Capillary electrophoresis of peptides and proteins in fused‐silica capillaries coated with derivatized polystyrene nanoparticles

Abstract

High-resolution capillary electrophoretic separation of proteins and peptides was achieved by coating the inner wall of 75 microm ID fused-silica capillaries with 40-140 nm polystyrene particles which have been derivatized with alpha-omega-diamines such as ethylenediamine or 1,10-diaminodecane. A stable and irreversibly adsorbed coating was obtained upon deprotonation of the capillary surface with aqueous sodium hydroxide and subsequent flushing with a suspension of the positively charged particles. At pH 3.1, the detrimental adsorption of proteins to the capillary inner wall was suppressed efficiently because of electrostatic repulsion of the positively charged proteins from the positively charged coating which enabled protein separations with maximum efficiencies of 400000 plates per meter. A substantial improvement of separation efficiency in particle-coated capillaries was observed after in-column derivatization of amino functionalities with 2,3-epoxy-l-propanol, resulting in a more hydrophilic coating. Five basic and four acidic proteins could be separated in less than 7 min with efficiencies up to 1900000 theoretical plates per meter. Finally, coated capillaries were applied to the high-resolution analysis of protein glycoforms and bioactive peptides.

Recent progress in high‐performance capillary bioseparations

“…Epoxy-based hydrophilic wall coatings allow separation efficiencies as high as 200 000 theoretical plates per meter [87]. Similar permanent wall coatings can be made by grafting polyglycidyl methacrylate [88] or derivatized polystyrene nanoparticles [89]. Zhang and Horváth [90], described the use of a dextrancoating, which allows the inner wall of microfluidic separation channels under mild conditions (Fig.…”

Wall coating for capillary electrophoresis on microchips

“…Many of these polymers can serve simultaneously as both a dynamic coating and sieving matrix in DNA sequencing or SDS gel electrophoresis. To reverse EOF, e.g., cationic detergents including cetyltrimethylammonium bromide (CTAB) [22], didodecyldimethylammonium bromide [23], polycations such as spermine [24], putrescine [25], polyarginine [26], polyethyleneimine [27], and chitosan [28], and diaminecoated polystyrene nanoparticles [29] were employed. To have an EOF of the same direction but independent of pH, anionic detergents such as SDS and anionic polymers such as dextran sulfate [30] were used.…”

Silica nanoparticles as pseudostationary phase for protein separation

“…Huang et al [36] reported their work on studying specificity of biocatalysis by GNP-conjugated trypsin with CE, in which trypsin was treated with NPs prior to CE separation. Huber and coworkers [22] coated the capillary surface with polystyrene NPs and separated peptides and proteins in non-NPs buffer [22].…”

“…Colloidal gold NPs were synthesized and added to CE buffer for the separation of toluidines [21]. Huber and co-workers [22,23] as well as Rodríguez and Colón [24] used polymer-based NPs to coat fused-silica capillaries for electrophoretic separation. In Kuo's work [25], SNPs were employed as PSP for the separation of catecholamines.…”