Palladium/Platinum/Ruthenium Trimetallic Dendritic Nanozymes Exhibiting Enhanced Peroxidase-like Activity for Signal Amplification of Lateral Flow Immunoassays

Developing ultrasensitive lateral flow immunoassays (LFIAs) has garnered significant attention in the field of point-of-care testing. In this study, a trimetallic dendritic nanozyme (Pd@Pt–Ru) was synthesized through Ru deposition on a Pd@Pt core and utilized to enhancing the sensitivity of LFIAs. Pd@Pt–Ru exhibited a Km value of 5.23 mM for detecting H2O2, which indicates an H2O2 affinity comparable with that of horseradish peroxidase. The Ru surface layer reduces the activation energy barrier, which increases the maximum reaction rate. As a proof of concept, the proposed Pd@Pt–Ru nanozyme was incorporated into LFIAs (A–Pd@Pt–Ru–LFIAs) for detecting human chorionic gonadotropin (hCG). Compared with conventional gold nanoparticle (AuNP)–LFIAs, A–Pd@Pt–Ru–LFIAs demonstrated 250-fold increased sensitivity, thereby enabling a visible detection limit as low as 0.1 IU/L. True positive and negative rates both reached 100%, which renders the proposed Pd@Pt–Ru nanozyme suitable for detecting hCG in clinical samples.