Sandwich-type electrochemical aptasensor based on Au-modified conductive octahedral carbon architecture and snowflake-like PtCuNi for the sensitive detection of cardiac troponin I.

The cardiac troponin I (cTnI) detection is increasingly significant given its promising value in the clinical acute myocardial infarction diagnosis. Here a sensitive sandwich-type cTnI electrochemical aptasensor was developed by using zirconium-carbon loaded with Au (Au/Zr-C) as electrode-modified material and snowflake-like PtCuNi catalyst as label material. The Au/Zr-C was prepared from a carbonation process and a reduction step. The PtCuNi was synthesized by a one-pot hydrothermal reaction. On the one hand, due to its many merits of large effective area, rich pores, high degree of graphitization, the assistance of Au, the Au/Zr-C exhibited remarkable electronic conductivity but low catalytical capacity, thus improving the electrochemical property but lowing the background signal of electrode. On the other hand, because of its accessible active sites of the special snowflake-like structure and the synergy of three elements, the PtCuNi catalyst presented excellent catalytic activity and improved stability compared to binary alloy. The recognition reactions were achieved by stepwise incubation of aptamer 1, cTnI, and aptamer 2-PtCuNi (denoted as Apt2-label) on the Au/Zr-C-modified electrode. The electrocatalytic signals of the immobilized Apt2-label towards the H ₂ O ₂ reduction were recorded in all tests for cTnI analysis. Consequently, this cTnI aptasensor exhibited excellent performance involving a wide linear range of 100 ng mL ^-1 to 0.01 pg mL ^-1 with a detection limit of 1.24 × 10 ^-3  pg mL ^-1 (S/N = 3), good selectivity, satisfying reproducibility, outstanding stability, and good recovery.
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