Chapter 10: Production of Singlet Oxygen by Nanoparticle-Bound Photosensitizers

New improvements in the field of targeted PDT concern the use of nanoparticles that can serve as carriers for anticancer agent delivery. Nanoparticles do indeed offer many advantages such as good colloidal stability, effective protection of encapsulated drugs against enzymes and hydrolysis, surface tailor ability and multipurpose, and easy, synthesis. More importantly, thanks to their size, nanoparticles are a means to allow selective accumulation of the PS in cancer cells due to the enhanced permeability and retention effect of tumor tissues. In this chapter, we will focus on the production of singlet oxygen (¹O₂*) after excitation of PS coupled or encapsulated into nanoparticles possessing a three-dimensional rigid matrix. We define three types of nano-objects: nanoparticles in which the Φ_Δ of photosensitizers increases compared to free photosensitizers, nanoparticles in which the Φ_Δ of the encapsulated PS decreases compared to Φ_Δ of the free photosensitizer and systems in which Φ_Δ of the encapsulated or free PS are similar.