Composite multilayer thin films morphology and their interactions with proteins as a function of polyanion structure

Abstract

Composite multilayer thin films have been constructed on planar substrates by the layer-by-layer deposition of chitosan (CS) and two strong polyanions different by the density of sulfonic groups, i.e., poly(sodium 2-acrylamido-2-methylpropanesulfonate) (PAMPS) and a random copolymer of AMPS with acrylic acid, P(AMPS 55 -co-AA 45 ); all deposition steps being performed at pH 5.5. The effect of the polyanion structure and number of adsorbed layers on the film morphology was examined by atomic force microscopy and contact angle measurements. The polyanion structure strongly affected the multilayer morphology, more swollen and less dense films being formed when P(AMPS 55 -co-AA 45 ) was used compared to PAMPS. The sorption of two proteins, human serum albumin and bovine serum albumin, on the film surface with CS as the last layer adsorbed, as a function of the polyanion structure, indicates that a higher amount of protein had been sorbed mainly on the film surface when PAMPS was used as a polyanion in the film construction.