Microstructure and retention properties of dextran-grafted agarose media

BIOT 72

Harun Koku, Brian D Bowes, and Abraham M Lenhoff, lenhoff@udel.edu. Department of Chemical Engineering, University of Delaware, Newark, DE 19716
Stationary phases in which the base matrix is modified by addition of secondary polymers can differ significantly in their adsorption and transport properties from unmodified media. In this work, electron microscopy, confocal microscopy, chromatographic measurements, and additional techniques are employed to attempt to relate the chemical composition and microstructure of Sepharose XL to its chromatographic performance. This agarose-based adsorbent is modified with dextran, and a study of its structure and function compared to that of the dextran-free Sepharose FF is used to probe the role of the dextran. TEM and SEM images are used to examine the distribution of dextran within the XL media as well as regions of protein retention. Chromatographic characteristics that are correlated with these observations include retention characteristics, binding capacities, and thermodynamic driving forces. Confocal microscopy is used to examine the uptake rate, which has been reported previously to be anomalously fast under some conditions.