NIR‐II Self‐Luminous Molecular Probe for In Vivo Inflammation Tracking and Cancer PDT Effect Self‐Evaluating

Abstract Optical imaging in the second near‐infrared (NIR‐II, 900–1700 nm) window has been extensively investigated for bioimaging. However, a strong autofluorescence background from real‐time excitation light significantly reduces the images’ quality of NIR‐II fluorescence (FL) imaging. To resolve this issue, a NIR‐II self‐luminous small molecule (CLPD) based on bioluminescence (BL) resonance energy transfer (BRET) mechanism is first developed. The reactive oxygen species (ROS) can trigger NIR‐II BL and reduce the NIR‐II FL signals of the CLPD simultaneously, enabling ROS‐correlated ratiometric BL/FL imaging. CLPD is used for high‐contrast NIR‐II BL imaging of osteoarthritis as well as guiding the treatment process by ratiometric BL/FL imaging. Moreover, CLPD is applied for NIR‐II BL imaging of tumor triggered by the generated ROS during PDT. A correlation between the ratiometric NIR‐II BL/FL signal and tumor size is constructed, providing a trustworthy tool for early assessment of PDT effect. Overall, this study presents a novel NIR‐II self‐luminous small molecular probe for in vivo imaging and provides a strategy for design a self‐evaluation system of therapeutic effect.