Surface Modification of Magnetic Silica Microspheres and Its Application to the Isolation of Plant Genomic Nucleic Acids

Solid-phase extraction of nucleic acids using magnetic particles has found widespread applications in biotechnological and biomedical research. On the basis of successful preparation of magnetic silica microspheres by a proprietary process, a further study was carried out on the surface modification of the magnetic silica microspheres and their applications in isolation of plant genomic nucleic acids. The surfaces of the magnetic silica microspheres were chemically bonded with silanol, epoxide, diol, and carboxyl groups, respectively. The adsorption and elution behaviors of the nucleic acids on the surface-modified magnetic silica microspheres were evaluated using calf thymus deoxyribonucleic acid (DNA) as a model compound. It was found that the magnetic silica microspheres, which were surface-modified with silanol groups, produced the highest DNA recovery yields. The surface-modified magnetic silica microspheres were applied to the extraction of genomic DNA from corn flour with high-purity DNA of fragment lengths > 8 kb obtained. The solid-phase process developed in this study offers several advantages over the traditional methods using liquid-liquid extraction: it is convenient to use, rapid, time-saving and amenable to automation. This method can be adapted for large-scale preparation of plant genomic DNAs.