自噬在肿瘤的不同发展阶段对疗效有不同的作用。因此，对肿瘤演进和自噬水平进行实时、动态可视化监测，并根据疗效，调节肿瘤组织的自噬特性，优化治疗策略，具有重要意义。传统的自噬研究虽然能准确检测细胞内的自噬状态，但不能观测自噬的动态变化，更不能实时监测活体肿瘤内自噬行为和肿瘤治疗的相关性。本项目中，我们利用肿瘤的自噬水平和瘤内活性氧（ROS）的正相关性，制备对ROS敏感的一氧化氮自由基修饰的四氧化三铁磁性纳米材料。这一材料运用于MRI，既可实时检测肿瘤的发展状况（大小，位置，四氧化三铁的信号），又可以监测肿瘤的自噬水平（氮氧自由基信号），建立核磁信号-自噬状态-肿瘤发展水平之间的准确关联，实现自噬程度的可视化动态监测，指导针对自噬为靶点的抗肿瘤药物的选择。在肿瘤治疗过程中，通过核磁影像实时监测自噬状态和肿瘤发展状态之间的变化，调整治疗顺序、用药种类、时间和剂量，优化肿瘤治疗方案

Autophagy shows different anti-tumor effects according to the tumor development stages. Thus, real-time visualization inspection of autophagy degree in the tumor developing procedure is of great therapeutic and fundamental significance. Based on the autophagy degree, we can optimize the therapeutic strategy to improve the anti-tumor effect. Unfortunately, there is no means that can in vivo read-out ofautophagy. As an attempt to readily monitor the autophagy flux, we herein proposedan autophagy-responsive magnetic resonance imaging based on radical-conjugatedmagnetic nanoparticles. In principle, both the NO• radical and Fe3O4nanoparticles are stable, and separately contributing to an observation of enhanced T1- and T2-weighted imaging, respectively. Meanwhile, the onset ofautophagy concomitantly simulates the mass production of reactive species, andconsequently quenches the T1-signal of NO•. On this basis, the content ofautophagy flux is reflected by the ratio of T1-signal intensity to that ofT2-signal.Through this stratagem, the tumor development (T2) and the autophagydegree (T1) could be simultaneously observed, which enable us to setup therelationship of MRI intensity-Autophagy degree-Tumor development, realize the.visualization inspection of autophagy degree in vivo, optimize the sequentialanti-tumor therapy, and improve the anti-tumor effect.