Poly-4-vinylpiridinium nanosponges as modifiers of the electrophoretic systems for the charged analytes separation

Novel hydrophilic ionic polymer nanoparticles based on the N-alkylated hypercrosslinked poly-4-vinylpyridine (nanosponges ‒ NS ) have porous structure, pH-independent positive charge and contain the aromatic rings. These nanosponges have not yet been studied in the capillary electrophoresis mode, but their characteristics suggest the possibility of creating the fused silica capillary walls coating for the separation of anionic and cationic analytes. In the current research, the authors, for the first time, have proposed the approaches to the formation of coatings based on the nanosponges with a molecular weight of 400 and 10 kDa. It was established that the stability of such coatings could be achieved by the introduction of NS into the background electrolyte. The pH range of background electrolytes for the subsequent electrophoretic experiments was determined to be from 4 to 9. The NS-based coatings were compared with the previously investigated coatings based on the crosslinked polystyrene nanoparticles ( NPs ), functionalized with the quaternary ammonium groups. Capillaries modified with NS (400 kDa) were tested for the electrophoretic separations of wide range of analytes: carboxylic acids, aminoacids, fluoroquinoline antibiotics, biogenic amines, and proteins. The separation selectivity of carboxylic acids on the NS-modified capillaries was different from the separation selectivity on the capillaries modified with NPs, functionalized with quaternary ammonium groups. NS affect the separation selectivity of aminoacids by interacting with these analytes, while for fluoroquinoline antibiotics NS act as an agent generating the reversed electroosmotic flow ( EOF ). The modification of fused silica capillary walls by NS with molecular mass of 400 kDa prevented the sorption of biogeniс amines and lysozyme protein during their electrophoretic separation.