In situ 18F-γ-ray-induced Ag nanoparticle formation in the presence of SiO2 nanoparticles under air

The in situ 18 F- γ -ray irradiation of SiO 2 nanoparticles in an aqueous solution containing Ag + led to the reduction of Ag + to Ag 0 aggregates or Ag 0 nanoparticles in a small volume (0.1 ml) under air. 18 F was used in the form of 18 F-fluorodeoxyglucose, produced by a cyclotron at our University hospital. The in situ average absorbed dose at the distance of 1 µm in the solution volume (0.1 ml) was calculated to be 12.2 kGy equivalent to a point source of 20 MBq. The SiO 2 nanoparticles had two effects; they enhanced the reduction of Ag + to Ag 0 aggregates and they acted as reaction sites to prevent aggregation. When Ag + adsorbed on the surface of the SiO 2 nanoparticles, Ag nanoparticles were formed by 18 F γ -rays. The absorption spectra of Ag nanoparticles and Ag 0 aggregates were markedly different.