Multicolor cyanine dendritic dots for real-time, high-resolution tracking of nanoparticle biodistribution

Fluorescence imaging has become a powerful tool for visualizing nanoparticles in drug delivery systems, and multicolor fluorescence imaging offers an intuitive approach to exploring complex biological systems. Here, we present multicolor cyanine-based polylysine (PLL) dendritic dots (Cy3/Cy5/Cy7-PLL; up to eight generations) with a well-defined single-molecule structure and bright, photostable fluorescence. Using these probes, we achieved low-crosstalk three-channel tracking in live mice, enabling high-resolution, real-time visualization of nanoparticle biodistribution and within-subject comparisons that reduce inter-animal variability. By systematically modulating size and surface chemistry, we investigated how these parameters govern biodistribution, encompassing their efficacy in in vitro and in vivo tumor imaging, as well as nanoparticle tracking at both cellular and organ levels. We demonstrate that these multicolor dendritic dots serve as an advanced method for simultaneous, real-time tracking of nanoparticles with different traits, offering significant potential for future applications in various biomedical fields.