Controllable Switching of Enzyme Activity by Poly(N‐isopropylacrylamide)‐Based Microgels Through Mineralization of Calcium Carbonate in High Pressure CO₂

Abstract

Stimuli-responsive hydrogels with high strength and toughness have received great interest in recent years. In this study, temperature-responsive composite hydrogels involved the Candida antarctica lipase B were prepared by using sodium alginate and poly(N-isopropylacrylamide), and were evaluated as catalysts using the model reaction of hydrolysis of p-nitrophenol butyrate. The experimental results demonstrated that enzymatic catalyst immobilized in the thermoresponsive carriers offered possibilities for external switching and manipulation for objective reaction system. The mechanical properties of the enzyme-polymer composites pretreated by high pressure carbon dioxide could be significantly improved. The number of recycling use was significantly increased. This work provided a new approach to smart regulation for enzymatic reaction.

Biocatalytically active microgels by precipitation polymerization of N-isopropyl acrylamide in the presence of an enzyme

“…It is not expected for an enzyme embedded within a thermoresponsive microgel with LCST characteristics, that an increased activity is occurring at elevated temperatures, as the microgel is only swollen in the aqueous dispersion medium below the cloud point. 6,23 The microgel is in the collapsed state above the transition temperature, therefore, substrate diffusion through the gel network should be hampered. Consequently, activities should be higher at lower temperatures relative to the enzymes in solution.…”

“…On top of that, the synthesis of nano scale carrier systems typically requires the use of certain additives such as surfactants for stabilization and/or lipophilic substances to establish a two-phase system. If additional features such as temperature responsivity for activity control 5,6 are wanted, the choice of involved materials is limited implementing an additional degree of complexity.…”

Electrical Field Reversibly Modulates Enzyme Kinetics of Hexokinase Entrapped in an Electro-Responsive Hydrogel

“…Reversible regulation of enzymatic reaction rate via application of external stimuli presents new opportunities over a variety of areas such as bioprocesses, enzymatic separation and recovery, drug delivery and biosensors, and bioelectronics. , Different techniques have been employed to externally regulate enzyme activity such as protein engineering, where the protein is modified to impart a stimuli-responsivity, , having effector molecules bind to allosteric sites and change the conformation of active site, and changing the microenvironmental parameters such as temperature, pressure, pH, and ionic strength. , One of the most convenient ways of enzyme activity regulation is to control the access of substrate molecules to the active site. This can be achieved through the reversible expansion and contraction of an enzyme embedded hydrogel matrix based on an applied stimulus.…”