Exo-III enzyme based colorimetric small extracellular vesicles (sEVs) detection via G-quadruplex-based signal quenching strategy

Abstract

Small extracellular vesicles (sEVs) are closely associated with physiological and pathological processes of a variety of diseases, such as osteosarcoma. Developing a simple and sensitive sEVs detection strategy is crucial to the in-deep study and clinical diagnosis of many disease. We developed here a colorimetric sEVs detection strategy based on SMBs (streptavidin magnetic beads)-capture probe-assisted sEVs recognition and Exo-III assisted signal amplification. Three processes were included in the established strategy: target sEVs recognition-mediated liberation of trigger sequence, Exo-III based signal amplification and DNAzyme catalyzed color reaction for signal output. Eventually, the proposed method exhibited a wide sEVs detection range from 102 to 106 particles/L, and possesses an excellent capability in discriminating CD63 positive sEVs. In addition, the detection assay can be potentially applied to accurate quantification of sEVs in constructed clinical samples, maintaining a favorable recovery rate of 98.7% to 102.4%. This method is easy-to-operate, highly sensitive, and free of complicated sEVs separation procedures and dye label.