A Multifunctional NIR‐II Rare‐Earth Nanoagent for In Vivo Monitoring Cancer Revascularization and Prognosis

Abstract Cancer remains a leading cause of mortality worldwide. Although chemotherapeutic agents can effectively induce tumor regression, they often cause severe vascular damage that adversely affects patient prognosis. To address this issue, using the representative chemotherapeutic agent doxorubicin (DOX) as the model, a biocompatible rare‐earth nanoagent capable of dual‐wavelength emission in the UV and NIR‐IIb (1500–1700 nm) regions upon excitation at 980 and 808 nm is reported. This unique property endows the spatiotemporally controlled release of Angiopoietin‐1 (Ang‐1), guided by NIR‐IIb imaging, to promote vascular repair following DOX chemotherapy. Furthermore, the system allows for real‐time monitoring of angiogenesis to assess therapeutic efficacy. In a 4T1 tumor‐bearing mouse, this combined strategy reduced the number of abnormal vascular branches by ≈50% at each time point and significantly prolonged the survival time of mice. This study introduces a novel therapeutic paradigm that integrates tumor eradication with concurrent nanomedicine‐driven vascular repair, paving the way for more effective and durable treatment strategies for tumors.