Dual-mode immunosensor based on Cu-doped Mo2C nanosheets as signal labels

A method for detecting of Carcinoembryonic antigen(CEA) with improved accuracy is urgently needed. In this work, a dual-mode immunosensor for accurate detection of CEA was fabricated, which used a Cu-doped Mo2C co-catalyst as an enhancer. Especially, Cu-doped Mo2C presents a strong different pulse voltammetry (DPV) signal for the electron transfer between Cu2+ and Cu+, without the addition of K3[Fe(CN6)] and other electron transfer mediators, but also shows high electrocatalytic activity towards H2O2 redox reactions. So that detection sensitivity of the chronoamperometry (CA) was enhanced. Furthermore, characterized by excellent conductivity, highly ordered pore distribution and great surface area, Ti3C2 Mxenes can be effective in promoting electron transfer and loading a large number of AuNPs. In the meantime, AuNPs can also immobilize CEA-Ab1 through Au-N bonds. Based on a Cu-Mo2C-Au dual-signal indicator, Ti3C2 Mxene-Au as the matrix, the immunsosensor was developed to achieve dual-signal detection of CEA. Satisfactory detection ranges (1 fg.mL-1 to 40 ng.mL-1) were obtained with limits of detection of 0.33 fg.ml-1 (DPV) and 1.67 fg.ml-1 (CA), respectively. Therefore, the prepared electrochemical immunosensor has good application prospects for the detection of CEA.