Development of nanoplasmonic thin films for gaseous molecules detection

Dissertação de mestrado em Biofísica e BionanossistemasFilmes finos nanocompósitos, constituídos por nanopartículas nobres incorporadas numa matriz de oxido metálico, têm despertado considerável interesse na deteção ótica de moléculas gasosas. A sensibilidade dos filmes pode ser otimizada de acordo com o efeito de ressonância de plasmões de superfície localizados (LSPR) revelado por estes materiais, que depende fortemente da composição, distribuição, tamanho e forma das nanopartículas, bem como do meio dielétrico que as rodeia. Neste trabalho, foram preparados filmes finos com diferentes concentrações de Au e/ou Ag incorporados numa matriz de CuO, com o objetivo de encontrar plataformas nanoplasmónicas capazes de detetar a presença de moléculas gasosas (ex. CO) através de desvios da banda de LSPR. Os sistemas de filmes finos (Au:CuO, Ag:CuO e Au:Ag-CuO) foram depositados por pulverização catódica reativa em magnetrão e, posteriormente, submetidos a tratamentos térmicos (temperaturas de 300 a 700 ºC), para promover a formação das nanopartículas de Au e/ou Ag. A composição, microestrutura e a resposta ótica dos filmes foram estudadas em função da concentração de metal e da temperatura do tratamento térmico e correlacionadas com o comportamento plasmónico. Quanto ao sistema Au:CuO, o efeito LSPR aparece após temperaturas de tratamento térmico de 300 ºC, ou superiores, com bandas de LSPR a tornarem-se progressivamente mais estreitas; comportamento associado ao crescimento das nanopartículas de Au e diferentes distribuições de tamanhos. No caso do sistema de Ag:CuO, apenas foi possível observar bandas LSPR para temperaturas de tratamento térmico de 500 ºC, e superiores. Para o sistema Au-Ag:CuO, um único pico de LSPR apareceu para temperaturas de tratamento térmico até aos 500 ºC. Para temperaturas superiores, foram observados dois picos LSPR, provavelmente devido à presença de nanopartículas de Au e Ag, embora a formação de nanopartículas bimetálicas de Au-Ag não possa ser descartada. A espectroscopia fotoeletrónica de raio X, com e sem a presença do gás CO, indicou que a superfície dos filmes finos nanoplasmónicos de Au:CuO está contaminada com uma camada sub-nanométrica (~0,6 nm) de hidrocarbonetos, onde algum CO pode ser quimissorvido. Contudo, parte das moléculas de CO expostas ao filme parecem ser fisissorvidas na superfície, o que é importante para a aplicação alvo. Para além disso, através de uma posterior aplicação de tratamentos de plasma com Ar, a camada de hidrocarbonetos pode ser removida e as nanopartículas de Au emergir à superfície. Durante este trabalho, um sistema ótico portátil foi também desenvolvido para realizar os ensaios de deteção molecular, seguindo os desvios da banda de LSPR.Nanocomposite thin films, containing noble nanoparticles embedded in an oxide matrix have been a subject of considerable interest for optical gas sensing, due to their localized surface plasmon resonance (LSPR) properties. The sensitivity of the films can be tailored according to the LSPR phenomenon revealed by these materials, which is strongly dependent on the composition, distribution, size and shape of the nanoparticles, and dielectric medium surrounding them. In the present work, thin films were prepared with different amounts of Au and/or Ag embedded in a CuO matrix, aiming to find nanoplasmonic platforms capable of detecting the presence of gaseous molecules (e.g. CO) through LSPR band shifts. The thin films systems (Au:CuO, Ag:CuO and Au:Ag.CuO) were deposited by reactive DC magnetron sputtering and then submitted to annealing treatments (temperatures from 300 to 700 ºC) to promote the Au and/or Ag nanoparticles formation. The composition, microstructure and optical response of the thin films were studied as a function of the metal concentration and annealing temperature and correlated with the LSPR behaviour. Regarding the Au:CuO system, a LSPR effect appeared after annealing temperatures of 300 ºC, or higher, with bands becoming progressively narrower; behaviour associated to the Au nanoparticles growth and different size distributions. In the case of the Ag:CuO system, LSPR bands were observed only for temperatures of 500 ºC and above. For the Au-Ag:CuO system, a unique LSPR peak appeared for annealing temperatures up to 500 ºC. For higher temperatures, two faint LSPR peaks were observed, probably due to the presence of both Ag and Au nanoparticles, although the formation of bimetallic Au-Ag nanoparticles was also suggested. X-Ray Photoelectron Spectroscopy, without and with the presence of CO gas, indicated that the surface of the Au:CuO nanoplasmonic thin film is contaminated with a sub-nanometric layer (~0.6 nm) of hydrocarbons, where some CO might be chemisorbed. However, part of the CO molecules exposed to the film seems to be physisorbed at the surface, which is important for the targeted application. Furthermore, through a subsequent application of Ar plasma treatments, the hydrocarbons layer may be removed, and the Au nanoparticles emerge at the surface. During this work, a portable optical system was designed and built in the laboratory to detect the presence of gas molecules, in particular CO, by following the shifts of the LSPR band in transmittance.Fundação para a Ciência e Tecnologia (FCT) - Projeto 9471 - Reforçar a Investigação, o Desenvolvimento Tecnológico e a Inovação (Projeto 9471-RIDTI) comparticipado pelo Fundo Comunitário Europeu FEDER. O mencionado Projeto tem designação de "NANOSENSING" e referência PTDC/FIS-NA/1154/2014

