Improved functionalization of oleic acid-coated iron oxide nanoparticles for biomedical applications

Superparamagnetic iron oxide nanoparticles can providemultiple benefits for biomedical applications in aqueous environments such asmagnetic separation or magnetic resonance imaging. To increase the colloidal stability and allow subsequent reactions, the introduction of hydrophilic functional groups onto the particles’ surface is essential. During this process, the original coating is exchanged by preferably covalently bonded ligands such as trialkoxysilanes. The duration of the silane exchange reaction, which commonly takes more than 24 h, is an important drawback for this approach. In this paper, we present a novel method, which introduces ultrasonication as an energy source to dramatically accelerate this process, resulting in high-quality waterdispersible nanoparticles around 10 nmin size. To prove the generic character, different functional groups were introduced on the surface including polyethylene glycol chains, carboxylic acid, amine, and thiol groups. Their colloidal stability in various aqueous buffer solutions as well as human plasma and serum was investigated to allow implementation in biomedical and sensing applications.status: publishe

Associação entre comportamentos externalizantes e baixo desempenho escolar: uma revisão de estudos prospectivos e longitudinais Association between externalizing behavior and underachievement: a review of prospective and longitudinal studies

Foi feito um levantamento na literatura de estudos prospectivos e longitudinais investigando a associação entre problemas de comportamento externalizantes e baixo desempenho escolar no ensino fundamental, no período de 1990 a 2006. Por meio dos sistemas PsycInfo, Medline, Lilacs, Scielo e Web of Science, foram selecionados e adquiridos 18 artigos, classificados em quatro categorias: estudos com amostras clínicas; estudos comparando grupos com ou sem comorbidade; estudos que buscam testar modelos de trajetória de desenvolvimento; estudos sobre precursores da associação entre problemas de comportamento e baixo desempenho escolar. A análise dos artigos evidencia que a co-ocorrência de baixo desempenho escolar e problemas externalizantes sugere a influência de variáveis antecedentes, como condições adversas na família e baixo nível socioeconômico. Indica, ainda, que a associação traz mau prognóstico às crianças, como comorbidades com transtornos psiquiátricos, posteriores problemas acadêmicos e de comportamento anti-social, evidenciando a situação de risco psicossocial em que se encontram.<br>A survey in the literature of prospective and longitudinal studies was made investigating the association between externalizing behavior and underachievement in the period of 1990-2006. It was used PsycInfo, Medline, Lilacs, Scielo and Web of Science systems and it was selected and acquired 18 articles, classified in four categories: studies with clinical samples; studies comparing groups with or without comorbidity; studies that try to establish or to test models of developmental trajectory; studies of precursors of the association between behavior problems and underachievement. The analysis of articles evidences that the co-occurrence of underachievement and externalizing behavior suggests the influence of antecedent variables, such as adverse conditions in the family and low socio-economic level. It indicates that the association brings bad prognostic to the children, such as comorbidity with psychiatric disorders, later academic problems, and antisocial behavior, evidencing the psychosocial risk situation in that they are