Technetium nitrido-peroxo complexes: An unexplored class of coordination compounds

The purpose of this work was to further expand the chemistry of mixed technetium nitrido-peroxo complexes, a still poorly explored class of compounds containing the Tc(VII) moiety, [99gTc][Tc(N)(O2)2]. A number of novel complexes of the formula [99gTc][Tc(N)(O2)2(L)] with bidentate ligands (L) (where L = deprotonated alanine, glycine, proline) were prepared by reacting a solution of nitrido-technetic(VI) acid with L in the presence of a source of H2O2. Alternatively, the complex [99gTc][Tc(N)(O2)2X]- (X = Cl, Br) was used as a precursor for substitution reactions where the halogenide ion was replaced by the bidentate ligand. The new complexes were characterized by elemental analysis and mass spectroscopy. The preparation of the analogous [99mTc][Tc(N)(O2)2] moiety, radiolabeled with the metastable isomer Tc-99m, was also studied at a no-carrier-added level, using S-methyl-N-methyl-dithiocarbazate as the donor of the nitrido nitrogen atoms

188W/188Re Generator System and Its Therapeutic Applications

The188Re radioisotope represents a useful radioisotope for the preparation of radiopharmaceuticals for therapeutic applications, particularly because of its favorable nuclear properties. The nuclide decay pattern is through the emission of a principle beta particle having 2.12 MeV maximum energy, which is enough to penetrate and destroy abnormal tissues, and principle gamma rays (Eγ=155 keV), which can efficiently be used for imaging and calculations of radiation dose.188Re may be conveniently produced by188W/188Re generator systems. The challenges related to the double neutron capture reaction route to provide only modest yield of the parent188W radionuclide indeed have been one of the major issues about the use of188Re in nuclear medicine. Since the specific activity of188W used in the generator is relatively low (<185 GBq/g), the elutedRe188O4-can have a low radioactive concentration, often ineffective for radiopharmaceutical preparation. However, several efficient postelution concentration techniques have been developed, which yield clinically usefulRe188O4-solutions. This review summarizes the technologies developed for the preparation of188W/188Re generators, postelution concentration of the188Re perrhenate eluate, and a brief discussion of new chemical strategies available for the very high yield preparation of188Re radiopharmaceuticals

Novel Tc-99m radiotracers for brain imaging

A novel class of Tc-99m complexes able to cross the blood brain barrier has been investigated and described here. These compounds are formed by reacting the bis-substituted nitrido precusors [99mTc(N)(PS)2] (PS = phosphino-thiol ligand) with triethylborane (BEt3) under strictly anhydrous conditions and using non-aqueous solvents. The molecular structure of these tracers was not fully established, but preliminary experimental evidence suggests that they result from the interaction of the Lewis base [99mTc(N)(PS)2] with the Lewis acid BEt3, which leads to the formation of the novel -B-Nº Tc- adduct. After purification and recovery in a physiological solution, the new borane-nitrido Tc-99m derivatives were injected in rats for evaluating their in vivo biological behavior. Results showed a significant accumulation in brain tissue, thus indicating that these complexes are capable of penetrating the intact blood brain barrier. Uptake in the central nervous system was confirmed by imaging the distribution of activity on the integrated living animal using a YAP(S)SPECT small animal scanner

Radioisotopic purity and imaging properties of cyclotron-produced 99mTc using direct 100Mo(p,2n) reaction

Evaluation of the radioisotopic purity of technetium-99m (99mTc) produced in GBq amounts by proton bombardment of enriched molibdenum-100 (100Mo) metallic targets at low proton energies (i.e. within 15\u201320 MeV) is conducted. This energy range was chosen since it is easily achievable by many conventional medical cyclotrons already available in the nuclear medicine departments of hospitals. The main motivation for such a study is in the framework of the research activities at the international level that have been conducted over the last few years to develop alternative production routes for the most widespread radioisotope used in medical imaging. The analysis of technetium isotopes and isomeric states (9xTc) present in the pertechnetate saline Na99mTcO4 solutions, obtained after the extraction/purification procedure, reveals radionuclidic purity levels basically in compliance with the limits recently issued by European Pharmacopoeia 9.3 (2018 Sodium pertechnetate (99mTc) injection 4801\u20133). Moreover, the impact of 9xTc contaminant nuclides on the final image quality is thoroughly evaluated, analyzing the emitted high-energy gamma rays and their influence on the image quality. The spatial resolution of images from cyclotron-produced 99mTc acquired with a mini-gamma camera was determined and compared with that obtained using technetium-99m solutions eluted from standard 99Mo/99mTc generators. The effect of the increased image background contribution due to Compton-scattered higher-energy gamma rays (E \u3b3 \u2009\u2009>\u2009\u2009200\u2009keV), which could cause image-contrast deterioration, was also studied. It is concluded that, due to the high radionuclidic purity of cyclotron-produced 99mTc using 100Mo(p,2n)99mTc reaction at a proton beam energy in the range 15.7\u201319.4 MeV, the resulting image properties are well comparable with those from the generator-eluted 99mTc

IAEA Contribution to Nanosized Targeted Radiopharmaceuticals for Drug Delivery

The rapidly growing interest in the application of nanoscience in the future design of radiopharmaceuticals and the development of nanosized radiopharmaceuticals in the late 2000 ' s, resulted in the creation of a Coordinated Research Project (CRP) by the International Atomic Energy Agency (IAEA) in 2014. This CRP entitled 'Nanosized delivery systems for radiopharmaceuticals' involved a team of expert scientist from various member states. This team of scientists worked on a number of cutting-edge areas of nanoscience with a focus on developing well-defined, highly effective and site-specific delivery systems of radiopharmaceuticals. Specifically, focus areas of various teams of scientists comprised of the development of nanoparticles (NPs) based on metals, polymers, and gels, and their conjugation/encapsulation or decoration with various tumor avid ligands such as peptides, folates, and small molecule phytochemicals. The research and development efforts also comprised of developing optimum radiolabeling methods of various nano vectors using diagnostic and therapeutic radionuclides including Tc-99m, Ga-68, Lu-177 and Au-198. Concerted efforts of teams of scientists within this CRP has resulted in the development of various protocols and guidelines on delivery systems of nanoradiopharmaceuticals, training of numerous graduate students/post-doctoral fellows and publications in peer reviewed journals while establishing numerous productive scientific networks in various participating member states. Some of the innovative nanoconstructs were chosen for further preclinical applications-all aimed at ultimate clinical translation for treating human cancer patients. This review article summarizes outcomes of this major international scientific endeavor

Promoting nuclear medicine in developing countries trough IAEA coordintated research projecs: technical report series 458 and 459

Promoting nuclear medicine in developing countries trough IAEA coordintated research projec

On the interpretation of the Namiki-Pascazio order parameter epsilon(ij)

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In vivo imaging of oligonucleotides with nuclear tomography

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Radiofarmaci

Radiofarmac