Visualizing Hydrophobic and Hydrophilic Enzyme Interactions during Immobilization by Means of Infrared Microscopy

Abstract

A novel Fourier transform infrared (FT-IR) microscopy method was developed and used to analyze the diffusion of lipase CalB in two different resins during immobilization. The method consisted of a streamlined sample preparation process and an automated transmission FT-IR microscopic measurement using a commercial benchtop device. The immobilization of CalB was performed on a hydrophobic resin containing aromatic groups (ECR1030M based on divinylbenzene) and on a hydrophilic resin containing ester groups and thus oxygen (ECR8204M based on methacrylate) and FT-IR revealed that the kinetic of immobilization and the distribution of the enzyme on the two resins were completely different. Furthermore, the technique revealed that CalB was immobilized on the external surface only in the case of the hydrophobic ECR1030M in a layer of about 50–70 µm, whereas when immobilized on the hydrophilic carrier ECR8204M the interaction of the enzyme with the carrier was uniform over the full diameter of the polymer bead. The enzyme activity however was higher on the hydrophobic support ECR1030M.

Keywords

• FT-IR microscopy
• enzyme immobilization
• lipase CalB
• methacrylate enzyme carrier
• covalent immobilization
• hydrophobic immobilization