It was a challenge to determine trace protein with high sensitivity using commercial capillary electrophoresis (CE) equipped with UV-detector. In this work, a mixed polymer brushes coated capillary with switchable protein adsorption/desorption properties was developed and applied for on-line extraction and preconcentration of proteins to enhance the detection sensitivity. Firstly, amine-terminated poly(2-methyl-2-oxazoline) (PMOXA-NH2) and thiol-terminated poly(acrylic acid) (PAA-SH) were synthesized by cationic ring-opening polymerization and reversible addition fragmentation chain transfer polymerization, respectively. Then, mixed brushes based on poly(2-methyl-2-oxazoline) (PMOXA) and poly(acrylic acid) (PAA) coated capillary were prepared by sequentially grafting of PMOXA-NH2 and PAA-SH onto fused-silica capillary inner surface through poly(dopamine) as an anchor. The study of electroosmotic flow showed that the inner surface charge of mixed polymer brushes coated capillary is function of the pH value and ionic strength (I) of the surrounding aqueous solution. Afterward, the protein adsorption/desorption performance of polymer coated capillary was investigated by using fluorescence microscope. The results showed that a selected mixed PMOXA/PAA coated capillary could adsorb high amounts of lysozyme, and then most of adsorbed protein could be desorbed upon pH and I change at high speed. This switchable protein adsorption/desorption ability of coated capillary were then used to extract and preconcentrate lysozyme during CE performance. The results displayed that the detection sensitivity of lysozyme in CE with UV-detector could reach to 10-9 M due to the amplification of lysozyme signal. Finally, this technique was applied successfully to amplify the detection signal of lysozyme existing in hen’s egg, and the detection sensitivity was boosted to a large extent.

Amplification of protein detection signal using poly(2-methyl-2-oxazoline) based mixed brushes with switchable properties

2019 Spring National Meeting

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