生物正交点击化学法18F标记DARPins用于Micro-PET/CT显像检测其在活体内的靶向功能

DARPins, a kind of engineering proteins with molecular recognition function like the antibody, are ideal targeting ligands, because they can recognize all the targeting molecules by changing their random residues. In this study DARPins is radiolabeled with 18F by Bioorthogonal Click-Radiolabeling Reaction and then Micro PET/CT dynamic imaging is used for screening the DARPins targeting to Her2 in vivo from 9 candidates which can target to Her2 in vitro. If the Micro PET/CT imaging feasibility screening for DARPins in vivo is confirmed, it will become the connection bridge between screening DARPins in vitro and specific clinical applications, and could significantly shorten the research cycle form the laboratory into clinical application. The filtered DARPins by Micro PET/CT imaging in vivo could be directly used for studying protein function in vivo, synthesis of targeting molecular probe, constructing carriers for targeting delivery drug, and being used as targeting therapy drugs directly.

DARPins是一类工程蛋白，具有类似于抗体的分子识别功能，理论上通过改变随机残基，DARPins可识别所有的目标靶分子，是理想的靶向配体分子。本课题以体外筛选获得的9个靶向Her2的DARPins作为候选配体分子，采用生物正交点击放射性标记反应法将18F标记于DARPins支架结构上，Micro PET/CT动态显像筛选出在活体内可与Her2高特异性及高亲和性结合的配体分子DARPins。如果Micro PET/CT显像进行DARPins活体内筛选的可行性得以证实，将在DARPins体外筛选与具体临床应用之间建立起连接的桥梁，可显著缩短DARPins从实验室进入临床应用的研究周期。经Micro PET/CT分子影像技术在活体内筛选出的DARPins，可直接用于活体内蛋白质功能的研究、制备疾病靶向诊断的分子探针、构建药物靶向投送载体，甚至直接用作疾病靶向治疗的药物。

DARPins通过改变随机残基，可识别所有的目标靶分子，是理想的靶向配体分子。但对同一目标靶分子，体外筛选技术可筛选出多个DARPins，并不是每个DARPins都适用于活体内，必需经活体内实验进一步筛选，以获得适用于活体内的DARPins。本课题以体外筛选获得的9个靶向Her2的DARPins作为候选配体分子，采用生物正交点击放射性标记反应法将18F标记于DARPins支架结构上。Micro PET/CT动态显像筛选出在活体内可与Her2高特异性及高亲和性结合的配体分子DARPins（G3），并经荧光动物显像、MRI动物显像实验，证实了Micro PET/CT显像进行DARPins活体内筛选的可行性，并建立方便、快捷、可靠的具体操作流程。该方法在DARPins体外筛选与具体临床应用之间建立起连接的桥梁，显著缩短DARPins从实验室进入临床应用的研究周期。经Micro PET/CT分子影像技术在活体内筛选出的DARPins，可直接用于活体内蛋白质功能的研究、制备疾病靶向诊断的分子探针、构建药物靶向投送载体，甚至直接用作疾病靶向治疗的药物。