Ratiometric near-infrared-II fluorescent probe based on gold nanoclusters for accurate imaging of acute kidney injury

Achieving reliable in vivo fluorescence imaging of acute kidney injury (AKI) at an early stage is critical to facilitating early diagnosis and targeted intervention. However, this is severely hindered by the fact that most traditional probes operate in the near-infrared-I (NIR-I) window and rely on a single-signal mode, which suffers from high background signal interference and signal instability caused by rapid metabolic clearance. Herein, a second near-infrared (NIR-II) ratiometric fluorescent probe based on gold nanoclusters (Au NCs) was designed and constructed for accurate imaging analysis of AKI. The probe incorporated two types of Au NCs that exhibited NIR-II luminescence under distinct excitation wavelengths. Leveraging their distinct responses to reactive oxygen species (ROS), which are renal injury markers, the probe enabled ratiometric imaging of ROS changes. With high sensitivity, good biocompatibility and renal imaging capability, the constructed probe allowed for accurate NIR-II fluorescence imaging of ischemia-reperfusion induced renal injury in a mouse model. These attributes collectively establish a new strategy for the early and reliable in vivo diagnosis of AKI.