Shi Ruobing, Wang Yucong, Hu Yunli, Chen Lei, Wan Qian-Hong
School of Pharmaceutical Science & Technology, Tianjin University, Tianjin 300072, China.
J Chromatogr A. 2009 Sep 4;1216(36):6382-6. doi: 10.1016/j.chroma.2009.07.016. Epub 2009 Jul 17.
Solid-phase extraction has been widely employed for the preparation of DNA templates for polymerase chain reaction (PCR)-based analytical methods. Among the variety of adsorbents studied, magnetically responsive silica particles are particularly attractive due to their potential to simplify, expedite, and automate the extraction process. Here we report a facile method for the preparation of such magnetic particles, which entails impregnation of porous silica microspheres with iron salts, followed by calcination and reduction treatments. The samples were characterized using powder X-ray diffractometry (XRD), scanning electron microscopy (SEM), nitrogen adsorption/desorption isotherms, and vibrating sample magnetometry (VSM). XRD data show that magnetite nanocrystals of about 27.2 nm are produced within the pore channels of the silica support after reduction. SEM images show that the as-synthesized particles exhibit spherical shape and uniform particle size of about 3 microm as determined by the silica support. Nitrogen sorption data confirm that the magnetite-loaded silica particles possess typical mesopore structure with BET surface area of about 183 m(2)/g. VSM data show that the particles display paramagnetic behavior with saturation magnetization of 11.37 emu/g. The magnetic silica microspheres coated with silica shells were tested as adsorbents for rapid extraction of genomic DNA from soybean-derived products. The purified DNA templates were amplified by PCR for screening of genetically modified organisms (GMOs). The preliminary results confirm that the DNA extraction protocols using magnetite-loaded silica microspheres are capable of producing DNA templates which are inhibitor-free and ready for downstream analysis.
固相萃取已被广泛用于制备基于聚合酶链反应（PCR）的分析方法所需的DNA模板。在众多已研究的吸附剂中，磁响应二氧化硅颗粒因其具有简化、加速和自动化萃取过程的潜力而格外引人注目。在此，我们报道了一种制备此类磁性颗粒的简便方法，该方法包括用铁盐浸渍多孔二氧化硅微球，随后进行煅烧和还原处理。使用粉末X射线衍射（XRD）、扫描电子显微镜（SEM）、氮气吸附/脱附等温线和振动样品磁强计（VSM）对样品进行了表征。XRD数据表明，还原后在二氧化硅载体的孔道内生成了约27.2 nm的磁铁矿纳米晶体。SEM图像显示，合成后的颗粒呈球形，由二氧化硅载体决定其粒径均匀，约为3微米。氮气吸附数据证实，负载磁铁矿的二氧化硅颗粒具有典型的介孔结构，BET表面积约为183 m²/g。VSM数据表明，这些颗粒表现出顺磁行为，饱和磁化强度为11.37 emu/g。对包覆有二氧化硅壳的磁性二氧化硅微球作为从大豆制品中快速提取基因组DNA的吸附剂进行了测试。通过PCR对纯化的DNA模板进行扩增，以筛选转基因生物（GMO）。初步结果证实，使用负载磁铁矿的二氧化硅微球的DNA提取方案能够产生无抑制剂且可用于下游分析的DNA模板。
