Fe3O4@SiO2 core-shell nanoparticles for plasmid DNA purification were prepared by ultrasound. The prepared nano-composite particles were investigated by transmission electron microscopy (TEM), infrared spectrum (FT-IR), vibrating sample magnetometer (VSM) and X photoelectron energy spectrum (XPS) in order to elucidate the morphology, magnetic and other properties of the nano-composites. The results showed that their uniform distribution of particle size about 20 nm and good magnetic responsiveness. Using the magnetic composite nanoparticles to extract plasmid DNA, the A260/A280 rations of DNA samples were 1.8±0.1. DNA structure was superhelix, not damaged with agarose gel electrophoresis confirm. The plasmid DNA could be used for PCR and other molecular biology operation.

Key words: Nano-composite magnetic particles, Ultrasonic, Fe3O4@SiO2, DNA, Purification