Magnetoluminescent Agents for Dual MRI and Time‐Gated Fluorescence Imaging

Abstract

AbstractThe synthesis and properties of two luminescent iron oxide nanoparticles for dual imaging by MRI and time‐gated confocal microscopy are presented. These magnetoplasmonic agents consist of macrocyclic terbium complexes conjugated onto magnetite nanoparticles by a polyethylene glycol linker. Two macrocyclic terbium complexes were investigated: Tb‐DOTAm‐(Phen)3 and Tb‐DOTAm‐(acetylene)3. Both complexes display the characteristic long luminescence lifetimes of lanthanides (0.8 ms and 1.3 ms, respectively), rendering them ideal for time‐gated luminescence spectroscopy and confocal imaging – a feature currently unexplored in multimodal imaging agents. Additionally, the 5 ± 1 nm magnetite nanoparticles, with their permeable PEG coating and stable dopamide anchor, render the two constructs efficient MRI contrast agents with longitudinal (r1) and transverse (r2) relaxivities of 9.8 mM–1Fe s–1 and 98 mM–1Fe s–1 at 60 MHz and 37 °C.