INVESTIGATION OF POLYSACCHARIDE ADSORPTION ON PROTEIN CONDITIONING FILMS BY ATTENUATED TOTAL-REFLECTION INFRARED SPECTROMETRY .1. GERMANIUM SURFACES

The formation of a biofilm at an aqueous/solid interface is preceded by the adsorption of organic macromolecules, typically proteins or glycoproteins. Adherent bacteria often produce extracellular polysaccharides that serve to anchor the cells to the conditioned substrate. In an effort to gain a better understanding of the interaction of polysaccharides with proteins, the initial fouling process was modeled using proteins (albumin, β-lactoglobulin, and myoglobin) to establish a conditioning film and polysaccharides (alginic acid and dextran) similar in composition to those produced by adherent bacteria. Kinetic studies of polymer adsorption and desorption were conducted in situ by attenuated total reflection infrared spectrometry. Each protein adsorbed tenaciously to the surface of a germanium internal reflection element. Alginic acid adsorption was enhanced in the presence of the protein conditioning film independent of the identity of the protein. Dextran, a neutral polysaccharide, was excluded from the conditioned substrate and was l retained to a greater extent on bare Ge than on the protein conditioning film. Dextran desorbed from the protein films at a rate three to four times greater than alginic acid. Differences in adsorption and desorption phenomena between the polysaccharides were attributed to differences in sugar composition. © 1993 by Academic Press, Inc.