Biomimetic Upconversion Nanoplatform Synergizes Photodynamic Therapy and Enhanced Radiotherapy against Tumor Metastasis

The easy recurrence and high metastasis of fatal tumorsrequirethe development of a combination therapy, which is able to overcomethe drawbacks of monomodal strategies such as surgery, photodynamictherapy (PDT), and radiotherapy (RT). Taking the complementary advantagesof PDT and RT, we present herein the integration of lanthanide-dopedupconversion nanoparticles (UCNPs) with chlorin e6 (Ce6)-imbeddedRBC membrane vesicles as a near-infrared-induced PDT agent for achievingsynchronous depth PDT and RT with reduced radiation exposure. In sucha nanoagent, gadolinium-doped UCNPs with strong X-ray attenuationability act not only as a light transductor to activate the loadedphotosensitizer Ce6 to allow PDT but also as a radiosensitizer toenhance RT. PDT with enhanced low-dose RT can achieve synergisticinhibition of tumor growth by producing reactive oxygen species todestroy local tumor cells and inducing strong T-cell-dependent immunogeniccell death to arrest systemic cancer metastasis. This combinationof PDT and RT might be a potential appealing strategy for tumor eradication.