Preparation of Dual-Layered Core-Shell Fe₃O₄@SiO₂ Nanoparticles and Their Properties of Plasmid DNA Purification

The rapid purification of biomaterials such as DNA, RNA, and antibodies has attracted extensive attention, and research interest has increased further with the COVID-19 pandemic. In particular, core-shell-structured superparamagnetic nanoparticles have been continuously studied for their application as biopurification materials. It has been reported that Fe₃O₄@SiO₂ nanoparticles are one of the most promising candidates for separating nucleic acids via a simple and rapid process. This study proposed a fabrication method for dual-layered Fe₃O₄@SiO₂ nanoparticles, in which the density of the SiO₂ shell was controlled using an intermediate surfactant during the SiO₂ coating. After the fabrication of dual-layered Fe₃O₄@SiO₂ nanoparticles, structural, morphological, and magnetic analyses were conducted. The results showed that the Fe₃O₄ nanoparticles were surrounded by a dense layer 15.6~27.9 nm thick and a porous layer 24.2~44.4 nm thick, and had superparamagnetic properties with high saturated magnetization at room temperature (86.9 emu/g). Then, the optimal conditions for the biopurification material were suggested based on analysis of the selective separation of plasmid DNA.