This study reports the use of membrane adsorbers for lysozyme (LZ) capturing and concentration: the membrane adsorbers are prepared by incorporation of ion exchange resins into an EVAL porous matrix. The mixed matrix membrane (MMM) adsorber possesses an open and interconnected porous structure with a large ion exchange surface available for enzyme adsorption. The adsorptive membrane features both a high static as well as a high dynamic LZ adsorption capacity. The measured LZ adsorption isotherm is of the Langmuir type, with a maximum adsorption capacity of 147 mg LZ/ml membrane. Dynamic LZ adsorption capacity at a flux of 25 I/h/m(2) was 63 mg LZ/ml membrane, which is significantly higher than the equivalent commercial membrane Sartobind C. Since the kinetics of desorption processes are faster than the kinetics of adsorption processes, the performance can be improved by exerting the desorption processes at higher fluxes than the adsorption processes. The MMM can be reused in multiple adsorption/desorption cycles maintaining the high binding capacity performance. Fluorescence spectra of the LZ after adsorption and elution were similar to native LZ. This is confirmed by activity tests showing that the activity of LZ was maintained after an adsorption and desorption cycle. (c) 2006 Elsevier B.V. All rights reserved.