How Does Photodynamic Therapy Work?

Caetano P. Sabino, BSc, PhD Student, Clinical Analysis, School of Pharmaceutical Sciences, University of Sao Paulo, explains how photodynamic therapy works.

Interview Transcript (slightly modified for readability)

“Photodynamic therapy works pretty much in a similar way as photosynthesis, for example, where plants use pigments—chlorophyll—to absorb sunlight in specific wavelengths. So, there’s blue light, and there’s red light, and it shines back the green light, that we see. The plants use it to donate electrons, [and] to produce glucose; so, this is a chemical reaction that is induced after light absorption. What we do is use other pigments, or dyes, or photoactive drugs that we term as photosensitizers, to absorb light at specific wavelengths, so we have a molecular targeting principle, to produce high yields of reactive oxygen species, and they will be produced only in the region where the photosensitive drug is. So, it’s going to be retained to the bacteria where it was selectively incorporated.”