title: PEG-capped, lanthanide doped GdF3 nanoparticles: luminescent and T2 contrast agents for optical and MRI multimodal imaging.
abstract: A facile method for the synthesis of water dispersible Er(3+)/Yb(3+) and Tm(3+)/Yb(3+) doped upconverting GdF(3) nanoparticles is reported. Strong upconversion emissions are observed in the red (for Er/Yb doped) and near-infrared (for Tm/Yb doped) regions upon laser excitation at 980 nm. The PEG coating ensures a good dispersion of the system in water and reduces the radiationless de-excitation of the excited states of the Er(3+) and Tm(3+) ions by water molecules. The r(2) relaxivity values are quite high with respect to the common T(2)-relaxing agents (22.6 ± 3.4 mM(-1) s(-1) and 15.8 ± 3.4 mM(-1) s(-1) for the Tm/Yb and Er/Yb doped samples, respectively), suggesting that the present NPs can be interesting as T(2) weighted contrast agents for proton MRI purpose. Preliminary experiments conducted in vitro, in stem cell cultures, and in vivo, after subcutaneous injection of the lanthanide-doped GdF(3) NPs, indicate scarce toxic effects. After an intravenous injection in mice, the GdF(3) NPs localize mainly in the liver. The present results indicate that the present Er(3+)/Yb(3+) and Tm(3+)/Yb(3+) doped GdF(3) NPs are suitable candidates to be efficiently used as bimodal probes for both in vitro and in vivo optical and magnetic resonance imaging.
authors.affiliation: Dipartimento di Biotecnologie, Università di Verona and INSTM, UdR Verona, Strada Le Grazie 15, I-37134 Verona, Italy.
authors.forename: Tiziana
authors.initials: T
authors.lastname: Passuello
authors.forename: Marco
authors.initials: M
authors.lastname: Pedroni
authors.forename: Fabio
authors.initials: F
authors.lastname: Piccinelli
authors.forename: Stefano
authors.initials: S
authors.lastname: Polizzi
authors.forename: Pasquina
authors.initials: P
authors.lastname: Marzola
authors.forename: Stefano
authors.initials: S
authors.lastname: Tambalo
authors.forename: Giamaica
authors.initials: G
authors.lastname: Conti
authors.forename: Donatella
authors.initials: D
authors.lastname: Benati
authors.forename: Fiorenzo
authors.initials: F
authors.lastname: Vetrone
authors.forename: Marco
authors.initials: M
authors.lastname: Bettinelli
authors.forename: Adolfo
authors.initials: A
authors.lastname: Speghini
mesh_terms: D000818:Animals; D003106:Colon / Q000000981:diagnostic imaging; D003287:Contrast Media / Q000737:chemistry*; D005063:Europium / Q000737:chemistry; D005682:Gadolinium / Q000737:chemistry*; D028581:Lanthanoid Series Elements / Q000737:chemistry*; D008279:Magnetic Resonance Imaging; D008297:Male; D053768:Metal Nanoparticles / Q000737:chemistry*; D051379:Mice; D008807:Mice, Inbred BALB C; D011092:Polyethylene Glycols / Q000737:chemistry*; D011859:Radiography; D014867:Water / Q000737:chemistry; D015019:Yttrium / Q000737:chemistry
chemical_list: D003287:Contrast Media; D028581:Lanthanoid Series Elements; D014867:Water; D011092:Polyethylene Glycols; D005063:Europium; D015019:Yttrium; D005682:Gadolinium