自组装PET/MR/PA三模式纳米探针的构建及在转铁蛋白受体高表达肿瘤中的应用

多模式成像是分子影像的热点和趋势，可提供解剖、功能及分子层面相结合的全方位信息。国内外对多模式分子显像及探针的研究还处于起步阶段，正电子发射计算机断层成像/磁共振成像/光声成像(PET/MRI/PA)三模式联合显像鲜有报道。本项目拟采用去铁铁蛋白，利用其pH依赖性加载黑色素和铁；利用其离子通道加载正电子金属核素68Ga；构建三功能探针，对铁蛋白受体阳性/阴性表达的肿瘤进行PET/MR/PA三模式显像。此新型探针尝试去铁铁蛋白包裹生物高分子，工艺简单，易于推广；选用天然材料，安全无毒，价廉节约；PET示踪灵敏度高，快速实现体内"暗箱"过程可视化；68Ga半衰期短，在体内清除快，对操作人员和环境均无影响；组合材料增强了MR和PA的信号，为PET显像补充提供解剖、功能、分子水平信息，体现了多模式显像的高灵敏度、高特异性和全面性；此探针还可作为有效的药物传输载体，为靶向分子显像和治疗翻开崭新的一页

Multimodality imaging is the current focus and future development in Molecular Imaging Field. For example, PET(Positron Emission Tomography) is high sensitive and MR(Magnetic Resonance) is anatomic with high spatial resolution. While PA (Photoacoustic) is frequently coregistered with ultrasonic imaging, can provide functional and cellular/molecular information about tissue. Combined with the above 3 techniques, anatomic, functional and molecular information can be collected for early and accurate diagnosis, therapy monitoring and adjustment. Multifunctional probes for PET/MR/PA are seldom reported. In this project, we want to develop a probe based on apoferritin, melanin, iron and 68Ga, set up transferrin receptor high/low expressed tumor models and try multimodel imaging. This is the first time to try to encapsulate large biopolymer into apoferritin in water solution with simple preparation method. All the materials are nature and endogenous, so the probe is safe, non-toxicity, biocompatible and cost-effective. The half life of 68Ga is short (about 60min), so the clearance of radiation is fast and no-worry to environment and operator. With PET, the target distribution, the metabolism and elimination route of the probe can be quickly and sensitively observed. MR and PA signal will be enhanced to supply more information about anatomic and molecular aspects. This probe can be a promising drug delivery platform too.