Facile and clean synthesis of dihydroxylatopillar[5]arene-stabilized gold nanoparticles integrated Pd/MnO nanocomposites for robust and ultrasensitive detection of cardiac troponin I.

In this work, a novel, facile, clean synthesis of monodisperse Au nanoparticles (AuNPs) with an average diameter of 5 nm was achieved by reducing HAuCl with dihydroxylatopillar[5]arene (2HP5) in basic solution without the use of harsh reagents and/or external energy. Accordingly, toluidine blue (TB), one electrochemcial indicator, could enter into the cavity of 2HP5 to fabricate host-guest complex through strong electrostatic interaction and charge-transfer interaction, which significantly enhanced the loading quantity of TB and effectively suppressed the leaking of TB resulting in an ultrasensitive and robust electrochemical response. More importantly, the integration of 2HP5-stabilized AuNPs and Pd-decorated MnO nanocomposites (2HP5@Au-Pd/MnO) might usually obtain a novel functional-enhanced materials and lead to new properties and improving the analytical performance and robustness of electrochemical devices. Therefore, we construct a sandwich-type electrochemical immunosensor using TB-2HP5@Au-Pd/MnO nanocomposites as the transducing materials for robust and ultrasensitive detection of cardiac troponin I (cTnI), a significant biomarker of acute myocardial infarction. As anticipated, this immunosensor had remarkable robustness, sensitivity, stability, specificity, and corresponded linearly to the concentration of cTnI over a wide range from 0.005 to 20 ng mL with a low detection limit of 2 pg mL (S/N = 3). The proposed electrochemical immunosensor showed acceptable recoveries in human serum, indicating that macrocycle-stabilized metal nanoparticle might be a promising emerging transducer material for the detection of biological markers.