Self-Reporting and Splitting Nanopomegranates Potentiate Deep Tissue Cancer Radiotherapy <i>via</i> Elevated Diffusion and Transcytosis.

Abstract

The efficacy of nanoradiosensitizers in cancer therapy has been primarily impeded by their limited accessibility to radioresistant cancer cells residing deep inside tumor tissues. The failure to report tumor response to radiotherapy generally delays adjustment of the treatment schedule and sets up another substantial obstacle to clinical success. Here, we develop a nanopomegranate (RNP) platform that not only visualizes the cancer radiosensitivities but also potentiates deep tissue cancer radiotherapy via elevated passive diffusion and active transcytosis. The RNPs are engineered through the programmed self-assembly of a tumor environment-targeting polymeric matrix and modular building blocks of ultrasmall gold nanoparticles (Au₅). Once RNPs reach the tumors, the environmental acidity triggers the splitting and surface cationization of Au₅. The small dimension of Au₅ allows its passive diffusion, while positive surface charge enables its active transcytosis to cross the tumor interstitium. Meanwhile, the reporter element monitors the feedback of favorable radiotherapy responsiveness by detecting the activated apoptosis after radiation. The pivotal role of RNPs in improving and identifying radiotherapeutic outcomes is demonstrated in various tumor bearing mouse models with different radiosensitivities. In summary, our strategy offers a promising paradigm for deep tissue drug delivery as well as individualized precision radiotherapy.