Recently, aqueous microgels turned out to be suitable candidates for numerous biomedical applications due to their unique properties. Microgels are highly crosslinked, soft polymer colloids which exhibit stimuli-responsive behavior depending on the incorporated monomers. The conventionally used method for microgel synthesis is precipitation polymerization, mainly initiated by thermic initiation with azo- or peroxide-based compounds. The heat needed for radical formation limits the possible reactants to thermo stable substances and thus hinders the direct incorporation of biomolecules into the polymer structure during synthesis. The use of enzymes for radical formation and polymerization initiation poses a promising alternative to thermic initiators. Enzymes are active at moderate temperatures and therefore enable a decrease of the polymerization temperature. In this work, we present the use of the fungal enzyme Glucose oxidase (GOx) for the synthesis of aqueous microgels. GOx catalyzes the oxidation of β-D-glucose with molecular oxygen to D-glucono-lactone and hydrogen peroxide. Through the addition of ferrous ions (Fe2+), the hydrogen peroxide gets cleaved into hydroxyl radicals. These radicals act as initiators for the polymerization reaction. With this method, we successfully synthesized temperature-responsive microgels based on N-vinylcaprolactam (VCL), showing that the active GOx gets encapsulated into the polymer network during synthesis. This enables the facile synthesis of core-shell microgels by the addition of a second monomer and new enzyme substrate.

Enzymatic synthesis of stimuli-responsive microgels

256th National Meeting (2018)

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