In situ poly(ethylene imine) coating of hollow fiber membranes used for microdialysis sampling

Abstract

A method for the in situ modification of hollow fiber membranes used as sampling units for microdialysis probes is presented. The method consists of adsorption-coating, high-molecular-weight poly(ethylene imine), PEI, onto membranes, already fitted on microdialysis probes. Modification of membranes was designed to specifically explore the socalled Andrade effects and thus enhance the interaction of membranes with enzyme. The performances of polysulfone, polyethersulfone, and polyamide membranes modified with PEI-enzyme complex were evaluated based on the membrane extraction fraction for maltose and maltotriose and membrane morphology as examined by scanning electron microscopy. Of the membranes tested, the PEI-enzyme complex least affected the performance of the polysulfone membranes. Conversion of maltoheptaose to maltotriose and maltose was increased reproducibly (within a 5% relative standard deviation) by 50% for modified membranes compared to the native hollow fiber membranes. The results demonstrate the potential to effectively modify membranes already fitted on a microdialysis probe. Such a procedure can be modified and employed to either promote or reduce membrane-protein interaction for hollow fibers used as microdialysis sampling units or other similar membrane applications.