Figure 3. Diffusion through acellular T-gelatin hydrogel scaffolds.

Diffusion, driven by a concentration gradient, was observed in static culture using PBS containing phenol red, serum albumin (BSA) and gamma globulins and placed in the top chamber reservoir versus PBS in the bottom reservoir. A. Visualization of small molecule (phenol red) diffusion comparing T-gelatin with dialysis tubing of 6–8 kDa or 50kDa molecular weight cutoff. Images were taken at the time points noted. B. Analysis of large molecule (albumin and γ-globulins) diffusion with denaturing polyacrylamide gel electrophoresis and a standard protein assay. Samples from the top (T) and bottom (B) reservoirs before (time point: 0 hour) and after diffusion (time point: 24 hours) and sampling was proportional to the total volume of the top and bottom reservoirs. Note this was a denaturing gel, resulting in dissociation of immunoglobulins into their composite heavy and light chains which then migrated at their individual molecular weights. However, in the experiment these proteins would have diffused as intact high molecular weight macromolecules. Results of independent colorimetric protein assays of the same samples run on the gel are shown below and are an average of three experiments (mean±SD).