Preparation of nanocube PtRhIr nanozyme and its application in ultrasensitive lateral flow immunoassay

The sensitivity of lateral flow immunoassay (LFIA) should be enhanced for detecting low-abundance markers. This study introduces a one-step synthesis method for a cuboidal nanozyme containing Pt, Rh, and Ir (PtRhIr) with a rough surface. The PtRhIr nanozyme exhibited peroxidase-like activity and effectively catalyzed the oxidation of 3,3 ',5,5 '-tetramethylbenzidine (TMB) in the presence of H2O2 to generate a blue product. Enzyme kinetics revealed that the PtRhIr nanozyme has an affinity for the H2O2 substrate (6.55 mM), which is comparable to that of horseradish peroxidase. When the PtRhIr-nanozyme-incorporated LFIA was used for detecting the model marker hCG, the sensitivity increased by 7.8-fold compared to that achieved using a conventional Au nanoparticles based LFIA, achieving a visible detection limit of 3.2 IU/L of hCG.