DNA Self-Assembly Generated by Aptamer-Triggered Rolling Circle Amplification Cascades for Profiling Colorectal Cancer-Derived Small Extracellular Vesicles

The analysis of small extracellular vesicles (sEVs) has shown clinical significance in early cancer diagnostics and considerable potential in prognostic assessment and therapeutic monitoring, offering possibilities for precise clinical intervention. Despite recent diagnostic progress based on blood-derived sEVs, the inability to specifically profile multiple parameters of sEVs proteins has hampered advancement in clinical applications. Herein, we report an approach to profile colorectal cancer (CRC)-derived sEVs by using multiaptamer-triggered rolling circle amplification (RCA) cascades. In practice, in the presence of target sEVs, the complementary strands are released from the duplexes of the structure-switching aptamer. Then, the RCA cascade occurs but only when the specific DNA strand pair is presented. As a result, the noncanonical DNA assemblies are generated whose size reaches micrometers that can be directly analyzed by conventional flow cytometry, thereby facilitating facile clinical diagnostics. In this study, the developed diagnostic method is verified on cell-derived sEVs, followed by achieving modeling based on clinical samples. The final diagnostic results from the clinical cohort indicate promising diagnostic efficacy for CRC-derived sEVs with 92% sensitivity, 86.7% specificity, and 90% overall accuracy, highlighting the substantial potential of sEVs as biomarkers for CRC diagnosis and significantly advancing the development of clinical tools for early disease diagnosis.