Petal-like g-C3N4-enabled electrochemical immunosensor for urinary cytokeratin 19 assessment in endometriosis: a proof-of-concept pilot study.

Endometriosis is a debilitating, estrogen-dependent gynecological disorder characterized by profound diagnostic delays due to clinical reliance on invasive laparoscopy. Developing noninvasive, point-of-care biomarker assessment remains a critical yet unmet medical need. Here, we report an integrated electrochemical immunosensing platform ("Flower-CN-EC") based on a structurally engineered, petal-like graphitic carbon nitride (g-C3N4) framework for the sensitive detection of urinary cytokeratin 19 (CK-19)-a promising candidate biomarker reflecting endometriosis-associated epithelial activity. The 3D hierarchical architecture of curled nanosheets provides an optimized microenvironment that facilitates unhindered mass transport and minimizes steric hindrance during covalent antibody immobilization. To bridge laboratory sensing with decentralized clinical translation, the sensor was coupled with a customized visual signal-processing interface featuring automated polynomial baseline correction. The sensor showed an excellent log-linear response to CK-19 (10 pg/mL-100 ng/mL), a low detection limit of 3.24 pg/mL, outstanding batch reproducibility (relative standard deviation 2.31%, n = 8), and exceptional ambient storage stability over 5 weeks. In a pilot clinical evaluation (n = 21), the platform successfully differentiated patients with histologically confirmed endometriosis from healthy controls with high statistical significance (p = 0.0011) and AUC of 0.899. These findings establish a robust, noninvasive proof-of-concept paradigm, paving the way for low-cost, decentralized endometriosis screening and longitudinal treatment monitoring.