Consider a porous tissue engineered matrix consisting of uniformly distributed sintered polymer microspheres, and space between the spheres is filled with a Newtonian solution. The microsphere diameter is 250 µm, and the microsphere density in the sintered matrix is 7.5 x 104 cm-3 .

(a) Determine the porosity ε of the material.

(b) The molecular radius of albumin is about 3 nm. Assume that there are no charge-charge interactions between albumin and the polymer. Estimate the partition coefficient β for albumin in the matrix. Is albumin diffusion hindered in the porous material relative to in solution?

(c) Suppose that you want to seed cells into the matrix to make a tissue graft. A typical human fibroblast in suspension is a sphere with diameter 10 µm. Estimate the partition coefficient β for cells in the porous material. Will cell flux through the material be hindered relative to flux in a homogeneous Newtonian fluid?