Label-Free Electrochemical Imaging of Single Extracellular Vesicles

Extracellular vesicles (EVs) are pivotal in various biological processes and diseases, yet their small size and heterogeneity pose challenges for single EV quantification. We introduce interferometric electrochemical microscopy (iECM), a sensitive label-free technique that combines interferometric scattering and electrochemical impedance imaging. This method enables the quantification of the impedance of single EVs, providing unique insights into their electrochemical properties, and allows for the simultaneous measurement of size and real-time monitoring of antibody binding. Notably, we discovered that the impedance spectra of EVs can serve as unique fingerprints to differentiate EVs from cancerous and healthy cells, offering potential advancements in clinical diagnostics and the profiling of extracellular biomarkers.