Tuning Near-Infrared-to-Ultraviolet Upconversion in Lanthanide-Doped Nanoparticles for Biomedical Applications

Ultraviolet (UV) radiation offers many exciting biomedical applications such as biosensing and cancer therapy. Photon upconversion through lanthanide (Ln)-doped nanoparticles is an attractive approach for UV generation by excitation of near-infrared (NIR) light, which is readily accessible and highly penetrating in tissue environments. By rationally engineering the emission property of upconversion nanoparticles (UCNPs) coupled with surface functionalization with photoactivatable molecules, various nanosystems can be constructed for biomedicine with the feature of minimal living tissue damage and remote light delivery at high spatiotemporal precisions. Such technology facilitates sensitive diagnosis and effective treatment of various diseases. This review focuses on the recent development of NIR-to-UV UCNPs, simultaneously highlighting emergent biomedical applications enabled by these materials.