Bimetallic Fe/Mn metal-organic-frameworks and Au nanoparticles anchored carbon nanotubes as a peroxidase-like detection platform with increased active sites and enhanced electron transfer

A hybrid of metal-organic frameworks (Fe, Mn) and Au nanoparticles anchored carbon nanotubes (Au/MOFs(Fe, Mn)/CNTs) was fabricated by a facile one-step hydrothermal process. The Au/MOFs(Fe, Mn)/CNTs exhibit highly enhanced peroxidase-like activity, because of the increased active sites, the enhanced partial charge density and electron transfer among the Fermi level of MOFs, Au and CNTs, as well as the synergistic action of Fe and Mn. The hybrid nanomaterials with high catalytic velocity (Vmax = 17.65 × 10-7 M s-1) and affinity (Km = 0.33 mM) for substrates of H2O2 display a great detection performance in the range of 0.34-53.05 nM with a limit of detection (LOD) of 0.18 nM (S/N = 3). Based on the cascade reaction of the artificial peroxidase and glucose oxidase (GOx), the glucose was further better detected in a linear range of 0.005-0.3 μM with a LOD of 0.002 μM (S/N = 3). Notably, considering the regulated peroxidase-like activity by sulfadimethoxine (SDM) aptamer, the concentration of SDM ranging from 0.54 to 41.58 μg L-1 was also detected with a LOD of 0.35 μg L-1 (S/N = 3). The as-synthesized hybrid nanozymes hold promising applications as the multifunctional sensing platform in environmental and biologic target detection with the combination of corresponding enzyme or specific aptamer.