Synthesis of Novel Porous Magnetic Silica Microspheres as Adsorbents for Isolation of Genomic DNA

Abstract

An improved procedure is described for preparation of novel mesoporous microspheres consisting of magnetic nanoparticles homogeneously dispersed in a silica matrix. The method is based on a three-step process, involving (i) formation of hematite/silica composite microspheres by urea-formaldehyde polymerization, (ii) calcination of the composite particles to remove the organic constituents, and (iii) in situ transformation of the iron oxide in the composites by hydrogen reductive reaction. The as-synthesized magnetite/silica composite microspheres were nearly monodisperse, mesoporous, and magnetizable, with as typical values an average diameter of 3.5 microm, a surface area of 250 m(2)/g, a pore size of 6.03 nm, and a saturation magnetization of 9.82 emu/g. These magnetic particles were tested as adsorbents for isolation of genomic DNA from Saccharomyces cerevisiae cells and maize kernels. The results are quite encouraging as the magnetic particle based protocols lead to the extraction of genomic DNA with satisfactory integrity, yield, and purity. Being hydrophilic in nature, the porous magnetic silica microspheres are considered a good alternative to polystyrene-based magnetic particles for use in biomedical applications where nonspecific adsorption of biomolecules is to be minimized.

Magnetic solids in analytical chemistry: A review

“…Then through the reaction of iminodiacetic acid (IDA) with 3-glycidoxypropyltrimethoxysilane (GLYMO), which is immobilized on the prepared magnetic silica nanospheres charged with Zn 2+ , the magnetic nanospheres can be used to separate a model protein mixture [19]. Other synthetic methods for porous silica microspheres have been reported such as that described by Zhang et al in which hematite/silica composite microspheres are prepared by urea-formaldehyde polymerization of the composite particles to remove the organic components and the iron oxide in the composites is in situ transformed by hydrogen reductive reaction [20]. Gao et al reported the synthesis of porous silica-encapsulated magnetic nanoparticles as a nano-absorbent using a modified microemulsion technique.…”

Facile synthesis and magnetic properties of monodisperse Fe3O4/silica nanocomposite microspheres with embedded structures via a direct solution-based route

“…In general, Fe 3 O 4 /silica composites are mostly prepared in solution or by sol-gel process [43][44][45][46][47][48][49]. However, the synthesis in solution needs many steps, even in sol-gel routes, where the formation requires calcination processes of high temperature and it is difficult to control the size and morphologies of the final products.…”

“…Up to date, many methods have been reported for coating metal oxide with silica including sol-gel process [38][39][40], microemulsion [41], and solution reaction [42]. