Photodynamic therapy of tumors with pyropheophorbide-a-loaded polyethylene glycol–poly(lactic-co-glycolic acid) nanoparticles

Photodynamic therapy (PDT) has many advantages in treating cancers, but the lack of ideal photosensitizers continues to be a major limitation restricting the clinical utility of PDT. This study aimed to overcome this obstacle by generating pyropheophorbide-a-loaded polyethylene glycol–poly(lactic-co-glycolic acid) nanoparticles (NPs) for efficient tumor-targeted PDT. The fabricated NPs were efficiently internalized in the mitochondrion by cancer cells, and they efficiently killed cancer cells in a dose-dependent manner when activated with light. Systemically delivered NPs were highly enriched in tumor sites, and completely ablated the tumors in a xenograft KB tumor mouse model when illuminated with 680 nm light (156 mW/cm(2), 10 minutes). The results suggested that this tumor-specific NP-delivery system for pyropheophorbide-a has the potential to be used in tumor-targeted PDT.