DNA nanohydrogel and Pb2 + -specific recognition enable one-pot electrochemical exosome aptasensor for staging of breast cancer

In this study, a one-pot electrochemical aptasensor was developed for the rapid and sensitive detection of tumor-derived exosomes. This strategy used a target-responsive DNA nanohydrogel that integrated an aptamer for specific recognition, with Pb²⁺ serving as the signal output element. The key innovation of this homogeneous method lied in its ability to distinguish between free Pb²⁺ and the G-quadruplex-Pb²⁺ complex through electrochemical analysis. Epithelial cell adhesion molecule (EpCAM) was selected as the target for breast cancer-derived exosomes. The binding of the aptamer to the target triggered the disintegration of the DNA nanohydrogel, exposing abundant G-quadruplexes that selectively bound to Pb²⁺, thereby amplifying the electrochemical signal and enabling sensitive detection. Additionally, the analysis system was completed within 45 min, with a limit of detection (LOD) of 300 particles/mL. Meanwhile, the application of this strategy to clinical samples enabled accurate differentiation between breast cancer patients (n = 40) and healthy controls (n = 12), achieving a specificity, sensitivity, and accuracy of 91.7 % (11/12), 95 % (38/40), and 96.2 %, respectively. Furthermore, this approach demonstrated strong capability in differentiating between early- and advanced-stage cancer with 86.1 % accuracy. These findings were in strong agreement with imaging and pathological results. Overall, this exosome-based liquid biopsy method demonstrates significant potential for enhancing breast cancer diagnosis and staging, providing valuable support for personalized treatment decisions.