Recent progress on lanthanide-doped photon conversion nanoparticles for biological and medical applications

Lanthanide-doped nanoparticles possess exceptional optical properties, including photon upconversion and downconversion, long emission lifetimes, narrow bandwidths, and outstanding photostability, establishing their prominence in optical detection and imaging, particularly in biological and medical contexts. This review offers a comprehensive overview of recent advancements in enhancing their photon conversion efficiency and explores their applications across biological and medical fields. While they have driven major progress in biological research, clinical adoption remains limited by regulatory and ethical hurdles, notably the lack of the U.S. Food and Drug Administration approval for human use. However, their compatibility with medical devices presents a promising avenue for overcoming these barriers. We conclude by highlighting current limitations and proposing strategic directions to advance the clinical translation of these luminescent systems.