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- Graphene-based composite laminates for structural applicationsPublication . Parente, João Miguel Nunes; Reis, Paulo Nobre Balbis dos; Silva, Abílio Manuel Pereira da; Pereira, João Pedro NunesThis thesis explores the synthesis, microstructure and properties of polymer-matrix composites reinforced with graphene nanoplatelets (GNP), carbon nanotubes (CNT) and carbon nanofibers (CNF), both as individual fillers and in hybrid combinations. The aim is to develop structural materials with high mechanical performance and integrated self-sensing capabilities. Nanocomposites were produced by dispersing nanoparticles in epoxy resin, followed by thermal curing. Mechanical and sensing behaviour were evaluated using three-point bending and cyclic fatigue tests under realistic loading conditions. Viscosity measurements show that GNP or CNF can increase resin viscosity by up to 74 %, which challenges processing at higher loadings. Curing at 5 °C yields the best flexural strength and surface hardness, with GNP-reinforced composites showing up to 24.8 % strength improvement. Volumetric shrinkage during cure varies with filler type: GNP increases shrinkage by 91 %, while CNF reduces it by 77 %, underscoring the role of nanoparticle–matrix interactions. In fibre-reinforced laminates, placing glass fibres on the compression side of hybrid carbon/glass layups enhances both load and deflection at peak, with a 3G/5C configuration achieving a 5.9 % higher peak force and 13.1 % greater deflection than the reverse. Incorporating 0.75 wt. % GNP into carbon-fibre laminates raises bending stiffness and extends fatigue life by 15.1 %, while increases of 10.6 % and 9.2 % are observed in hybrid and glass-fibre laminates. These enhancements show that even low graphene concentrations effectively delay fatigue damage. Combining CNT and GNP at equal loadings (0.375 wt. % each) yields synergistic gains in stiffness and strength. In carbon-fibre composites, strength and stiffness rise by 11 % and 18 %, respectively; glass-fibre composites show gains of 8 % and 55 %. Electrical resistance monitoring during fatigue reveals gauge factors up to three times those of commercial strain gauges, with stress-amplitude sensitivity improving by 20.1 % in carbon composites and 32.4 % in glass composites. This confirms high-sensitivity and stable self-sensing. The integration of hybrid nanofillers with mechanical and electrical performance validation forms a framework for designing multifunctional composites. Key challenges remain in scaling uniform nanoparticle dispersion, ensuring long-term network stability and standardizing sensor calibration. Addressing these issues is essential for translating laboratory results into practical Structural Health Monitoring (SHM) applications.
- Exploring One-Hit Multiple Target Strategies for Lung CancerPublication . Alexandre, Daniela de Jesus; Cruz, Carla Patrícia Freire Madeira Alves da; Baptista, Pedro Miguel Ribeiro VianaNon-small cell lung cancer (NSCLC) requires biomarkers that are both sensitive and actionable, as well as network-level therapies. In this context, microRNAs (miRs) have emerged as a unique bridge to meet these needs: their dysregulated signatures discriminate healthy individuals from NSCLC patients, while serving as regulators, each miR can coordinate multiple gene targets, making them compelling therapeutic levers. Leveraging this duality, the present thesis harnesses that property to test a “one-hit, multiple-target” strategy centered on miRs (miR-21, miR-155-3p, miR-3196), integrating sensitive detection with therapeutic modulation. To this end, multiple miRs were initially profiled in NSCLC liquid biopsies (LBs). Subsequently, molecular beacons (MBs) were engineered and qualified for the direct detection of two NSCLC-associated miRs (miR-21/miR-155) in biological samples, laying the groundwork for a diagnostic platform; additionally, one probe was integrated into a microchip, enabling a point-of-care diagnostic prototype. Therapeutically, miR-155-3p was silenced with an antisense strategy, and miR-3196 was reactivated by destabilizing a G-quadruplex (G4) within its precursor using a G4 ligand (phenylpyrrolocytosine; PhpC). To enable efficient intracellular delivery, gold nanoparticles (AuNPs) were developed to deliver both oligonucleotides and PhpC ligand, with complete physicochemical and cellular characterization. Overall, the expression profile analysis identified upregulation of miR-21/miR-155 and downregulation of miR-3196, with clinical correlations. The MB assays achieved high specificity and low-nanomolar sensitivity, enabling rapid readouts. Additionally, the AuNPs targeting miR-155-3p produced efficient cellular uptake and robust knockdown, attenuating oncogenic signaling and outperforming lipid transfection. Moreover, to the best of our knowledge, we have identified, for the first time, a G4-forming region within the human precursor of miR-3196 that restricts its maturation. Subsequently, using the G4 ligand, PhpC, unfolded this structure and restored mature miR-3196. In addition, PhpC-functionalized AuNPs preserved activity, enhanced intracellular persistence, and maintained low acute cytotoxicity across the tested ranges. These studies establish a theragnostic framework for NSCLC: MBs enable minimally invasive detection and real-time pharmacodynamic tracking, while miR modulation, via miR-155 inhibition and G4-guided rescue of miR-3196, may yield broad antitumor effects from a single molecular hit. Furthermore, the AuNP delivery overcomes key barriers to nucleic-acid and small-molecule therapeutics. Collectively, the work advances a translatable, miR-centered one-hit/multi-target paradigm and outlines clear next steps toward in vivo validation and clinical integration.