SiO2 entrapment of animal cells. Part 2: Protein diffusion through collagen membranes coated with sol-gel SiO2

Membranes of collagen on a paper scaffold were manufactured to a thickness of 0.64 +/- 0.03 mm and reacted with gaseous silicon alkoxide precursors un til a 0.1 mu m deposit of sol-gel SiO2 was achieved. Diffusion of protein m acromolecules myoglobin, albumin, gamma-globulin and fibrinogen in an aqueo us solution through these membranes was studied; kinetic runs for coated an d uncoated SiO2 were performed under experimental conditions suitable for c alculating relevant diffusion parameters. The data show linear lowering of the diffusion coefficient with molecular size, the effect being enhanced by the deposition of the SiO2 layer, which behaves as an effective barrier to the diffusion of high molecular weight protein macromolecules.