Novel Charged Ultrafiltration Membranes for Protein Separations

Although there have been no significant studies of the effects of different coupling chemistries, spacer arm length, or the nature of the functional group on the performance of ultrafiltration membranes, there is an extensive literature on these parameters in the field of chromatography. An optimal spacer arm ensures that the functional groups are placed a suitable distance from the surface of the solid support and are easily accessible to the macromolecules. Results from a variety of studies in ion exchange and dye-affinity chromatography suggest that the ideal spacer arm has : (1) proper length (at least three atoms); (2) no active center that could cause nonspecific adsorption; and (3) at least two functional groups, one to react with the base support and one to serve as the chromatographic ligand.