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This study introduces a gamma pretreatment of water hyacinth powder for activated carbon (AC) production with improved electrochemical properties for supercapacitor applications. The structural and morphological changes of post-irradiation were meticulously analyzed using scanning electron microscopy (SEM), Raman spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET) analysis, and X-ray photoelectron spectroscopy (XPS). The pretreatment significantly modifies the pore structure and reduces the particle size of the resulting activated carbon (WHAC). Nitrogen adsorption-desorption isotherms indicated a substantial increase in micropore volume with escalating doses of gamma irradiation. Electrochemically, the activated carbon produced from pretreated WH at 100 kGy exhibited a marked increase in specific capacitance, reaching 257.82 F g -1 , a notable improvement over the 95.35 F g -1 of its untreated counterpart, while maintaining 99.40% capacitance after 7000 cycles. These findings suggest that gamma-pretreated biomasses are promising precursors for fabricating high-performance supercapacitor electrodes, offering a viable and environmentally friendly alternative for energy storage technology development.

Recently, radiolabelled antagonists targeting somatostatin receptors subtype 2 (SST2) in neuroendocrine neoplasms demonstrated certain superior properties over agonists. Within the ERA-PerMED project "TECANT" two 99m Tc-Tetramine (N4)-derivatized SST2 antagonists (TECANT-1 and TECANT-2) were studied for the selection of the best candidate for clinical translation. Receptor-affinity, internalization and dissociation studies were performed in human embryonic kidney-293 (HEK293) cells transfected with the human SST2 (HEK-SST2). Log D , protein binding and stability in human serum were assessed. Biodistribution and SPECT/CT studies were carried out in nude mice bearing HEK-SST2 xenografts, together with dosimetric estimations from mouse-to-man. [ 99m Tc]Tc-TECANT-1 showed higher hydrophilicity and lower protein binding than [ 99m Tc]-TECANT-2, while stability was comparable. Both radiotracers revealed similar binding affinity, while [ 99m Tc]Tc-TECANT-1 had higher cellular uptake (>50%, at 2 h/37 °C) and lower dissociation rate (<30%, at 2 h/37 °C). In vivo, [ 99m Tc]Tc-TECANT-1 showed lower blood values, kidney and muscles uptake, whereas tumour uptake was comparable to [ 99m Tc]Tc-TECANT-2. SPECT/CT imaging confirmed the biodistribution results, providing the best tumour-to-background image contrast for [ 99m Tc]Tc-TECANT-1 at 4 h post-injection (p.i.). The estimated radiation dose amounted to approximately 6 µSv/MBq for both radiotracers. This preclinical study provided the basis of selection of [ 99m Tc]Tc-TECANT-1 for clinical translation of the first 99m Tc-based SST2 antagonist.

Hybrid imaging combining the beneficial properties of radioactivity and optical imaging within one imaging probe has gained increasing interest in radiopharmaceutical research. In this study, we modified the macrocyclic gallium-68 chelator fusarinine C (FSC) by conjugating a fluorescent moiety and tetrazine (Tz) moieties. The resulting hybrid imaging agents were used for pretargeting applications utilizing click reactions with a trans -cyclooctene (TCO) tagged targeting vector for a proof of principle both in vitro and in vivo. Starting from FSC, the fluorophores Sulfocyanine-5, Sulfocyanine-7, or IRDye800CW were conjugated, followed by introduction of one or two Tz motifs, resulting in mono and dimeric Tz conjugates. Evaluation included fluorescence microscopy, binding studies, logD, protein binding, in vivo biodistribution, µPET (micro-positron emission tomography), and optical imaging (OI) studies. 68 Ga-labeled conjugates showed suitable hydrophilicity, high stability, and specific targeting properties towards Rituximab-TCO pre-treated CD20 expressing Raji cells. Biodistribution studies showed fast clearance and low accumulation in non-targeted organs for both SulfoCy5- and IRDye800CW-conjugates. In an alendronate-TCO based bone targeting model the dimeric IRDye800CW-conjugate resulted in specific targeting using PET and OI, superior to the monomer. This proof of concept study showed that the preparation of FSC-Tz hybrid imaging agents for pretargeting applications is feasible, making such compounds suitable for hybrid imaging applications.

Aspergillus fumigatus ( A. fumigatus ) is a human pathogen causing severe invasive fungal infections, lacking sensitive and selective diagnostic tools. A. fumigatus secretes the siderophore desferri-triacetylfusarinine C (TAFC) to acquire iron from the human host. TAFC can be labelled with gallium-68 to perform positron emission tomography (PET/CT) scans. Here, we aimed to chemically modify TAFC with fluorescent dyes to combine PET/CT with optical imaging for hybrid imaging applications. Starting from ferric diacetylfusarinine C ([Fe]DAFC), different fluorescent dyes were conjugated (Cy5, SulfoCy5, SulfoCy7, IRDye 800CW, ATTO700) and labelled with gallium-68 for in vitro and in vivo characterisation. Uptake assays, growth assays and live-cell imaging as well as biodistribution, PET/CT and ex vivo optical imaging in an infection model was performed. Novel fluorophore conjugates were recognized by the fungal TAFC transporter MirB and could be utilized as iron source. Fluorescence microscopy showed partial accumulation into hyphae. µPET/CT scans of an invasive pulmonary aspergillosis (IPA) rat model revealed diverse biodistribution patterns for each fluorophore. [ 68 Ga]Ga-DAFC-Cy5/SufloCy7 and -IRDye 800CW lead to a visualization of the infected region of the lung. Optical imaging of ex vivo lungs corresponded to PET images with high contrast of infection versus non-infected areas. Although fluorophores had a decisive influence on targeting and pharmacokinetics, these siderophores have potential as a hybrid imaging compounds combining PET/CT with optical imaging applications., Competing Interests: The authors declare no conflict of interest.

