A Signal-Amplified Electrochemiluminescent Biosensor Based on Iridium Nanocluster Synergies with a Bipedal DNA Walker...

Iridium-based nanomaterials have shown great potential for development in electrochemiluminescence (ECL) analysis, in response to the bottlenecks of traditional ECL materials in terms of stability and surface engineering. In this study, novel iridium nanoclusters (Ir NCs) were synthesized and first applied in ECL, enabling efficient anodic ECL signal output. During synthesis, N,N-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.