Poly(N,N-dimethylamino)ethyl methacrylate/sodium alginate multilayers and their interaction with proteins/enzymes

The aim of the present work is to construct and investigate the properties of novel polyelectrolyte multilayers consisting of poly(N,N-dimethylamino)ethyl methacrylate (PDMAEMA) and sodium alginate (SA). The influence of PDMAEMA's pH dependent ionization degree on the charge balance, thickness and roughness of the multilayer films was assessed by potentiometric titrations, dye sorption and atomic force microscopy. Moreover, the cross-linking of PDMAEMA/SA films with a dihalogenated aromatic derivative with high reactivity (α,α'-dichloro-p-xylene) by means of Menshutkin reaction and the stability of the multilayer architecture to repeated treatments with NaOH are demonstrated. Also, the interaction of the obtained films with various proteins/enzymes (pepsin, bovine serum albumin, haemoglobin and lysozyme) is investigated. It was found that biomolecules with the isoelectric point in the acidic region of pH were adsorbed in a higher amount than the biomolecules with the isoelectric point in the basic region of pH.