Upconversion nanoparticles possess the distinctive power of converting low absorption photons to high emission energies, enabling minimal tissue absorptions and optimal tissue penetrations. Upconversion nanoparticles have a wide range of applications in bioimaging, diagnostics, and therapeutics.

This collection seeks original research across diverse facets of upconversion nanoparticles in bioimaging, encompassing the organelle, subcellular, cellular, tissue, organ and living body levels. Beyond material engineering and imaging application, this collection embraces broad aspects of upconversion nanoparticle synthesis, internalization dynamics and mechanisms, biodistribution and toxicity, property optimizations, as well as coupled to multiple functions and instruments.