Toward Design Rules for Enzyme Immobilization in Hierarchical Mesoporous Metal-Organic Frameworks

The immobilization of enzymes on or in solid supports is crucial for the industrialization of enzymes as chemical catalysts because immobilization provides stabilization, easy separation, and recyclability. Here, we show that a water-stable metal-organic framework, NU-1000, with hierarchical pore structure has the right combination of properties to be particularly well-suited as a scaffold for immobilizing enzymes such that they maintain full enzymatic catalytic activity. The immobilized enzyme shows greater resistance to organic solvent and denaturant than does the free enzyme and is characterized by greater reactant accessibility and higher activity than the same enzyme encapsulated in topologically simpler metal-organic frameworks. These findings suggest design rules for hierarchical pore structuring of host frameworks for enzyme-encapsulation applications by demonstrating enzyme immobilization in a solid support whereby the enzyme is highly accessible and retains catalytic activity under chemically challenging conditions.