Mechanisms of Adsorption of the Neutral Polysaccharide Dextran on Hematite, Goethite and Amorphous Silica
Abstract
The adhesion of bacteria to materials is an issue of fundamental importance for many medical (e.g. avoiding infection of replacement bones) and environmental (economically applying bioremediation, understanding rock weathering) applications. In the absence of pili or flagella the exterior of Gram negative cells is characterized by various proteins and polysaccharides. Recent work has suggested that bacterial adhesion may be mediated by the interaction of these polysaccharides with materials. Gram negative cell surface polysaccharides take two general forms which both occur on individual cell surfaces: a polysaccharide composed, predominantly, of glucose monomers which is neutral at physiological pH and a polysaccharide which is polyelectrolytic at physiological pH. In this work we conduct batch adsorption experiments of varying sizes of the D-Glucose polymer dextran to goethite, hematite and silica particles. We find that dextran does not adsorb under our experimental conditions to silica, and is ~2x as adsorptive to goethite as hematite. We rationalize these observations with a series of vibrational spectroscopy measurements and ab initio electronic structure calculations. Taken together the results of each approach are consistent with a scenario in which dextran adsorption is controlled by the strength of hydrogen bonds formed between glucose and various surface groups. This conclusion is qualitatively consistent with the observed adhesion of bacteria in the subsurface.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2002
- Bibcode:
- 2002AGUFM.B11A0702C
- Keywords:
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- 0400 BIOGEOSCIENCES;
- 1045 Low-temperature geochemistry;
- 1831 Groundwater quality