Poly(Lactide-Co-Glycolide) Nanoparticles Co-Loaded with Chlorophyllin and Quantum Dots as Photodynamic Therapy Agents

Abstract

Photodynamic therapy (PDT) is an approach to treating cancer and involves light-induced activation of a photosensitizer that triggers the formation of reactive oxygen species (ROS) in targeted cells and subsequent cell death. Examples of photosensitizers are porphyrins, including the natural compound chlorophyll. These molecules can be delivered alone or co-formulated with an agent, such as quantum dots (QDs), that is able to excite them through a fluorescence resonance energy transfer (FRET)-based mechanism. We encapsulated a chlorophyllin copper complex and CdSe/ZnS core-shell QDs into biodegradable nanoparticles (NPs) composed of poly(lactide-co-glycolide) (PLGA), that allow modification with specific targeting ligands. When excited at 365 nm, FRET occurs between co-encapsulated QDs and chlorophyllin to result in the formation of ROS. This chlorophyllin-QD coformulation allows generation of ROS both in an aqueous environment and in cells, thus confirming the potential of this formulation in PDT.

Keywords: chlorophyllin; cytotoxicity; nanoparticles; photodynamic therapy; quantum dots.