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.