Development of Enzyme Loaded Polyion Complex Vesicle (PICsome): Thermal Stability of Enzyme in PICsome Compartment and Effect of Coencapsulation of Dextran on Enzyme Activity.

Applications of enzymes are intensively studied, particularly for biomedical applications. However, encapsulation or immobilization of enzymes without deactivation and long-term use of enzymes are still at issue. This study focuses on the polymeric vesicles "PICsomes" for encapsulation of enzymes to develop a hecto-nanometer-scaled enzyme-loaded reactor. The catalytic activity of a PICsome-based enzyme nanoreactor is carefully examined to clarify the effect of compartmentalization by PICsome. Encapsulation by PICsome provides a stability enhancement of enzymes after 24 h incubation at 37 °C, which is particularly helpful for maintaining the high effective concentration of β-galactosidase. Moreover, to control the microenvironment inside the nanoreactor, a large amount of dextran, a neutral macromolecule, is encapsulated together with β-galactosidase in the PICsome. The resulting dextran-coloaded nanoreactor contributes to the enhancement of enzyme stability, even after exposure to 24 h incubation at -20 °C, mainly due to the antifreezing effect.