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Fusarinine C (FSC) has recently been shown to be a promising and novel chelator for 89 Zr. Here, FSC has been further derivatized to optimize the complexation properties of FSC-based chelators for 89 Zr-labeling by introducing additional carboxylic groups. These were expected to improve the stability of 89 Zr-complexes by saturating the 8-coordination sphere of [ 89 Zr] Zr 4+ , and also to introduce functionalities suitable for conjugation to targeting vectors such as monoclonal antibodies. For proof of concept, succinic acid derivatization at the amine groups of FSC was carried out, resulting in FSC(succ)₂ and FSC(succ)₃. FSC(succ)₂ was further derivatized to FSC(succ)₂ AA by reacting with acetic anhydride (AA). The Zr 4+ complexation properties of these chelators were studied by reacting with ZrCl₄. Partition coefficient, protein binding, serum stability, acid dissociation, and transchelation studies of 89 Zr-complexes were carried out in vitro and the results were compared with those for 89 Zr-desferrioxamine B ([ 89 Zr]Zr-DFO) and 89 Zr-triacetylfusarinine C ([ 89 Zr]Zr-TAFC). The in vivo properties of [ 89 Zr]Zr-FSC(succ)₃ were further compared with [ 89 Zr]Zr-TAFC in BALB/c mice using micro-positron emission tomography/computer tomography (microPET/CT) imaging. Fusarinine C (succ)₂AA and FSC(succ)₃ were synthesized with satisfactory yields. Complexation with ZrCl₄ was achieved using a simple strategy resulting in high-purity Zr-FSC(succ)₂AA and Zr-FSC(succ)₃ with 1:1 stoichiometry. Distribution coefficients of 89 Zr-complexes revealed increased hydrophilic character compared to [ 89 Zr]Zr-TAFC. All radioligands showed high stability in phosphate buffered saline (PBS) and human serum and low protein-bound activity over a period of seven days. Acid dissociation and transchelation studies exhibited a range of in vitro stabilities following the order: [ 89 Zr]Zr-FSC(succ)₃ > [ 89 Zr]Zr-TAFC > [ 89 Zr]Zr-FSC(succ)₂AA >> [ 89 Zr]Zr-DFO. Biodistribution studies of [ 89 Zr]Zr-FSC(succ)₃ revealed a slower excretion pattern compared to [ 89 Zr]Zr-TAFC. In conclusion, [ 89 Zr]Zr-FSC(succ)₃ showed the best stability and inertness. The promising results obtained with [ 89 Zr]Zr-FSC(succ)₂AA highlight the potential of FSC(succ)₂ as a monovalent chelator for conjugation to targeted biomolecules, in particular, monoclonal antibodies.

The high overexpression of cholecystokinin-2 receptors (CCK2R) in tumors, such as medullary thyroid carcinoma, allows for highly specific diagnostic and therapeutic targeting with radiolabeled peptide probes derived from natural ligands for the receptor. Based on the ideal imaging characteristics, high availability and low cost of technetium-99m ( 99m Tc)-labeled radiopharmaceuticals we have developed two hydrazinonicotinic acid (HYNIC) conjugated minigastrin analogs allowing labeling at high specific activity. The CCK2R targeting peptide conjugates show specific amino acid substitutions in the C-terminal receptor-specific sequence with the aim to increase stability and tumor targeting. The CCK2R affinity and the cell uptake of the new radioligands were analyzed using A431 human epidermoid carcinoma cells stably transfected with human CCK2R and mock transfected cells. Metabolic studies in BALB/c mice revealed a high resistance against enzymatic degradation for both radioligands. Biodistribution studies in tumor-xenografted athymic BALB/c nude mice at 1 h and 4 h p.i. showed that the two 99m Tc-labeled compounds showed varying uptake in receptor expressing organs, stomach and pancreas (1.3⁻10.4% IA/g), as well as kidneys, the main route of excretion (7.8⁻19.9% IA/g). The tumor uptake in A431-CCK2R xenografts was 24.75 ± 4.38% IA/g for [ 99m Tc]Tc-HYNIC-MGS5 and 42.48 ± 6.99% IA/g for [ 99m Tc]Tc-HYNIC-MGS11 at 4 h p.i., whereas the tumor-to-kidney ratio was comparable (2.6⁻3.3). On demand availability and potential application for radioguided surgery of a 99m Tc-labeled minigastrin analog support the further evaluation of these highly promising new compounds.