An Electrochemical Aptasensor for Accurate and Sensitive Detection of Exosomes Based on Dual-Probe Recognition and Hybridization Chain Reaction

The accurate and sensitive detection of tumor-derived exosomes holds significant promise for the early diagnosis of cancer. In this study, an electrochemical aptasensor was developed for the high-performance detection of exosomes by integrating dual-probe recognition and hybridization chain reaction (HCR). A dual-probe recognition unit composed of a MUC1 aptamer (MUC1-Apt) probe and cholesterol probe was designed for capturing target exosomes and reducing the interference from free proteins, significantly improving the accuracy of exosome detection. It should be noted that the dual-probe recognition unit was formed in conjunction with the HCR. Moreover, a large number of biotins were also assembled on the HCR product, which were used to capture avidin-horseradish peroxidase (SA-HRP) for signal amplification. The CD63 aptamer (CD63-Apt) was immobilized on the surface of a gold electrode for specifically capturing exosomes to construct a classical sandwiched structure. The loaded SA-HRP can efficiently catalyze the reaction of 3, 3', 5, 5' tetramethylbenzidine (TMB) and hydrogen peroxide (H₂O₂) to generate a large electrochemical signal. According to this phenomenon, a linear relationship of this proposed aptasensor was achieved between the electrochemical response and 1 × 10²-1 × 10⁷ particles/mL exosomes, with a detection limit of 45 particles/mL. Moreover, the aptasensor exhibited accepted stability and potential clinical applicability. All results proved that this aptasensor has a promising application in exosome-based disease diagnostics.