Poly(glycidyl methacrylate)-Polystyrene Diblocks Copolymer Grafted Nanocomposite Microspheres from Surface-Initiated Atom Transfer Radical Polymerization for Lipase Immobilization: Application in Flavor Ester Synthesis

Abstract

Functional hairy poly(styrene-b-glycidylmethacrylate) (P(S-GMA)) brushes were generated by grafting from bromoacetylated poly(styrene-divinylbenzene) (P(S-DVB)) microspheres via surface-initiated atom transfer radical polymerization (SI-ATRP). Two different approaches for the covalent immobilization of lipase onto microspheres were studied for the first time: (1) direct immobilization of lipase to the polymer brushes via their epoxy groups, and (2) immobilization of lipase via glutaraldehyde coupling after attachment of a spacer arm (hexamethylendiamine (HMDA)) to the polymer brushes. The covalent immobilization of the lipase on microspheres after spacer-arm attachment and glutaraldeyhde coupling was found to be the more effective than the direct binding method. In this case, a maximum value of the immobilized enzyme activity 498.5 U g -1 was found with an enzyme loading of 27.6 mg per gram of support. Thermal and storage stabilities increase upon immobilization on the P(S-DVB)-g-P(S-GMA)-HMDA-GA microspheres. Finally, esterification reactions have been performed to produce ethyl acetate and isoamyl acetate in a solvent-free system and in n-hexane using lipase-immobilized P(S-DVB)-g-P(S-GMA)-HMDA-GA microspheres. The immobilized lipase was effectively reused in successive batch runs in a solvent-free system for isoamyl acetate synthesis, and only 21% activity was lost after 10 cycles.

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

“…Preparation of 2-bromoacetyl bromide modified P(S-DVB) beads P(S-DVB) beads were prepared by cross-linking copolymerization of styrene-divinyl benzene mixture (with 9/1 M ratio) in aqueous suspension using Gum Arabic as stabilizer, according to the method given in the literature [4]. The beads were dried, sieved, and 210-422 lm size of fraction was used for acetoxy mercuration reaction.…”

“…Esters of carboxylic acids are important components of natural aromas, contributing to the flavor in most fruits and many other foods. The lipase-catalyzed synthesis of several flavoring esters has been described to date [3][4][5] and in principle, the reaction can be carried out in a mixture of alcohol and carboxylic acid with or without solvents, resulting in very high productivities and yields [6,7]. However, like many other enzymes, lipases have limited use in industrial applications due to their short life-times.…”

Immobilization of Proteins in Poly-Styrene-Divinylbenzene Matrices: Functional Properties and Applications

“…In this case, hairy poly(styrene-glycidylmethacrylate) brushes were prepared by grafting using bromoacetylated poly(styrene-divinylbenzene) microspheres as starting compound via surface-initiated atom transfer radical polymerization [35]. Two different strategies for the covalent immobilization of lipase onto the aforementioned microspheres were adopted: (1) direct immobilization of the lipase on the polymer brushes by means of the epoxy groups, and (2) immobilization of lipase via coupling of the glutaraldehide moieties after modification of the epoxy group with hexamethylenediamine on the polymer brushes.…”

Design of novel nano-carriers for multi-enzyme co-localization

“…Even after reuse ten times, over 63% of the initial activity was still maintained. Karagoz and co-workers synthesized "hair-like" poly(styrene-b-glycidylmethacrylate) brushes via atom transfer radical polymerization on bromoacetylated poly(styrene-divinylbenzene) and covalently immobilized lipase on microspheres (Karagoz et al, 2010). The immobilization was found to be effective in enhancing both thermal and storage stability.…”