An Electrochemical Immunosensor for Sensitive Detection of Exosomes Based on Au/MXenes and AuPtPdCu

Exosomes are important biomarkers for liquid biopsy in early cancer screening which play important roles in many biological processes, including apoptosis, inflammatory response, and tumor metastasis. In this study, an electrochemical aptamer immunosensor based on Au/MXene and AuPtPdCu was constructed for the sensitive detection of colorectal cancer-derived exosomes. AuNPs were deposited in situ on the surface of MXenes as a sensing platform due to their large specific area, excellent conductivity, and higher number of active sites for aptamer immobilization. The aptamer CD63 immobilized on Au/MXene can specifically capture target exosomes. Therefore, the AuPtPdCu-Apt nanoprobe further enhanced the sensitivity and accuracy of the immunosensor. A low limit of detection of 19 particles μL^-1 was achieved in the linear range of 50 to 5 × 10⁴ particles μL^-1 under optimal conditions. The immunosensor developed herein showed satisfactory electrochemical stability and anti-interference ability for the detection of exosomes in real serum samples.