acetyl-aspartyl-glutamyl-valyl-aspartal and pyropheophorbide-a

We report a new concept for type-II photosensitization, based on incorporating the photosensitizer (PS) and a singlet-oxygen (1O2) quenching/scavenging molecule onto a disease-targeting linker, such that the PS becomes activatable by light only when targeting has occurred. In this first proof-of-concept report, a model photosensitizing beacon was synthesized containing a pyropheophorbide as the PS and a carotenoid as the 1O2 quencher. These were kept in close proximity by the self-folding of a caspase-3-specific peptide sequence. Upon caspase-3-induced cleavage, the 1O2 production increased markedly, as measured directly by 1O2 near-infrared luminescence and lifetime measurements.

Topics: Carotenoids; Caspase 3; Caspase Inhibitors; Caspases; Chlorophyll; Luminescent Measurements; Oligopeptides; Photosensitizing Agents; Singlet Oxygen