Radiolabeled magnetic nanoparticles (MNPs) coated with hydrophilic phosphate ligands, i.e., imidodiphosphate (IDP) and inositol hexaphosphate (IHP), were developed as multifunctional agents to localize both radioactivity and magnetic energy at a tumor site. The coating of MNPs with phosphates made them biocompatible, increased their colloidal stability and allowed binding of the radionuclide ⁹⁰Y to the available functional groups on the surface of the MNPs. IDP and IHP have not hitherto been used for the coating of MNPs and the results of this study of the functionalized MNPs showed that the phosphate groups influenced the modification of the surface of MNPs. Characterization of the MNPs was performed using X-ray powder diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, dynamic light scattering and laser Doppler electrophoresis. The specific power absorption values obtained for MNPs (46.95–80.76 W g⁻¹) in different physiological media indicated their possible application in hyperthermia treatment. Both types of coated MNPs were ⁹⁰Y-labeled in a reproducible high yield (>98%). In vitro studies of ⁹⁰Y-MNPs in saline and human serum showed their high stability after 72 h. The biodistribution pattern of the MNPs after intravenous administration to healthy Wistar rats was followed by the radiotracer method, revealing that ⁹⁰Y-Fe₃O₄-IDP and ⁹⁰Y-Fe₃O₄-IHP MNPs were predominantly found in the liver (85.21% ID and 86.22% ID), followed by the spleen (9.23% ID and 8.82% ID) and the lungs (1.53% ID and 1.53% ID). The results of this comprehensive study showed that radiolabeled biocompatible phosphate magnetic complexes hold great promise for therapeutic uses combining magnetic hyperthermia and radiotherapy.

As an alternative to classical brachytherapy, intratumoral injection of radionuclide-labeled nanoparticles (nanobrachytherapy, NBT) has been investigated as a superior delivery method over an intravenous route for radionuclide therapy of solid tumors. We created superparamagnetic iron oxide nanoparticles (SPIONs) coated with meso-1,2-dimercaptosuccinic acid (DMSA) and radiolabeled with Lutetium-177 (¹⁷⁷Lu), generating ¹⁷⁷Lu-DMSA@SPIONs as a potential antitumor agent for nanobrachytherapy. Efficient radiolabeling of DMSA@SPIONS by ¹⁷⁷Lu resulted in a stable bond with minimal leakage in vitro. After an intratumoral injection to mouse colorectal CT-26 or breast 4T1 subcutaneous tumors, the nanoparticles remained well localized at the injection site for weeks, with limited leakage. The dose of 3.70 MBq/100 µg/50 µL of ¹⁷⁷Lu-DMSA@SPIONs applied intratumorally resulted in a high therapeutic efficacy, without signs of general toxicity. A decreased dose of 1.85 MBq/100 µg/50 µL still retained therapeutic efficacy, while an increased dose of 9.25 MBq/100 µg/50 µL did not significantly benefit the therapy. Histopathology analysis revealed that the ¹⁷⁷Lu-DMSA@SPIONs act within a limited range around the injection site, which explains the good therapeutic efficacy achieved by a single administration of a relatively low dose without the need for increased or repeated dosing. Overall, ¹⁷⁷Lu-DMSA@SPIONs are safe and potent agents suitable for intra-tumoral administration for localized tumor radionuclide therapy.

Two diphosphonates, etidronic acid (HEDP) and zoledronic acid (ZOL), were radiolabelled with ¹⁶¹Tb and evaluated as potential bone-targeting radiopharmaceuticals. Radiolabeling was performed at pH 7, achieving high radiolabeling yields (greater than 98%) and demonstrating excellent in vitro stability in saline and human serum. Both radiolabeled complexes exhibited hydrophilic behavior, a strong binding affinity to hydroxyapatite, and moderate to high plasma protein binding. Biodistribution studies in healthy Wistar rats demonstrated that ¹⁶¹Tb-HEDP and ¹⁶¹Tb-ZOL achieve high and stable skeletal uptake with rapid blood clearance and minimal soft tissue accumulation. ¹⁶¹Tb-HEDP favored higher initial bone localization, while ¹⁶¹Tb-ZOL showed lower renal and hepatic accumulation, indicating higher safety and selectivity. Compared to unchelated ¹⁶¹TbCl₃, both diphosphonate complexes exhibited significantly higher bone-to-kidney and bone-to-liver ratios, resulting in superior targeting. Complementary experiments with non-radioactive terbium were performed to investigate the redox behavior and confirm complex formation, providing valuable insight into the stability and binding modes of the ligands. Both terbium and the ligands displayed well-defined redox behavior within the potential range of −1 to 1.7 V, with complex formation evidenced by shifts in the oxidation peaks. Density functional theory (DFT) calculations further supported these findings, showing that both phosphonate groups of a ligand coordinate to Tb³⁺, while the hydroxyl groups in HEDP enable intermolecular hydrogen bonding, contributing to additional structural stabilization. Results encourage further investigations of ¹⁶¹Tb-labeled diphosphonates as promising candidates for radionuclide therapy of bone metastases and other skeletal diseases.

A MINI-REVIEW OF ELECTROANALYTICAL METHODS FOR PESTICIDES QUANTIFICATION

Radiopharmaceuticals based on 90Y are widely used in the treatment of malignant deseases. In order to meet the requirements for their future application, a 90Sr/90Y generator was developed and 90Y eluted from this locally produced generator was used for the radiolabelling of the DOTA-conjugated somatostatin analog [DOTA0,Tyr3] octreotate and the preparation of [90Y-DOTA0,Tyr3] octreotate (90Y-DOTATATE) for peptide receptore radionuclide therapy. 90Sr/90Y generator was based on the electrochemical separation of 90Y from 90Sr in a two-cycle electrolysis procedure. Three electrode cells were used to perform both electrolyses. In both cycles, working electrodes were kept on constant potential. The pH of the solution was adjusted to 2.7 of the value before the electrolyses. The radionuclidic purity of the 90Y solution was analysed by ITLC and extraction paper chromatography. The labelling of peptide (100 mg DOTATATE) with 90YCl3 was performed at 95?C for 30 minutes. Radiochemical purity was determined by HPLC and chromatographic separation, using a solid SepPak C-18 column. Results obtained confirmed the efficiency of our electrochemical separation technique and quality control methods for 90Y. The achieved efficiency of the 90Sr/90Y generator above 96% of the theoretical value represents a good basis for the further development of this generator. The labelling of the DOTATATE with 90Y exhibited a high efficiency, too: there was less than 1% of 90Y3+in the 90Y-DOTATATE.