Dye: Photodynamic Therapy

Definition

Photodynamic therapy may be thought of as a directed and controlled application of the cellular damage possible from light energy. There are two main areas of clinical interest, these being the photodynamic therapy of cancer (shortened to PDT) and the parallel application to microbial disease and infection control, the latter having several names, including photodynamic antimicrobial chemotherapy (PACT, used in this review), antimicrobial photodynamic therapy (APDT), and photodynamic disinfection (PDD). For both areas of clinical interest, in order to target and mediate cellular damage, a light-absorbing chemical, called a photosensitizer, is employed.

In both the anticancer and antimicrobial guises, the underlying science is the same, namely, (i) uptake by or association of the target cell with a photosensitizer, (ii) illumination of the target cell and the concomitant electronic excitation of the photosensitizer, and (iii) chemical reaction of the photosensitizer with its...