Nanozyme-based electrochemical biosensors have emerged as an alternative to enzyme-based biosensors for next-generation bioanalysis. However, potential antibody modifications limit the catalytic sites of the nanozyme, thereby reducing sensor sensitivity. Here, a sensitive method for determining carcinoembryonic antigen (CEA) was developed. It involved coupling a cascade enzyme - enzyme - like catalytic reaction using Fe - Co Prussian blue analog nanozymes with high peroxidase - like activity (79.42 U mg