Ultrasensitive electrochemical immunosensor integrated trimetallic PtCuRu alloy and N-rich interpenetrating twin porous carbon for quantitative detection of cTnI

• An enhanced sandwich-type immunoassay was designed for quantitative analysis of cTnI. • N-rich interpenetrating twin porous ITPC can effectively enrich H 2 O 2 and bind Ab 1 . • PtCuRu NF with open structure and optimized d-orbital facilitate H 2 O 2 reduction. • Extremely low LOD and wide linear range were achieved for cTnI sensing. As a gold standard biomarker for acute myocardial infarction (AMI), cardiac troponin I (cTnI) plays a crucial role in the prevention and monitoring of this condition. Herein, an efficient sandwich-type electrochemical immunosensor is developed for the quantitative measurement of cTnI utilizing highly active trimetallic PtCuRu as a signal amplification platform and N-rich interpenetrating twin porous carbon (ITPC) decorated with gold nanoparticles (Au NPs/ITPC) as matrix material. The morphologically controlled ZIF-8-derived ITPC, synthesized via a facile and green method, features enlarged surface area and high nitrogen content, enabling effective H 2 O 2 enrichment and Ab 1 immobilization, thereby enhancing the stability and sensitivity of the biosensor. In addition, thanks to its open structure and optimized d-orbital coupling features, the meticulously designed flower-like PtCuRu (PtCuRu NF) possess efficient mass and electron transfer ability, favoring amplifying its H 2 O 2 electroreduction activity. These intrinsic advantages of the precisely fabricated electrochemical immunosensor enable outstanding sensitivity, wide dynamic linear range (10 fg mL −1 to 100ng mL −1 ) as well as ultralow detection limit (0.58 fg mL −1 ) for cTnI. In addition, excellent reproducibility, ideal selectivity and long-term stability were also achieved for the cTnI detection. This work pioneered an innovative precisely designed method for sandwich-type electrochemical immunosensor enabling early, quantitative measurement and prognosis of cTnI.