Multifunctional beta-NaGdF4:Ln(3+) (Ln = Yb, Er, Dy) nanoparticles with NIR to visible upconversion and high transverse relaxivity: a potential bimodal contrast agent for high-field MRI and optical imaging

© 2016 The Royal Society of Chemistry. A novel series of active-core/active-shell upconverting nanoparticles (AC/AS-UCNPs) based on NaGdF4doped with Yb3+/Er3+in the core and Yb3+/Dy3+in the shell having average particle size between 29.2 and 32.9 nm were synthesized. The UCNPs exhibit favorable properties for bimodal magnetic resonance imaging (MRI) and optical imaging (OI). Excitation of the UCNPs at 980 nm dispersed in water at room temperature resulted in intense green upconversion emission of Er3+. The proton nuclear magnetic relaxation dispersion (1H-NMRD) studies show very low longitudinal relaxivity (r1) values, which decreases with an increase of magnetic field. On the other hand, the transverse relaxivity (r2) values show an increasing trend with both increase in doping of Dy3+as well as the increase in magnetic field reaching a maximum value of r2= 70.07 s-1mM-1(per Ln3+ion) for NaGdF4:Yb3+/Er3+# NaYbF4:38.06% Dy3+at 500 MHz and 310 K. Exhibiting such a high r2value at high magnetic field and intense upconversion luminescence under 980 nm excitation makes these NPs exceptional candidates towards bioimaging applications.

Publication year:2016

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IOF-keylabel:yes

BOF-publication weight:1

CSS-citation score:1

Authors from:Private, Higher Education

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