Preparation and characterization of PDA/SiO2 nanofilm constructed macroporous monolith and its application in lipase immobilization.

• PDA/SiO 2 nano-film constructed millimeter-sized macroporous composite has been prepared. • The activity of CRL immobilized on PDA/MMS was significantly enhanced. • CRL–PDA/MMS shows high storage, thermal and operational stabilities. • CRL–PDA/MMS can be easily recovered from the reaction system. A monolithic macroporous silica (MMS) was prepared by using a pillared epoxy resin macroporous polymer as template. Polydopamine (PDA) as a spacer-arm polymer was modified on the surface of MMS for immobilization of Candida rugosa lipase (CRL), aiming to improve the performance of CRL and overcome the limitations of the immobilized enzymes on mesoporous materials and fine particles. The immobilization conditions and the properties of the immobilized CRL were investigated. The as-prepared monolithic macroporous materials were characterized by SEM, TEM, MIP, BET, FT-IR and TG-DTA. The results revealed that MMS possessed two sets of well-defined and uniform continuous macroporous channels (pore size of 300–500 nm), high mechanical strength, large pore volume and specific surface area, and that the PDA/MMS macroporous composite was constructed by PDA/SiO 2 /PDA nano-film with a thickness of about 50 nm. Because of its surface chemical properties and unique macropore structure, the PDA/MMS composite provided a simple, cost-effective way to enhance the catalytic activity of directly immobilized enzyme. The activity recovery of CRL–PDA/MMS was 201%, and the stability of the immobilized lipase was remarkably improved. Moreover, this biocatalyst can be easily recovered from the reaction system without centrifugation or filtration. [ABSTRACT FROM AUTHOR]