Post-synthesis modification of metal-organic framework-bedded lipases proved efficient in the solvent-free system

Metal-organic frameworks (MOFs) have been widely used as carriers in bio-catalysis. However, the micropores of the MOFs usually decrease the activity of bio-catalysts in the solvent-free and viscous reaction system. Herein, we report a post-modification method with adjustable apertures to reduce the mass transfer resistance in the described reaction system. The defected lipase-MOF composites (CRL@dZIF-90), synthesized by the post-modification method, can efficiently catalyze the esterification reactions in the solvent-free systems to synthesize phytosterol esters, including stigmasterol oleate, stigmasterol linoleate, stigmasterol linolenic ester, and stigmasterol octanoate. The CRL@dZIF-90 demonstrated comparable activity to the free CRL with reusability and enhanced stability, validating that post-modification of the MOFs is a potential way to boost the activity of enzyme@MOF biocomposite in the solvent-free system, and might be applicable in the industries in the future