Fickian Behavior and Concentration-Dependence of the Diffusion of Dextran in Agarose

Various studies have attempted to quantify the effects of loading on nutrient transport in cartilage and other soft tissues. The application of a dynamic mechanical stimulus has been shown to significantly enhance the mechanical properties of chondrocyte-seeded agarose [1]. While the mechanism for this enhancement is still not completely understood, dynamic loading has been shown theoretically [2] as well as experimentally [3] to increase the uptake of large molecules. Since dextran is available in a wide range of molecular weights and can be conjugated with fluorphores, it has become a popular model system for studying solute transport in statically loaded and free swelling gels and tissues [4, 5]. To better characterize this model system, this study uses fluorescence recovery after photobleaching (FRAP) to investigate the Fickian behavior of linear dextran macromolecules as well as the dependence of its diffusivity on concentration.