Traditionally, charged ligands are introduced into ion-exchange matrices by random chemical derivitization, producing a heterogeneous charge distribution. We demonstrated the improved protein-binding capacity and selectivity of ion-exchange adsorbents that display an engineered �clustered� rather than random, distribution of surface charges. We also found that clustered-charge (penta-argininamide and penta-lysinamide) adsorbents selectively favor biomolecules with inherent charge clustering, such as apo-a-Lactalbumin, cytochrome b5 and nucleic acids. In order to prepare cost effective clustered-charge adsorbents, we also have explored the possibility of use of spermine, a natural polycation, as a ligand. At the single-molecule level, we were also able to observe the specific protein ion-exchange adsorption by direct confocal laser scanning imaging and to quantitatively distinguish free diffusion from hindered diffusion caused by interactions with the adsorbent (clustered-charge anion exchanger on agarose support) using fluorescence correlation spectroscopy.

Enhanced binding on clustered-charge adsorbents: Ensemble and single-molecule studies

243rd National Meeting (2012)

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