resumo
The design and synthesis of a combined MRI-optical probe for bio-imaging are reported. The materials studied join the properties of lanthanide (Ln(3+)) complexes and nanoparticles (NPs), offering an excellent solution for bimodal imaging. The hybrid SiO(2)@APS/DTPA:Gd:Ln (Ln = Eu(3+) or Tb(3+)) (APS: 3-aminopropyltriethoxysilane, DTPA: diethylenetriamine pentaacetic acid) system increases the payload of the active magnetic centre (Gd(3+)) and introduces a Ln(3+) long-life excited state (Eu(3+): 0.35 +/- 0.02 ms, Tb(3+): 1.87 +/- 0.02 ms), with resistance to photobleaching and sharp emission bands. The Eu(3+) ions reside in a single low-symmetry site. Although the photoluminescence emission is not influenced by the simultaneous presence of Gd(3+) and Eu(3+), a moderate r(1) increase and a larger enhancement of r(2) are observed, particularly at high fields, due to susceptibility effects on r(2). The presence of Tb(3+) instead of Eu(3+) further raises r(1) but decreases r(2). These values are constant over a wide (5-13) pH range, indicating the paramagnetic NPs stability and absence of leaching. The uptake of NPs by living cells is fast and results in an intensity increase in the T(1)-weighted MRI images. The optical properties of the NPs in cellular pellets are also studied, confirming their potential as bimodal imaging agents. (C) 2011 Elsevier Ltd. All rights reserved.
palavras-chave
ORGANIC-INORGANIC HYBRIDS; SOL-GEL APPROACH; DIETHYLENETRIAMINEPENTAACETIC ACID; GAMMA-AMINOPROPYLTRIETHOXYSILANE; EUROPIUM COMPLEXES; LUMINESCENT PROBES; MODIFIED SBA-15; QUANTUM DOTS; MRI; FLUORESCENT
categoria
Engineering; Materials Science
autores
Pinho, SLC; Faneca, H; Geraldes, CFGC; Delville, MH; Carlos, LD; Rocha, J
nossos autores
João Rocha
Diretor
Luís António Ferreira Martins Dias Carlos
Professor CatedráticoProjectos
Nanostructured Photoluminescent rare-earth nanotubes and microporous silicates (PTDC/CTM/73243/2006)
agradecimentos
This work was supported by Fundacao para a Ciencia e Tecnologia (FCT), Portugal (project PTDC/CTM/73243/2006 and SFRH/BD/38313/2007 grant to SLCP), the CNRS France, the Region Aquitaine France, FEDER, COST Action D38