Auger Electrons Constructed Active Sites on Nanocatalysts for Catalytic Internal Radiotherapy

Excess electrons play important roles for the construction of superficial active sites on nanocatalysts. However, providing excess electrons to nanocatalysts in vivo is still a challenge, which limits the applications of nanocatalysts in biomedicine. Herein, auger electrons (AEs) emitted from radionuclide 125 (¹²⁵I) are used in situ to construct active sites in a nanocatalyst (TiO₂) and the application of this method is further extended to cancer catalytic internal radiotherapy (CIRT). The obtained ¹²⁵I-TiO₂ nanoparticles first construct superficial Ti³⁺ active sites via the reaction between Ti⁴⁺ and AEs. Then Ti³⁺ stretches and weakens the O-H bond of the absorbed H₂O, thus enhancing the radiolysis of H₂O molecules and generating hydroxyl radicals (•OH). All in vitro and in vivo results demonstrate a good CIRT performance. These findings will broaden the application of radionuclides and introduce new perspectives to nanomedicine.