# Gd2O3 Doped with Yb3+/Er3+ for Boosted Downshifting Pathway in NIR-IIb Region and Exploring the Dynamics of MRI/NIR-II Imaging in the Nanophosphor

## TL;DR

This paper introduces Gd2O3 nanoparticles doped with Yb3+ and Er3+ for enhanced NIR-IIb imaging and MRI, offering high brightness and biocompatibility for potential clinical use.

## Contribution

The study presents a novel Gd2O3:Yb3+/Er3+ nanophosphor with high quantum efficiency for NIR-IIb imaging and MRI capabilities.

## Key findings

- The Gd2O3:Yb3+/Er3+ system achieves 22.8% quantum efficiency in the NIR-IIb window.
- The nanophosphor demonstrates superior tissue penetration and low autofluorescence for clearer in vivo imaging.
- Gd3+ ions enable magnetic resonance imaging (MRI) due to their magnetic properties.

## Abstract

Lanthanide-ion-activated
nanoparticles stimulated by
808 or 980
nm lasers present promising applications in biological imaging. This
contribution reveals their physicochemical properties and explores
their potential as near-infrared-II (NIR-II) fluorescent agents for
bioimaging. Specifically, the NIR-IIb window (1500–1700 nm)
has the advantages of low scattering and less autofluorescence from
the tissues, which makes this region suitable for imaging with greater
clarity. Lanthanides offer diverse emission possibilities due to their
rich energy levels, which make them highly effective nanoprobes. This
study focuses on gadolinium oxide (Gd2O3) as
the host material due to its facile fabrication and low toxicity.
The Gd2O3 system is doped with Yb3+ and Er3+ ions and achieves a high quantum efficiency
of 22.8% in the NIR-IIx and NIR-IIb windows. Moreover, the superior
penetrability of the NIR-IIb window is unveiled by the penetration
depth testing and in vivo imaging studies. Additionally,
Gd3+ ions exhibit magnetic properties, which support their
application in magnetic resonance imaging (MRI). This work reveals
the high brightness and high energy transfer efficiency of the Yb3+–Er3+ system and explores the feasibility
of Gd2O3 nanoparticles in MRI. Therefore, we
believe that this work provides a superior and biocompatible candidate
for understanding the dynamics of MRI/NIR-II imaging of the nanophosphor
for clinical applications.