superior bioactivity and biocompatibility of the alkoxide-derived glasses is attributed to their ease of dissolution and lack of residual toxic anions. Overall, calcium ethoxide was found to be the preferred precursor with respect to extent of calcium-incorporation, homogeneity, bioactivity and biocompatibility

Cylindrical Three-Dimensional Porous Anodic Alumina Networks

The synthesis of a conformal three-dimensional nanostructure based on porous anodic alumina with transversal nanopores on wires is herein presented. The resulting three-dimensional network exhibits the same nanostructure as that obtained on planar geometries, but with a macroscopic cylindrical geometry. The morphological analysis of the nanostructure revealed the effects of the initial defects on the aluminum surface and the mechanical strains on the integrity of the three-dimensional network. The results evidence the feasibility of obtaining 3D porous anodic alumina on non-planar aluminum substrates

Cuidamos tu salud cuidando tus dientes : Labores educativas, preventivas y puesta en práctica de la metodología PRAT en niños y adolescentes

La caries dental constituye uno de los flagelos que sufre la población general, la suma de esfuerzos para erradicarla resulta imprescindible. Parte de dicha población carece de recursos económicos y se encuentra excluida para solventar su tratamiento. Motiva el presente proyecto, la necesidad de implementar en los niños y adolescentes a los efectos de preservar y promover la salud bucal, terapéuticas concebidas para eliminar y restaurar las piezas dentales que padecen de caries. Para esta finalidad se llevarán a cabo, tratamientos basados en la técnica conocida bajo la sigla PRAT (Prácticas Restaurativas Atraumáticas).Facultad de Odontologí

Ticagrelor in patients with diabetes and stable coronary artery disease with a history of previous percutaneous coronary intervention (THEMIS-PCI) : a phase 3, placebo-controlled, randomised trial

Background: Patients with stable coronary artery disease and diabetes with previous percutaneous coronary intervention (PCI), particularly those with previous stenting, are at high risk of ischaemic events. These patients are generally treated with aspirin. In this trial, we aimed to investigate if these patients would benefit from treatment with aspirin plus ticagrelor. Methods: The Effect of Ticagrelor on Health Outcomes in diabEtes Mellitus patients Intervention Study (THEMIS) was a phase 3 randomised, double-blinded, placebo-controlled trial, done in 1315 sites in 42 countries. Patients were eligible if 50 years or older, with type 2 diabetes, receiving anti-hyperglycaemic drugs for at least 6 months, with stable coronary artery disease, and one of three other mutually non-exclusive criteria: a history of previous PCI or of coronary artery bypass grafting, or documentation of angiographic stenosis of 50% or more in at least one coronary artery. Eligible patients were randomly assigned (1:1) to either ticagrelor or placebo, by use of an interactive voice-response or web-response system. The THEMIS-PCI trial comprised a prespecified subgroup of patients with previous PCI. The primary efficacy outcome was a composite of cardiovascular death, myocardial infarction, or stroke (measured in the intention-to-treat population). Findings: Between Feb 17, 2014, and May 24, 2016, 11 154 patients (58% of the overall THEMIS trial) with a history of previous PCI were enrolled in the THEMIS-PCI trial. Median follow-up was 3·3 years (IQR 2·8–3·8). In the previous PCI group, fewer patients receiving ticagrelor had a primary efficacy outcome event than in the placebo group (404 [7·3%] of 5558 vs 480 [8·6%] of 5596; HR 0·85 [95% CI 0·74–0·97], p=0·013). The same effect was not observed in patients without PCI (p=0·76, p interaction=0·16). The proportion of patients with cardiovascular death was similar in both treatment groups (174 [3·1%] with ticagrelor vs 183 (3·3%) with placebo; HR 0·96 [95% CI 0·78–1·18], p=0·68), as well as all-cause death (282 [5·1%] vs 323 [5·8%]; 0·88 [0·75–1·03], p=0·11). TIMI major bleeding occurred in 111 (2·0%) of 5536 patients receiving ticagrelor and 62 (1·1%) of 5564 patients receiving placebo (HR 2·03 [95% CI 1·48–2·76], p<0·0001), and fatal bleeding in 6 (0·1%) of 5536 patients with ticagrelor and 6 (0·1%) of 5564 with placebo (1·13 [0·36–3·50], p=0·83). Intracranial haemorrhage occurred in 33 (0·6%) and 31 (0·6%) patients (1·21 [0·74–1·97], p=0·45). Ticagrelor improved net clinical benefit: 519/5558 (9·3%) versus 617/5596 (11·0%), HR=0·85, 95% CI 0·75–0·95, p=0·005, in contrast to patients without PCI where it did not, p interaction=0·012. Benefit was present irrespective of time from most recent PCI. Interpretation: In patients with diabetes, stable coronary artery disease, and previous PCI, ticagrelor added to aspirin reduced cardiovascular death, myocardial infarction, and stroke, although with increased major bleeding. In that large, easily identified population, ticagrelor provided a favourable net clinical benefit (more than in patients without history of PCI). This effect shows that long-term therapy with ticagrelor in addition to aspirin should be considered in patients with diabetes and a history of PCI who have tolerated antiplatelet therapy, have high ischaemic risk, and low bleeding risk