Ultrasensitive Electrochemiluminescence Multiplex Immunoassays of Circulating Tumor Cells via Cerasomes within MXene-Modified Single-Electrode Electrochemical Systems

Breast cancer (BC) remains one of the most prevalent malignancies worldwide. Notably, the primary cause of mortality is not the primary tumor itself but rather the spread of tumor cells to distant sites. Circulating tumor cells (CTCs), which detach from primary tumors and enter the peripheral bloodstream, are key contributors to metastasis. Therefore, the precise and sensitive detection of CTCs is vital for early cancer diagnosis and monitoring. In this study, we report the development of an integrated MXene-modified Single-Electrode Electrochemical System (SEES) for visual and high-throughput electrochemiluminescence (ECL) immunoassays. ECL immunoassays have attracted significant interest due to their visual readout, high sensitivity, and suitability for parallel analysis. The SEES platform utilizes a carbon ink-based screen-printed electrode, which enables effective antibody immobilization through bioaffinity interactions and adsorption. Moreover, cerasomes are employed as nanocarriers for encapsulated luminol. These hybrid vesicles not only offer high encapsulation efficiency and stability but also enhance ECL emission due to the presence of siloxane groups on their surface. The system is designed with 24 individually isolated reaction wells, enabling simultaneous analysis of multiple samples while preventing cross-contamination. Under optimized conditions, the platform demonstrated impressive detection limits of 5, 5, and 10 cells mL^-1 for MCF-7, MDA-MB-231, and SK-BR-3 cell lines, respectively. This multiplexed biosensor enables the evaluation of various cell surface receptors, offering a promising diagnostic approach for breast cancer and its subtypes.