Polyoxomolybdate (POM) Nanoclusters with Radiosensitizing and Scintillating Properties for Low Dose X-ray Inducible Radiation-Radiodynamic Therapy

In order to overcome the weak penetrability of near infrared (NIR) light in photodynamic therapy (PDT), X-ray radiation (X-RT) with high deep tissue penetration could be served as a therapeutic option to destruct completely tumor. Herein, polyoxomolybdate nanoclusters (POMo NCs) with rose Bengal (RB) loading, and then functionalize with chitosan (CS) and polyethylene glycol (PEG) for X-ray inducible radiation and radiodynamic therapy (X-RRDT). Our obtained POMo NCs demonstrate the strawberry shape containing 163 of Mo (Mo)3 units of three edge sharing MoO6 octahedra and connecting to the central PO4 octahedron. Under low dose of X-ray radiation, communal effect of radiosensitization and scintillation of POMo NCs along with RB, can decrease the side effect of RT and enhance both RT and PDT efficacy. It is because that the POMo NCs can not only augment RT efficacy by producing auger electrons which directly provoke DNA damages, but also enhance PDT efficacy by converting high energy X-ray into light to stimulate RB to generate singlet oxygen (1O2). In vivo results show that X-RRDT using POMo NCs significant inhibit the tumor growth under low dose X-ray radiation. More importantly, the as-made PEGylated POMo NCs cause no obvious side-effect to the major normal organs through the histological examination. This work describes a simple strategy to design effective X-RRDT agents with multiple properties including X-ray radiosensitizing, X-ray scintillating and photosensitizing for X-RRDT under low dose X-ray irradiation. Our developed strategy will further promote the cancer therapeutic efficiency under low dose of X-ray radiation, and bring hopeful for clinical cancer treatment.