Reduction of wall adsorption in capillary zone electrophoresis of a basic single-chain antibody fragment by a cationic polymeric buffer additive

Reduction of adsorptive protein-wall interactions by poly(diallyldimethyl ammonium chloride), a permanently cationic polymer, at a concentration of 0.5% (w/v) is demonstrated for a basic single-chain antibody fragment (scFv, pi about 9.5) even in the range of physiological pH of around 7. The polymer additive forms a positively charged layer at the silica surface which reverses electroosmosis and leads to electrostatic repulsion of the positively charged basic protein.