Optimization of Au:CuO thin films by plasma surface modification for high-resolution LSPR gas sensing at room temperature

In this study, thin films composed of gold nanoparticles embedded in a copper oxide matrix (Au:CuO), manifesting Localized Surface Plasmon Resonance (LSPR) behavior, were produced by reactive DC magnetron sputtering and post-deposition in-air annealing. The effect of low-power Ar plasma etching on the surface properties of the plasmonic thin films was studied, envisaging its optimization as gas sensors. Thus, this work pretends to attain the maximum sensing response of the thin film system and to demonstrate its potential as a gas sensor. The results show that as Ar plasma treatment time increases, the host CuO matrix is etched while Au nanoparticles are uncovered, which leads to an enhancement of the sensitivity until a certain limit. Above such a time limit for plasma treatment, the CuO bonds are broken, and oxygen is removed from the film’s surface, resulting in a decrease in the gas sensing capabilities. Hence, the importance of the host matrix for the design of the LSPR sensor is also demonstrated. CuO not only provides stability and protection to the Au NPs but also promotes interactions between the thin film’s surface and the tested gases, thereby improving the nanocomposite film’s sensitivity. The optimized sensor sensitivity was estimated at 849 nm/RIU, which demonstrates that the Au-CuO thin films have the potential to be used as an LSPR platform for gas sensors.This research was sponsored by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UIDB/04650/2020 and by the project CO2Plasmon with reference EXPL/CTM-REF/0750/2021. M.P. acknowledges her Ph.D. Scholarship from FCT, with reference SFRH/BD/137076/2018. Diana I. Meira acknowledges her Ph.D. Scholarship from FCT, with reference SFRH/BD/143262/2019

Ventilação, Qualidade do Ar e Saúde em creches e infantários - Resultados preliminares do projeto ENVIRH

É do conhecimento geral que a qualidade do ar interior influencia a qualidade de vida dos ocupantes dos edifícios e que pode ter implicações significativas no seu estado de saúde. As crianças constituem um grupo de risco que pode apresentar vulnerabilidades quando exposto a um ambiente interior de menor qualidade. Neste âmbito, correntemente constata-se que parece haver uma tendência para as crianças adoecerem com maior frequência quando iniciam a sua exposição ao ambiente de creches e infantários, ocorrendo em especial um aumento das doenças do foro respiratório. O projeto ENVIRH, reunindo uma equipa multidisciplinar, tem por objetivo principal estabelecer associações entre as condições de ventilação desses locais, a qualidade do ar interior (QAI) e a prevalência de doenças do foro respiratório. O projeto desenvolve-se essencialmente através de duas fases. De entre um total de 48 creches e infantários (Instituições Privadas de Solidariedade Social - IPSS) em Lisboa e 40 no Porto, foram selecionadas aleatoriamente 45 IPSS (sendo 25 em Lisboa e 20 no Porto), tendo sido analisadas na fase preliminar as suas condições construtivas, realizadas medições pontuais e instantâneas do teor de CO2 em salas de atividades, realizado um inquérito aos hábitos dos ocupantes relacionados com a ventilação e realizado um questionário médico para identificação de sibilância baseado no questionário ISAAC (International Study on Allergy and Asthma in Childhood). Com base na análise dos resultados preliminares, através do desenvolvimento de uma análise de “clusters”, foi selecionado um conjunto mais restrito de 20 IPSS, as quais integraram a segunda fase do estudo, onde foram realizadas medições das taxas de ventilação (método PFT), da QAI (CO2, CO, formaldeído, COVTs, PM10, bactérias, fungos e ácaros), do conforto térmico e feito um acompanhamento das condições de saúde das crianças (questionário médico, recolha de condensado brônquico do ar exalado,identificação de vírus respiratórios). A análise estatística dos resultados da primeira fase evidencia uma clara associação do incremento do teor de CO2 com as práticas de manter as janelas exteriores e as portas interiores fechadas (que reduzem as taxas de ventilação) e, por outro lado, uma associação do incremento do teor de CO2 com a sibilância (sintoma de doença respiratória). Esta comunicação detalha a metodologia seguida no estudo e apresenta os resultados da primeira fase

