A Kidney-Targeted Rapid Photoacoustic Probe Activated by Sulfur Dioxide for 3D Visual Diagnosis of Iodinated Contrast-Induced Acute Kidney Injury.

Sulfur dioxide (SO2) dysmetabolism is closely associated with various diseases such as acute kidney injury (AKI). Nevertheless, the relationship between SO2 levels and iodinated contrast-induced AKI remains largely unclear. Therefore, accurate imaging of SO2 level fluctuations in vivo is therefore critically important. However, no photoacoustic (PA) imaging method is currently available for the detection of SO2. To address this gap, we designed and synthesized a PA probe toward SO2, namely, Rho-QL, for the first time and performed in situ PA imaging of SO2 in deep tissues in vivo. A novel method was accordingly developed for the 3D visual diagnosis of AKI based on PA imaging of SO2 in kidney tissues with high spatial resolution. Rho-QL exhibited a PA response time of 5 s for SO2 and displayed remarkable turn-on absorption changes at 700 nm, making it a suitable probe for detecting SO2 levels via PA imaging. Moreover, Rho-QL exhibited an excellent targeting ability to the kidney, thereby facilitating in situ imaging of SO2 in the kidney. Notably, through real-time PA imaging, Rho-QL was successfully applied for 3D visualization of the detailed SO2 distribution with high spatial resolution and revealed a remarkable increase in the SO2 levels in the kidney during a contrast-induced AKI process. Based on the current findings, Rho-QL is expected to become a powerful tool for the study and diagnosis of AKI-related diseases.