Development of Chemical Tags for Universal Lipid Nanoparticle Visualization and Tracking in 2D and 3D Imaging

Precise delivery of therapeutic agents to specific cells and subcellular compartments is crucial for effective disease treatment. Lipid nanoparticles (LNPs) are promising drugs and gene nanocarriers, but understanding their transport within cells and tissues remains limited. We developed SPARKLE (Strategic Peptide, Anchored, Retained, and Kept after Lipid Elimination), a fluorescent peptide tag designed to track LNPs with advanced optical imaging techniques that involve lipid disruption (e.g., cell permeabilization or tissue clearing). Unlike conventional lipophilic dyes that wash out during lipid disruption, SPARKLE tags are retained and fluorescently mark the positions of LNPs. As proof of concept, we demonstrated the utility of SPARKLE tags by tracking LNPs <i>in vitro</i> using the cell painting assay and <i>in vivo</i> within tissues using CLARITY tissue clearing and 3D light-sheet microscopy. SPARKLE tags can offer valuable insights into LNP behavior in biological environments, enhancing the understanding of their targeting and cargo release for clinical translation.