IMMOBILIZATION AND ASSESSMENT OF CARBONIC ANHYDRASE ON HOLLOW FIBER MEMBRANES FOR ENZYME-ENHANCED ARTIFICIAL LUNGS

Abstract

Enzyme immobilized artificial lungs are being developed in our laboratory to accelerate CO2 removal from the blood. We hypothesize that the CO2 removal of the artificial lungs would be improved via catalytic activity of carbonic anhydrase (CA) which covalently immobilizes on hollow fiber membranes (HFMs). Radio frequency glow discharge (RFGD) treatment was used to introduce functional groups on the outer surface of HFM for CA immobilization. Scanning electron microscopy analysis and gas permeance measurements were performed to evaluate the surface characterization for various RFGD modification conditions. 25 W for 30 s was chosen as the optimal RFGD modification condition which does not cause physical damage on the polymethyl-pentene HFM with up to 88% functional coverage as a CA immobilization efficiency. The gas permeance measurements for various levels of CA immobilized HFM (surface coverage of 0, 16, 33, 42, and 71%) showed no significant statistical differences. A comparison of the CO2 removal rates between non-modified and CA immobilized HFMs was performed for various liquid flow rates (1.5–15 ml/min) under a constant sweep gas flow rate (O2 of 30 ml/min) using a mini-lung module. Bicarbonate solution, which is a major form of CO2 in blood, was used as a CO2 source. CO2 removal of the CA immobilized mini-lung which has approximately 30% functional coverage was improved about 34% compared to that of the non-modified one. This may have proved our hypothesis to be applicable. CO2 removal from the blood will be evaluated in future work.