Lanthanide-doped upconversion nanoparticles (UCNPs) are a promising new generation of imaging agents for bioimaging. Water dispersible UCNPs can be dispersible in aqueous solution, making them highly suitable for applications in biomedicine, environmental monitoring, and other fields where compatibility with water is essential. Like all UCNPs, they absorb low-energy near-infrared (NIR) light and emit higher-energy visible or ultraviolet light through a non-linear optical process.
