Multiplexed Profiling of Breast Cancer Exosomes Based on an Asymmetric Bipolar Electrode Electrochemiluminescence Immunochip

Abstract

Early and sensitive diagnosis is critical for improving the survival rate of breast cancer patients. However, the early detection of triple-negative breast cancer (TNBC) remains a significant challenge due to the lack of specific biomarkers. Herein, we developed a four-channel asymmetric bipolar electrode (BPE)-based microfluidic chip for the highly sensitive and multiplexed profiling of breast cancer exosomes. By leveraging the spatial separation of the capture end (cathode) and the reporting end (anode) in a closed BPE configuration, this chip enables efficient on-chip capturing of tumor exosomes and labeling with electrochemical probes at the cathode. The resulting Faradaic current is coupled to drive the electrochemiluminescence (ECL) of luminol at the anode, allowing for simultaneous quantification of multiple surface markers on exosomes. The BPE features a fan-shaped asymmetric design, in which the enlarged cathode area increases exosome capture capacity, while the confined anode area enhances local current density, thereby significantly boosting the detection sensitivity. Furthermore, this fan-shaped geometry promotes a stable potential distribution and facilitates the integration of a multi-channel array for synchronous detection of multiple biomarkers. The sensing platform achieved an ultra-low detection limit of 1.39 particles/μL for exosomes derived from MDA-MB-231 cells, with a linear range spanning three orders of magnitude. Multiplexed analysis of surface marker expression on exosomes from three cell lines, i.e. MDA-MB-231 (TNBC), MCF-7 (luminal A breast cancer), and MCF-10A (normal mammary epithelial cells), demonstrated that the combined biomarker profile significantly improved the accuracy of discriminating exosomes from different cancer cells. Finally, the method was successfully applied to analyze exosomes in human serum, accurately distinguishing patients with TNBC from those with luminal A breast cancer and from healthy individuals. Overall, this strategy enhances sensitivity via asymmetric BPE design, achieving LODs of 1.39-2.22 particles/μL, and improves classification accuracy through multiplexed detection with AUC values of 0.93-1.00, offering a powerful tool for early screening and molecular subtyping of breast cancer.