Polyaniline-polystyrene membrane for simple and efficient retrieval of double-stranded DNA from aqueous media

Extraction of nucleic acids from biological samples is a necessary step in almost all biotechnological procedures. However, while DNA-containing samples are usually very distinct in origin, no unique common methodology for performing these tasks is currently available and no single material that could satisfy the necessary requirements to carry them out exists. Consequently, the development of new systems or methods devoted to the improvement of DNA extraction protocols in terms of yield, purity, time, and cost continues to be of great interest. In this work, we describe the preparation of a novel type of polyaniline/polystyrene (PANI/PS) membrane that not only exhibits high levels of capture of DNA strands dissolved in aqueous solutions but also allows for their simple and efficient posterior release. The composite membrane consists of electrospun PS fibres that were modified by the incorporation of PANI nanograins obtained through an in situ chemical polymerization. We have used sodium salt of Salmon Sperm DNA aqueous solutions as a model system to examine how large would be the adsorption capacity of these membranes towards nucleic acid molecules. In batch-mode experiments, we have found a maximum adsorption capacity of 153.8 mg of DNA per gram of PANI, with the saturation limit attained within only 9 min. In addition, we have demonstrated that it is possible to achieve the complete release of the adsorbed DNA by simple changes on the pH of the aqueous medium. We also performed DNA adsorption experiments by adapting the composite membrane to a spin column. The corresponding results indicate that in this experimental setup the PANI/PS composite membranes appear as a promising material for the purification of nucleic acids and other valuable biomolecules.