Adsorption of concanavalin A on the well-characterized macroporous chitosan and chitin membranes

Macroporous chitosan membranes were prepared by solvent evaporation method in the presence of silica particles which were used as a porogen. These membranes were cross-linked under alkaline conditions, using epichlorohydrin as the cross-linking agent. The macroporous chitin membranes were obtained by acetylating the chitosan membranes with acetic anhydride in methanol. SEM photographs showed a homogeneous pore distribution throughout the membranes with 16.1-17.9 mum average pore sizes. The adsorption and desorption properties of concanavalin A (Con A) on the membranes were investigated by fluorescence spectroscopy. The equilibrium adsorption time was found to be 2 h during the static adsorption experiments. The calculated adsorption rates for chitosan and chitin membranes were r(ad) = 0.613 and 0.541 mg Con A/g dry membrane-minute, respectively at the initial protein concentration of 1.0 mg ml(-1). The adsorption isotherms represented a monolayer of Con A at 0.5-2.0 mg ml(-1) concentration range. The adsorption studies which were carried out at flow rate of 2 ml min(-1) showed that adsorbed quantities of Con A decreased markedly in the presence of flow, and they were similar (similar to14-15 mg Con A/g dry membrane) for both chitosan and chitin membranes. The fluorescence studies verified the absence of denaturation in the recovered Con A. (C) 2004 Elsevier B.V. All rights reserved.