Hydroxyethylcellulose‐graft‐poly(2‐(dimethylamino)ethyl methacrylate) as physically adsorbed coating for protein separation by CE

Abstract

In this work, a novel graft copolymer, hydroxyethylcellulose-graft-poly(2-(dimethylamino)ethyl methacrylate) (HEC-g-PDMAEMA), used as physical coatings of the bare fused-silica capillaries, was synthesized by using ceric ammonium nitrate initiator in aqueous nitric acid solution. EOF measurement results showed that the synthesized HEC-g-PDMAEMA graft copolymer-coated capillary in this paper could suppress EOF effectively compared to the bare fused-silica capillary, and efficient separations of basic proteins were also achieved. The electrical charge of the coated capillary wall could be modulated by varying not only the pH of the running buffer, but also the grafting ratio of poly(2-(dimethylamino)ethyl methacrylate) grafts, which makes possible the analysis of basic and acidic proteins in the same capillary. The effects of poly(2-(dimethylamino)ethyl methacrylate) grafting ratio in HEC-g-PDMAEMA and buffer pH on the separation of basic proteins for capillary electrophoresis were investigated in detail. Furthermore, egg white proteins and milk powder samples were separated by the HEC-g-PDMAEMA-coated capillary. The results demonstrated that the HEC-g-PDMAEMA copolymer coatings have great potential in the field of diagnosis and proteomics.

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

“…The main constituent of proteins from egg white is ovalbumin (54%), conalbumin (12%), ovomucoid (11%), ovomucin (3.5%), lysozyme (3.4%), ovoinhibitor (1.5%), ovoflavoprotein (0.8%), ovomacroglobulin (0.5%), avidin (0.5%), among smaller fractions of other proteins [46,47]. The content of conalbumin and ovalbumin were similar to our previous work (conalbumin and ovalbumin were 11.511 and 65.383 mg/mL, respectively [33]). The results demonstrated that the QDED-1 coating was suitable for analysis of biosamples.…”

“…QDED was different from P (VP-co-DMAEMA) [28] and HEC-g-PDMAEMA [33], because the weak positively charged amine groups in PDMAEMA block were quaternized to take with positive charges not only in acid solution, but also in alkaline solution, therefore the chain backbone of quaternized PDMAEMA block strongly adsorbed onto the capillary surface through electrostatic interactions. However, P(VPco-DMAEMA) and HEC-g-PDMAEMA were pH-sensitive polymers, the net positive charges were decreasing with the increasing of pH value.…”

“…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].…”

Recent advances in the analysis of therapeutic proteins by capillary and microchip electrophoresis

“…Polysaccharides are also attractive candidates for dynamic coatings for protein separations because they are non-toxic, readily abundant, and biocompatible [19–21]. Two novel dynamic coatings based on the chemical substitutions of cellulose have recently been reported [22, 23].…”

Synthesis of hydroxyethylcellulose‐g‐methoxypoly (ethylene glycol) copolymer and its application for protein separation in CE

“…On the basis of the abundant reactive hydroxyl groups on HEC, HEC can be easily modified through its graft polymerization with hydrophilic vinyl monomers to derive new materials with improved properties 13. Partly HEC grafting copolymers have been used as physical coating in fused‐silica capillary inner wall for protein separation, such as HEC‐ g ‐PDMA (poly ( N, N ‐dimethylacrylamide),14 HEC‐ g ‐PDMAEMA (poly (2‐(dimethylamino) ethyl methacrylate),15 HEC‐ g ‐P4VP (poly (4‐vinylpyridine)) 16. HEC can tightly adsorb onto the fused‐silica capillary inner wall, however, resisting protein adsorption ability of HEC is not very well, comparing to another antifouling polymer PEG (poly (ethylene glycol)).…”