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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 [ 68 Ga]Ga-NODASA-H8 and [ 68 Ga]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 [ 68 Ga]Ga-NODASA-H8 and [ 68 Ga]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, [ 68 Ga]Ga-NODASA-PH1 remained stable in blood plasma for up to 2 h, while [ 68 Ga]Ga-NODASA-H8 degraded within 30 min. For both 68 Ga peptides, minimal whole-blood cell binding and plasma protein binding were observed, indicating a favorable pharmaceutical behavior. [ 68 Ga]Ga-NODASA-PH1 is a promising candidate for further in vitro/in vivo evaluation as a tuberculosis-specific infection imaging agent., (© 2024 The Author(s). Journal of Labelled Compounds and Radiopharmaceuticals published by John Wiley & Sons Ltd.)

α,β-aromatic lactams are highly abundant in biologically active molecules, yet so far they cannot be radiolabeled with short-lived (t 1/2 =20.3 min), β + -decaying carbon-11, which has prevented their application as positron emission tomography tracers. Herein, we developed, optimized, and applied a widely applicable, one-pot, quick, robust and automatable radiolabeling method for α,β-aromatic lactams starting from [ 11 C]CO 2 using the reagent POCl 3 ⋅AlCl 3 . This method proceeds via intramolecular Friedel-Crafts acylation of in situ formed [ 11 C]isocyanates and shows a broad substrate scope for the formation of five- and six-membered rings. We implemented our developed labeling method for the radiosynthesis of the potential PARP1 PET tracer [carbonyl- 11 C]DPQ in a clinical radiotracer production facility following the standards of the European Pharmacopoeia., (© 2024 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

In order to accommodate the growing demand for positron emission tomography (PET), it will be necessary to create innovative radiochemical and engineering technologies to optimize the manufacture and development of PET probes. Microfluidic devices allow radiosynthesis to be performed in microscale amounts, significantly impacting PET tracer production. Compared to traditional methods, microfluidic devices can produce PET tracers in a shorter time, higher yields, with lower reagent consumption, higher molar activity, and faster purification. This review examines microfluidic devices from an engineering perspective. Recently developed microfluidic radiosynthesis devices are classified into three categories according to their reaction volume: continuous-flow, batch-flow, and droplet-based microreactors. The principles of device architecture, radiosynthesis process, and the relative strengths and limitations of each category are emphasized by citing typical examples. Finally, the possible future applications of this technology are outlined. A flexible, miniature, fully automated radiochemical microfluidic platform will offer more straightforward and cheaper molecular imaging procedures and the potential for precision medicine that could allow operators to create customized tracers for individual patient doses., (© 2022 Wiley-VCH GmbH.)

Functionalization of macromolecules (antibodies, polymers, nanoparticles) with click-reactive groups greatly enhances the versatility of their potential applications. Click chemistry based on tetrazine - trans-cyclooctene (TCO) ligation is especially promising and is already widely applied for pretargeted imaging and therapy. Indirect radiolabeling of TCO-functionalized macromolecules with substoichiometric amounts of radioactive tetrazines is a convenient way to monitor the fate of those macromolecules by means of positron emission tomography (PET) imaging after their administration into the test subject. In this work, the preparation is reported of TCO-containing graft copolymers, namely PeptoBrushes (polyglutamic acid-graft-polysarcosine), novel [ 11 C]carboxylated tetrazines, and their combined use in radiolabeling the polymer by inverse electron demand Diels Alder reaction, to investigate it is potential for an application in pretarget imaging or injectable brachytherapy. The procedure for [ 11 C]tetrazine production is easy and scalable, while indirect TCO-PeptoBrushes labeling with these [ 11 C]tetrazines is mild, fast, and quantitative. This strategy allows facile 11 C-labeling of diverse TCO-functionalized macromolecules, so that their localization and distribution shortly after injection can be assessed by PET., (© 2021 The Authors. Macromolecular Rapid Communications published by Wiley-VCH GmbH.)