Extraction of plasmid DNA by use of a magnetic maghemite-polyaniline nanocomposite.

We describe the use of a hybrid magnetic nanocomposite (HMNC) for the extraction and purification of plasmid DNA (pDNA) from Escherichia coli aqueous solutions. The HMNC, which was synthesized via emulsion polymerization, was characterized by transmission electron microscopy, scanning electron microscopy, UV-Vis spectroscopy, Fourier transform infrared spectroscopy, dynamic light scattering and magnetic measurements. The results confirmed the incorporation of polyaniline (Pani) in its conducting form onto a core formed by the magnetic iron oxide, with the hybrid particles presenting an average size of (95 ±â€¯30) nm and a saturation magnetization of 30 emu/g. The yield, purity and quality of the pDNA purified by using the Pani HMNC were evaluated by UV-Vis spectroscopy, agarose gel electrophoresis, and Polymerase Chain Reaction (PCR), respectively. An average yield of ~6.9 µg was obtained in the DNA extraction process, with the collected material presenting a good purity (a ₳260/280 ratio in the 1.68-1.82 range) and an excellent quality, as confirmed by subsequent PCR assays. Hence, this HMNC appears as a promising material for use in pDNA purification protocols, and we suggest that this novel HMNC-based methodology can be of general interest and find widespread application in different biomedical procedures.

Magnetic extraction and purification of DNA from whole human blood using a γ-Fe2O3@Chitosan@Polyaniline hybrid nanocomposite.

We examined the properties of the nanocomposite γ-Fe2O3@Chi@Pani as an adsorbent of deoxyribonucleic acid (DNA). As a model system, we used an aqueous solution of salmon sperm DNA, whose decreasing concentration was followed by monitoring the 260 nm UV-vis absorption. After adjusting the data collected to a Langmuir isotherm curve, we estimated the adsorption capacity (qe) of the nanocomposite as 49.5 mg/g. We also observed that the kinetic model of the DNA capture presents a mixed character, with both chemical mechanisms and intraparticle diffusion processes involved. When the MNC was used to extract the DNA from complex samples (human blood), a capture rate of 80 ng/µL was achieved, with the collected fraction exhibiting good quality, as evaluated by PCR analysis and electrophoresis assays. These results suggest that the γ-Fe2O3@Chi@Pani nanocomposite is a promising adsorbent for use in protocols for purification of DNA from complex samples.

Use of magnetic polyaniline/maghemite nanocomposite for DNA retrieval from aqueous solutions.

We demonstrated that the magnetic polyaniline/maghemite nanocomposite (Pani/γ-Fe2O3 MNC) is an efficient agent for retrieval of pure double stranded deoxyribonucleic acid (dsDNA) chains from aqueous solutions. The dsDNA chains used in the retrieval experiments were of sodium salt of Salmon Sperm DNA. Based on λ=260 nm absorption measurements, we have employed UV-Vis spectroscopy to estimate the concentration of DNA present in solutions, before and after the interaction with the MNC. The best results corresponded to a maximum amount of 75.2 mg of DNA absorbed per gram of MNC reached within only 10 min of joint exposure into the aqueous solution. After magnetic separation of the fully DNA-loaded Pani/γ-Fe2O3 MNC, we achieved essentially complete DNA desorption by appropriate changes in the pH of the solution. We have shown that it is possible to recycle the use of these MNC in several adsorption-desorption cycles. By comparing the present results to those of other DNA retrieval systems reported in the literature, we argued that the Pani/γ-Fe2O3 MNC here described represent a promising low-cost material for use as a fast, simple and efficient method of DNA separation and concentration.