Sensitive analysis of pneumonia related small extracellular vesicles (sEVs) through Exo-III assisted catalytic DNA amplification

As a crucial medium of intercellular communication in a variety of pathological process, small extracellular vesicles (sEVs) are currently expected to be a novel diagnostic biomarker and therapeutic target. However, highly sensitive and quantitative detection of sEVs remains challenging. Herein, we propose a novel sEVs sensing system through integration of CD63 aptamer based identification and exonuclease III (Exo-III) assisted signal recycling. In this method, streptavidin magnetic beads (SMBs)-Capture probe is designed to specially recognize sEVs, in which process the blocker sequences is released from the complex to induce the following signal amplification. Based on the Exo-III enzyme assisted triple signal amplification, the method exhibits a wide detection range from 102 particles/μl to 105 particles/μl and a low limit of detection of 87 particles/μl. The biosensor is robust and is successfully applied for the study of sEVs expression in pneumonia patients and health volunteer. Besides the sEVs detection, we hypothesize that this sensing system can also be used for the detection of other targets by substituting the target-recognition elements.