Multimodal bioimaging using a rare earth doped Gd2O2S:Yb/Er phosphor with upconversion luminescence and magnetic resonance properties

Abstract

While infrared upconversion imaging using halide nanoparticles are so common the search for a very efficient halide free upconverting phosphors is still lacking. In this article we report Gd2O2S:Yb/Er,YbHo,YbTm systems as a very efficient alternative phosphors that show upconversion efficiency comparable or even higher than existing halide phosphors. While the majority of rare earth dopants provide the necessary features for optical imaging, the paramagnetic Gd ion also contributes to the magnetic imaging,thereby resulting in a system with bimodal imaging features. Results from imaging of the nanoparticles together with aggregates of cultured cells have suggested that imaging of the particles in living animals may be possible. In vitro tests revealed no signficant toxicity because no cell death was observed when the nanoparticles were in the presence of growing cells in culture. Measurement of the magnetization of the phosphor shows that the particles are strongly magnetic, thus making them suitable as an MRI agent.

Stokes emission in GdF3:Nd3+nanoparticles for bioimaging probes

“…35 In our recent studies, downconversion (Stokes) emission at 1064 nm from fluoride based nanoparticles was detected through a thickness up to 4.93 mm of pig skin under 800 nm excitation compared to that of 1.3 mm for UC emission (red) under 980 nm excitation. 36, 37 These effects may be due to the higher absorption coefficient of water (0.48 cm −1 ) at 980 nm compared to that of 0.02 cm −1 at 800 nm. More importantly, at 800 nm excitation, a larger portion of incident photons is absorbed by hemoglobin, instead of water.…”

Water dispersion of magnetic nanoparticles with selective Biofunctionality for enhanced plasmonic biosensing

“…The data clearly showed that the NaOL-coated MNPs were the most magnetic in nature which was again confirmed by measuring the magnetic moment per nanoparticle. By fitting the magnetization curve with the Langevin function [23], the moment per particle was found to be 10,050 μ B , 11,390 μ B , and 14,740 μ B respectively for oleic acid-coated (in solvent), CTAB-coated (aqueous) and NaOL-coated (aqueous) MNPs. For the CTAB-coated MNPs, the saturation magnetization (15 emu/g) was reduced after phase transfer, as compared to the MNPs in solvent (20 emu/g).…”

Eu3+ doped α-sodium gadolinium fluoride luminomagnetic nanophosphor as a bimodal nanoprobe for high-contrast in vitro bioimaging and external magnetic field tracking applications

“…Therefore, it is a hypersensitive transition . 2,16,17 The number of the 5 D 0 – 7 F J (J = 1, 2, 3, 4) emission lines is governed by the selection rules, which depend on the local symmetry of the crystal fields around the sites that the Eu 3+ ions occupy. 21 The inset of Fig.…”