Ocean green tide derived hierarchical porous carbon with bi-enzyme mimic activities and their application for sensitive colorimetric and fluorescent biosensing

The hierarchical porous carbon with high specific surface area was facilely synthesized by calcination of Enteromorpha prolifera (EP), a renewable ocean waste biomass. The resultant carbon exhibited bienzyme mimetic properties including oxidase-like and peroxidase-like activities, which can be regulated by varying carbonized temperature. The reaction mechanism of the oxidase-like activity of EP-based hierarchical porous carbon (EPC) contributes to singlet oxygen and superoxide anions generated during the reaction, while the peroxidase-like activity arises from hydroxyl radicals. Finally, a sensitive colorimetric biosensor for acid phosphatase was explored based on the oxidase-like activity, demonstrating a linear range of 0.5–15 U/L and the limit of detection (LOD) of 0.1 U/L (S/N = 3). A fluorescent biosensor for H2O2 was also developed with the linear range of 0.05–80 μM and a LOD of 0.017 μM (S/N = 3), based on OH produced with the peroxidase-like activity, which react with terephthalic acid to form 2-hydroxyterephthalic acid. Further, incorporated with glucose oxidase, fluorometric sensing of glucose was realized with the linear range of 0.05–10 mM and a LOD of 30 μM. The bi-enzyme mimics also exhibited high reproducibility and stability. Thus, this EPC can be promising candidates for broad applications in sensing, nanomedicine, industrial catalysis and environmental engineering.