Transformation of europium metal-organic framework from 3D via 2D into exfoliating 3D for enzyme immobilization

Abstract

Metal-organic frameworks (MOFs) have emerged as highly promising materials for hosting functional biomolecules. Here, a 1,2,4-benzenetricarboxylate ligand with a flat asymmetric shape is applied to infuse an unusual behavior to a 3D europium MOF (SLU-1). Solvent addition results in the 3D MOF splitting into a 2D one (SLU-2), and in the presence of excess water, gets cross-linked into a different 3D MOF (SLU-3) prone to spontaneous exfoliation. SLU-3 features a combination of highly hydrophilic and hydrophobic spots and serves as an attractive host for incorporating large active species. As a representative demonstration, horseradish peroxidase (HRP) is incorporated into the exfoliated 3D-layered structure by simple mixing, and secured by an outer silica layer in the form of core-shell structures. The resulting HRP-based biocatalyst exhibited enhanced stability and reusability, effectively degrading phenol. This work showcases the potential of reconfigurable MOFs, offering upheld applications through the controlled uptake and retention of biocatalytic agents. Metal-organic frameworks are promising materials for hosting functional biomolecules. Here, a 3D europium metal-organic framework could split into a 2D one upon solvent addition and re-cross-link to 3D with excess solvent which can host enzymes as a biocatalyst.