Three-step evolutionary enhanced capillary electrophoresis-SELEX for aptamer selection of exosome vesicles

As various disease biomarkers, drugs/biomolecules carriers and physiological function regulator, exosomes play significant roles in various physiological and pathological process. Thus, the purification and detection of some exosome are of great significance, which make it necessary for the development of the recognition elements. Aptamers with high affinity and specificity exhibited well in the above areas. In this work, a new three-step evolutionary enhanced strategy based on capillary electrophoresis (CE)-SELEX was proposed for effective aptamer selection of exosome vesicles for the first time. Natural killer cells (NK) exosome was used as the model target. And the aptamer could be obtained in five round CE selection within three steps evolution including precise nucleic acid sequence convergence (with NK exosome specific proteins as targets in round 1st and 3rd), affinity evolution (with NK exosome as target in round 2nd and 4th) and specific evolution (negative selection in round 5th). Arising from the compatibility of CE-SELEX for exosome vesicles aptamer selection, and the proposed strategy, aptamer against NK exosome had been selected with good affinity (K_D value of 27.6 nM) and excellent specificity. The as proposed CE-SELEX strategy paves a novel way for recognition element selection of exosome vesicles.