Preparation Of Cu-modified Lanthanide Metal MOFs And Study Of Multi-biological Enzyme Activitie

Nanozymes is a kind of artificial enzyme based on nanomaterials.With the rapid development of nanotechnology,nanozymes has gradually shown its advantages compare with protein enzyme:higher catalytic stability,easier modification and lower preparation cost.Among many nanomaterials,metal-organic framework materials（MOFs）show great potential in enzyme simulation due to their unique modular structure.Lanthanide MOFs are 3D structures formed by the combination of lanthanide metals with low energy 4f orbitals and rigid polyhedral carboxylate or heterocyclic ligands.They have excellent catalytic performance and been widely used as catalysts in the fields of environmental governance,energy conversion and organic synthesis,but there are few studies on the simulation of biological enzymes.In this paper,the lanthanide metal MOFs（Cu⁺/Ce-BTC）doped with different proportions of copper ions were prepared by simple hydrothermal method.Due to the synergistic effect of copper ions and cerium ions,Cu⁺/Ce-BTC had good double-enzyme activity（laccase and peroxidase）.When Cu⁺doping ratio was 1/2,the double enzyme activity reached the best.In order to further increase the catalytic activity,1/2Cu⁺/Ce-BTC was oxidized with H₂O₂ solution to prepare Cu O/Ce O₂ derivative.Cu O/Ce O₂ showed excellent oxidase and phosphohydrolase activities,but also increased peroxidase activity without losing its laccase activity.So far,Cu O/Ce O₂ has four kinds of bioenzyme simulation activities:oxidase and peroxidase activities under acidic condition,laccase activity under neutral condition,and phosphohydrolase activity under alkaline condition.We used Cu O/Ce O₂ as an efficient colorimetric probe for the detection of cysteine,with a linear range of 50-900μM and detection limit of 5μM,and achieved good accuracy and recovery in actual samples.We used a similar method to prepare the lanthanide metal MOFs(Cu⁺/Tb-BTC and Cu²⁺/Tb-BTC)doped with different valence states.The introduction of copper ions made the composites have laccase activity and increased the peroxidase activity.Its laccase activity was used to degrade phenolic substances（2,4-p-chlorophenol,phenol and p-chlorophenol）,and its peroxidase activity was used to degrade dye pollutants（methyl violet and rhodamine B）.The results show that the composite material has good degradation effect on 2,4-p-chlorophenol,and has certain degradation ability on phenol and p-chlorophenol.At the same time,methyl violet and rhodamine B have excellent degradation effect（degradation rate is more than 90%after 30min）.