Application of mixed polymer brushes based on poly(2-methyl-2-oxazoline) and poly(acrylic acid) to on-line preconcentration of lysozyme by capillary electrophoresis

doi:10.3724/SP.J.1123.2020.02027

Abstract

Abstract:

A capillary coated with mixed polymer brushes that shows switchability toward lysozyme adsorption was developed. This capillary was applied for the on-line preconcentration of lysozyme by capillary electrophoresis (CE) in order to enhance the detection sensitivity. First, poly(2-methyl-2-oxazoline) (PMOXA) and poly(acrylic acid) (PAA) were synthesized by cationic ring-opening polymerization and reversible addition-fragmentation chain transfer (RAFT) polymerization, respectively. Then, glycidyl methacrylate (GMA) and PMOXA were used to prepare poly(2-methyl-2-oxazoline)-random-glycidyl methacrylate (PMOXA-r-GMA) via radical copolymerization, and poly(acrylic acid)-block-poly(glycidyl methacrylate) (PAA-b-PGMA) was obtained by the RAFT polymerization of GMA and PAA. A mixed solution of PMOXA-r-GMA and PAA-b-PGMA at a certain mass ratio was then injected into the capillary. Subsequent annealing provided capillary materials coated with mixed polymer brushes based on PMOXA and PAA. X-ray photoelectron spectroscopy (XPS) analysis was performed to determine the surface composition of the capillary raw materials. When the mass concentration of the mixed solution was 20 g/L and the mass ratio of PMOXA-r-GMA and PAA-b-PGMA was 1:1, the carboxyl content in the coating increased with increasing chain length of PAA. Fluorescein isothiocyanate-labeled lysozyme (FITC-lysozyme) adsorption assay demonstrated that the coated capillary had switchable properties for lysozyme adsorption upon pH and ionic strength (I) trigger. At pH 7 (I=10^-5mol/L), the capillary could adsorb a large amount of lysozyme, which could be released at pH 3 (I=10^-1mol/L). Subsequently, this coated capillary was applied to the on-line preconcentration of lysozyme by CE. The sensitivity enhancement factor was 17.69 when the chain length of PAA was 2.2 times that of PMOXA. The limit of detection could reach 8.7×10^-5g/L. On-line preconcentration of lysozyme was performed for five successive times on the same day and on five consecutive days. The intraday and interday relative standard deviations (RSDs) for the peak areas were 2.9% and 4.1%, respectively. The intraday and interday RSDs for the migration times were 0.9% and 2.1%, respectively. The developed method for the preparation of the coated capillary with good stability only needs one step in this work, and this research will supply a simple and effective way to analyze trace protein by CE.

Key words: capillary electrophoresis (CE), on-line preconcentration, mixed polymer brushes, poly(2-methyl-2-oxazoline) (PMOXA), poly(acrylic acid) (PAA)

ZHANG Miao, WANG Yuchen, MUHAMMAD Atif, CHEN Lijuan, WANG Yanmei. Application of mixed polymer brushes based on poly(2-methyl-2-oxazoline) and poly(acrylic acid) to on-line preconcentration of lysozyme by capillary electrophoresis[J]. Chinese Journal of Chromatography, 2020, 38(9): 1085-1094.

Figures/Tables 7

Fig. 1 Preparation of PMG/PAG coated capillary

Fig. 2 XPS spectra of wide scan for bare and coated capillary raw materials

Table 1 Atomic percentages of elements on the bare and coated capillary raw material surfaces

Capillary raw materials	Element mole percent/%				N/C
Capillary raw materials	C	O	N	Si	N/C
Bare	9.33	58.56	0.19	31.92	0.02
PMG	65.30	19.85	10.97	3.88	0.17
PAG₂₁	35.99	44.52	1.09	18.40	0.03
PAG₄₈	55.87	35.70	1.28	7.15	0.02
PAG₈₁	66.44	30.04	1.34	2.18	0.02
PMG/PAG₂₁	62.65	25.98	7.31	4.06	0.12
PMG/PAG₄₈	64.73	25.04	6.99	3.24	0.11
PMG/PAG₈₁	65.11	26.80	6.52	1.57	0.10

Fig. 3 Zeta potential values of bare and coated capillaries at pH 7 and pH 3

Fig. 4 (a) Fluorescence images of fluorescein isothio-cyanate-labeled lysozyme (FITC-lysozyme) adsorbed on bare and coated capillaries at pH 7 and pH 3 and (b) relative fluorescence intensities of above images Relative fluorescence intensity: intensity of FITC-lysozyme adsorbed on PAG81 coated capillary at pH 7 normalized to 100%.

