Preparation of Lipase–Electrospun SiO2 Nanofiber Membrane Bioreactors and Their Targeted Catalytic Ability at the Macroscopic Oil–Water Interface

Lipase is one of the most widely used enzymes in biocatalysis. Because of the special structure of the catalytic active center, lipases show high catalytic activity at oil–water interfaces. Hence, the interface plays a key role in activating and modulating lipase biocatalysis. Compared with traditional catalytic systems that offer interfaces, such as emulsions, a lipase–membrane bioreactor exhibits many obvious advantages when at the macroscopic oil–water system. In our current research, a series of new Burkholderia cepacia lipase (BCL)–SiO2 nanofiber membrane (NFM) bioreactors prepared via combined electrospinning and immobilization strategies were reported. These SiO2 NFMs assisted BCL in reaching the oil–water interface for efficient catalysis. The enzyme loading capacity and catalytic efficiency of BCL–SiO2 NFMs varied with the surface hydrophobicity of the electrospun NFMs. As the hydrophobicity increased, the activity decreased from 2.43-fold to 0.74-fold that of free BCL. However, the lipase-loading capacity increased obviously when the hydrophobicity of the SiO2 NFMs increased from 0 to 143°, and no significant change was observed when the hydrophobicity of the SiO2 NFMs increased from 143 to 153°. The gel trapping technique proved that the hydrolytic activity of the different BCL–SiO2 NFM bioreactors depends on the contact area of the membrane at the oil–water interface. BCL–SiO2 NFM, BCL–SiO2 NFM-C12, and BCL–SiO2 NFM-C18 retained 32, 83, and 42% of activity, respectively, after five cycles of reuse. The current work was a useful exploration of the construction and modification of lipase–membrane reactors based on electrospun inorganic silicon.