Chitosan-coated magnetic iron oxide nanoparticles for DNA and rhEGF separation

The obtention and purification of DNA and recombinant proteins are critical steps in the biotech industries. In this research, the use of chitosan-coated magnetic iron oxide nanoparticles as magnetic nano-adsorbent was investigated. Iron oxide nanoparticles were obtained through a simple coprecipitation method. The spinel structure of the nanoparticles was confirmed by X-Ray diffraction analysis. The particle size before (16 nm) and after chitosan coating (14 nm) was measured using scanning electron microscopy. Infrared spectroscopy and thermogravimetric analysis measurements confirmed the presence of chitosan on the surface of magnetic nanoparticles coated in a percentage of 11.24%. The Redlich-Peterson isotherm yielded the best fit for the DNA experimental adsorption capacity and a maximum of 98 mg/g was obtained. The structural integrity of DNA, after the elution process, was confirmed by agarose gel electrophoresis. An adsorption capacity of 440 mg/g for rhEGF was found and the Langmuir-Freundlich isotherm showed the best fit for the experimental results. Finally, SDS-PAGE and Western blot assays confirmed that the adsorption/desorption process did not affect the rhEGF identity, thereby, suggesting that the biological activity was preserved.