Aptamer-Cholesterol-Mediated Proximity Ligation Assay for Accurate Identification of Exosomes

Accurate identification of exosomes plays an essential role in facilitating disease diagnosis and therapies. Herein, we proposed an Aptamer-cholesterol-mediated Proximity Ligation Assay (AcmPLA) for accurate identification of exosomes in a dual-probe strategy, one aptamer probe for recognition of exosomal innate surface protein CD63 and another cholesterol probe for biolipid layer targeting. By integrating a proximity ligation of probes bound with exosomal biomarkers for specific recognition and a rolling circle amplification (RCA) strategy for signal amplification, we have successfully developed an exosomes-surface approach that can perform "AND" logic analysis of dual biomarkers, which not only could be used for exosomes quantification, but also for exosomes tracing. Besides RCA-initiated signal amplification, CD9 antibody-labeled magnetic beads were used to capture exosomes for isolation and secondary signal enrichment. Our approach can achieve specific exosomes isolation and accurate identification and thus could be exploited for broad applications in biological science, biomedical engineering, and personalized medicine.