Immobilization of catalase on electrospun nanofibrous membranes modified with bovine serum albumin or collagen: Coupling site-dependent activity and protein-dependent stability

Abstract

The properties of immobilized enzyme preparation are governed by the properties of both the enzyme and the carrier material. The interaction between the two provides an immobilized enzyme with specific biological and chemical properties. To more clearly understand the role of the carrier surface in the activity and stability of immobilized enzyme, we modified poly(acrylonitrile-co-acrylic acid) nanofibrous membrane with bovine serum albumin (BSA), which has a heart shape, and collagen, which is a fibril. The protein coverage density was verified with UV-vis spectrophotometry and confocal laser scanning microscopy. Catalase from bovine liver was then immobilized on the protein-modified nanofibrous membranes using either glutaraldehyde or N-(3-dimethylaminopropyl)-N′-ethyl-carbodiimide hydrochloride as coupling agent. Atomic force microscopy and water contact angle measurement were used to evaluate the topographical and hydrophilic/hydrophobic properties of the protein-modified surfaces. Results indicate that the enzyme loading and the specific activity of immobilized catalase depend on the protein coverage density, kinds of proteins and coupling agents. The activity of catalase can be enhanced by surface modification with both BSA and collagen. However, they show different effects on the thermal stabilities of the immobilized catalase, which is ascribed to whether hydrophobic interaction occurs between the immobilized catalase and the protein-modified surface.