Graft copolymer composed of cationic backbone and bottle brush‐like side chains as a physically adsorbed coating for protein separation by capillary electrophoresis

Abstract

To stabilize electroosmotic flow (EOF) and suppress protein adsorption onto the silica capillary inner wall, a cationic hydroxyethylcellulose-graft-poly (poly(ethylene glycol) methyl ether methacrylate) (cat-HEC-g-PPEGMA) graft copolymer composed of cationic backbone and bottle brush-like side chains was synthesized for the first time and used as a novel physically adsorbed coating for protein separation by capillary electrophoresis. Reversed (anodal) and very stable EOF was obtained in cat-HEC-g-PPEGMA-coated capillary at pH 2.2-7.8. The effects of degree of cationization, PEGMA grafting ratio, PEGMA molecular mass, and buffer pH on the separation of basic proteins were investigated. A systematic comparative study of protein separation in bare and HEC-coated capillaries and in cat-HEC-g-PPEGMA-coated capillary was also performed. The basic proteins can be well separated in cat-HEC-g-PPEGMA-coated capillary over the pH range of 2.8-6.8 with good repeatability and high separation efficiency, because the coating combines good protein-resistant property of bottle brush-like PPEGMA side chains with excellent coating ability of cat-HEC backbone. Besides its success in separation of basic proteins, the cat-HEC-g-PPEGMA coating was also superior in the fast separation of other protein samples, such as protein mixture, egg white, and saliva, which indicates that it is a promising coating for further proteomics analysis.

Conformation–function relationships for the comb-shaped polymer pOEGMA

“…Because of the versatility of ATRP, pOEGMA can also be incorporated into substantially more architecturallycomplex structures by synthesis from well-defined multifunctional macro-initiators, thereby producing socalled "bottlebrush" or double-branched architectures [40][41][42][43]. Yamamoto et al [44] have performed a detailed investigation of the temperature-responsiveness of such bottlebrush polymers composed of pOEGMA homo-/copolymers grafted to poly(2-(2-bromoisobutyryloxy)ethyl methacrylate) (PBIEM) (Fig.…”

Recent advances in capillary electrophoresis coupled to mass spectrometry for clinical proteomic applications

“…The authors reported that polybrene‐dextran sulfate‐polybrene coating offered long‐term stability with migration time RSD values of 1.6% and peak area RSD values of 9%. Other cationic polymers have also been evaluated as coating agent for the analysis of basic proteins, such as hydroxyethylcellulosegraft‐poly(PEG methyl ether methacrylate) (cat‐HEC‐g‐PPEGMA), and showed variability from capillaries to capillaries of <3% RSD for migration times across a wide range of pH, as well as better separation for neutral and acidic proteins compared to bare‐fused silica capillaries . However, cationic polymers such as polybrene‐based tend to result in higher pH‐independent EOF leading to poorer resolution and separation of compounds .…”

Recent developments in capillary and microchip electroseparations of peptides (2011–2013)

“…Static (permanent) modifications of the inner capillary wall involve covalent bonding or strong physical adsorption of the synthetic and natural polymers, such as polyacrylamide, PVA, PEG, linear and grafted cellulose derivatives , brush‐like copolymer , or cationic triblock copolymer . In addition to suppression of wall adsorption, dynamic and/or permanent capillary coatings are used also for control of the EOF, which influences separation efficiency, resolution, and speed of CE analyses of all types of analytes, including peptides and proteins.…”