Preparation of macroporous hybrid monoliths via iron-based MOFs-stabilized CO2-in-water HIPEs and use for β-amylase immobilization

The current study reports the utilization of MIL-100(Fe) as Pickering emulsifiers to stabilize CO 2 -in-water high internal phase emulsions, thereby synthesizing interconnected macroporous hybrid monoliths with adjustable pore sizes. During such a green synthesis procedure, the influences of Fe-MOF type and content, carbon dioxide density, and the amount of crosslinker have been explored respectively. The as-synthesized MOF-containing poly(HIPE)s were characterized by FT-IR, XRD, SEM, CLSM, and TGA. The morphology of the monoliths was mainly observed by EDS-mapping and SEM, which showed that Fe-MOFs were uniformly distributed into the monolithic matrix and the void sizes and interconnected pore sizes were 20 to 150 μm and 5 to 50 μm, respectively. Furthermore, the MIL-100(Fe)-containing monoliths exhibited an excellent elasticity and can quickly return to their original state when reaching up to 90% compressive strain without failing. To evaluate the adsorptive properties of the composite monoliths, the immobilization of β-amylase on the obtained monoliths was studied. The results of immobilized enzymes showed that the highest protein adsorption rate can reach 55% and the immobilization efficiency can reach 89%. Since our synthetic route is clean and controllable, biocompatible monoliths with good elasticity and toughness were prepared, which presents a viable strategy to produce hybrid monoliths for bio-medical applications.