Upper Critical Solution Temperature Type Thermoresponsive Reactive Copolymers for Enzyme Immobilization

Functional thermoresponsive copolymers poly(N-acryloyl glycinamide-co-glycidyl methacrylate) (PNAGA-co-GMA) and poly(N-acryloyl glycinamide-co-N-(methacrylate)succinimide) (PNAGA-co-MNHS) were prepared by free-radical polymerization. With increasing functional comonomer content, the phase transition temperature increased. The functional copolymers reacted with the enzyme α-amylase by W/O emulsion to form water-soluble biohybrid nanogels. The hydrodynamic radius of biohybrid nanogels increased with temperature due to thermophilic swelling. Biohybrid nanogels of PNAGA-co-GMA and PNAGA-co-MNHS revealed a 1.2- and 1.5-fold increase of enzyme activity at 40 and 15 °C, respectively. Free α-amylase showed a 1.1-fold increase in comparison. Therefore, nanogels of these reactive thermoresponsive copolymers could be used to modulate the enzyme activity of various enzymes. As reactive polymers, they could be used as an initiation site for grafting polymerization to introduce functionality to PNAGA copolymers in further work.