ABSTRACT
The factors contributing to protein adsorption include electrostatic, hydrophobic, and hydrogen-bonding interactions. Several strategies were developed to reduce protein adsorption on the silica surface. When the CZE analyses are performed at a low pH ( < 2), the charges of the silica surface are close to zero and the electrostatic interactions of the protein with the silica surface are eliminated. At high pH, above the isoelectric point (pi) of the protein, the adsorption of protein is diminished because of the Coulombic repulsion between the negative charges of the protein and the deprotonated silanol groups of the surface. The strategy of altering pH has the disadvantage of limiting the range of pH operation. Moreover, a degradation of proteins may occur at extreme pH. An alternative approach is to introduce additives in the running buffer [5] to form a dynamic coating and decrease protein-wall interactions. The main disadvantages are decrease of detector sensitivity and protein-modifier interactions.
