Reactivity and Stability of Catalase-Bound Liposomes Containing Glucose Oxidase in an Airlift Bubble Column

Catalase-bound liposome containing glucose oxidase (CLG) has been used to catalyze the oxidation of glucose in an external loop airlift bubble column. In a static liquid system suspending CLG, glucose was steadily oxidized at 40 degrees C at the initial pH of 7.4 for 73 h, although the oxidation rate is significantly small because of strong permeation resistance of the CLG membrane to glucose. In the airlift, the rate of oxidation catalyzed by the CLG with initial mean diameter D-P of 324.9 nm significantly increases at superficial gas velocity U-G of 0.5-3.0 cm/s compared to that in the static liquid. The gas-liquid flow has thus been found to induce permeabilization of the CLG. The reactivity of CLG in the airlift is influenced by the interaction between catalase (CA) and the membrane. Furthermore, the structural stability of CLG in the airlift is dependent on its initial D-P. The CLG with D-P of 168.8 nm remains practically unchanged in its size in the airlift at U-G of 1.0 cm/s. On the other hand, the CLG with D-P of 269.5 nm shows to be partly disrupted with deactivation of CA under the above condition. The reactivity and stability of CLG have also been elucidated in catalyzing the fed-batch oxidation of glucose for 34 h in the airlift.