Upconversion Nanoparticles for Biomedical Imaging

Abstract

Rare-earth upconversion (UC) nanoparticles, when excited by continuous-wave near-infrared (NIR) light, exhibit a unique narrow photoluminescence with higher energy. Such special UC luminescence makes UCNPs promising as bio-imaging probes with attractive features, such as no auto-fluorescence from biological samples and deep penetration depth. As a result, UCNPs have emerged as novel imaging agents for small animals. In this chapter, recent reports regarding the biomedical imaging investigation using UCNPs are summarized. The applications of UCNPs for small-animal imaging, including optical imaging, optical tomography, and multimodal imaging are reviewed in detail. The recent techniques for upconversion imaging and toxicity assessment of UCNPs are also presented. Finally, we discuss the challenges and opportunities in the development of UCNPs for biomedical imaging.