Coumarin derivative dye sensitized NaYGdF4:Yb,Er nanoparticles with enhanced NIR II luminescence for bio-vascular imaging

Lanthanide-doped biocompatible nanoparticles have promising applications in near-infrared second region imaging due to their high chemical stability, enhanced photostability and sharp emission bandwidth. However, the weak light absorption capacity limits the application of rare-earth nanoparticles (RENPs) for bioimaging. We prepared a coumarin-derived dye sensitized NaYGdF4:Yb,Er nanoparticle probe, in which the organic dye enhances photon absorption through the sensitization process, improving the luminescence efficiency of the rare earth particles near 1000 and 1500 nm. In addition, good water solubility and stability of the probe are imparted by coating the particles with amphiphilic polymers distearoyl phosphatidylethanolamine-polyethylene glycol (DSPE-PEG) and polyacrylic acid. This composite probe with good biocompatibility and NIR II luminescence properties can be used for vascular imaging, providing a tool for the detection of hematologic-related diseases.