pH-Mediated Clustering of Exosomes: Breaking Through the Size Limit of Exosome Analysis in Conventional Flow Cytometry

Exosomes have recently emerged as some of the most promising biomarkers for disease diagnosis. Due to their small sizes and composition heterogeneity, exosomes are difficult to detect by currently available platforms. Here, we report a pH-mediated assembly system that converts single nanosized exosomes into microsized clusters, which can be directly analyzed by conventional flow cytometry (FCM), breaking through the size limit of exosome analysis. We demonstrated the clinical utility of the pH-mediated clustering system by profiling the exosomal proteins from blood plasma samples of 33 cancer patients and 11 benign controls. The results indicated that the combination of MUC-1 and PD-L1 could serve as a new biomarker panel for the early diagnosis of liver cancer with high clinical accuracy. This pH-mediated assembly strategy allows rapid, sensitive, and high-throughput analysis of exosome biomarkers by conventional FCM, which can be easily refined for use in both basic and clinical settings.