Silica-coated iron oxide nanoparticles for magnetic separation: polyol synthesis, superparamagnetic properties, and nucleic acid extraction efficiency
https://doi.org/10.1007/s11051-025-06467-z
The possibility of using magnetite nanoparticles as a sorbent in the isolation of nucleic acids from cells was investigated in this study. Nanoparticles were synthesized by polyol method in ethylene glycol with addition of polyethylene glycol. Then, the nanoparticles were coated with silicon oxide by Stöber method. Particles characterization was performed by transmission electron microscopy, infrared spectroscopy, vibrational magnetometry, and ferromagnetic resonance. The study of the IR spectra showed the presence of bands characteristic of polyethylene glycol related to hydroxide and ether groups. The magnetization curves in the region of approaching magnetization to saturation were investigated and the saturation magnetization, magnetic anisotropy constant, and average size of nanoparticles were determined. The fitting of the temperature dependences of the linewidth and resonance field of the ferromagnetic resonance also allowed us to determine the magnetic characteristics of the nanoparticles. Three different methods used to determine the anisotropy constant (from the line width and resonance field of the ferromagnetic resonance and from the field dependence of the magnetization) showed good agreement with each other. The determined anisotropy constant was approximately 1–2·105 erg/cm3, which is close to the anisotropy constant of bulk magnetite. It is shown that 0.5 mg of the developed particles allows obtaining 2.88 (2.67–3.08) μg μg of nucleic acids. Gel electrophoresis has demonstrated a high degree of purity and integrity of the isolated molecules. The results of evaluating the expression of the ACTB and GAPDH housekeeping genes using particle-isolated RNAs were similar to those using a commercial nucleic acid isolation kit.