Maria C. Gomes

The Role of Surface Functionalization of Silica Nanoparticles for Bioimaging

Among the several types of inorganic nanoparticles available, silica nanoparticles (SNP) have earned their relevance in biological applications namely, as bioimaging agents. In fact, fluorescent SNP (FSNP) have been explored in this field as protective nanocarriers, overcoming some limitations presented by conventional organic dyes such as high photobleaching rates. A crucial aspect on the use of fluorescent SNP relates to their surface properties, since it determines the extent of interaction between nanoparticles and biological systems, namely in terms of colloidal stability in water, cellular recognition and internalization, tracking, biodistribution and specificity, among others. Therefore, it is imperative to understand the mechanisms underlying the interaction between biosystems and the SNP surfaces, making surface functionalization a relevant step in order to take full advantage of particle properties. The versatility of the surface chemistry on silica platforms, together with the intrinsic hydroph...

Fluorescence biolabeling using methylated silica nanoparticles containing a lanthanide complex

This research demonstrates that fluorescent silica nanoparticles containing a lanthanide picolinate complex can be used as optical biolabels by using Candida albicans cells as the model targeting system. As such, new fluorescent biolabels have been prepared by encapsulation of the picolinate terbium(iii) complex K2[Tb2(pic)8]·7H2O (Tbpic) in silica particles through a reverse microemulsion process. The surfaces of the ensuing core-shell nanoparticles were functionalized with 3-aminopropyltriethoxysilane and then quaternized with methyl iodide in order to increase their water-stability and promote uptake by the cells. Confocal microscopy experiments demonstrated that in comparison to the non-quaternized analogues, the uptake of the functionalized nanoparticles by Candida albicans was improved. Therefore the methylation of silica surfaces as described here appears to be a more general strategy to improve the uptake of functionalized nano-silica particles by these cells. There is evidence from these studies that in this case the nanoparticles penetrated the cell wall but did not penetrate the nuclear membrane, thus allowing selective cell biolabeling.

Quality of life: a reappraisal

Purpose – With this reappraisal, the purpose of this paper is to present a reflexion on and discussion of the concept of quality of life (QL) with the intention of delimiting its meaning and application within the scope of the research project entitled “Costs and benefits of urban dispersion on a local scale”.Design/methodology/approach – The concept of QL contains a significant degree of complexity and multidimensional variables, in addition to the dynamic nature inherent in all social phenomena. The application of this concept at a local level and within the context of the Portuguese socio‐territorial reality requires rethinking the concept through the different authors and approaches, in order to delineate the research process, and guarantee its operationalisation, selecting the social indicators than can serve this purpose, with the intent of gaining a clearer understanding of QL as perceived and evaluated by the people and groups living in various dispersed urban areas.Findings – From the readings of...

Movimentos migratórios internos em Portugal (1995-2011): Caracterização exploratória considerando grupos de idades, níveis de habilitações e atividade

Portugal nao dispoe de instrumentos que permitam uma analise aprofundada dos seus movimentos migratorios internos, apesar da sua importância na dinâmica populacional. Neste artigo partimos dos dados do questionario individual do censo de 2001, em que se perguntava a cada individuo se residia no concelho em que e recenseado nos dois e cinco anos anteriores, e dos globais de 2011 relativos a mesma pergunta. Concluimos que, nos dois censos, mais de 6% do total dos residentes num determinado concelho, migraram em data anterior pelo menos uma vez, e cerca de 2% do total de residentes tiveram residencia anterior no estrangeiro. Por outro lado, em 2001, considerando o desenvolvimento dos dados trabalhados, os que se moveram dispunham de mais habilitacoes do que a media da populacao portuguesa no mesmo grupo etario e mostravam niveis mais elevados de emprego.