Upconverting rare-earth nanoparticles with a paramagnetic lanthanide complex shell for upconversion fluorescent and magnetic resonance dual-modality imaging

Abstract

Multi-modal imaging based on multifunctional nanoparticles is a promising alternative approach to improve the sensitivity of early cancer diagnosis. In this study, highly upconverting fluorescence and strong relaxivity rare-earth nanoparticles coated with paramagnetic lanthanide complex shells and polyethylene glycol (PEGylated UCNPs@DTPA-Gd(3+)) are synthesized as dual-modality imaging contrast agents (CAs) for upconverting fluorescent and magnetic resonance dual-modality imaging. PEGylated UCNPs@DTPA-Gd(3+) with sizes in the range of 32-86 nm are colloidally stable. They exhibit higher longitudinal relaxivity and transverse relaxivity in water (r1 and r2 values are 7.4 and 27.8 s(-1) per mM Gd(3+), respectively) than does commercial Gd-DTPA (r1 and r2 values of 3.7 and 4.6 s(-1) per mM Gd(3+), respectively). They are found to be biocompatible. In vitro cancer cell imaging shows good imaging contrast of PEGylated UCNPs@DTPA-Gd(3+). In vivo upconversion fluorescent imaging and T1-weighted MRI show excellent enhancement of both fluorescent and MR signals in the livers of mice administered PEGylated UCNPs@DTPA-Gd(3+). All the experimental results indicate that the synthesized PEGylated UCNPs@DTPA-Gd(3+) present great potential for biomedical upconversion of fluorescent and magnetic resonance dual-modality imaging applications.

Fluorescent Nanocomposites

“…In a similar manner, fl uorescent carbon dots were loaded with Gd 3+ ions (Bourlinos et al 2012 ). For functioning as up-converting fl uorescent and magnetic resonance dualmodality imaging contrast agents, the up-converting nanocrystals were coated with paramagnetic lanthanide complex shells (Wang et al 2013 ). They show excellent enhancement of both fl uorescent and NMR signals in experiments in vivo .…”

Synthesis, Characterization and Properties of Novel Coumarin Derivatives and Their Europium Complexes

“…Their fascinating optical properties make the complexes attractive for multiple applications, such as MRI contrast agents [1,2], optical amplifiers [3,4], organic light emitting diodes (OLEDs) [5,6], probes [7,8], lasers [9], etc. The luminescence intensity of rare earth complexes is strongly dependent on the efficiency of ligand absorption in the UV region, the efficiency of ligand-to-metal energy transfer, and the efficiency of rare earth luminescence [10], thus the luminescence intensity of rare earth complexes is relationship to central ion and the structure of organic ligand.…”

Luminescence Enhancement Mechanism of Lanthanide-Doped Hybrid Nanostructures Decorated by Silver Nanocrystals

“…Interest in lanthanide (Ln)-doped luminescent nanocrystals (NCs) continues to be strong due to their potential use in applications such as solar cells, flat panel displays, lasers, drug delivery, and bioimaging [1][2][3][4][5]. Ln-doped NCs show unique luminescent properties, such as large anti-Stokes shift, long excited state lifetimes, and narrow luminescence band widths [6,7].…”

“…Ln-doped NCs show unique luminescent properties, such as large anti-Stokes shift, long excited state lifetimes, and narrow luminescence band widths [6,7]. Several strategies have been proposed for improving their luminescence efficiency including the introduction of co-dopant ions/sensitizers, surface modification of nanoparticles (NPs), local symmetry and interaction adjustment [8][9][10][11][12], and other strategies for increasing the luminescence emission efficiency of Ln-doped NCs [2,4,5].…”