Label-Free Impedance Imaging of Single Extracellular\nVesicles Using Interferometric Electrochemical Microscopy

Extracellular\nvesicles (EVs) are pivotal in various biological\nprocesses and diseases, yet their small size and heterogeneity pose\nchallenges for single EV quantification. We introduce interferometric\nelectrochemical microscopy (iECM), a sensitive label-free technique\nthat combines interferometric scattering and electrochemical impedance\nimaging. This method enables the quantification of the impedance of\nsingle EVs, providing unique insights into their electrochemical properties,\nand allows for the simultaneous measurement of size and real-time\nmonitoring of antibody binding. Notably, we discovered that the impedance\nspectra of EVs can serve as specific fingerprints to differentiate\nEVs from cancerous and healthy cells, establishing iECM as a unique\nplatform for EV characterization and classification.