Amplifying metabolic profiling of extracellular vesicle dynamics with ACTIVITY.

Extracellular vesicles (EVs) are emerging as promising circulating biomarkers for liquid biopsy due to their abundant molecular information, such as proteins, nucleic acids, and metabolites. However, the metabolic profiling of EVs remains largely unexplored, much less exploiting their intrinsic metabolic features for disease diagnosis. In this study, we demonstrate that the metabolic-related inducible nitric oxide synthase (iNOS) activity of macrophage-derived EVs serves as an effective biomarker for phenotypic profiling and further evaluating lung inflammation. By integrating a cascade amplification strategy that combines the biocatalysis of EV iNOS activity with the electrocatalysis of defective tungsten disulfide quantum dots (WS QDs), we develop an ACTIVITY (Amplified Cascade-catalysis TestIng for VesIcular meTabolic activitY) method for rapid assaying of metabolically active EVs. When applied to bronchoalveolar lavage fluid samples, this activity-based EV profiling differentiates pneumonia patients from healthy controls and further facilitates the monitoring of disease treatment, suggesting the potential of EV metabolic activity for diagnostics.