Real-Time Monitoring of Exosomes Secretion from Single Cell Using Dual-Nanopore Biosensors

Exosomes secreted from cells carry rich information fromtheirparent cells, representing a promising biomarker for investigationof diseases. We develop a dual-nanopore biosensor using DNA aptamersto specifically recognize CD63 protein on the exosome's surface,which enables label-free exosome detection based on ionic currentchange. The sensor allows for sensitive detection of exosomes witha detection limit of 3.4 x 10(6) particles/mL. The dual-nanoporebiosensor was able to form an intrapipette electric circuit for ioniccurrent measurement due to its unique structure, which is crucialto achieve detection of exosome secretion from a single cell. We utilizeda microwell array chip to entrap a single cell into a confined microwellwith small volume, enabling the accumulation of exosomes with highconcentration. The dual-nanopore biosensor was positioned into themicrowell with a single cell, and monitoring of exosome secretionfrom a single cell in different cell lines and under different stimulationshas been achieved. Our design may provide a useful platform for developingnanopore biosensors for detecting cell secretions from a single livingcell.