Chapter 13 – Upconversion Nanoparticles

Upconversion is an optical process that converts low energy pump photons to high energy pump photons. Surface-modified upconversion nanoparticles (UCNPs) are used for several biomedical applications. Compared to quantum dots, organic flurophores, gold nanoparticles, and other bioimaging agents, UCNPs have low toxicity, high photostability, and show sharp emission wavelength. The intense visible emission from these nanoparticles come under near-infrared region and is not detrimental to biological samples. In this chapter, we review recent advancements of UCNPs in drug delivery, bioimaging, and biological detection, bringing to the forefront the characteristics, strengths, and weakness of these nanoparticles.