Pt-Decorated Magnetic Nanozymes for Facile and Sensitive Point-of-Care Bioassay

Development of facile and sensitive bioassays is important for many point-of-care applications. In this study, we fulfilled such demand by synthesizing Pt-decorated magnetic nanozymes and developing a bioassay based on unique properties of the newly synthesized nanozymes. Fe3O4–Pt/core–shell nanoparticles (MPt/CS NPs) with various compositions were synthesized and characterized. Fe3O4 NP itself is a good nanozyme with catalytic activity superior to that of natural enzymes, but catalytic activity can be further improved by incorporating Pt to the outer layers of the Fe3O4 NPs and building heterogeneous nanostructures. Magnetic properties of MPt/CS NPs enable magnetic enrichment of liquid samples, whereas catalytic properties of MPt/CS NPs allow signal amplification by enzyme-like reactions. By integrating MPt/CS NPs in lateral flow immunoassay strips, one of the widely used point-of-care bioassay devices, and harnessing magnetic and enzyme-like properties of MPt/CS NPs, an increase in sensitivity of two orders of magnitude was achieved compared to the sensitivity of conventional lateral flow immunoassay based on Au nanoparticles.