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 <i>in vivo</i> 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 <i>in vivo</i>. 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 <i>in situ</i> 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.