Enzymes are key components of the biological microenvironment, possessing outstanding catalytic properties and exceptional biorecognition capabilities. Abnormal expression or activity of the enzyme is associated with many disease-associated micro-environments and aberrant cell processes. Therefore, dynamic imaging for enzyme activity is tremendously meaningful for disease diagnosis and treatment. Magnetic resonance imaging (MRI) is a reliable imaging technology for disease diagnosis with the merits of high resolution, non-invasive, and sufficient penetration depth. To monitor enzyme activity, various enzyme-activated MRI probes were developed, which possess a weak background signal and high-sensitivity enzyme imaging for tumors in vivo. Furthermore, certain probes can realize both diagnosis and treatment of cancer as well as other ailments. This leads to a more efficient and secure therapeutic approach guided by imaging techniques. And the therapeutic methods of enzyme-sensitive MRI probes primarily encompass phototherapy, photodynamic therapy, chemodynamic therapy, chemotherapy, radiotherapy, as well as combination therapy. In this review, we systematically introduced the types and mechanisms of enzyme-activated probes and further summarized their application on disease diagnosis and therapy. Finally, we also prospected the development tendency of enzyme-responsive MRI probes.

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用于磁共振成像和肿瘤治疗的酶激活纳米材料

酶是生物微环境的关键组成部分，具有优异的催化性能和卓越的生物识别能力。该酶的异常表达或活性与许多疾病相关的微环境和异常细胞过程有关。因此，酶活性的动态成像对于疾病的诊断和治疗具有重要意义。磁共振成像（MRI）是一种可靠的疾病诊断成像技术，具有高分辨率、无创、穿透深度足够的优点。为了监测酶活性，开发了各种酶激活MRI探针，其具有微弱的背景信号和对体内肿瘤的高灵敏度酶成像。此外，某些探针可以实现癌症以及其他疾病的诊断和治疗。这导致了在成像技术指导下更有效、更安全的治疗方法。酶敏感MRI探头的治疗方法主要包括光疗、光动力疗法、化学动力疗法、化疗、放疗以及联合治疗。本文系统介绍了酶激活探针的类型和作用机制，并进一步总结了其在疾病诊断和治疗中的应用。最后，我们还展望了酶响应MRI探针的发展趋势。