Emerging NIR light-responsive delivery systems based on lanthanide-doped upconverting nanoparticles.

Together with the development of nanoscience, lanthanide (Ln)-doped upconversion nanoparticles (UCNPs), which can emit UV/VIS light upon irradiation by near-infrared laser sources, is emerging as one of the most favorable materials in the field of nanomedicines. Light-responsive drug delivery is known as an efficient strategy to achieve temporal and spatial controlled drug release. Compared to conventional light-sensitive drug delivery systems, UCNPs are endowed with many advantages, such as deeper tissue penetration and low toxicity. With their unique properties, UCNPs not only serve as potential optical probes for bioimaging but also perform a critical role in therapeutic applications through photon-triggered mechanisms. In particular, UCNPs in combination with different materials and delivery strategies could overcome therapy resistance and enhance therapeutic effectiveness. This article focuses on the current achievements in the last decade of modification methods, diagnostics, and designs of UCNP-based nanoplatforms for successful phototherapy, chemotherapy, and bioimaging.