Upconversion nanoparticles for potential cancer theranostics

摘要

Rare earth upconversion nanoparticles (UCNPs) are able to emit high-energy photons under excitation by near-infrared (NIR) light, referring to a nonlinear optical upconversion process in which the sequential absorption of two or more photons leads to the emission of light at shorter wavelengths than the excitation photons (anti-Stokes emission). The upconversion luminescence (UCL) from UCNPs exhibits a range of unique properties, such as sharp emission bandwidths, long lifetime, tunable emission, high photostability, low cytotoxic-ity, and importantly, little background auto-fluorescence, making them attractive contrast agents in optical biomedical imaging [1-3].