A Reversible NIR-II Ratiometric Fluorescent Probe for Real-Time In Vivo ATP Detection

ATP plays a prominent role in shaping the evolution of immune cell responses to injury, infection, and cancer. However, real-time monitoring of ATP levels in vivo remains a challenge, due to the lack of reliable tools that work reversibly in deep tissues. Herein, based on the Forster resonance energy transfer (FRET) strategy, a reversible ratiometric second near-infrared window (NIR-II) molecular fluorescent probe (CX-RATP) is designed and synthesized. CX-RATP exhibits a significant fluorescence ratio change with the existence of 0-10 mM ATP in vitro, which is within the range of physiological and pathological ATP concentrations. Meanwhile, the recognition process can be reversed by apyrase. It can capture the increase and decrease in ATP levels in real time before and after the treatment of acute inflammation. Besides, CX-RATP is also successfully applied to the hepatocellular carcinoma (HCC) model and achieves in situ imaging of tumor lesions. These results all provide solid proof that CX-RATP is a powerful tool for in vivo real-time ATP detection.