Embodiments of the synthesis, radiolabeling and biological applications of an activatable tracer that undergoes intramolecular cyclization and aggregation upon activation by cleavage of a blocking moiety are provided. The probes of the disclosure allow for target-controlled self-assembly of small molecules in living subjects for imaging and drug delivery. The aggregated nanoprobes of the disclosure may be detectable optically, by PET detection, magnetic resonance imaging, and the like depending on the detectable reporter attached to the nanoprobe.
