Immobilization of lipase enzyme in polyvinyl alcohol (PVA) nanofibrous membranes

Lipase enzyme from Candida rugosa (E.C. 3.1.1.3) has been successfully immobolized in 100–500 nm diameter fibers via electrospinning of aqueous mixtures of lipase and polyvinyl alcohol (PVA). Enzyme loading in these bicomponent fibers reached as high as 50%. The catalytic activity of the fiber bound lipase was the same as the crude enzyme, showing no adverse effects from either electric charges or PVA on the structure or functions of the enzyme proteins. Thermal behaviors and enzyme activities showed the lipase protein molecules to be dispersed among a semi-crystalline PVA matrix. Most significantly, the lipase-loaded bicomponent fibers exhibited far superior activity than the crude enzyme following exposures to elevated temperatures and humidity. The lipase/PVA bicomponent fibers could be rendered insoluble in water by chemical cross-linking with glutaraldehyde (GA) in ethanol, however, with reduced activities. The fibrous and porous structures of the bicomponent fibers were retained upon the cross-linking.