Fig. 5 Electropherograms of lysozyme detection using different capillaries

Table 2 SEF values for lysozyme detection under on-line preconcentration on bare and coated capillaries

Capillary	SEF
SEF: sensitivity enhancement factor, calculated through equation (5) where A₀ was obtained from Fig. 5a, A₁ was obtained from Fig. 5b, and n was 1 here.
Bare	7.11
PAG₂₁	7.47
PAG₄₈	10.83
PAG₈₁	12.62
PMG/PAG₂₁	9.46
PMG/PAG₄₈	15.48
PMG/PAG₈₁	17.69

References

1	Wu T T , Wu C H , Fu S L , et al. Carbohydr Polym, 2017, 155: 192
2	Jiang S S , Qin Y , Yang J , et al. Food Chem, 2017, 221: 1507
3	Chen Y , Jiang M F , Ye Y H , et al. Journal of Biology, 2009, 26 (2): 64
3	陈艳, 江明锋, 叶煜辉, et al. 生物学杂志, 2009, 26 (2): 64
4	Li Y Y , Zhang X , Chen W J , et al. Chinese Journal of Chromatography, 2019, 37 (4): 392
4	李园园, 张鑫, 陈炜杰, et al. 色谱, 2019, 37 (4): 392
5	Schneider N , Weigel I , Werkmeister K , et al. J Agric Food Chem, 2010, 58 (1): 76
6	Liao Y H , Brown M B , Martin G P J Pharm Pharmacol, 2001, 53 (4): 549
7	Yang M W , Wu W H , Ruan Y J , et al. Anal Chim Acta, 2014, 812: 12
8	Li L S , Zhao Y , Wang H M , et al. Chinese Journal of Chromatography, 2019, 37 (5): 463
8	李林森, 赵毅, 汪慧敏, et al. 色谱, 2019, 37 (5): 463
9	Thang L Y , Breadmore M C , See H H J Chromatogr A, 2016, 1461: 185
10	Gu Y , Guo M , Lü D , et al. Chinese Journal of Chromatography, 2018, 36 (1): 69
10	顾奕, 郭明, 吕达, et al. 色谱, 2018, 36 (1): 69
11	Liu L H , Wan Q , Xu X Y , et al. Food Chem, 2017, 219: 7
12	Morani M , Taverna M , Mai T D Electrophoresis, 2019, 40 (18/19): 2618
13	Gao F F , Liu J Y , Lu W H , et al. Chinese Journal of Chromatography, 2018, 36 (6): 573
13	高芳芳, 刘军英, 鹿文慧, et al. 色谱, 2018, 36 (6): 573
14	Lee H G , Kwon J Y , Chung D S Talanta, 2018, 181: 366
15	Hou M X , Zhang M , Chen L J , et al. Talanta, 2019, 202: 426
16	Liu X R , Pan C , Wang Y M Chinese Journal of Chemical Physics, 2019, 32 (4): 497
17	Zhao X J , Li J Z , Ma C Journal of Atomic and Molecular Physics, 2020, 37 (2): 177
17	赵新军, 李九智, 马超. 原子与分子物理学报, 2020, 37 (2): 177
18	Bratek-Skicki A , Eloy P , Morga M , et al. Langmuir, 2018, 34 (9): 3037
19	Pan C , Liu X R , Gong K , et al. J Mater Chem B, 2018, 6 (4): 556
20	Delcroix M F , Laurent S , Huet G L , et al. Acta Biomater, 2015, 11: 68
21	Delcroix M F , Demoustier-Champagne S , Dupont-Gillain C C Langmuir, 2014, 30 (1): 268
22	Delcroix M F , Huet G L , Conard T , et al. Biomacromolecules, 2013, 14 (1): 215
23	Gong K , Pan C , He K , et al. J Appl Polym Sci, 2019, 136 (42): 1
24	Li Y F , Liu Y X , Yu H P , et al. Acta Materiae Compositae Sinica, 2009, 26 (5): 1
24	李永峰, 刘一星, 于海鹏, et al. 复合材料学报, 2009, 26 (5): 1
25	Masigol M , Fattahi N , Barua N , et al. Biomacromolecules, 2019, 20 (7): 2852
26	Aden B , Street D P , Hopkins B W , et al. Langmuir, 2018, 34 (18): 5204
27	Mao K , Du H Q , Bai L C , et al. Talanta, 2017, 168: 230
28	Mumtaz F , Chen C S , Zhu H K , et al. Chin J Polym Sci, 2018, 36 (12): 1328
29	Williams B A , Vigh G Anal Chem, 1996, 68 (7): 1174
30	Sepehrifar R , Boysen R I , Danylec B , et al. Anal Chim Acta, 2016, 917: 117
31	Xu L , Dong X Y , Sun Y Electrophoresis, 2009, 30 (4): 689
32	Muir B W , Tarasova A , Gengenbach T R , et al. Langmuir, 2008, 24 (8): 3828
33	He T , Janczewski D , Jana S , et al. J Polym Sci, Part A: Polym Chem, 2016, 54 (2): 275
34	Pidhatika B , Moeller J , Vogel V , et al. Chimia, 2008, 62 (4): 264
35	Drechsler A , Synytska A , Uhlmann P , et al. Langmuir, 2010, 26 (9): 6400
36	Currie E P K , Sieval A B , Fleer G J , et al. Langmuir, 2000, 16 (22): 8324
37	Liu J X , Zhao M Z , Deng Y , et al. Electrophoresis, 2013, 34 (9/10): 1352

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