A Renal-Clearable Tantalum Contrast Agent Enables Precise CT Diagnosis and Subtyping of Acute Kidney Injury

Precise diagnosis and subtyping of acute kidney injury (AKI) are crucial for clinical decision-making and prognosis. However, current in vivo imaging techniques lack the necessary precision, sensitivity, and resolution to meet this demand. Here, we report a renal-clearable, tantalum-rich carbon dot (Ta-rCD) contrast agent that enables high-performance computed tomography (CT) imaging for noninvasive visualization and differentiation of multiple AKI subtypes. The Ta-rCDs are synthesized via a simple and efficient air-assisted carbonization method, featuring ultrahigh Ta content (48%), gram-scale production capacity, ultrasmall hydrodynamic size (∼2.8 nm), excellent water solubility (>500 mg mL^-1), and strong x-ray attenuation capability. Benefiting from their renal-clearable nature, Ta-rCDs avoid long-term retention in vivo while enabling effective renal imaging. Notably, Ta-rCDs enable high-resolution anatomical and functional CT imaging across pre-renal, renal, and post-renal AKI models, facilitating precise detection of renal dysfunction beyond the reach of conventional biochemical markers. Furthermore, this approach allows accurate differentiation of AKI subtypes based on their distinct CT imaging features. In vitro and in vivo studies confirm their favorable biocompatibility. Our work provides a new paradigm for the development of sensitive and high-resolution CT imaging contrast agents and offers a promising method for the accurate diagnosis of kidney diseases.