Triple signal-enhancing sandwich-type electrochemical immunosensor based on Au@SNHC and PtPdCu/BNC for detection of Cardiac Troponin I.

A novel multiple amplification strategy for electrochemical immunoassay was developed elaborately. The realization of this strategy is based on the high efficiency catalysis of boron nitrogen double-doped carbon loaded trimetallic PtPdCu mulberry-like nanospheres (PtPdCu/BNC) and the satisfactory conductivity of gold nanoparticles modified with sulfur nitrogen co-doped hollow porous carbon (Au@SNHC). Single crystal anisotropic Pt octahedral seeds were synthesized with sodium citrate as shape-directing agent, and then three metals were grown in situ to prepare the trimetallic PtPdCu mulberry nanospheres, which had excellent utilization of atoms and a significant number of catalytic active centers. Boron nitrogen double-doped carbon (BNC) with abundant free electrons and high electron density micro-mesoporous can be used as the supported dispersion material of PtPdCu MBNSs, further catalytically enrich H2O2. Moreover, the etching vulcanization of small ZIF template and the co-doping of sulfur and nitrogen endow sulfur nitrogen co-doped hollow porous carbon (SNHC) with shorter the diffusion distance of charge carrier and lower mass transfer resistance. Under optimal conditions, the developed immunosensor exhibits good sensing performance with a detection limit of 4.27 fg⋅mL-1, and the wide linear dynamic range (10 fg⋅mL-1-100 ng⋅mL-1). This study provides a possible strategy for early diagnosis and postoperative monitoring of AMI.