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In this study we tested functionalized AuNPs as an improved drug delivery tool in pancreatic and colon cancer cell lines AR42J and HT-29, using radioimmunoassay method. Ga radiolabeled DOTA-Tyr(3)-octreotide, DOTA-NaI(3)-octreotide and DOTA-NT peptides were linked on nanoparticles surface, aiming to increase the peptide density at the tumor site and thus interaction probability, resulting in higher photon signal of Ga radioisotope used in positron emission tomography. In vitro ligand-receptor binding evaluation of the radiolabeled compound has showed increased retention of the positron emitter radionuclide Ga in the presence of the gold nanoparticles. [ABSTRACT FROM AUTHOR]

18F-FDG is a glucose analog in which the hydroxyl group on the second carbon is substituted with 18 F, being used as an indicator of glucose uptake and cell viability. The aim of this work was to synthesize the 18F-FDG and to validate the methodology for the assessment of its both radiochemical and chemical purities, according to the European Pharmacopoeia. The proposed methodology encompasses three chromatographic methods: radio-HPLC, radio-TLC and HS/GC. Radiochemical impurities may originate from radionuclide production, incomplete purification and radiolysis after synthesis. Chromatographic methods should effectively separate these species, as radioactive impurities can affect the clinical outcome of positron emission tomography imaging studies because of nonspecific uptake. Chemical impurities, on the other hand, can affect nucleophilic substitution mechanism. Keeping these contaminants at as low concentrations as possible is the key of a successful synthesis. Therefore, the determination of both type of impurities in short time is an essential step in characterizing of each batch, due to the rapid decay of 18F (109.8 min half-life). By optimizing the operating conditions, both chemical and radiochemical impurities analysis can be done within 12 min. The optimized methodology shows good performance: linearity, specificity, precision, limit of quantification, limit of detection and reproducibility, thus it could be successfully applied in the quality control tests of radiopharmaceuticals according to the European Pharmacopoeia. [ABSTRACT FROM AUTHOR]

The neurotensin is a tridecapeptide involved in the proliferation of colon cancer, the overexpression of neurotensin receptors occurring at an early stage development of many tumours. Targeting neurotensin receptors by using the same biological active molecule is an effective approach for both imaging quantification and treatment. The present work aimed to demonstrate the ability of radiolabelled neurotensin to specifically target colon cancer cells, and substantiate its usefulness in targeted imaging and radiotherapy, depending on the emission of the coupled radioisotope. Syntheses of 68Ga–DOTA–NT and 177Lu–DOTA–NT were developed to obtain a level of quality suitable for preclinical use with consistent high synthesis yields. Radiochemical purity meets the pharmaceutical requirements, and it is maintained 4 h for 68Ga–DOTA–NT and 48 h for 177Lu–DOTA–NT. Extensive in vitro studies were conducted to assess the uptake and retention of 68Ga–DOTA–NT, the amount of non-specific binding of neurotensin and the effect of 177Lu–DOTA–NT on HT–29 cells. In vivo biodistribution of 68Ga–DOTA–NT revealed significant uptake at the tumour site, along with fast clearance evidenced by decreasing activity in kidneys and blood after 60 min p.i. 177Lu–DOTA–NT exhibited similar uptake in the tumour, but also a significant uptake at 14 days p.i. in the bone marrow was reported. These results successfully demonstrated the potential of neurotensin to deliver imaging/therapeutic 68Ga/177Lu radioisotopes pair, but also the need for further evaluation of the possible radiotoxicity effects on the liver, kidneys or bone marrow. [ABSTRACT FROM AUTHOR]