Preparation of ternary composite hydrogels of agarose, concanavalin A and a glycolipid monolayer, and their permeation properties

Abstract

Synthetic glycolipids (2C₁₈-de-glu and 2C₁₈-de-gal) form condensed surface monolayers, which have been successfully deposited on the agar hydrogel by the Langmuir–Blodgett (LB) technique. The monolayer-deposited gel membranes were satisfactory for use in the permeation experiments of ammonium salts such as tetramethylammonium bromide or hexyltrimethylammonium bromide over a wide temperature range. The permeability of the salts through the modified gel membranes depends strongly upon the hydrophobicity of the permeants and could be controlled by the phase transition of the deposited monolayers. Concanavalin A (ConA)-bound agar gels were modified with the 2C₁₈-de-glu monolayer, having the α-D-glucopyranosyl head group, but not with the 2C₁₈-de-gal, having the β-D-galactopyranosyl head group, owing to the specific binding ability of ConA. The permeability of the 2C₁₈-de-glu monolayer-deposited ConA-bound agar gel was selectively controlled by the addition of monosaccharides: the permeability was enhanced by the addition of D-mannose, whereas it was hardly changed by the addition of D-galactose, resulting from the high binding constant of D-mannose with ConA.