Ultrasmall Ag₂Se@Mn quantum dots enable dual-modal imaging-guided early detection and antioxidant therapy of acute kidney injury.

Acute kidney injury (AKI) is a serious clinical condition with high morbidity and mortality, yet early detection and effective treatment remain challenging. Herein, we developed ultrasmall quantum dots (QDs) for dual-modal imaging-guided early detection and antioxidant therapy of AKI. Benefiting from the ultrasmall hydrodynamic size, the as‑prepared Ag₂Se@Mn QDs exhibit favorable renal clearance and prolonged retention in injured kidneys. The QDs possess concentration-dependent T1-weighted magnetic resonance imaging (MRI) contrast and near-infrared fluorescence properties, enabling real-time, non-invasive visualization of cisplatin-induced AKI progression. Especially, MRI revealed renal dysfunction up to 66 h earlier than conventional clinical indicators, providing a critical window for early intervention. Furthermore, the inherent ROS-scavenging activity of Mn²⁺ endows QDs with potent antioxidant capacity by efficiently eliminating hydroxyl radicals (·OH) and superoxide anions (O₂•-), and thus comprehensively alleviate renal damage and recover renal functions without obvious side-effects. This "all-in-one" theranostic strategy offers an alternative approach for precision management of AKI.