Label-free electrochemical immunosensor based on PdCuPt/PPY/DCSC as a signal amplification platform for sensitive detection of cardiac troponin I

Abstract

Monitoring cardiac troponin I (CTnI) by immunosensor is of great significance in the diagnosis of acute myocardial infarction (AMI). The core of extending immunosensor technology to micro-detection is the excellent performance of immunosensor, emphasizing that the constructed immunosensor needs to have high sensitivity. For this reason, we synthesized a kind of trimetallic PdCuPt nanoparticles (NPs) with excellent catalytic performance. Due to the combination of the electronic and geometric effect originating from the formation of near surface alloy (NSA) with special ultra-small polyhedral spherical structure, PdCuPt NPs exhibit excellent catalytic performance, which provides a good foundation for achieving high sensitivity. In the light of the unique hollow window structure of the dice-shaped cobalt square cage (DCSC), we combined DCSC with PdCuPt NPs by polypyrrole (PPY) as a signal amplification platform (PdCuPt/PPY/DCSC) to further amplify the response signal. The introduction of PPY into DCSC (PPY/DCSC) can enhance conductivity to accelerate electron transfer and improve mechanical stability. The hierarchical porous structured PPY/DCSC can not only accelerate the mass transfer but also promote the adhesion of PdCuPt NPs and improve the dispersion. In view of the above-mentioned signal amplification platform, the fabricated label-free electrochemical immunosensor shows ultra-high sensitivity, wide dynamic range (50 fg/mL~1 μg/mL) and low limit of detection (LOD, 16.03 fg/mL). The introduction of this sensitive electrochemical immunosensor provides a reference for clinical sensitive detection of CTnI.