Advanced diagnostic procedures are required to satisfy the continuously increasing demands of modern biomedicine while also addressing the need for cost reduction in public health systems. The development of infrared luminescence-based techniques for in vivo imaging as reliable alternatives to traditional imaging enables applications with simpler and more cost-effective apparatus. To further improve the information provided by in vivo luminescence images, the design and fabrication of enhanced infrared-luminescent contrast agents is required. In this work, we demonstrate how simple dopant engineering can lead to infrared-emitting rare-earth-doped nanoparticles with tunable (0.1-1.5 ms) and medium-independent luminescence lifetimes. The combination of these tunable nanostructures with time-gated infrared imaging and time domain analysis is employed to obtain multiplexed in vivo images that are used for complex biodistribution studies.
Keywords: biological windows; in vivo multiplexing; infrared bioimaging; lifetime spectroscopy; rare-earth-doped nanoparticles.