Co-immobilization of a bi-enzymatic cascade into hierarchically porous MIL-53 for efficient 6′-sialyllactose production

6'-Sialyllactose (6'-SL), the most abundant sialylated human milk oligosaccharide, has attracted attention for its potential application in supplementary infant formulas. Herein, we report a facile strategy to construct a cascade bioreactor for the enzymatic synthesis of 6'-SL by co-immobilizing an enzymatic module consisting of CMP-sialic acid synthase and α-2,6-sialyltransferase into hierarchically porous MIL-53 (HP-MIL-53). The as-prepared HP-MIL-53 showed high enzyme immobilization capacity, reaching 226 mg g