| Abstract
| - To provide insights into the diffusion properties of micelles in hydrogels and, in general, ofsolutes in dextran gels, self-diffusion coefficients of small organic solutes and large micelles were measuredin dextran solutions and gels, using pulsed-field gradient NMR. The self-diffusion of the solutes wasshown to be slower in dextran solutions than in D2O and even slower in dextran gels. The extent of thediffusion reduction was more pronounced for higher dextran concentrations. For a series of moleculeswith a molecular weight between 46 and 78, the self-diffusion coefficient in dextran gels (20% w/w)corresponded, on average, to about 0.39 of the values measured in bulk water. This hindered diffusionwas mainly associated with the obstacles created by the polysaccharide segments. There was no evidencein the diffusion measurements of interaction between dextran and solutes capable of hydrogen bonding.The reduction of diffusion in dextran solutions and gels was very drastic in the case of micelles. ForTriton X-100, the self-diffusion coefficient in dextran gel was about 7% of that observed in water. Thevalues were, in fact, on the same order of the dextran chain diffusion coefficient. This finding suggeststhat these large macroassemblies can hardly move in dextran gels.
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