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.