Gd- and Eu-Loaded Iron Oxide@Silica Core-Shell Nanocomposites as Trimodal Contrast Agents for Magnetic Resonance Imaging and Optical Imaging


Superparamagnetic maghemite core-porous silica shell nanoparticles, gamma-Fe2O3@SiO2 (FS), with 50 nm diameter and a 10 nm core, impregnated with paramagnetic complexes b-Ln ([Ln(btfa)(3)(H2O)(2)]) (where btfa = 4,4,4-trifluoro-L-phenyl-1,3-butanedione and Ln = Gd, Eu, and Gd/Eu), performing as promising trimodal T-1-T-2 MRI and optical imaging contrast agents, are reported. These nanosystems exhibit a high dispersion stability in water and no observable cytotoxic effects, witnessed by intracellular ATP levels. The structure and superparamagnetic properties of the maghemite core nanocrystals are preserved upon imbedding the b-Ln complexes in the shell. Hela cells efficiently and swiftly internalize the NPs into the cytosol, with no observable cytotoxicity below a concentration of 62.5 mu g mL(-1). These nanosystems perform better than the free b-Gd complex as T-1 (positive) contrast agents in cellular pellets, while their performance as T-2 (negative) contrast agents is similar to the FS. Embedding of the b-Eu complex in the silica pores endows the nanoparticles with strong luminescence properties. The impregnation of gadolinium and europium complexes in a 1:1 ratio afforded a trimodal nanoplatform performing as a luminescent probe and a double T-1 and T-2 MRI contrast agent even more efficient than b-Gd used on its own, as observed in cell-labeled imaging experiments and MRI cell pellets.






Pinho, SLC; Sereno, J; Abrunhosa, AJ; Delville, MH; Rocha, J; Carlos, LD; Geraldes, CFGC

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This work was funded by FEDER through the Operational Program Competitiveness Factors-COMPETE and national funds from FCT-Foundation for Science and Technology (Nos. PTDC/NAN-MAT/28060/2017, CENTRO-01-0145FEDER-028060, UID/QUI/00313/2013, PEst-OE/QUI/UI0313/2014) and UID/NEU/04539/2019, the CNRS, the Region Nouvelle Aquitaine France, FEDER, COST Action D38 Metal -Based systems for Molecular Imaging Applications. The work was developed in the scope of the project CICECO Aveiro Institute of Materials (FCT ref. UID/CTM/50011/2019), financed by national funds through FCT/MEC.

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