Abstract: Provided is an activatable probe that undergoes intramolecular cyclization and subsequent aggregation in apoptotic tumor cells upon peptidase-initiated, and most advantageously caspase-3, activation. These caspase-sensitive nano-aggregation probes (C-SNAFs) are generally biocompatible, possess NIR spectral properties or may serve as PET or MRI imaging agents, and have a mechanism of target-mediated nanostructure self-assembly amenable to in vivo use. The probes encompass biocompatible condensation chemistry products that comprise D-cysteine and 2-cyano-6-hydroxyquinoline (CHQ) moieties linked to an amino-luciferin scaffold, and which can be activated by a two-step reaction requiring caspase-3/7-mediated cleavage of an aspartate-glutamate-valine-aspartate (L-DEVD) capping peptide and the free intracellular thiol-mediated reduction of the disulfide bond.

Abstract: Provided is an activatable probe that undergoes intramolecular cyclization and subsequent aggregation in apoptotic tumor cells upon peptidase-initiated, and most advantageously caspase-3, activation. These caspase-sensitive nano-aggregation probes (C-SNAFs) are generally biocompatible, possess NIR spectral properties or may serve as PET or MRI imaging agents, and have a mechanism of target-mediated nanostructure self-assembly amenable to in vivo use. The probes encompass biocompatible condensation chemistry products that comprise D-cysteine and 2-cyano-6-hydroxyquinoline (CHQ) moieties linked to an amino-luciferin scaffold, and which can be activated by a two-step reaction requiring caspase-3/7-mediated cleavage of an aspartate-glutamate-valine-aspartate (L-DEVD) capping peptide and the free intracellular thiol-mediated reduction of the disulfide bond.