Polydopamine-coated open tubular column for the separation of proteins by capillary electrochromatography

Abstract

The separation and determination of proteins in food is an important aspect in food industry. Inspired by the self-polymerization of dopamine under alkaline conditions and the natural adhesive properties of polydopamine, in this paper, a simple and economical method was developed for the preparation of polydopamine-coated open tubular column, in which ammonium persulfate was used as the source of oxygen to induce and facilitate the polymerization of dopamine to form polydopamine. In comparison with a naked fused-silica capillary, the direction and magnitude of the electro-osmotic flow of the as-prepared polydopamine-coated open tubular column could be manipulated by varying the pH values of background solutions due to the existence of amine and phenolic hydroxyl groups on polydopamine coating. The surface morphology of the polydopamine-coated open tubular column was studied by scanning electron microscopy, and the thickness of polydopamine coating was 106 nm. The performance of the polydopamine-coated open tubular column was validated by analysis of proteins. The relative standard deviations of migration times of proteins representing run-to-run, day-to-day, and column-to-column were less than 3.5%. In addition, the feasibility of the polydopamine-coated open tubular column for real samples was verified by the separation of proteins in chicken egg white and pure milk.

Poly(norepinephrine)‐coated open tubular column for the separation of proteins and recombination human erythropoietin by capillary electrochromatography

“…The difference in the electrophoretic mobilities of proteins and PNE coating combined to play roles for the separation of these proteins. In comparison with the previous work aiming at the separation of proteins by OT‐CEC , the PNE‐coated column showed good separation ability for acidic and basic proteins. More importantly, the column can resolve the glycoforms of rhEPO.…”

“…To improve the reproducibility, the preconditioning of the capillary should be performed. Open tubular capillary electrochromatography (OT-CEC), combining the high separation efficiency of CE and high selectivity of LC, has demonstrated superiority in proteins separation due to the advantages including simple column preparation, no bubble formation, and simple instrumental handling [9][10][11][12][13][14][15][16][17][18][19]. More importantly, the coatings in CEC can effectively restrain the adsorption of proteins on the inner surface of columns and improve the resolution of proteins separation [9].…”

Versatile Surface Modification Using Polydopamine and Related Polycatecholamines: Chemistry, Structure, and Applications

“…Another aspect of polycatecholamine aggregates that seems to be determined in part by the oxidative conditions is the ampholyte character. Isoelectric points for polydopamine have been measured at between pH 2 and 3 for particles produced under acidic, hydrothermal conditions; at pH 3.1 for polydopamine nanoparticles; at pH 4 for films prepared with oxygen as the oxidant; and at pH 4.6 for films prepared using ammonium persulfate . Presumably in this instance, the oxidative conditions help to determine the density of unreacted amines and acidic oxidative degradation products in the aggregate, and hence the final surface charge.…”

Applications of polydopamine modifications in capillary electrophoretic analysis

“…However, due to the limited oxygen sealed in the capillary, the deposition efficiency of PDA was low. To overcome the problem of dissolved oxygen, Xiao et al [44] used APS as an oxygen source to promote the deposition of PDA, thereby shortening the deposition time of PDA (12 h). Meanwhile, the prepared coating column had good stability and reproducibility, and was successfully applied in the separation of proteins in egg white and pure milk samples.…”