Dual-responsive electrochemical immunosensor for CYFRA21-1 detection based on Au/Co Co-loaded 3D ordered macroporous carbon interconnected framework

Cytokeratin 19 fragment antigen 21–1 (CYFRA21–1) is a protein fragment released into the bloodstream during the death of lung epithelial cells, serving as a predictive biomarker in diagnosing non-small cell lung cancer (NSCLC) and need to be accurately detected. Herein, a dual-responsive label-free electrochemical immunosensor was developed based on a three-dimensional ordered interconnecting macroporous carbon skeleton material modified with gold-cobalt nanoparticles (Au/Co NPs-3D MCF) to detect cytokeratin-19 fragment (CYFRA21–1). The three-dimensional ordered interconnect macroporous structure, by providing a high specific surface area and an electrochemically active area, not only enhances the electron transport channel and reduces mass transfer resistance, but also offers a confined region that elevates the collision frequency with the active site. In addition to exhibiting excellent biocompatibility for antibody binding, gold-cobalt nanoparticles contribute significantly to the overall robustness of the immunosensor. By capitalizing on the 3D network structure and collective effect of Au and Co NPs, the Au/Co NPs-3D MCF immunosensors exhibit exceptional response signals in both chronocurrent testing and square-wave voltammetry, allowing for a wide linear response range of 0.0001–100 ng/mL and a low detection limit. Moreover, the constructed immunosensor is capable of detecting CYFRA21–1 in human serum and has the potential for further extension to detect multiple biomarkers. This work opens up new avenues for the construction of other highly selective 3D network immunosensors.