Gas–liquid flow-induced permeabilization of phospholipid bilayer membranes for regulating catalytic performance of liposome-encapsulated bovine liver catalase

The catalytic performance of bovine liver catalase-containing liposomes (CALs) was regulated by use of the gas–liquid flow generated in an external loop airlift bubble column. The CALs were prepared by extruding through a membrane with the mean pore diameter DP of 30, 50, 80, 100, 200 or 400 nm. The airlift was operated at 40 °C for 5 h at the superficial gas velocity UG of 0.47–1.9 cm/s. Significant deactivation of free catalase was observed in the airlift because of its structural alteration at the gas–liquid interface. On the other hand, the activity of CAL prepared at DP of 100 nm was stable in the airlift almost regardless of UG because the liposomal interior is free of gas phase. The CAL prepared at DP of 400 nm was structurally unstable while the membrane integrity of smaller CALs was maintained in the airlift operated even at the highest UG. The reactivity of liposomal catalase to H2O2 added to the liquid bulk of the airlift increased at 40 °C in the UG-dependent manner. This was because the permeation of H2O2 through the CAL membranes was enhanced through the gas–liquid flow-induced structural perturbation of the membrane. Modulation of membrane permeability of liposomes with the gas–liquid flow is suggested to be a versatile method for regulating catalytic performance of liposomal enzymes without employing any chemical and biological means.