Enzyme Mimetic Activity of Intercalated Pd–H Nanosheets for Bioanalysis

Nowadays, modulating and tuning the lattice strain of nanozymes has emerged as a powerful tool to boost the enzymatic performance of the material for sensitive bioassays. Here, a two-step lattice strain tuning method was adopted to synthesize highly curved, porous, and thin palladium nanosheet assemblies (Pd–H NSAs), serving as oxidase mimics. These nanostructures showed excellent oxidase-like activity due to hydrogen intercalation, enabling rapid electron transfer and substrate accumulation. Utilizing Pd–H NSAs, we designed a sensitive colorimetric platform for detecting acid phosphatase and alkaline phosphatase activity with a limit of detection (LOD) of 0.0032 and 0.0057 U/L, respectively. We also created a simple colorimetric assay for malathion detection, achieving a linear range of 0.1–10 μM and an LOD of 0.014 μM. Moreover, we applied a paper-based smartphone sensing platform for real fruit sample analysis, highlighting the potential of our biosensor assay for environmental pesticide detection.