Electrochemical immunosensor based on Au/Co-BDC/MoS2 and DPCN/MoS2 for the detection of cardiac troponin I.

The content of cardiac troponin I (CTnI) in human blood is the key factor in judging acute myocardial infarction (AMI). In order to detect the content of CTnI, we constructed a sandwich-type electrochemical immunosensor based on hydrogen peroxide (H2O2) as a signal source. Dendritic platinum-copper alloy nanoparticles (DPCN) loaded on molybdenum disulfide (MoS2) nanosheets (DPCN/MoS2) as secondary antibodies (Ab2) label provided signal amplification. The hollow three-dimensional (3D) pyramid-shaped structure of DPCN exposed abundant active sites and exhibited excellent catalytic properties. MoS2 nanosheets with flower-like structure and a larger specific surface area can effectively load more DPCN. The combination of MoS2 and DPCN enhanced the catalytic performance of DPCN/MoS2 towards H2O2 reduction and realized signal amplification. For the substrate material, the two-dimensional (2D) metal-organic framework (Co-BDC, 1,4-benzenedicarboxylate is abbreviated as BDC) was hybridized with MoS2 nanosheets to load gold nanoparticles (Au NPs). The obtained Au/Co-BDC/MoS2 had low catalytic activity and excellent electrical conductivity, which was used to load primary antibodies (Ab1) to effectively enhance the sensitivity. Under the best conditions, we constructed the immunosensor with the detection range of 10 fg/mL to 100 ng/mL and the limit of detection (LOD) of 3.02 fg/mL. At the same time, the content of CTnI in human serum was tested with satisfactory results. Therefore, the constructed immunosensor has important significance in the sensitive and accurate detection of CTnI and early diagnosis of AMI.