Synthesis and characterization of radioisotope nanospheres containing two gamma emitters

Silica-coated gold–silver alloy nanospheres prepared by Stöber’s method were irradiated in a nuclear reactor to prepare radioisotope nanospheres for use as radiotracers. The radioisotope nanospheres included two gamma nuclides: (i) Au-198, emitting major photons with 0.412 MeV and (ii) Ag-108, emitting photons with 0.434 and 0.633 MeV. The nanospheres shell and core diameters were 100–112 nm and 20–50 nm, respectively, depending on their preparation. The gamma-emitting nanospheres could be used as tracers in high-temperature petrochemical and refinery processes in which conventional organic radioactive labels will decompose.