Synergistic dual-enzyme-like Cu/Os nanozymes enable multimodal biosensing platforms

Synergistic coupling between Cu and Os endowed nanozyme with dual enzyme-like activities. • Cu modulation simultaneously improved efficiency and reduced noble metal consumption. • Peroxidase- and ascorbate oxidase–like activities were integrated into a single nanozyme. • Multimodal biosensing was realized via colorimetric and fluorescence readouts. Dual metal nanozymes with synergistic catalytic effects provide a versatile platform for biosensing applications. In this work, a carboxylated chitosan–supported Cu/Os dual-metal nanozyme (CC-CuOs) was developed. The incorporation of Cu introduced ascorbate oxidase–like activity, enhanced the intrinsic peroxidase-like performance of the Os-based nanozyme, and reduced noble metal consumption, thereby improving overall cost efficiency. Benefiting from these dual enzyme-like activities, CC-CuOs was employed as a unified catalytic platform to construct two complementary biosensing systems. A cascade colorimetric assay for choline detection was developed based on peroxidase-like activity, exhibiting a linear response over 1–400 μM with a detection limit of 0.85 μM. In parallel, a fluorescence-based sensing strategy for alkaline phosphatase was realized by exploiting the ascorbate oxidase–like activity of CC-CuOs, enabling quantitative detection from 10 to 500 U·L −1 with a detection limit of 0.91 U·L −1 . Both sensing platforms exhibited satisfactory accuracy, selectivity, and reproducibility when applied to human serum. Overall, this study highlights the potential of CC-CuOs nanozymes for constructing multimodal biosensing platforms through synergistic dual enzyme-like activities. Download: Download high-res image (66KB) Download: Download full-size image