Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 2 de 2
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Small ; 10(16): 3325-37, 2014 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-24797733

RESUMO

Understanding the relation between the structure and the reactivity of nanomaterials in the organism is a crucial step towards efficient and safe biomedical applications. The multi-scale approach reported here, allows following the magnetic and structural transformations of multicore maghemite nanoflowers in a medium mimicking intracellular lysosomal environment. By confronting atomic-scale and macroscopic information on the biodegradation of these complex nanostuctures, we can unravel the mechanisms involved in the critical alterations of their hyperthermic power and their Magnetic Resonance imaging T1 and T2 contrast effect. This transformation of multicore nanoparticles with outstanding magnetic properties into poorly magnetic single core clusters highlights the harmful influence of cellular medium on the therapeutic and diagnosis effectiveness of iron oxide-based nanomaterials. As biodegradation occurs through surface reactivity mechanism, we demonstrate that the inert activity of gold nanoshells can be exploited to protect iron oxide nanostructures. Such inorganic nanoshields could be a relevant strategy to modulate the degradability and ultimately the long term fate of nanomaterials in the organism.


Assuntos
Biodegradação Ambiental , Compostos Férricos/química , Ouro/química , Nanoestruturas , Imageamento por Ressonância Magnética , Microscopia Eletrônica de Transmissão
2.
ACS Nano ; 6(12): 10935-49, 2012 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-23167525

RESUMO

In the pursuit of optimized magnetic nanostructures for diagnostic and therapeutic applications, the role of nanoparticle architecture has been poorly investigated. In this study, we demonstrate that the internal collective organization of multi-core iron oxide nanoparticles can modulate their magnetic properties in such a way as to critically enhance their hyperthermic efficiency and their MRI T(1) and T(2) contrast effect. Multi-core nanoparticles composed of maghemite cores were synthesized through a polyol approach, and subsequent electrostatic colloidal sorting was used to fractionate the suspensions by size and hence magnetic properties. We obtained stable suspensions of citrate-stabilized nanostructures ranging from single-core 10 nm nanoparticles to multi-core magnetically cooperative 30 nm nanoparticles. Three-dimensional oriented attachment of primary cores results in enhanced magnetic susceptibility and decreased surface disorder compared to individual cores, while preserving a superparamagnetic-like behavior of the multi-core structures and potentiating thermal losses. Exchange coupling in the multi-core nanoparticles modifies the dynamics of the magnetic moment in such a way that both the longitudinal and transverse NMR relaxivities are also enhanced. Long-term MRI detection of tumor cells and their efficient destruction by magnetic hyperthermia can be achieved thanks to a facile and nontoxic cell uptake of these iron oxide nanostructures. This study proves for the first time that cooperative magnetic behavior within highly crystalline iron oxide superparamagnetic multi-core nanoparticles can improve simultaneously therapeutic and diagnosis effectiveness over existing nanostructures, while preserving biocompatibility.


Assuntos
Compostos Férricos/uso terapêutico , Hipertermia Induzida/métodos , Imageamento por Ressonância Magnética/métodos , Nanopartículas/uso terapêutico , Ácido Cítrico/química , Meios de Contraste/química , Meios de Contraste/uso terapêutico , Compostos Férricos/química , Humanos , Células MCF-7 , Fenômenos Magnéticos , Nanopartículas/química , Tamanho da Partícula , Eletricidade Estática
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...