Poly(styrene-divinylbenzene) beads surface functionalized with di-block polymer grafting and multi-modal ligand attachment: performance of reversibly immobilized lipase in ester synthesis.

Fibrous poly(styrene-b-glycidylmethacrylate) brushes were grafted on poly(styrene-divinylbenzene) (P(S-DVB)) beads using surface-initiated atom transfer radical polymerization. Tetraethyldiethylenetriamine (TEDETA) ligand was incorporated on P(GMA) block. The ligand attached beads were used for reversible immobilization of lipase. The influences of pH, ionic strength, and initial lipase concentration on the immobilization capacities of the beads have been investigated. Lipase adsorption capacity of the beads was about 78.1 mg/g beads at pH 6.0. The Km value for immobilized lipase was about 2.1-fold higher than that of free enzyme. The thermal, and storage stability of the immobilized lipase also was increased compared to the native lipase. It was observed that the same support enzyme could be repeatedly used for immobilization of lipase after regeneration without significant loss in adsorption capacity or enzyme activity. A lipase from Mucor miehei immobilized on styrene-divinylbenzene copolymer was used to catalyze the direct esterification of butyl alcohol and butyric acid.