Dual-color fluorescence detection of tumor-derived extracellular vesicles using a specific and serum-stable membrane-fusion approach

Tumor-derived extracellular vesicles (tEVs), which are essential mediators for cell-to-cell communication during tumorigenesis and tumor development, have demonstrated significant diagnostic potential in cancer liquid biopsy, particularly through biomarkers like membrane proteins and inner microRNAs. However, traditional detection methods such as ELISA and qRT-PCR encounter challenges with low sensitivity and specificity, complex procedures, and high costs. Although emerging biosensors have been developed, these methods are limited to detecting a single type of tEV biomarker, which may result in misdiagnoses due to false-positive or false-negative signals. Herein, we introduce a specific and serum-stable membrane-fusion approach (SSMFA) capable of simultaneously detecting tEV proteins and microRNAs via dual-color fluorescence analysis. In this strategy, the established epithelial cell adhesion molecule (EpCAM) aptamer-modified serum-stable membrane-fusion liposome (AptSMFL) is labeled with fluorescence resonance energy transfer (FRET) dye pairs, which can specifically recognize EpCAM-overexpressed tEVs and induce serum-stable membrane fusion, allowing the quantification of EpCAM protein levels through red fluorescence changes resulting from FRET alterations. Meanwhile, SSMFA facilitates efficient transfection of the CRISPR/Cas13a probe into tEVs to analyze the levels of microRNA-21 (miR-21) in EpCAM-positive tEVs via green fluorescence detection. When tested on serum samples from hepatocellular carcinoma models, the SSMFA exhibited minimal sample volume requirement and rapid assay time (2 h) to effectively achieve accurate quantification of both tEV EpCAM protein and miR-21 levels. Additionally, this dual-biomarker detection method showed a strong correlation with tumor burden and significantly improved cancer diagnostic accuracy (AUC = 0.98), underscoring the potential of SSMFA as a promising tEV-based liquid biopsy assay for cancer diagnosis.