Versatile Nanoplatforms for Bioimaging and Therapy Using Upconversion Nanoparticles

Upconverting nanoparticles (UCNPs) exert on emitting photons in the visible or ultraviolet range after excitation with near-infrared by upconversion. With the rising need for precise diagnosis and less invasive therapy, bioimaging probes with high signal-to-noise ratios and low intrusive therapeutic approaches are crucial to elevating the medical level. The exclusive characteristics of prolonged lifetimes, sharp emissions, broad antiStokes shift, and almost insignificant photobleaching make UCNPs attractive candidates in bioimaging, biosensors, and cancer therapy. This review encompasses the fundamental mechanisms of UCNPs, followed by various synthesis strategies with multiple bioimaging modalities and clinical approaches. The review aims to provide statistical and concrete information on recent progress in UCNPs implemented in bioimaging and therapy and disclose the prospective potential of UCNPs as theranostic material.