Sorption behavior of polyaramides in relation to isolation of nucleic acids and proteins

The effect of chemical composition and morphology of the surface layers of new polyaramide-containing sorbents on the mechanism of selective sorption of nucleic acids and proteins was investigated as compared to the previously studied sorbents modified with fluoropolymers and polyaniline (high-throughput materials providing one-step isolation of DNA from biological mixtures). A series of silica-based sorbents modified with polyaramides having consistently varying structure and containing the set of "key" structural elements (aromatic units and nitrogen atoms in the backbone, fluorinated groups), and various donor and acceptor moieties was prepared. The chemical composition of the polymer coatings was evaluated by X-ray photoelectron spectroscopy. The surface morphology was studied by scanning probe microscopy. The sorption properties were investigated by passing the mixtures containing DNA, RNA and proteins of different nature through the cartridges containing the obtained sorbents. All the investigated materials weakly retain double-stranded DNA but effectively retain RNA and proteins. The sorption capacity of the sorbents depends on the protein nature. The observed sorption behavior was shown to be determined by the chemical structure and not by the morphology of the polymer coating. It was proposed that similarity of the sorption properties of the series of chemically different polymers could be determined by similar total input of different sorption mechanisms.