Enzyme@silica nanoflower@metal-organic framework hybrids: A novel type of integrated nanobiocatalysts with improved stability

A novel integrated nanobiocatalyst system based on an enzyme@silica nanoflower@metal-organic framework (enzyme@SNF@ZIF-8) structure with improved stability is fabricated for the first time. The versatility of this system is validated using penicillin G acylase (PGA) and catalase (CAT) as model enzymes. The microporous ZIF-8 layer can be controlled by varying the number of ZIF-8 coating cycles, which produces PGA@SNF@ZIF-8 nanobiocatalysts with different ZIF-8 layer thicknesses. After the second ZIF-8 coating cycle, a PGA@SNF@ZIF-8(2) structure with a homogeneous and well-intergrown ZIF-8 layer is formed, which possesses excellent mechanical and chemical stability. Moreover, PGA@SNF@ZIF-8(2) shows improved thermal/storage stability and reusability compared with free PGA and PGA immobilized on silica nanoflowers (PGA@SNF). The obtained CAT-based nanobiocatalysts (CAT@SNF@ZIF-8(2)) also show excellent catalytic performance.