In vivo detection of extracellular vesicles by flexible needle-type microbiosensor

Extracellular vesicles (EVs) contain a wealth of biological information and hold great value for disease diagnosis. In contrast to conventional in vitro detection, in vivo detection has the ability to improve the detection efficiency, reduce external interferences and enable continuous or real-time dynamic monitoring. However, developing a simple and accurate in vivo assay for EVs remains challenging. In this study, we constructed an allosteric aptamer-based flexible microneedle biosensor capable of measuring disease-associated EVs in vivo. Firstly, the aptamer binding to CD63 captures EVs and immobilizes it on the electrode, and then the aptamer binding to EGFR contacts the EVs, which results in a change in redox current, due to the proximity of the reporter molecule to the electrode surface decreases electron efficiency. Continuous monitoring of tumor-derived EVs revealed significant variations in EVs concentrations across different tumor stages, which exhibited a strong correlation with tumor volume. This flexible microneedle sensor offers the advantages of selectivity, biocompatibility, and analytical performance, presenting a promising approach for tumor monitoring in vivo .