Realizing the label-free sensitive detection of carcinoembryogenic antigen (CEA) in blood serum a MNC-decorated flexible immunosensor.

A label-free electrochemical immunosensor utilising nitrogen-rich mesoporous carbon (MNC) as the substrate material was developed for the sensitive quantification of carcinoembryonic antigen (CEA). The synergic interactions between MNC and AbCEA also eliminated the need for coupling agents such as EDC/NHS. The novel immunosensor demonstrated a wide detection range from 500 fM (9.04 pg mL) to 50 nM (1 μg mL) and a low detection limit (LOD) of 500 fM. Moreover, the immunosensor showed sensitivities of 12.27 mA nM cm and 0.066 mA nM cm for detecting CEA in the linear ranges 10 pM to 1 nM and 2 nM to 50 nM, respectively, while maintaining long-term storage stability of 6 weeks. Analysis of real serum sample analysis yielded highly accurate results with recovery rates ranging from 99.3% to 103.7%. Furthermore, the developed paper-based screen-printed electrode exhibited a similar detection range, suggesting its potential for use in point-of-care detection devices in future applications.