Construct efficient substrate transport and catalytic sub-nanochannels in metal-organic framework-based nanozymes for boosting peroxidase-like catalytic activity

Transition metal-based metal-organic frameworks (MOFs) nanozymes, as an ideal artificial metalloenzymes, have recently attracted extensive attention due to their unique porous structure and promising applications in many fields. However, due to the lack of in-depth understanding of the catalytic mechanisms of MOF-based nanozymes, especially the influence of the inherent structure of MOFs on the enzyme-like catalytic process, it is still a very difficult task to reasonably construct high-performance MOF-based nanozymes to date. Inspired by biological ion channels with ultra-high ion conductivity and selectivity, a facile metal node engineering strategy was developed in this study to directly construct highly efficient 1D substrate transport and catalytic sub- nanochannels within Fe-based (MIL-53(Fe)) nanozymes. Through Ni-doping and H2-treatment at low tempera-ture (200 degrees C), NiII and mixed-valence FeII/FeIII nodes were successfully generated in 1D iron oxide octahedral chains of MIL-53(Fe) to act as adsorption and reversible catalytic sites of H2O2, respectively. Benefiting from the confinement effect and optimized catalytic microenvironment of NiII and FeII decorated sub-nanochannels, the as-obtained NixFe-MOF-based nanozymes exhibited lower values of Km (0.068 mM) toward H2O2 and larger nu max (2.92 x107 M s1) in comparison with previously reported studies. Furthermore, the well-designed nanozymes illustrated high sensitivity and selectivity toward the detection of H2O2 and glutathione. This work not only deepens our understanding of enzyme-mimetic activity of MOF, but also the proposed strategy could be potential used for the design and synthesis of other highly efficient MOF-based catalysts.

Automated summary

Transition metal-based metal-organic frameworks (MOFs) nanozymes have attracted extensive attention due to their unique porous structure and promising applications. However, the lack of understanding the catalytic mechanisms of MOF-based nanozymes makes it difficult to construct high-performance MOF-based nanozymes. This study developed a metal node engineering strategy to construct highly efficient 1D substrate transport and catalytic sub-nanochannels within Fe-based (MIL-53(Fe)) nanozymes, showing improved sensitivity and selectivity for the detection of H2O2 and glutathione.