| Compared with traditional nucleic acid purification methods, the purification adopting magnetic composite particles as carriers is a very promising system for its simplicity, high reproducibility and stability. In this study, we firstly synthesized Fe3O4 magnetic particles using hydrothermal synthesis method, then modified the surface of magnetic particles with silica to get composite microspheres with good magnetic responsivity and chemical stability. The obtained silica magnetic microspheres were adopted in the purification of genomic DNA from whole blood as carriers. Afterwards, the purification system was optimized, and a fast, high-throughput and efficient automated system for nucleic acid purification was established.1. Synthesis and characterization of Fe3O4 magnetic particles:the Fe3O4 magnetic particles was synthesized by hydrothermal reduction approach and characterized by XRD, TEM, SEM and FT-IR analysis. The results showed that the size of the Fe3O4 magnetic particles is in the range of 200 nm-300 nm with uniform particle size, good dispersion, saturation magnetization of 72.6 emu/g and superparamagnetic property at room temperature.2. Synthesis and characterization of silica composite magnetic particles:the silica composite magnetic particles was obtained by TEOS hydrolysis and characterized by XRD,TEM,FT-IR. The results showed that the composite particles is in a submicron size range, and it is a core-shell structure with amorphous SiO2 shell evenly coated on the surface. Its dispersion is greatly improved. The saturation magnetization of the SiO2 shell coated composite particles is 68.8 emu/g.3. Application of the silica composite magnetic particles in genomic DNA purification. The silica composite magnetic particles was used as carriers in the purification of genomic DNA from whole blood. The purification process was optimized. The results showed that the optimized purification system can extract 29.8μg genomic DNA from per milliliter of fresh blood without degradation. As the electrophoresis results showed after integrated with automated open nucleic acid purification workstation, a efficient, rapid and stable nucleic acid purification system was established, which makes it possible for application in clinical large-scale DNA purification.
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