In situ poly(ethylene imine) coating of hollow fiber membranes used for microdialysis sampling
N. Torto, M. Ohlrogge, L. Gorton, J. M. Van Alstine, T. Laurell, and G. Marko-Varga
Department of Chemistry, University of Botswana, P/Bag
UB 00704, Gaborone,
Botswana; Department of Analytical Chemistry, University of Lund, P.O.
Box 124, SE-221 00, Lund, Sweden; Department of Chemical Engineering
and Technology, KET/TS, Royal Institute of Technology, SE-100 44, Stockholm,
Sweden; Department of Electrical Measurements, University of Lund, P.O.
Box 118, SE-221 00, Lund, Sweden; Bioanalytical Research, Astra-Zeneca,
Pre-Clinical Research and Development, P.O.Box 34, SE-221 00, Lund,
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 so-called 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 membraneprotein
interaction for hollow fibers used as microdialysis sampling units or
other similar membrane
*Plenary lectures presented at the Inaugural Conference for the Southern and Eastern Africa Network of Analytical Chemists (SEANAC), Gaborone, Botswana, 7-10 July 2003. Other presentations are published in this issue, pp. 697-888.