A novel diazoresin/polystyrene-poly(ethylene oxide) covalent capillary coating for the analysis of proteins by capillary electrophoresis

A novel method for the preparation of covalently linked capillary coatings of polystyrene-poly (ethylene oxide) (PS-PEO) was demonstrated by using photosensitive diazoresin (DR) as coupling agents. Layer by layer (LBL) self-assembly membrane of DR and PS-PEO based on hydrogen bonding firstly was fabricated on the inner wall of capillary, then with the treatment of UV light through the unique photochemistry reaction of DR, the hydrogen bonding was converted into covalent bonding. The covalently bonded coatings have the ability of inhibiting protein adsorption on the inner surface of capillary, and thus a baseline separation of Lysozyme (Lys), cytochrome c (Cyt-c), bovine serum albumin (BSA), ribonuclease A (RNase A) and myoglobin (Mb) was achieved by using capillary electrophoresis (CE). Compared with bare capillary or non-covalently bonded DR/PS-PEO coatings, the covalently linked DR/PS-PEO capillary coatings improved the CE separation performance for proteins; what's more, it exhibited good stability and repeatability. This method can provide a green and easy way to make the covalently coated capillaries for CE, replacing of the old way which using highly toxic and moisture sensitive silane coupling agent by DR in the covalent coating preparation.