Engineered gadolinium-doped carbon dots for magnetic resonance imaging-guided radiotherapy of tumors.

Abstract

The effectiveness of radiotherapy can decrease due to inaccurate positioning of machinery and inherent radioresistance of tumors. To address this issue, we present a novel theranostic nanoplatform based on gadolinium-doped carbon dots (Gd-doped CDs) designed specifically for magnetic resonance imaging (MRI)-guided radiotherapy of tumors. The Gd-doped CDs (∼18 nm) with dispersibility in water and stable photoluminescence were synthesized via a one-step hydrothermal approach. After tail vein injection of the Gd-doped CDs, they exhibited a relatively long circulation time (∼6 h), enabled efficient passive tumor targeting. Gd-doped CDs accumulate in the kidney and could be cleared out of the body from bladder. Importantly, they exhibited favorable biocompatibility with excellent performance in longitudinal relaxivity rate (r₁) of 6.45 mM^-1S^-1 and radiosensitization enhancements. These results show that Gd-doped CDs are excellent T₁ contrast agents and radiosensitizers, possessing great promise for MRI-guided radiotherapy of tumors.