Immobilization of laccase onto poly(glycidylmethacrylate) brush grafted poly(hydroxyethylmethacrylate) films: Enzymatic oxidation of phenolic compounds

Poly(hydroxyethylmethacrylate), p(HEMA) films were prepared via UV-initiated photo-polymerization. After activation of the hydroxyl groups of p(HEMA) by bromination, surface-initiated atom transfer radical polymerization (ATRP) of glycidylmethacrylate was conducted in dioxane/bipyridine mixture with CuBr as catalyst at 65 °C. The epoxy groups of the poly(glycidylmethacrylate) brushes were converted into amino groups with the reaction of ammonia. The modified p(HEMA-g-GMA)-NH2 films were used as an ion-exchange support for the immobilization of laccase. The influence of pH and initial laccase concentration on the immobilization capacity of the p(HEMA-g-GMA)-NH2 films has been investigated. The amount of immobilized laccase on the p(HEMA-g-GMA)-NH2 films was determined as 139 μg/cm2 films. The recovered activity of the immobilized laccase on the fibrous polymer grafted films was about 71% compared to free enzyme. The maximum activity (Vmax) and Michealis constant (Km) of laccase immobilized on the films, were found to be 15.4 U/mg and 23 mM, respectively. Finally, the immobilized laccase was operated in a batch system for enzymatic oxidation of phenol, p-chlorophenol and aniline.