RESUMEN
Polyaniline (PANI) and polyaramides deposited on the surfaces of glass slides and particulate silica were studied as adsorbents of nucleic acids and proteins by flow-through spectral correlation interferometry and solid-state extraction using spin-cartridges. Double stranded DNA from E. coli as well as pepsin, bovine serum albumin and lysozyme were the analytes studied in contact with the polymer nanolayers in phosphate buffer solution, pH 7.2. None of the coated glass slides could bind the DNA, which passed them practically without adsorption. In contact with polyaramides, the proteins of pIâ¯>â¯4 reversibly formed the 0.2-2.5 nm-thick adsorption layers decomposing on further rinsing with the protein-free eluent. In contact with PANI, the proteins formed stable adsorption layers at pH 7.2, which needed the pH 3.0 to be eluted. Thus, in a neutral aqueous medium optimal for separation of biopolymers, polyaramides, although did not retain DNA, had a weaker affinity to proteins as compared to PANI. Since the recovery of DNA passed through the PANI-coated silica was the maximal among the particulate adsorbents, the PANI-modified composites were preferred as the carriers for the single-step isolation of nucleic acids from complex biological mixtures.
Asunto(s)
Compuestos de Anilina/química , ADN Bacteriano/aislamiento & purificación , Muramidasa/química , Nylons/química , Pepsina A/química , Albúmina Sérica Bovina/química , Adsorción , Cromatografía/métodos , Escherichia coli/química , Vidrio/química , Concentración de Iones de Hidrógeno , Concentración Osmolar , Dióxido de Silicio/químicaRESUMEN
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.