Mixed matrix membranes: a new platform for enzymatic reactions

Glucose oxidase (GOx) was covalently bound onto Eupergit® C particles embedded in mixed matrix hollow fiber membranes prepared using polyethylene vinyl alcohol (EVAL) as the polymeric macroporous matrix. The Eupergit ® C particles were chemically modified with ethylenediamine and activated with glutaraldehyde, ground and fractionated into 20-40 and < 20 μm size classes. GOx was immobilized in the fibers in dynamic mode. Fibers containing the smallest particles show the highest immobilization capacity due to the increased external particle surface area. The activity of immobilized enzyme was evaluated by dynamic conversion of glucose. The results proved that the enzyme retains enzymatic activity after immobilization. The highest glucose conversion yields are obtained with fibers which contain the bigger particles, which is attributed to a better fiber wall morphology leading to an improved flow distribution. The results further showed that GOx covalently immobilized in EVAL/Eupergit® fibers has a lower enzymatic activity than GOx that is physically immobilized in polyether sulfone (PES) fibers containing strong cation exchange (SCIEX) resins. The reduced activity is explained by the differences in the materials used, immobilization methods, fiber morphologies and applied pH’s in each case.