Electron Transfer-Supported Photodynamic Therapy

Abstract

Photodynamic therapy (PDT) is a less-invasive treatment of cancer and precancerous lesions. Porphyrin derivatives have been used and studied as the photosensitizers for PDT. In general, the biomacromolecules oxidation by singlet oxygen, which is produced through energy transfer from the photoexcited photosensitizers to oxygen molecules, is an important mechanism of PDT. However, the traditional PDT effect may be restricted, because tumors are in a hypoxic condition and in certain cases, PDT enhances hypoxia via vascular damage. To solve this problem, the electron transfer-mediated oxidation of biomolecules has been proposed as the PDT mechanism. Specifically, porphyrin phosphorus(V) complexes demonstrate relatively strong photooxidative activity in protein damage through electron transfer. Furthermore, other photosensitizers, e.g., cationic free-base porphyrins, can oxidize biomolecules through electron transfer. The electron transfer-supported PDT may play the important roles in hypoxia cancer therapy. Furthermore, the electron transfer-supported mechanism may contribute to antimicrobial PDT. In this chapter, recent topics about the biomolecules photooxidation by electron transfer-supported mechanism are reviewed.