Figure 2 shows the fitted MSALVFX diffusion coefficients in agarose hydrogels of various concentrations. To ensure the results, all diffusion coefficient data were averaged from the subtracted images at , 400, and and , and the corresponding was taken four times from the neighbored fringe images. As shown in Fig. 2, solute diffusion coefficients decrease as the concentration of hydrogel increases. It is believed that the increase of polymer concentration will lead to a decrease in the mesh size of the gel network and shrinkage of the available space for the diffusing solute,8 thereby retarding the solute diffusivity. Meanwhile, the diffusion coefficient reduces as solute concentration increases. This may be because the hydrodynamic drag enhances with the amount of solute and thereby obstructs the diffusivity. For a different molecule concentration, Zhang et al. demonstrated that Kohlrausch’s law was still holding at a high concentration of polymer-solvent electrolyte system.4 The molar conductivity of an electrolyte solution linearly decreases with the increase in the square root of the electrolyte concentration, and the diffusion coefficient approximately yields as follows:4, where is a constant independent of the concentration and is the extrapolated value of the diffusion coefficient at the infinite concentration. In present drug delivery system, all the experimental data showed good linearities, implying that the MSALFVX diffusion also adapts to Kohlrausch’s law. Moreover, the diffusion coefficient can be obtained by linear extrapolation as about (inset of Fig. 3).