Silver impregnated nanoparticles of titanium dioxide as carriers for 211At

Abstract

Abstract The 211At radioisotope exhibits very attractive nuclear properties for application in radionuclide therapy. Unfortunately use of 211At is limited, because astatine as the heaviest halogen forms weak bond with carbon atoms in the biomolecules which makes 211At bioconjugates unstable in physiological conditions. In our work we propose a new solution for binding of 211At which consists of using nanoparticles of titanium dioxide modified with silver atoms as carriers for 211At. Ag+ cations have been absorbed on the nanometer-sized TiO2 particles (15 and 32 nm) through ion exchange process and were reduced in Tollens' reaction. The obtained TiO2-Ag nanoparticles were labeled with 211At. It was found that labeling yields were almost quantitative under reducing conditions, while under oxidizing conditions they dropped to about 80%. The labeled nanoparticles exhibited very high stability in physiological salt, PBS buffer, solutions of peptides (0.001 M cysteine, 0.001 M glutathione) and in human blood serum. To make TiO2/Ag nanoparticles well dispersed in water and biocompatible their surface was modified with a silane coupling agent containing poly(ethyleneglycol) molecules. The developed functionalization approach will allow us to attach biomolecules to the TiO2/Ag surface.