Assessment of indoor air quality in elderly care centers, 2013-2014: GERIA project

O risco da população idosa desenvolver efeitos adversos em virtude da exposição a contaminantes químicos e microbiológicos do ar interior é mais elevado tanto pelo facto do seu sistema imunitário ser mais débil, como por este grupo etário permanecer no interior de edifícios por períodos mais longos. O objetivo deste estudo foi a caraterização da qualidade do ar interior numa amostra representativa de lares de idosos de modo a estudar a sua relação com a ventilação dos locais e a saúde/qualidade de vida dos utentes. O estudo apresentado incidiu sobre a avaliação da qualidade do ar interior em 18 lares de idosos situados em Lisboa (116 locais avaliados), em duas campanhas, uma no inverno e outra na primavera/verão e incluiu a avaliação de contaminação do ar por agentes químicos - dióxido de carbono (CO2 ), monóxido de carbono (CO), formaldeído (HCHO), compostos orgânicos voláteis totais (COVT), PM10 e PM2,5; por agentes microbiológicos – bactérias e fungos. Os resultados indicam que, de um modo geral a contaminação do ar por compostos orgânicos voláteis totais e formaldeído é baixa. Contudo, os valores de referência são excedidos para o dióxido de carbono, microrganismos e as partículas em 20%, 35% e 25-30% dos locais estudados respetivamente. Assim, há que identificar as fontes de contaminação do ar por partículas por forma e reduzir os efeitos adversos associados à exposição e melhorar a ventilação dos lares, particularmente no inverno, por forma a conseguir ambientes interiores mais saudáveis.Elderly people are at a greater risk for adverse health effects from exposure to indoor air pollutants because their immune system become less effective with age and they stay more than 80% of their time indoors. The aim of this study was to characterize indoor air quality in a representative sample of Elderly Care Centers (ECC) in order to associate it with ventilation, health and comfort. Indoor air quality was performed twice, during winter and summer/spring in 18 ECC located in Lisbon and included the monitoring of chemical agents - carbon dioxide, carbon monoxide, formaldehyde, Total Volatile Organic Compounds (TVOC) and Particulate matter (PM10 and PM2,5) and biological agents – bacteria and fungi. The results obtained for TVOC and formaldehyde indicate a low air contamination. However, reference concentrations of dioxide of carbon, particulate matter and microorganisms were exceeded in 20%, 25-30% and 35% of the rooms respectively. Consequently it is necessary to identify particulate matter contamination sources to reduce related adverse effects and to improve ventilation in ECC, particularly in the Winter, in order to achieve healthier indoor environments.Este projeto foi financiado pela Fundação para a Ciência e Tecnologia (FTC), PTDC/SAU-SAP/116563/2010

Chitosan micro-membranes with integrated gold nanoparticles as an LSPR-based sensing platform

