An Electrochemical Immunosensor for Sensitive Detection of Cardiac Troponin I Based on the Amplification Effect of Asymmetric Bowl-Shaped Mesoporous Nanospheres

Abstract

Here, a sandwich-type electrochemical immunosensor was constructed to detect cardiac troponin I (cTnI) via asymmetric bowl-shaped PdAgFe mesoporous nanospheres (PdAgFe ABMS) as signal amplification label and core–shell cubic Au/Co-LDH@ZIF-67 as substrate material. PdAgFe ABMS prepared by dual-template directional anisotropic island growth method has abundant mesoporous channels to accelerate molecular mass transfer in solution. In particular, the asymmetric bowl-like structure allows more active sites to be exposed, which improves the utilization of atoms to stabilize and high current response signals. The synergistic effect between PdAgFe increased the activation energy of the catalytic reaction and further amplified the current signal. In addition, the biosensing interface based on Au/Co-LDH@ZIF-67 not only exhibits a high electron transfer rate, but also can capture more bioactive molecules. Under the optimal conditions, the constructed immunosensor was detected to exhibit a low limit of detection (LOD, 4.47 fg ml−1) and a wide detection range (10 fg ml−1–100 ng ml−1). This work provides an accurate and convenient scheme for the clinical detection of cTnI.