Fig. 1

Emerging techniques for probing single extracellular vesicles. a EVs are driven electrophoretically inside a microchannel toward the anode. The microchannel is made of poly(dimethylsiloxane) (PDMS) and coated with a phospholipid copolymer containing 2-methacryloyloxyethyl phosphorylcholine (MPC) and 3-methacryloxyethyl triethoxysilane (METESi) to suppress electroosmotic flow and nonspecific adsorption. The movement of EVs, visualized under dark-field microscopy, may change its speed upon binding of antibodies [57]. b Schematic of multispectral optical tweezers which allows for the simultaneous measurement of fluorescence and Raman spectra on trapped EVs [75]. c Schematic diagram of AFM-IR. The AFM tip detects the local IR absorption of the sample excited by a pulsed tunable laser source [89]. d EVs labeled with biocompatible anchor molecule (BAM)-DNA or antibody-DNA conjugates are randomly distributed into microfluidic chambers. Nuclei acid-based amplification gives digitalized signals from each chamber, indicating the presence of EVs or specific target molecules [92]. Images reprinted with permissions