Construction of enzyme@glutathione hybrid metal-organic frameworks: glutathione-boosted microenvironment fine-tuning of biomimetic immobilization for improving catalytic performance

Zeolitic imidazolate framework (ZIF) has recently emerged as a promising material for the encapsulation of enzymes because of their high surface area and facile construction conditions. However, the enzymes are partial even completely inactive after encapsulation owing to the confinement effect and competing coordination, and otherwise, the alkaline environment caused by the protonation effect of 2-methylimidazole also damages enzyme molecules. Herein, a novel glutathione (GSH)-boosted one pot embedding strategy that enabled to rapidly encapsulate enzyme within GSH hybrid MOF (named enzyme@GMOF) with a high embedding efficiency was constructed. Hybrid of GSH and imidazole as synchronous ligands for GMOF to immobilize enzyme can offer sufficient well microenvironment for enzyme exhibiting high activity. The obtained catalysts (CAT@GZIF-67) displayed 9.0-fold higher catalytic activity than traditional ZIF-67 immobilized CAT (CAT@ZIF-67) and superior reusability and storage stability compared with CAT@ZIF-67 and free CAT. As one kind of biomacromolecules, bio-affinity of GSH can create an affinitive microenvironment for enzymes and reduce the influence of other factors during the use of biomacromolecules on their conformation and activity.