Protein purification with novel porous sheets containing derivatized cellulose

Novel porous sheets containing commercially available cellulosic ion exchange media of several different functionalities in a PVC matrix have been prepared and evaluated. The advantages of these materials are resistance to alkali, clean in place procedures and low nonspecific binding. These sheets thus provide well-known and well-characterized particulate chromatographic media in a porous sheet format. The porous sheet format permits use of short, squat geometries (stacked sheets) as well as tolerance of high pressure gradients. The net result is the ability to handle much higher flow rates (10-fold or greater) than achievable by comparable cellulosic packed columns of the neat particulate media. Chromatographic separation of natural egg white proteins by a linear salt gradient on a single sheet of 1.3-mm thickness was demonstrated. In addition, a very significant advantage of the porous sheet format is that it permits the fabrication of devices which are not possible with particulate media. An example of such a device is the Acti-Mod Spiral Module. In the spiral module a spiral flow channel is formed by wrapping the porous sheet material around a mandrel. Embossed ribbing in the porous sheet provides channel spacing. The small open channel accommodates high flow rates of biological suspensions while the porous sheet walls selectively remove components of the suspension.