Application of the copolymers containing sulfobetaine methacrylate in protein separation by capillary electrophoresis

Abstract

This study describes the formation of highly efficient antiprotein adsorption random copolymer coating of poly(N,N-dimethylacrylamide-co-sulfobetaine methacrylate) (poly(DMA-co-SBMA)) on the fused-silica capillary inner wall. Firstly, the poly(DMA-co-SBMA)s with different feed ratio (SBMA/DMA) were synthesized via the reversible addition fragmentation chain transfer polymerization. And then, X-ray photoelectron spectroscopy (XPS) and water contact angle (CA) were used to investigate the composition and hydrophilicity of poly(DMA-co-SBMA) coating formed on the glass slide surfaces. CA measurements revealed that the poly(DMA-co-SBMA) coating became more hydrophilic with the increment of feed ratio (SBMA/DMA), and at the same time, the XPS results showed that the coating ability was also increased with the increment of feed ratio. Followed, the copolymer was applied to coat the fused-silica capillary inner wall, and the coated capillary was used to separate the mixture of proteins (lysozyme, cytochrome c, ribonuclease A, and α-chymotrypsinogen A) in a pH range from 3.0 to 5.0. Under the optimum conditions, an excellent separation of basic proteins with peak efficiencies ranging from 551,000 to 1509,000 N/m had been accomplished within 10 min. Furthermore, the effect of coating composition on protein separation was also investigated through the comparison of separation efficiency achieved by using bare, PSBMA- and poly(DMA-co-SBMA)-coated capillary, respectively.

Surface modification by grafting of poly(SBMA-co-AEMA)-g-PDA coating and its application in CE

“…The coating stability was evaluated for a period of one week. The obtained stability profiles are presented in Figure 3, the amplitude of water contact angles variation at 16 ± 4°, 16 ± 2°, and 12.5 ± 3.5°for co (SBMA) 5 (AEMA) 2 , co(SBMA) 8 (AEMA) 2 , and co(SBMA) 13 (AEMA) 2 -g-PDA were investigated in one week, respectively. It can be seen that the hydrophilicity of the coatings does not significantly change with the time; to some extent, the co (SBMA) 8 (AEMA) 2 -g-PDA coating presents much better hydrophilic stability during one week.…”

“…Zhao et al [5] have successfully prepared a kind of antifouling surfaces by using ultra violet (UV)-induced graft polymerization and surface-initiated atom transfer radical polymerization (SI-ATRP) method to modify the polypropylene (PP) surface through graft poly(SBMA), the poly(SBMA)-modified PP surface showed greatly protein resistance performance to reduce bovine serum albumin fouling. Wang et al [13] have synthesized the copolymer of poly (N,N-dimethylacrylamide-co-SBMA), which has been used as a physical coating of capillary inner surface to separate the proteins by using capillary electrophoresis (CE). Although the poly(N,N-dimethylacrylamide-co-SBMA)-modified capillary presented excellent protein resistance performance, the coating is unstable due to the weak physical interaction between the copolymer and capillary inner surface.…”

“…[24,25] However, there is limited number of papers involving modified capillaries in CE by using zwitterionic polymers. [13,26] Jiang et al [26] have Journal of Biomaterials Science, Polymer Edition 767 covalently bonded poly(SBMA) by photograft polymerization of SBMA onto the inner surface of a fused-silica capillary with a UV-transparent perfluorinated polymer coating, which could suppress the electro-osmotic flow (EOF) effectively. However, the UVtransparent fused-silica capillary is necessary, and very brittle in the liquid cooling, which also limited its application in the conventional fused-silica capillary.…”

“…The obtained results are presented in Figure 3. From Figure 3, for the first day measurement, it can be seen that the water contact angle of the surface decreases from 46.2 ± 1.9°for the PDAcoated surface to 18.2 ± 2.0°, 15.5 ± 0.2°, and 13.7 ± 1.0°for the modified surface with co(SBMA) 5 (AEMA) 2 , co(SBMA) 8 (AEMA) 2 , and co(SBMA) 13 (AEMA) 2 , respectively. Obviously, zwitterionic copolymer could improve the hydrophilicity of PDA coating effectively.…”

“…Molecular weights and molecular weight distributions were determined by gel permeation chromatography (GPC) equipped with Wyatt DAWN HELEOS II and Waters HSPGel TM (AQ 4 column, the column temperature was 40°C), the eluent was pure water at a flow rate of 1 mL/min. Other copolymers with different molar ratios of SBMA/AEMA (named as co(SBMA) 5 (AEMA) 2 , co(SBMA) 8 (AEMA) 2 , and co(SBMA) 13 (AEMA) 2 , respectively) were obtained by altering initial ratios of monomers as shown in Table 1.…”