Peroxidase-Mimicking Nanozyme with Surface-Dispersed Pt Atoms as the Label for the Lateral Flow Immunoassay of C-Reactive Protein

We report a new approach to synthesize nanozyme with low consumption of precious Pt-precursor and high peroxidase-mimicking activity. The synthesis includes the formation of gold nanoparticles (Au NPs), the overgrowth of a silver layer over Au NPs (Au@Ag NPs), and the galvanic replacement of Ag with PtCl₆^2- leading to the formation of Au@Ag–Pt NPs with uniformly deposited catalytic Pt sites. The reported approach facilitates up to 20-times lower consumption of Pt precursor. The use of Au@Ag-Pt NPs as the catalytic label in lateral flow immunoassay results in a 65-fold lower limit of detection (15 pg/mL in serum).