Core-shell AgSiO_2-Protoporphyrin Ⅸ nanoparticle: Effect of the Ag core on reactive oxygen species generation

摘要

Photodynamic therapy (PDT) for cancer is based on the use of a light sensitive molecule to produce, under specific irradiation, toxic reactive oxygen species (ROS). A way to improve the therapy efficiency is to increase the amount of produced ROS near cancer cells. This aim can be achieved by using a metal enhanced process arising when an optically active molecule is located near a metallic nanoparticle (NP). Here, the coupling effect between silver (Ag) NPs and protoporphyrin Ⅸ (PpⅨ) molecules, a clinically approved photosensitizer, is studied compared first, to PpⅨ fluorescence yield and second, to ROS production efficiency. By applying a modified Stober process, PpⅨ was encapsulated into a silica (SiO_2) shell, surrounding a 60 nm sized Ag core. We showed that, compared to SiO_2-PpⅨ NPs, Ag coated SiO_2-PpⅨ NPs dramatically decreased PpⅨ fluorescence together with singlet oxygen production efficiency. However, after incubation time in the dark, the amount of superoxide anions generated by the Ag doped sample was higher than the control sample one.