Dopamine-modified pectins for laccase induced hydrogel formation and immobilization

Abstract

Pectins belong to a group of a plant polysaccharides that are structural components of plant cell walls. These polysaccharides have big potential for use in the food industry as a gelling agents and biomedical application due their biocompatibility, biodegradability, low price, etc. Chemical modifications of pectin are useful methods for introducing various functional groups, which give pectin hydrogels novel properties. In this study, pectin was modified by oxidation with sodium periodate at molar ratios of 5, 10 and 15 mol% and reductive amination with dopamine and sodium cyanoborohydride afterwards. This modification of pectin was confirmed by UV-VIS and NMR spectroscopy. Dopaminepectins showed gelling properties in the presence of laccase and oxygen. These pectin derivatives were tested as carriers for laccase immobilization within microbeads formed in an emulsion based enzymatic polymerization reaction. Laccase was expressed in functional form in E. coli, isolated and additionally purified. We determined optimal conditions for immobilization andobtained microbeads with specific activity of 0.0006 IU/mg and 40% yield of immobilization. The immobilized laccase could be used for various application, such as decolorization of textile dyes .