abstract
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.
keywords
ORGANIC-INORGANIC HYBRIDS; SOL-GEL APPROACH; DIETHYLENETRIAMINEPENTAACETIC ACID; GAMMA-AMINOPROPYLTRIETHOXYSILANE; EUROPIUM COMPLEXES; LUMINESCENT PROBES; MODIFIED SBA-15; QUANTUM DOTS; MRI; FLUORESCENT
subject category
Engineering; Materials Science
authors
Pinho, SLC; Faneca, H; Geraldes, CFGC; Delville, MH; Carlos, LD; Rocha, J
our authors
João Rocha
Full Professor
Luís Carlos
Full professorProjects
Nanostructured Photoluminescent rare-earth nanotubes and microporous silicates (PTDC/CTM/73243/2006)
acknowledgements
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