The development of stimulus-responsive photosensitizer delivery systems that carry a high payload of photosensitizers is of great importance in photodynamic therapy. In this study, redox-responsive polysilsesquioxane nanoparticles (PSilQNPs) built by a reverse microemulsion approach using 5,10,15,20-tetrakis(carboxyphenyl) porphyrin (TCPP) silane derivatives as building blocks, were successfully fabricated. The structural properties of TCPP-PSilQNPs were characterized by dynamic light scattering (DLS)/ζ-potential, scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The photophysical properties were determined by UV-vis and fluorescence spectroscopy. The quantity of singlet oxygen generated in solution was measured using 1,3-diphenylisobenzofuran. The redox-responsive release of TCPP molecules was successfully demonstrated in solution in the presence of a reducing agent. The internalization of TCPP-PSilQNPs in cancer cells was investigated using laser scanning confocal microscopy. Phototoxicity experiments in vitro showed that the redox-responsive TCPP-PSilQNPs exhibited an improved phototherapeutic effect on cervical cancer cells compared to a non-responsive TCPP-PSilQNP control material.
Keywords: cancer therapy; photodynamic therapy; photosensitizer delivery; polysilsesquioxane nanoparticles; porphyrin; stimulus-responsive materials.