en Radiation Biology Radiation Biology تحقيق بديع Original Research <div style="text-align: justify;"><span style="font-size:10pt"><span style="text-justify:newspaper"><span style="text-kashida-space:50%"><span style="line-height:119%"><span style="font-family:Calibri"><span style="color:black"><span lang="en-US" style="font-size:9.0pt"><span style="font-family:Calibri"><span style="color:#1f497d"><span style="font-style:italic"><span style="font-weight:bold"><span style="language:en-US">Background:</span></span></span></span></span></span> <span lang="en-US" style="font-size:9.0pt"><span style="font-family:Calibri"><span style="language:en-US">Staphylococcus aureus (S. aureus) is the most common causative pathogen associated with a wide range of infections, from mild to life-threatening conditions such as osteomyelitis, endocarditis, and pneumonia. Early detection and reliable differentiation between infection and sterile inflammation are essential for accurate diagnosis and effective treatment. However, most radiopharmaceuticals currently available fail to discriminate between these conditions, underscoring the need for infection-specific imaging agents. </span></span></span><span lang="en-US" style="font-size:9.0pt"><span style="font-family:Calibri"><span style="color:#1f497d"><span style="font-style:italic"><span style="font-weight:bold"><span style="language:en-US">Materials and Methods: </span></span></span></span></span></span><span lang="en-US" style="font-size:9.0pt"><span style="font-family:Calibri"><span style="language:en-US">In this study, a Gallium-68 (Ga-68)-labeled S. aureus-specific aptamer was developed as a potential PET infection imaging probe. Aptamers were selected using the cell- systematic evolution of ligands by exponential enrichment (SELEX) method, and their specificity was verified by fluorescence-based binding assays. Radiolabeling was achieved via DOTA chelation, and radiochemical purity was determined. Additionally, in vitro binding assays were performed with S. aureus, while Escherichia coli (E. coli) served as a control. </span></span></span><span lang="en-US" style="font-size:9.0pt"><span style="font-family:Calibri"><span style="color:#1f497d"><span style="font-style:italic"><span style="font-weight:bold"><span style="language:en-US">Results: </span></span></span></span></span></span><span lang="en-US" style="font-size:9.0pt"><span style="font-family:Calibri"><span style="language:en-US">The aptamer exhibited an affinity constant (Kₐ) of 2260 &plusmn; 634 CFU/mL and a linear detection range of 250-2&times;10⁴ CFU/mL, with a limit of detection of 171 CFU/mL for S. aureus. The Ga-68-labeled aptamer demonstrated radiochemical purity greater than 99%. In vitro binding increased linearly with rising S. aureus concentrations (10&sup3;-2&times;10⁴ CFU/mL), while minimal binding to E. coli confirmed its specificity. </span></span></span><span lang="en-US" style="font-size:9.0pt"><span style="font-family:Calibri"><span style="color:#1f497d"><span style="font-style:italic"><span style="font-weight:bold"><span style="language:en-US">Conclusion: </span></span></span></span></span></span><span lang="en-US" style="font-size:9.0pt"><span style="font-family:Calibri"><span style="language:en-US">These results demonstrate that the Ga-68-labeled S. aureus-specific aptamer holds promise as an infection-targeted PET imaging agent. Although currently limited to in vitro evaluation, such aptamer-based radiopharmaceuticals may contribute to improved diagnosis and imaging of infectious diseases.</span></span></span></span></span></span></span></span></span></div> Aptamer, gallium-68, Staphylococcus aureus, PET agent for infection imaging. 1037 1042 http://ijrr.com/browse.php?a_code=A-10-1-1432&slc_lang=en&sid=1 S. Bargh 7900319475328460032616 7900319475328460032616 No Department of Radiopharmacy, Faculty of Pharmacy, Hacettepe University, Ankara, Turkiye C. Ozkul 7900319475328460032617 7900319475328460032617 No Department of Pharmaceutical Microbiology, Faculty of Pharmacy, Hacettepe University, Ankara, Turkiye S.S. Timur 7900319475328460032618 7900319475328460032618 No Department of Pharmaceutical Technology, Faculty of Pharmacy, Hacettepe University, Ankara, Turkiye V.C. Ozalp 7900319475328460032619 7900319475328460032619 No Department of Biology, Faculty of Medicine, Atılım University, Ankara, Turkiye S. Erdogan serdogan@hacettepe.edu.tr 7900319475328460032620 7900319475328460032620 Yes Department of Radiopharmacy, Faculty of Pharmacy, Hacettepe University, Ankara, Turkiye