Kidney-Targeted Near-Infrared Fluorescence Probe Reveals That SO₂ Is a Biomarker for Cisplatin-Induced Acute Kidney Injury

With the widespread use of drugs, drug-induced acute kidney injury (AKI) has become an increasingly serious health concern worldwide. Currently, early diagnosis of drug-induced AKI remains challenging because of the lack of effective biomarkers and noninvasive imaging tools. SO₂ plays important physiological roles in living systems and is an important antioxidant for maintaining redox homeostasis. However, the relationship between SO₂ (in water as SO₃^2–/HSO₃^–) and drug-induced AKI remains largely unknown. Herein, we report the highly sensitive near-infrared fluorescence probe DSMN, which for the first time reveals the relationship between SO₂ and drug-induced AKI. The probe responds to SO₃^2–/HSO₃^– selectively and rapidly (within seconds) and shows a significant turn-on fluorescence at 710 nm with a large Stokes shift (125 nm). With these properties, the probe was successfully applied to detect SO₂ in living cells and mice. Importantly, the probe can selectively target the kidneys, allowing for the detection of changes in the SO₂ concentration in the kidneys. Based on this, DSMN was successfully used to detect cisplatin-induced AKI and revealed an increase in the SO₂ levels. The results indicate that SO₂ is a new biomarker for AKI and that DSMN is a powerful tool for studying and diagnosing drug-induced AKI.