Radiolabeling of [68GA] radionuclide with different buffer solution and different peptides,investigation of buffer activity in the labeling reaction and quality control parameters of the labeled radiopharmaceutica

In the diagnosis of prostate cancer and imaging of metastases, 68Ga-PSMA-11 and 68Ga-PSMA-I&T compounds are PET (Positron Emission Tomography) radiopharmaceuticals widely used in the field of Nuclear Medicine. The synthesis of these radiopharmaceuticals is primarily carried out by combining the 68Ga isotope obtained from the 68Ge/68Ga generator with the PSMA peptide in computer-controlled automatic synthesis systems. The synthesis process is affected by various parameters such as pH level, reaction temperature and reaction time. Changes in radiochemical purity values can be observed depending on these factors. Buffer solutions are used to provide the desired pH level in the reaction medium. HEPES and acetate buffer systems are generally preferred due to their high biocompatibility and low toxicity. In addition to regulating the pH of the medium, these buffers positively affect the synthesis yield by increasing stability. The main purpose of this study is to develop an alternative buffer system other than the commonly used (2-hydroxyethyl)-1-piperazineethane sulfonic acid (HEPES) and sodium acetate (CH₃COONa). The new buffer system to be used within the scope of the research is aimed to prevent colloid formation by forming weak complexes with Ga-68⁺³ ion and to keep the pH in the range of 4.0–4.5. As a result of the experimental studies, sodium ascorbate buffer, which is not widely used in the literature, was integrated into the synthesis system. High yields and results consistent with theoretical values were obtained in the 68Ga-PSMA-11 syntheses performed with this buffer. KEYWORDS: Gallium-68 PSMA, Gallium-68 Buffers, HPLC, TLC, Quality Control.