Controllable Cascade Aggregation Ion Programmed Nanomachines and Simple Isolation Enable Tumor-Derived Small...

Small extracellular vesicles (sEVs) carry biomolecules that reflect their cellular origin, making them attractive biomarkers for breast cancer assessment and human epidermal growth factor receptor 2 (HER2)-status discrimination. However, existing methods involve lengthy isolation procedures and exhibit poor detection performance due to severe interference from excessive impurities. In this study, we constructed a dual-target electrochemical (EC) sensing platform based on cascade aggregation effects. Combined with a facile filter-based isolation strategy, this enables rapid and convenient dual-marker (epithelial cell adhesion molecule (EpCAM) and HER2) analysis of breast cancer-derived sEVs. This mechanism relies on the target-triggered disassembly of DNA nanospheres to release Ag⁺/Hg²⁺ for EC signaling. Subsequently, colistin specifically binds to G-quadruplexes on unreacted nanospheres and induces their aggregation, sequestering background signal sources and preventing ion leakage. This noise-silencing strategy improved matrix tolerance and reduced background leakage under a standardized diluted-plasma workflow, enabling reliable detection of sEVs-associated signals in filtration-derived clinical samples. A proof-of-concept clinical study involving 63 breast cancer patients and 22 nonmalignant controls successfully demonstrated the platform's capability to distinguish cancer patients from controls. Furthermore, the platform achieved a 88.9% accuracy in differentiating HER2 status within this cohort. Overall, this streamlined "filtration-to-detection" platform offers a promising strategy for analyzing breast cancer-specific sEVs signals and conducting exploratory HER2-status assessments.