Adsorption of globular proteins on polymeric microfiltration membranes

Adsorption of a globular model proteins lysozyme, cytochrome c, myoglobin, haemoglobin and human serum albumin on a polymeric microfiltration membrane (MF-Millipore, mixed esters of cellulose) was studied using a method based on the measurement of streaming potential. The coverage of adsorbed protein on the membrane pore wall was detected as a change in surface charge density, which is accessible from a simple microscopic theory through the measured values of the streaming potential. Adsorption seemed to obey the Langmuir isotherm but the desorption was at least partially irreversible. The adsorption of chloride ions appeared to be independent of the adsorption of human serum albumin. Furthermore, it was experimentally found that a strongly adsorbing protein can be used to modify the membrane matrix so that the adsorption of other proteins is significantly reduced.