Journal of labelled compounds & radiopharmaceuticals最新文献

DOTA-functionalized bisphosphonates can be useful tools for PET imaging of bone metastases when radiolabeled with ⁶⁸Ga. Moreover, the versatility of DOTA allows the complexation of radiometals with therapeutic applications (e.g., ¹⁷⁷Lu), positioning these bisphosphonates as attractive theranostic agents. Among these molecules, BPAMD is a compound whose radiolabeling with ⁶⁸Ga has already been described, but only through manual methods. Thus, a fully automated protocol for ⁶⁸Ga radiolabeling of BPAMD on the GAIA® ± LUNA® synthesis module was designed, and a thorough study of the radiolabeling conditions was undertaken. [⁶⁸Ga]Ga-BPAMD was produced in good radiochemical purity (> 93%) and high radiochemical yield (> 91%) using 0.3 M HEPES buffer. The nature of the reaction vessel showed no significant effect on the radiolabeling outcome. Similarly, addition of an antiradiolysis compound to the reaction medium did not significantly improve the already excellent stability of [⁶⁸Ga]Ga-BPAMD over time. The radiolabeled product obtained by automated synthesis was evaluated in vivo in healthy mice and confirmed high accumulation in the joints and along the backbone.

Deuterium-labeled pyocyanin was prepared from deuterium-labeled phenazine methosulfate in gram scale by a simplified flow photosynthesis in water. The main product was the protonated red form of pyocyanin-d₃ (Pyo-d₃-H⁺) in 85 % yield. Quantum chemical calculations of NMR support that nitrogen-10 is protonated. The by-products of the photolysis and the stability of the photolysis mixture were carefully characterized by LC-MS and NMR. Four by-products were identified: An isomer of pyocyanin-d₃ (9%), 8-hydroxypyocyanin-d₃ (4%), 1-hydroxyphenazine (0.4%), and phenazine (1%). The Pyo-d₃-H⁺ product was stable in the photolysis solution after storage at 8°C for 2.5 years. Pure blue pyocyanin-d₃ powder was isolated from the red photolysis solution by the Surrey method in 94 % yield. The addition of the red photolysis solution of Pyo-d₃-H⁺ (100 μM) and commercial pyocyanin (100 μM) to Pseudomonas aeruginosa cultures showed the same growth curves demonstrating that the minor impurities in the photolysis solution do not affect the growth behavior of the bacteria. The protonated deuterium-labeled pyocyanin may be used directly in biological experiments, which make the methodology extremely simple and useful for biologists.

The rise of nucleic acid-based therapeutics continues apace. At the same time, the need for radiolabelled oligonucleotides for determination of spatial distribution is increasing. Complex molecular structures with mostly multiple charges and low solubility in organic solvents increase the challenge of integrating radionuclides. In preclinical research, it is important to understand the fate of new drug candidates in biodistribution studies, target binding or biotransformation studies. Depending on a specific question, the selection of a respective radiolabelling strategy is crucial. Radiometals for molecular imaging with positron emission tomography or single-photon computed tomography generally require an attached chelating agent for stable complexation of the metal with the oligonucleotide, whereas labelling using carbon-11/-14 or tritium allows incorporation of the radioisotope into the native structure without altering it. Moreover, the suitability of direct radiolabelling of the oligonucleotide of interest or indirect radiolabelling, for example, by a two-step pretargeting approach, for the study design requires consideration. This review focuses on the challenges of radiolabelling nucleic acid-based molecules with beta-plus, gamma and beta-minus emitters and their use for tracking and monitoring.

Herein, the successful syntheses of D₃- and ¹³C-N-methyl and D₉-tert-butyl Hoechst dyes are presented. This includes the preparation of the labelled D₃- and ¹³C-N-methyl piperazines and D₉-tert-butylated hydroxytoluene precursors. The tert-butyl Hoechst dye is known to bind a specific RNA aptamer. Spectroscopic NMR studies of the labelled Hoechst dye-aptamer complexes allowed for the unambiguous assignment of chemical shifts, as well as the dynamics of the bound dye.

Radionuclide therapy employing alpha emitters holds great potential for personalized cancer treatment. However, certain challenges remain when designing alpha radiopharmaceuticals, including the lack of stability of used radioconjugates due to nuclear decay events. In this work, ultrasmall silver telluride nanoparticles with a core diameter of 2.1 nm were prepared and radiolabeled with lead-212 using a chelator-free method with a radiolabeling efficiency of 75%. The results from the in vitro radiochemical stability assay indicated a very high retention of bismuth-212 despite the internal conversion effects originating from the decay of ²¹²Pb. To further evaluate the potential of the nanoparticles, they were radiolabeled with indium-111, and their cell uptake and subcellular distribution were determined in 2D U87 cells, showing accumulation in the nucleus. Although not intentional, it was observed that the indium-111-radiolabeled nanoparticles induced efficient tumor cell killing, which was attributed to the Auger electrons emitted by indium-111. Combining the results obtained in this work with other favorable properties such as fast renal clearance and the possibility to attach targeting vectors on the surface of the nanoparticles, all well-known from the literature, these ultra-small silver telluride nanoparticles provide exciting opportunities for the design of theragnostic radiopharmaceuticals.

This research presents the development of positron emission tomography (PET) radiotracers for detecting Mycobacterium tuberculosis (MTB) for the diagnosis and monitoring of tuberculosis. Two phage display–derived peptides with proven selective binding to MTB were identified for development into PET radiopharmaceuticals: H8 (linear peptide) and PH1 (cyclic peptide). We sought to functionalize H8/PH1 with NODASA, a bifunctional chelator that allows complexation of PET-compatible radiometals such as gallium-68. Herein, we report on the chelator functionalization, optimized radiosynthesis, and assessment of the radiopharmaceutical properties of [⁶⁸Ga]Ga-NODASA-H8 and [⁶⁸Ga]Ga-NODASA-PH1. Robust radiolabeling was achieved using the established routine method, indicating consistent production of a radiochemically pure product (RCP ≥ 99.6%). For respective [⁶⁸Ga]Ga-NODASA-H8 and [⁶⁸Ga]Ga-NODASA-PH1, relatively high levels of decay-corrected radiochemical yield (91.2% ± 2.3%, 86.7% ± 4.0%) and apparent molar activity (A_m, 3.9 ± 0.8 and 34.0 ± 5.3 GBq/μmol) were reliably achieved within 42 min, suitable for imaging purposes. Notably, [⁶⁸Ga]Ga-NODASA-PH1 remained stable in blood plasma for up to 2 h, while [⁶⁸Ga]Ga-NODASA-H8 degraded within 30 min. For both ⁶⁸Ga peptides, minimal whole-blood cell binding and plasma protein binding were observed, indicating a favorable pharmaceutical behavior. [⁶⁸Ga]Ga-NODASA-PH1 is a promising candidate for further in vitro/in vivo evaluation as a tuberculosis-specific infection imaging agent.