Biosafety of Rare-Earth-Doped Nanomaterials

Upconversion nanoparticles (UCNPs) exhibit a unique luminescence phenomenon in which lower-energy photons, such as NIR excitation, are converted into higher-energy photons spanning the NIR to the UV region. They are anticipated to have a promising future in clinical applications. Given the extensive potential bio-applications of UCNPs, their biosafety is a matter of great concern and has drawn significant attention. This chapter comprehensively examines representative findings on cellular internalization, biodistribution, excretion, cytotoxicity, and in vivo toxic effects of UCNPs. Finally, the challenges associated with ensuring the biosafety in vivo of UCNPs are also discussed.