Currently, there is an increasing need to develop highly sensitive plasmonic sensors able to provide good biocompatibility, flexibility, and optical stability to detect low levels of analytes in biological media. In this study, gold nanoparticles (Au NPs) were dispersed into chitosan membranes by spin coating. It has been demonstrated that these membranes are particularly stable and can be successfully employed as versatile plasmonic platforms for molecular sensing. The optical response of the chitosan/Au NPs interfaces and their capability to sense the medium’s refractive index (RI) changes, either in a liquid or gas media, were investigated by high-resolution localized surface plasmon resonance (HR-LSPR) spectroscopy, as a proof of concept for biosensing applications. The results revealed that the lowest polymer concentration (chitosan (0.5%)/Au-NPs membrane) presented the most suitable plasmonic response. An LSPR band redshift was observed as the RI of the surrounding media was incremented, resulting in a sensitivity value of 28 ± 1 nm/RIU. Furthermore, the plasmonic membrane showed an outstanding performance when tested in gaseous atmospheres, being capable of distinguishing inert gases with only a 10−5 RI unit difference. The potential of chitosan/Au-NPs membranes was confirmed for application in LSPR-based sensing applications, despite the fact that further materials optimization should be performed to enhance sensitivity.This research was sponsored by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UIDB/04650/2020, by the project CO2Plasmon with reference EXPL/CTM-REF/0750/2021 and by the project with reference PTDC/CTM-CTM/2846/2020. Diana I. Meira acknowledges her Ph.D. Scholarship from FCT, with reference SFRH/BD/143262/2019. Manuela Proença acknowledges her Ph.D. Scholarship from FCT, with reference SFRH/BD/137076/2018

Abdominal aortic aneurysm is associated with a variant in low-density lipoprotein receptor-related protein 1

Abdominal aortic aneurysm (AAA) is a common cause of morbidity and mortality and has a significant heritability. We carried out a genome-wide association discovery study of 1866 patients with AAA and 5435 controls and replication of promising signals (lead SNP with a p value < 1 × 10-5) in 2871 additional cases and 32,687 controls and performed further follow-up in 1491 AAA and 11,060 controls. In the discovery study, nine loci demonstrated association with AAA (p < 1 × 10-5). In the replication sample, the lead SNP at one of these loci, rs1466535, located within intron 1 of low-density-lipoprotein receptor-related protein 1 (LRP1) demonstrated significant association (p = 0.0042). We confirmed the association of rs1466535 and AAA in our follow-up study (p = 0.035). In a combined analysis (6228 AAA and 49182 controls), rs1466535 had a consistent effect size and direction in all sample sets (combined p = 4.52 × 10-10, odds ratio 1.15 [1.10-1.21]). No associations were seen for either rs1466535 or the 12q13.3 locus in independent association studies of coronary artery disease, blood pressure, diabetes, or hyperlipidaemia, suggesting that this locus is specific to AAA. Gene-expression studies demonstrated a trend toward increased LRP1 expression for the rs1466535 CC genotype in arterial tissues; there was a significant (p = 0.029) 1.19-fold (1.04-1.36) increase in LRP1 expression in CC homozygotes compared to TT homozygotes in aortic adventitia. Functional studies demonstrated that rs1466535 might alter a SREBP-1 binding site and influence enhancer activity at the locus. In conclusion, this study has identified a biologically plausible genetic variant associated specifically with AAA, and we suggest that this variant has a possible functional role in LRP1 expression

Genome-wide association identifies nine common variants associated with fasting proinsulin levels and provides new insights into the pathophysiology of type 2 diabetes.

OBJECTIVE: Proinsulin is a precursor of mature insulin and C-peptide. Higher circulating proinsulin levels are associated with impaired β-cell function, raised glucose levels, insulin resistance, and type 2 diabetes (T2D). Studies of the insulin processing pathway could provide new insights about T2D pathophysiology. RESEARCH DESIGN AND METHODS: We have conducted a meta-analysis of genome-wide association tests of ∼2.5 million genotyped or imputed single nucleotide polymorphisms (SNPs) and fasting proinsulin levels in 10,701 nondiabetic adults of European ancestry, with follow-up of 23 loci in up to 16,378 individuals, using additive genetic models adjusted for age, sex, fasting insulin, and study-specific covariates. RESULTS: Nine SNPs at eight loci were associated with proinsulin levels (P < 5 × 10(-8)). Two loci (LARP6 and SGSM2) have not been previously related to metabolic traits, one (MADD) has been associated with fasting glucose, one (PCSK1) has been implicated in obesity, and four (TCF7L2, SLC30A8, VPS13C/C2CD4A/B, and ARAP1, formerly CENTD2) increase T2D risk. The proinsulin-raising allele of ARAP1 was associated with a lower fasting glucose (P = 1.7 × 10(-4)), improved β-cell function (P = 1.1 × 10(-5)), and lower risk of T2D (odds ratio 0.88; P = 7.8 × 10(-6)). Notably, PCSK1 encodes the protein prohormone convertase 1/3, the first enzyme in the insulin processing pathway. A genotype score composed of the nine proinsulin-raising alleles was not associated with coronary disease in two large case-control datasets. CONCLUSIONS: We have identified nine genetic variants associated with fasting proinsulin. Our findings illuminate the biology underlying glucose homeostasis and T2D development in humans and argue against a direct role of proinsulin in coronary artery disease pathogenesis

