Sequential Growth of NaYF4:Yb/Er@NaGdF4 Nanodumbbells for Dual-Modality Fluorescence and Magnetic Resonance Imaging

ACS Appl Mater Interfaces. 2017 Mar 22;9(11):9226-9232. doi: 10.1021/acsami.6b16842. Epub 2017 Mar 9.

Abstract

Upconversional core-shell nanostructures have gained considerable attention due to their distinct enhanced fluorescence efficiency, multifunctionality, and specific applications. Recently, we have developed a sequential growth process to fabricate unique upconversion core-shell nanoparticles. Time evolution of morphology for the NaYF4:Yb/Er@NaGdF4 nanodumbbells has been extensively investigated. An Ostwald ripening growth mechanism has been proposed to illustrate the formation of NaYF4:Yb/Er@NaGdF4 nanodumbbells. The hydrophilic NaYF4:Yb/Er@NaGdF4 core-shell nanodumbbells exhibited strong upconversion fluorescence and showed higher magnetic resonance longitudinal relaxivity (r1 = 7.81 mM-1 s-1) than commercial contrast agents (Gd-DTPA). NaYF4:Yb/Er@NaGdF4 nanodumbbells can serve as good candidates for high efficiency fluorescence and magnetic resonance imaging.

Keywords: MR imaging compatibility; nanodumbbells; sequential growth; upconversion nanoparticles.