ИСТИНА

The possibilities for diagnostic and therapy of oncological diseases are based on the accumulation of radionuclides in the affected tissues. Nanoparticles can be considered as a platform for combined radiopharmaceuticals both for diagnostic and therapy. Due to their small size, nanoparticles can deliver the radionuclide closer to the tumor cell nucleus which can reduce the harmful effect of ionizing radiation on healthy tissues. The radionuclide can be bound to the surface of the nanoparticles by surface modification using bifunctional chelators which binds to the nanoparticle and quickly binds the metal into a stable complex. The properties of magnetic nanoparticles make it possible to use them both in diagnostics as a contrast for MRI and magneto-mechanical therapy. Strontium hexaferrite nanoparticles are one of the few hard magnetic materials on the basis of which biocompatible stable colloidal solutions can be obtained. In this work, conjugates of nanoparticles of strontium hexaferrite coated with silicon dioxide (the plate-like shape of nanoparticles with an average diameter of 40 nm) and azacrown ether L with six nitrogen atoms in a macrocycle were obtained by chemical surface modification. Modified strontium hexaferrite nanoparticles were analyzed by IR and Raman spectrometry. Confirmation of the modification of the surface of nanoparticles at each stage were also studied by a series of ζ-potentials measurements at different pH values in the range from 2 to 11 (I = 0.01M) and determination of the isoelectric point by dynamic light scattering. It was shown that the modification of the particles surface with amino groups leads to a shift of the isoelectric point to the region of higher pH values, while the modification of nanoparticles by the ligand shifts it to the region of lower pH values. It was demonstrated by competitive liquid extraction that the resulting conjugates form a stable complex with 207Bi3+ at bismuth concentrations of 10-9M and particle concentrations of 10-3 g/l. Furthermore, the labeled nanoparticle-ligand-radionuclide structure was investigated for their stability in biologically significant media by thin layer chromatography. Thus, conjugates of strontium hexaferrite nanoparticles and azacrown ether L can be further studied as a potential component of radiopharmaceutical for theranostics. The research was funded by RFBR and Moscow city Government, project number 21-33-70023