A flexible paper-based microneedle array electrochemical sensor for CEA detection in interstitial fluid at the point of care.

Carcinoembryonic antigen (CEA) detection is crucial for early cancer diagnosis and prognostic monitoring. However, traditional CEA detection is mainly based on blood samples, which is invasive and less conducive to point-of-care testing (POCT). Therefore, in this study, we developed a flexible paper-based microneedle (MN) array electrochemical sensor, integrated with portable electronics and a mobile application, to detect CEA in interstitial fluid (ISF). The MN array was fabricated from a composite of UV-curable biocompatible resin and microcrystalline cellulose on a paper substrate impregnated with flexible UV-curable resin. The MN array was functionalized as an electrochemical sensor to detect CEA by modification with conductive ink, rGO/Thi/AuNPs nanocomposites and anti-CEA antibodies. The performance of the MN array electrochemical sensor was validated through in vitro and in vivo experiments, and the sensor demonstrated high sensitivity, good selectivity, broad linear ranges, robust stability, and strong concordance with reference methods. This study provides a new tool for CEA monitoring and offers new insights into the development of minimally invasive biomarker detection devices for POCT.