A new concept for photodynamic therapy (PDT) has been developed based on incorporating a photosensitizer (PS) and a singlet oxygen (¹O₂) quenching/scavenging molecule (Q) onto a disease-targeting carrier, such that the PS becomes activatable by light only when targeting has occurred. This has the potential to give very high disease specificity in PDT treatment. The first model compound designed using this concept 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 increase has been validated by direct ¹O₂ luminescence and lifetime measurements, providing proof-of-concept of this 'PDT beacon.'

Date Published: 18 January 2005
PDF: 10 pages
Proc. SPIE 5630, Optics in Health Care and Biomedical Optics: Diagnostics and Treatment II, (18 January 2005); doi: 10.1117/12.573915

Published in SPIE Proceedings Vol. 5630:
Optics in Health Care and Biomedical Optics: Diagnostics and Treatment II
Britton Chance; Mingzhe Chen; Arthur E. T. Chiou; Qingming Luo, Editor(s)