NIR‐II Ratiometric Fluorescent Nanoplatform for Real‐Time Monitoring and Evaluating Cancer Sonodynamic Therapy Efficacy

Abstract Real‐time monitoring the therapeutic process of sonodynamic therapy (SDT) is essential to optimize the treatment course in time and eventually improve the efficacy. The generation of singlet oxygen ( 1 O 2 ) is a quintessential characteristic of SDT, which permits non‐invasive monitoring of SDT by real‐time imaging of 1 O 2 inside the tumor. Nonetheless, the majority of probes are unable to measure 1 O 2 in real time because of its short half‐life and strong oxidative capacity. Here, the study constructs a ratiometric nanoplatform (DTPI) utilizing two fluorescent probes and the sonosensitizer TiO 2 . The poisonous 1 O 2 generated by DTPI following ultrasonic (US) radiation efficiently destroys tumor cells. The structural disruption of fluorescent dye IR‐1061 by 1 O 2 leads to a reduction in the DTPI fluorescence signal at 1100 nm, while US radiation has no impact on the fluorescence signal at 1550 nm. Thus, DTPI provides a precise and consistent reflection of the treatment efficacy at the tumor site, leveraging the ratiometric fluorescence signal and variations in oxygen content throughout the treatment process. This ratiometric‐fluorescence‐based reflection strategy establishes an effective and dependable platform for the real‐time monitoring and assessment of the cancer therapeutic effect through ratiometric probes.