Multicenter validation of PIM3 and PIM2 in Brazilian pediatric intensive care units

ObjectiveTo validate the PIM3 score in Brazilian PICUs and compare its performance with the PIM2.MethodsObservational, retrospective, multicenter study, including patients younger than 16 years old admitted consecutively from October 2013 to September 2019. We assessed the Standardized Mortality Ratio (SMR), the discrimination capability (using the area under the receiver operating characteristic curve – AUROC), and the calibration. To assess the calibration, we used the calibration belt, which is a curve that represents the correlation of predicted and observed values and their 95% Confidence Interval (CI) through all the risk ranges. We also analyzed the performance of both scores in three periods: 2013–2015, 2015–2017, and 2017–2019.Results41,541 patients from 22 PICUs were included. Most patients aged less than 24 months (58.4%) and were admitted for medical conditions (88.6%) (respiratory conditions = 53.8%). Invasive mechanical ventilation was used in 5.8%. The median PICU length of stay was three days (IQR, 2–5), and the observed mortality was 1.8% (763 deaths). The predicted mortality by PIM3 was 1.8% (SMR 1.00; 95% CI 0.94–1.08) and by PIM2 was 2.1% (SMR 0.90; 95% CI 0.83–0.96). Both scores had good discrimination (PIM3 AUROC = 0.88 and PIM2 AUROC = 0.89). In calibration analysis, both scores overestimated mortality in the 0%–3% risk range, PIM3 tended to underestimate mortality in medium-risk patients (9%–46% risk range), and PIM2 also overestimated mortality in high-risk patients (70%–100% mortality risk).ConclusionsBoth scores had a good discrimination ability but poor calibration in different ranges, which deteriorated over time in the population studied

A genome-wide association search for type 2 diabetes genes in African Americans.

African Americans are disproportionately affected by type 2 diabetes (T2DM) yet few studies have examined T2DM using genome-wide association approaches in this ethnicity. The aim of this study was to identify genes associated with T2DM in the African American population. We performed a Genome Wide Association Study (GWAS) using the Affymetrix 6.0 array in 965 African-American cases with T2DM and end-stage renal disease (T2DM-ESRD) and 1029 population-based controls. The most significant SNPs (n = 550 independent loci) were genotyped in a replication cohort and 122 SNPs (n = 98 independent loci) were further tested through genotyping three additional validation cohorts followed by meta-analysis in all five cohorts totaling 3,132 cases and 3,317 controls. Twelve SNPs had evidence of association in the GWAS (P<0.0071), were directionally consistent in the Replication cohort and were associated with T2DM in subjects without nephropathy (P<0.05). Meta-analysis in all cases and controls revealed a single SNP reaching genome-wide significance (P<2.5×10(-8)). SNP rs7560163 (P = 7.0×10(-9), OR (95% CI) = 0.75 (0.67-0.84)) is located intergenically between RND3 and RBM43. Four additional loci (rs7542900, rs4659485, rs2722769 and rs7107217) were associated with T2DM (P<0.05) and reached more nominal levels of significance (P<2.5×10(-5)) in the overall analysis and may represent novel loci that contribute to T2DM. We have identified novel T2DM-susceptibility variants in the African-American population. Notably, T2DM risk was associated with the major allele and implies an interesting genetic architecture in this population. These results suggest that multiple loci underlie T2DM susceptibility in the African-American population and that these loci are distinct from those identified in other ethnic populations

Amianto: ação de sensibilização (jornalistas)

Tópicos: - Amianto: propriedades, aplicações e efeitos na saúde - Legislação aplicável: profissionais em riscos - Tipos de exposição - Metodologia de análise: materiais e ar ambiente. - Fibrocimento: Resultados de estud