DEXTRAN-GRAFTED SILICA-GEL FOR HIGH-PERFORMANCE SIZE-EXCLUSION CHROMATOGRAPHY OF PROTEINS

A hydrophilic stationary phase for aqueous high-performance size-exclusion chromatography (HPSEC), viz., dextran-grafted silica gel, was synthesized and tested. Using dextran or dextran derivatives covalently grafted on to epoxysilica gel, it was possible to achieve good hydrophilic shielding of the silica gel surface, preserving the unique physical properties of silica matrix. The retention of proteins on the stationary phase was studied to optimize the modification procedure. The undesired silica matrix effect was minimized by combination of three phenomena: chemical removal of silanols by silanization, steric shielding of residual silanols with grafted macromolecules and electrostatic compensation of SiO- groups by a positively charged anchoring group. Optimized dextran-grafted silica is a suitable packing material for the HPSEC of proteins, operating with a wide range of ionic strength of the eluent.