Nanozyme-catalyzed cascade reactions for high-sensitive glucose sensing and efficient bacterial killing

The development of nanomaterial-based artificial enzymes with multiple functions that mimic the complexity and function of natural systems is essential for the design of biomimetic devices that imitate physiological processes. In this work, a biomimetic nanozyme fabricated using single-layer graphitic carbon nitride incorporating copper was developed, which triggers catalytic cascade reactions for glucose sensing and bactericidal action. This nanozyme that mimics glucose oxidase was capable of photocatalytic production of hydrogen peroxide by coupling glucose oxidation and dioxygen reduction under visible light irradiation. The hydrogen peroxide produced in situ served as the substrate in the subsequent peroxidase-like reaction, allowing the oxidation of chromogenic substrates to complete the bifunctional oxidase-peroxidase action on the same catalyst. The bifunctional cascade catalysis was successfully applied for the real-time and colorimetric sensing of glucose with a limit of detection (LOD) of 0.71 μM. Furthermore, the system exhibited striking bactericidal performance against the gram-negative bacteria Shewanella putrefaciens (S. putrefaciens, associated with food spoilage) that was attributed to the production of detrimental free radicals via nanozyme catalysis. This study not only paves the way for the construction of enzyme-like cascade systems, but also provides an efficient route for defect engineering in food preservation.