Hybrid Nanostructures of Hyperbranched Polyester Loaded with Gd(III) and Dy(III) Ions

Hyperbranched polymers are successful nanoscale functional platforms for loading metal ions and creating promising nanomaterials for medicine. This work presents the synthesis of metal–polymer nanostructures based on a second generation hyperbranched polyester with eight terminal benzoylthiocarbamate (BTC) groups loaded with Gd(III) or Dy(III) ions. Their structure (Fourier transform infrared spectroscopy) and morphology (transmission electron microscopy), photophysical (ultraviolet–visible and luminescence spectroscopy), thermophysical, magnetic activity, relaxivity, and aggregation properties (nanoparticle tracking analysis) were studied. The formation of the metal–polymer complex is carried out by chelation of lanthanide ions −C═O and −C═S groups of the BTC fragment of polyester. Coordination units with composition Ln(III)-3BTC (Ln = Dy, Gd) were localized on the branched polymer platform. The load is three lanthanide ions per branched polyester polybenzoylthiocarbamate macromolecule. Logarithms of stability constants of complexes and composition of coordination polyhedron have been determined. The dysprosium complex is in a paramagnetic state with antiferromagnetic correlations, and the gadolinium complex is in a paramagnetic state. The relaxivity of the Dy(III) and Gd(III) complexes increased by 2.5 and 3 times, respectively, compared to their nitrates. An important achievement is the identification of rare-earth metal (REM)-controlled morphology and self-organization for Dy(III) and Gd(III) complexes with branched polyester polybenzoylthiocarbamate in solution and on the surface. Spherical nanostructures for the dysprosium complex and nanorods for the gadolinium complex were observed. Synthesized REM-loaded nanostructures with polyester polybenzoylthiocarbamates have low hemotoxicity and can be applied in biomedicine.