Hydrogel polymer coating for capillary electrophoretic separation of proteins

Abstract

Abstract. Three hydrogel polymers, poly(2-hydroxypropylmethacrylate), poly(2-hydroxyethylmethacrylate) , and hydroxypropylcellulose, were coated and immobilized on fused silica capillary surfaces using three different methods, all involving modification of the surfaces before polymerization and/or cross-linking. Since the hydrogel polymers swelled in aqueous solution and allowed permeation of low-molecular-weight compounds, an equilibrated state was attained between the hydrogel polymer layers and the buffer solution, which eliminated the interactions between proteins and the capillary surface, and allowed highly efficient and reproducible capillary electrophoretic separations of both basic and acidic proteins. The experimental results indicated that silanol groups on the capillary surface were covered and phosphate anions were trapped in the coating layers, which produced defined, but reduced, electroosmotic flows when compared to uncoated capillaries. High resolution separations of ribonuclease B variants and cytochrome c proteins from different sources were obtained.

Cellulose acetate-coated fused-silica capillaries for the separation of proteins by capillary zone electrophoresis

“…Four different approaches have been reported and involve, briefly, (i) elimination of the interaction by adjusting the pH of the buffer to such a value that the silanol groups are non-charged [1]; (ii) adjusting the pH of the buffer of such a value that the charges of the silanol groups and protein have the same sign [2,3]; (iii) dynamic modification of the surface by neutral and cationic additives in the buffer [4][5][6][7][8][9]; and (iv) chemical modification using covalent bonding of the fusedsilica surface [10][11][12][13][14][15][16][17][18].…”

Topographical properties of polymer films deposited in capillaries for electrophoretic separations of large organic molecules

“…[12], who obtained highly reproducible coatings by the atom-transfer radical polymerization of HEMA. Good performance of hydrogel coatings has also been demonstrated by Huang et al [13,14], who successfully used poly(HEMA)-coated or poly(HEMA)/HPC-coated columns for separations of ribonuclease B variants.…”

“…This is probably due to the trapping of the small buffer ions in the hydrogel that contributes to the zeta potential at the capillary wall [13]. In addition, the polymer swelling may cause clogging of capillaries.…”

Direct immunoassay of estrone by capillary electrophoresis with laser‐induced fluorescence detection

“…Modifying the background electrolyte is another effective route. It has been demonstrated that with the aid of thermosensitive hydrogel the inner surface of a capillary can be changed from hydrophilic to hydrophobic, thus eliminating protein adsorption [24] with resultant improved resolution and reproducibility. Using a thermally reversible hydrogel, the capillary electrophoretic immunoassay was optimized for the determination of free E 1 in women's serum.…”