Interactions Between Plasmonic Nanostructures and Proteins

In the development of a nanodevice for biomedical applications, the study of the interactions with the biomolecules is essential. Proteins, in particular, are known to be easily adsorbed on the surface of the nanoparticles and the resulting complex is the one that will be effectively internalized by the target cells. Owing to the versatility of the preparation methods available and the unique optical properties, gold nanomaterials represent an excellent choice to study this interaction. This chapter will initially describe the synthesis of gold nanorods and nanoshells that are able to absorb light in the near-infrared (NIR) region. Then, the methods available for the functionalization of their surface will be discussed. The surface plasmon absorption will be used as an optical tool to monitor the process of preparation and surface modification. In the last section of the chapter, fluorescence and microscopy techniques will be used to follow the formation and characterize the protein-nanoparticle complex. The modifications of the emission spectra of two model proteins, bovine serum albumin (BSA) and myoglobin (Mb), will be analyzed in detail. The data will demonstrate that structural rearrangements following the adsorption on the surface of the nanoparticles are responsible for the changes in the fluorescence of the tryptophan residues of the protein. The data will be discussed in terms of static and dynamic quenching, proving the formation of a protein-nanoparticle complex. Atomic force microscopy (AFM) measurements will allow the direct visualization of this complex

UV Treatment of the Stabilizing Shell for Improving the Photostability of Silver Nanoparticles

Silver nanoparticles or nanoclusters are quite sensitive to light exposure. In particular, irradiation in the localized surface plasmon resonance (LSPR) region brings about a drastic modification of their optical properties due to growth and reshaping of the nanoparticles. In order to obtain luminescent colloids, small silver colloidal nanoparticles were prepared in chloroform using vinylpyrrolidone oligomers as capping agent and their luminescence properties were used to control their stability upon prolonged exposure to visible light. The polymeric shell around the metal clusters was hardened through photo-cross-linking by UV light. This process did not alter the morphology and the optical properties of the nanoparticles but greatly improved the particle photostability as confirmed also by confocal laser scanning microscopy measurements. The data clearly show that UV curing of the stabilizing layer could be a simple postsynthetic procedure to obtain materials with stable properties

Environmental impacts of a digital health and well-being service in elderly living schemes

Over the past decade, digitalization and digital technologies (DTs) have undergone rapid evolution, transforming how goods and services are produced and consumed in modern societies. Health and well-being sectors have embraced this digital revolution. Besides the economic and social benefits, digitalization can significantly enhance patient diagnostics and prognostics while improving overall service efficiency. To ensure long-term sustainability, it is important to assess and reduce the environmental impacts of digital services. This article examines the life cycle impacts of a digital service implemented in three elderly living schemes (ELSs) located in the United Kingdom (UK). The digital service consists of six electronic devices (EDs) that enable communication between residents, visitors, staff, and offsite monitoring (OM). The equipment is connected using Power over Ethernet (PoE) technology, which includes smart network switch and uninterruptable power supply units. The digital service's global warming potential (GWP) was estimated at 718–741 kg CO2 eq./resident for two of the ELSs and 1509 kg CO2 eq./resident for a third ELS, considering a service period of 20 years. The reason for the significant difference is the greater use of air conditioner (A/C) units to cool down server rooms and fewer residents in the third scheme. The consumption of electricity was found to be the main contributor to most of the environmental impacts. However, in certain categories such as mineral resource scarcity, freshwater eutrophication, and freshwater and marine ecotoxicity potentials, printed circuit boards (PCBs) were the main contributors. A sensitivity analysis considering different national electricity mixes demonstrated that the French electricity grid promoted the reduction in 14 impact categories, whereas the German, Italian, Spanish and Japanese grids increased on average impacts on most categories. Another sensitivity analysis demonstrates that reducing A/C unit running time by 28% resulted in an average impact reduction of 5.5%, becoming equivalent to the results obtained for the French electricity grid. Finally, extending the expected lifespan of electronic equipment by 20% yielded the highest average decrease in environmental impacts (8.1%). While digitalization has the potential to enhance patient healthcare and reduce costs, it is crucial to carefully assess its environmental impacts and implement mitigation strategies to ensure sustainable development in the healthcare sector.<br/

