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

• Published in: Inorganic chemistry Vol. 58; no. 24; pp. 16618 - 16628
• Main Authors: Pinho, Sonia L. C, Sereno, José, Abrunhosa, Antero J, Delville, Marie-Hélène, Rocha, João, Carlos, Luís D, Geraldes, Carlos F. G. C
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 16.12.2019
• Subjects: Bioengineering; Chemical Sciences; Imaging; Life Sciences; Material chemistry
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/acs.inorgchem.9b02655

Superparamagnetic maghemite core–porous silica shell nanoparticles, γ-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 μg 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.