Hydroxyethylcellulose‐graft‐poly (4‐vinylpyridine) as a novel, adsorbed coating for protein separation by CE

Abstract

A novel graft copolymer, hydroxyethylcellulose-graft-poly (4-vinylpyridine), used as a physically adsorbed coating of the fused-silica (FS) capillaries, was synthesized by using ceric ammonium nitrate initiator in aqueous nitric acid solution. EOF measurements showed that the above graft copolymer coating of the FS capillaries could suppress EOF effectively compared with the bare FS capillaries. The adsorbed coating exhibited minimal interactions with proteins, providing efficient protein separations with excellent repeatability. Interestingly, the electrical charge of the coated capillary wall could be modulated by varying the pH of the running buffer, which makes possible the analysis of basic and acidic proteins in the same capillary. The effects of pH on suppressing EOF and protein separation were investigated in detail. The results demonstrated that the hydroxyethylcellulose-graft-poly (4-vinylpyridine) copolymer coatings have great potential in the diagnosis and proteomics.

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

“…Then cat‐HEC‐ g ‐PPEGMA was prepared by grafting PEGMA onto cat‐HEC backbone using CAN initiator (in nitric acid aqueous solution) 27, 28, 41, as shown in Fig. 1.…”

“…This is because HEC cannot be adsorbed strongly to the capillary surface due to its high hydrophilicity and thus can be easily rinsed away. Some improved HEC coatings were developed to overcome these problems in our lab 26–28. Another common coatings, poly(ethylene oxide) (PEO), poly(ethylene glycol) (PEG, the low‐molecular mass form of PEO), and their derivatives (such as PEG methyl ether methacrylate (PEGMA)), are well known to be the most desirable and effective molecules for reducing the surface adsorption of proteins 29–31.…”

A novel cationic triblock copolymer as noncovalent coating for the separation of proteins by CE

“…2C indicates that the triblock copolymer was 100% quaternization [41]. The degree of polymerization (DP) of the PDMAEMA block in the triblock copolymer was estimated from DP DMAEMA 32,[2874][2875][2876][2877][2878][2879][2880][2881][2882][2883] and at 3.65 ppm from the PEO methylene groups, respectively, and DP EO was the polymerization degree of PEO. The molecular mass of the triblock copolymer (M n,NMR ) was calculated according to the DP DMAEMA as M n,NMR 5 DP DMAEMA Â M DMAEMA 1M Br-PEO-Br , where M DMAEMA and M Br-PEO-Br were the molar mass of PDMAE-MA and PEO macroinitiator [38,42].…”

“…Neutral polymers are easily rinsed away from the capillary wall, the polymer of PDMA adsorbed to the capillary wall tightly but it would interact with proteins via hydrophobic interactions. To combine advantages of different homopolymers, several kinds of copolymers were synthesized recently, such as poly(1-vinylpyrrolidone-co-2-dimethylaminoethyl methacrylate) (P(VP-co-DMAEMA)) [28], poly (ethylpyrrolidine methacrylate-methylmethacrylate) (EPyM-MMA) [29], poly(N,N-dimethylacrylamide-co-4-(ethyl)-morpholine methacrylamide) (DMA-MAEM) [30], poly (ethylene oxide)-block-poly(4-vinylpyridine) (PEO-b-P4VP) [31], and some derivatized HEC coatings were developed in our laboratory [32][33][34].…”

Brush‐like copolymer as a physically adsorbed coating for protein separation by capillary electrophoresis

“…For this purpose, copolymerization offers the possibility to obtain the desirable properties by adjusting the molecular architecture and chemical compositions. To combine hydrophilicity with adsorbing property, several copolymers have been developed and used for the protein separation: epoxy‐PDMA 31, poly(ethylpyrrolidine methacrylate‐dimethylacrylamide (DMA)) 32, 33, PEO‐ b ‐poly(4‐vinylpyridine) 34, PDMA‐ b ‐PEO‐ b ‐PDMA 35, and some improved HEC 36–38.…”