Amperometric myeloperoxidase immunoassay based on the use of CuPdPt nanowire networks

This research describes a nanowire network-based method for detecting the activity of myeloperoxidase (MPO), a biomarker of acute coronary syndromes (ACS). Trimetallic CuPdPt nanowire networks (CuPdPt NWNWs) were prepared by a one-step chemical reduction method. The metallic precursors quickly form nanowire network structures without the need for additional capping agents or surfactants. This process creates a product with a clean surface. The NWNWs were dropped onto a glassy carbon electrode (GCE) to obtain a sensor with good catalytic activity towards the reduction of hydrogen peroxide (H₂O₂), which was used as an electrochemical probe working at -0.4 V (vs. SCE). It also provided a large surface for further modification. Next, an antibody against MPO was immobilized on the modified GCE via the stable conjunction between Cu, Pt, Pd and amino groups. Upon binding of MPO to the antibody on the GCE, the current response to H₂O₂ was reduced by 35 μA·cm^-2. The immunosensor had a linear response within the 100 fg·mL^-1 to 50 ng·mL^-1 MPO concentration range and a 33 fg·mL^-1 detection limit (at an S/N ratio of 3). The recovery of spiked serum samples ranged from 99.8 to 103.6%. This result suggests that the method can be applied to the quantitation of MPO in human serum samples. Graphical abstract A trimetallic CuPdPt nanowire networks was placed on a glassy cabon electrode (GCE) to design an immunosensor for myeloperoxidase (MPO), a biomarker for the acute coronary syndrome (ACS). Antibody against MPO was immobilized on the network via conjugation between Cu, Pt, Pd and amino groups. Amperometric i-t measurements were conducted to quantify the amount of MPO that binds to the antibody on the surface of the modified GCE.