High Singlet Oxygen Yield Photosensitizer Based Polypeptide Nanoparticles for Low-Power Near-Infrared Light Imaging-Guided Photodynamic Therapy

NIR photosensitizer is attractive for photodynamic therapy (PDT). Low-power light irradiation and imaging-guided PDT makes it possible to increase tissue penetration depth. The pyrrole-substituted iodinated BODIPY (BDPI) molecule was designed and synthesized, and it possesses an intense NIR absorption and emission band, and exhibits a high singlet oxygen quantum yield (Φ_Δ = 0.80) which leads remarkable cytotoxicity upon low power illumination (IC50 = 0.60 μg/mL, 6.1 mW/cm²). After being encapsulated with biocompatibility polypeptide PEG–PLys, polymeric micelles nanoparticles (PBDPI NPs) was obtained that are water-dispersed and passively tumor-targetable. Such enhanced accumulation in tumor area makes it easily traced in vivo due to its NIR fluorescence. In addition, such nanoparticles offer an unprecedented photodynamic therapeutic effect by using a low-power irradiation light, which makes it possible to kill cancer cells in deep tissue efficiently.