Radionuclide ⁶⁸Ga And Fluorescence Labeled HER2 Nanobody Probes For The PET/NIRF Optical Imaging Of Cancer

With the increasing application values of tumor targeted molecular imaging in cancer imaging diagnosis,treatment evaluation,guided-surgery and so on,it is very necessary to develop tumor target specific molecular imaging probes,which can be used to develop and establish a novel molecular imaging method to guide accurate diagnosis and treatment of cancer.Therefore,in order to develop new molecular imaging methods for HER2-targeted tumor therapy and HER2 expression detection in vivo,this thesis aims to carry out the research on radionuclide ⁶⁸Ga and fluorescent molecular labeled HER2 nanobody probes for PET/NIRF imaging of tumor,including the following three chapters.The first chapter is the introduction,which mainly summarizes the research status of radionuclides and near-infrared fluorescent molecular labeled probes of tumor HER2 target,and briefly introduces the research content of this thesis.The second chapter is the preparation,in vitro and in vivo property evaluation and tumor PET/CT imaging of ⁶⁸Ga-HER2-Nb probe.Firstly,on the basis of the preparation conditions of NOTA-HER2-Nb complex and the labeling conditions of⁶⁸Ga-NOTA,the preparation and labeling conditions of ⁶⁸Ga-HER2-Nb were optimized,which was beneficial to obtain the target probe ⁶⁸Ga-HER2-Nb with stable properties and high yield.Secondly,the in vitro and in vivo properties of ⁶⁸Ga-labeled HER2 Nb showed good stability in vitro,high binding rate of HER2-positive cells and rapid blood clearance in vivo.Moreover,PET/CT imaging results of tumor in vivo showed that ⁶⁸Ga-HER2-Nb had strong HER2-positive tumor imaging signal,high uptake and high contrast,while HER2 negative tumor signal was almost the same with background,and its tumor uptake could be effectively blocked,indicating that⁶⁸Ga-HER2-Nb probe had strong HER2 targeting and high specificity.Therefore,⁶⁸Ga-HER2-Nb is a highly targeted and specific PET imaging probe for HER2-positive tumors,which has a strong translation potential.In third chapter,four kinds of HER2-targeted NIRF fluorescent probes were prepared and tumor imaging was carried out.Firstly,the results of laser confocal imaging showed that Cy5-HER2-Nb specifically bound to the surface of HER2-positive cells,and the fluorescence intensity of cells was positively correlated with the expression level of HER2.Secondly,tumor NIRF imaging showed that Cy7-HER2-Nb,Cy7.5-HER2-Nb and IRDye800cw-HER2-Nb could specifically target HER2-positive tumor tissues,with high NIRF signal and clear tumor imaging,while HER2 negative tumor had no obvious NIRF signal.Therefore,fluorescent molecular labeled nanobody probe has high HER2 specificity and high contrast of tumor NIRF imaging,which has potential application in intraoperative navigation of tumor resection.In the final chapter,the main experimental results and findings of this thesis are summarized,focusing on the development of radionuclide ⁶⁸Ga and fluorescent molecular labeled HER2 nanobody probe and the high contrast PET/CT and NIRF imaging of HER2-positive tumor.Secondly,the potential application of PET/NIRF probe in HER2-positive tumor detection and guided-surgery and the follow-up experimental plan are prospected.