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.