Rice straw-derived 3D porous carbon-based electrochemical immunosensor for ultrasensitive detection of alpha-fetoprotein

To detect the core tumor marker of alpha-fetoprotein (AFP) for the early diagnosis and prognostic evaluation, N/O co-doped 3D porous carbons (SDNOC3D PCs) were synthesized using rice straw as the green precursor to construct the sensitive electrochemical immunosensor. The SDNOC3D PCs possess the hierarchically interconnected 3D porous network with the specific surface area of ca. 1333 m2 g−1, accompanied by uniformly distributed N/O heteroatomic functional groups and abundant defect sites. The SDNOC3D PCs electrochemical immunosensor exhibits a linear response range of 0.001–1000 pg ml−1 for AFP, with the limit of detection of ca. 0.93 fg ml−1. The excellent electrochemical detection performance may be due to the unique structure of SDNOC3D PCs, which enables the efficient immobilization of AFP antibodies by the synergy of physical adsorption and electrostatic interactions, accelerating the electron transfer kinetics at the electrode interface. This work provides a novel green paradigm for the high-value utilization of agricultural wastes for the rapid clinical detection of tumor markers.