A Signal-Amplified Electrochemiluminescent Biosensor Based on Iridium Nanocluster Synergies with a Bipedal DNA Walker for CYFRA21-1 Detection

-dimethylformamide served as a mild ligand, offering a controllable reduction environment and suitable thermal annealing conditions. This coordination effect achieved the surface functionalization of Ir NCs, successfully preparing Ir NCs with a uniform size and a stable structure. The target analyte cytokeratin 19 fragment 21-1 drove the DNA walker to perform cyclic catalytic walking at the biosensing interface, continuously introducing Ir NCs-labeled DNA strands through strand growth reactions. This process achieved significant cascade amplification of the ECL signal. This biosensor showed a good linear relationship within the concentration range of 100 fg/mL to 100 ng/mL, with a detection limit as low as 42 fg/mL. This study demonstrates good application potential in the early screening and clinical diagnosis of diseases.