68Ga标记铁载体作为“特洛伊木马”分子可被病原体通过铁载体转运通道特异吸收从而用于感染显像，前期实验结果初步证明了68Ga-Yersiniabactin（Ybt）对大肠杆菌感染的靶向特异性及在µPET/CT显像中定位细菌感染性炎症的能力，但它是否能够区分类型不同的大肠杆菌感染和严重程度不同的感染病灶从而为精准诊断和治疗提供依据？这是本项目研究的关注点。针对以上问题，本项目将制备分子探针68Ga-Ybt和64Cu-Ybt，通过对其体内外评价，包括稳定性实验、蛋白结合实验、细胞实验、正常鼠生物学分布实验以及模型鼠µPET/CT显像实验，并与68Ga-Citrate进行对比，研究其在感染诊断中的不同靶向作用机制，评估其在感染诊断中的应用价值，以期为细菌感染灶的早期精准诊断提供依据。

68Ga-labelled siderophores can be specifically taken up by pathogens using a "Trojan horse" strategy and can be used as a diagnostic agent for infection imaging. Pre-experimental results with 68Ga-Yersiniabactin (Ybt), a siderophore found in some pathogenic E. coli strains, demonstrated its specificity in E. coli infection, and the ability to discriminate infection from inflammation using µPET/CT imaging in a mouse model. However, it is unknown whether 68Ga-Ybt can discriminate different types of E. coli infection and the severity of infections which may provide precision diagnosis and treatment of infections. To demonstrate aforementioned, in this project the molecular probes 68Ga-Ybt and 64Cu-Ybt will be prepared. In vitro and in vivo evaluation including partition coefficient, protein binding property, serum stability, cell uptake, biodistribution as well as µPET/CT imaging will be performed. The target mechanisms of 68Ga-Ybt and 64Cu-Ybt as well as clinical 68Ga-Citrate will be compared in normal mice and in infection mice models. Additionally the clinical potential in the diagnosis of infection will be evaluated. We are sure that the project will provide new insight on the early diagnosis and precision diagnosis of infection.