Synthesis of silica-coated magnetic nanoparticles and application in the detection of pathogenic viruses

摘要

Magnetic Fe_3O_4 nanoparticles were prepared by coprecipitation and then coated with silica. These Fe_3O _4/SiO_2 nanoparticles consisted of a 10-15 nm magnetic core and a silica shell of 2-5 nm thickness. The superparamagnetic property of the Fe_3O_4/SiO_2 particles with the magnetization of 42.5 emu/g was confirmed by vibrating sample magnetometer (VSM). We further optimized buffers with these Fe_3O_4/SiO_2 nanoparticles to isolate genomic DNA of hepatitis virus type B (HBV) and of Epstein-Barr virus (EBV) for detection of the viruses based on polymerase chain reaction (PCR) amplification of a 434 bp fragment of S gene specific for HBV and 250 bp fragment of nuclear antigen encoding gene specific for EBV. The purification efficiency of DNA of both HBV and EBV using obtained Fe _3O_4/SiO_2 nanoparticles was superior to that obtained with commercialized Fe_3O_4/SiO_2 microparticles, as indicated by (i) brighter PCR-amplified bands for both HBV and EBV and (ii) higher sensitivity in PCR-based detection of EBV load (copies/mL). The time required for DNA isolation using Fe_3O _4/SiO_2 nanoparticles was significantly reduced as the particles were attracted to magnets more quickly (15-20 s) than the commercialized microparticles (2-3 min).