pH‐Switchable Multi‐Enzyme‐Mimicking via Liquid Metal Nanozyme

Liquid metal (LM), with unique reversible morphology and tunable electronic properties, has become a promising platform for designing advanced nanozymes. The catalytic activity in nanozymes is typically highly dependent on the environmental pH value. Here a magnetic LM-buffered iron oxide nanozyme (FeO_x@EGaIn) is designed with pH-switchable enzymatic activities, in which LM serves as an electron transport substrate effectively promoting the catalytic efficiency. Due to the different oxidation forms and local electronic properties of iron-oxides in acid-base systems, FeO_x@EGaIn nanozymes exhibit excellent peroxidase (POD) catalytic activity under acidic conditions (K_m = 2.12 mM, v_max = 1.96 × 10^-6 M s^-1), which switched to catalase activity (CAT) under neutral to alkaline conditions with high catalytic stability. And its unique magnetic responsiveness provides the possibility of more convenient catalyst recovery. Moreover, the switchable enzymatic activities of nanozymes offer new avenues for biosensing applications, especially in the detection of broad pH-responsive biomolecules. Using liquid metal nanozymes as a colorimetric sensing platform for dynamic detection of biomolecules, this study reveals the key role of electronic microenvironment in regulating the catalytic activity of nanozymes, and also expands the application prospects of liquid metals in catalysis, sensing detection, and biomedical fields.