Far red and NIR dye-peptoid conjugates for efficient immune cell labelling and tracking in preclinical models

Innate immune cell ingress into the site of inflammation is central for the efficient clearance of pathogens. However, in some circumstances the inflammatory response may become pathogenic to the host. Understanding the temporal ingress of innate immune cells is thus essential to predict both the defensive and adverse effects mediated by these cells in an infectious process and for developing novel therapeutic strategies. In this context, optical imaging has emerged as a powerful technique for the visualization of specific cellular events in preclinical models. Herein we describe a non-covalent tagging strategy to stably label innate immune cells using in vivo-traceable cell penetrating peptoids and their application in real-time imaging of cell migration in murine models, thereby providing a sensitive and cost effective way to visualize cellular recruitment in preclinical models of inflammation.