DESIGN OF AN ARTIFICIAL SKIN .3. CONTROL OF PORE STRUCTURE

Several methods are compared for preparing collagen-glycosaminoglycan (GAG) membranes of high or low porosity. Methods studied as means for controlling pore size are confined to purely physical processes which do not require use of additives or chemical reagents to form the porous membrane. Membranes, initially swollen in distilled water or saline, shrink linearly to no less than 94% of original dimension after freeze drying; to 75% after critical point drying (from CO//2, following water-ethanol exchange); and to 41% of original dimension following air drying from the swollen state. Scanning electron microscopic study of the pore structure resulting from each drying procedure confirms the major conclusion: A carefully designed freeze drying process, two variants of which are described in detail, yields membranes with the highest mean pore size, as measured by quantitative stereological procedures. Critical point drying gave significantly more shrinkage and a lower mean pore size than either one of the two freeze drying procedures used.