A novel material that combines mechanical resistance with ampholyte character was easily obtained by the reaction of methacrylic acid, 2-methylimidazole and ethylene glycol diglycidyl ether. The structure was studied by solid-state C-13 NMR and FT IR spectroscopy, scanning electron microscopy (SEM) and potentiometric titration. The interaction of this new material with bovine serum albumin (BSA) as a model protein was explored. The protein bound electrostatically to the basic form of the polyampholyte at low ionic strength even when both species had negative net charge. The BSA polyampholyte complex was evidenced by FT IR and SEM. The adsorption properties were optimal, attributed to the combination of basic and acid groups in the same network, with a maximum loading capacity of 0.7307 g g(-1) and a K-d: 5.70 x 10(-6) evaluated by the Langmuir model. The release of BSA was controlled by dissociation kinetics of the complex rather than by diffusion, and the total desorbed amount depended on the electrolyte content of the medium. (C) 2007 Elsevier Ltd. All rights reserved.