Charpy impact toughness of conventional and advanced composite laminates for aircraft construction

A weight-based analysis was made of the translaminar Charpy impact toughness performance of conventional and advanced composite materials for aircraft fabrication. The materials were carbon-epoxy (C-Ep) and hybrid fiber-metal TiGr (Titanium-Graphite) laminates. 5 mm-thick three-point bend specimens were tested over a temperature range of -70 to 180 ºC to reproduce typical in-service conditions of supersonic jetliners. The energies required for the processes of damage initiation (Ei), damage propagation (Ep), and whole fracture (Et = Ei + Ep), were evaluated at two loading rates, namely, 2.25 and 5.52 m/s in an instrumented Charpy impact testing machine. C-Ep laminates with unidirectional fiber tapes arranged in cross-ply architecture consistently showed the best performance in terms of damage initiation toughness, whereas the hybrid fiber-metal laminate TiGr excelled in terms of propagation toughness. On the other hand, the overall performance of bi-directional fabric C-Ep laminates was very disappointing. The impact behavior of composite laminates was substantiated by a qualitative analysis of topographic aspects of fracture surfaces.Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES

Damage characterization and residual resistance of fiber/metal laminate after low energy repeated impact

A energia absorvida pelo laminado metal/fibra Glare® durante impactos repetidos de baixa energia aplicados segundo três diferentes sequências de carregamento dinâmico foi determinada através de um aparato Laser-Doppler. Os resultados indicaram que a energia absorvida (Ea) foi cerca de 40% da energia total disponibilizada (Et = 6 Joules), independentemente da sequência de impactos empregada. As propriedades mecânicas residuais do laminado em condições de flexão monotônica sob três pontos, assim como os danos visualmente detectáveis criados por impacto no material, também não revelaram efeitos significativos da história de cargas dinâmicas experimentada pelo laminado híbrido.The energy absorbed by the fiber/metal laminate GlareTM during low-energy repeated impact events according to three different dynamic loading sequences has been determined using a Laser-Doppler apparatus. The results indicated that the absorbed energy (Ea) was approximately 40% of the total available energy (Et = 6 Joules) regardless of the impact sequence applied. The residual mechanical properties of the laminate under three-point flexural conditions, as well as the visually detectable damage created by impact on the material, did not show any significant effect of the dynamic loading sequence withstood by the hybrid laminate

Translaminar dynamic fracture toughness of a hybrid fiber-metal laminate devised to high-temperature applications

A tenacidade à fratura translaminar dinâmica do laminado híbrido metal-fibra titânio-grafite com matriz termoplástica foi determinada sob as velocidades de impacto de 2,25 e 5,52 m/s, no intervalo de temperaturas de -196 a +180 °C, e comparada à de laminados compósitos convencionais de fibras de carbono e resina epóxi. Constatou-se que o laminado híbrido exibe uma tenacidade à iniciação da fratura inferior à dos compósitos tradicionais com fibras na forma de fita unidirecional, porém superior à dos laminados convencionais com fibras na forma de tecido bidirecional. Os ensaios de impacto revelaram que, comparativamente ao desempenho mecânico dos laminados carbono-epóxi, o emprego do laminado híbrido metal-fibra se justifica mais pela sua resistência à propagação do que à iniciação da fratura dinâmica.The translaminar dynamic fracture toughness of titanium-graphite hybrid fiber-metal laminate with thermoplastic matrix has been determined at the impact velocities of 2.25 and 5.52 m/s, within the temperature range from -196 to +180 ºC, and compared to that of conventional carbon-epoxy composite laminates. The hybrid laminate exhibits lower initiation fracture toughness than traditional unidirectional tape composites though it is tougher than conventional woven fabric laminates. Impact tests revealed that, if compared to the mechanical performance of conventional carbon-epoxy laminates, the fiber-metal laminate application must rely on its resistance to dynamic fracture propagation rather than on fracture initiation.Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES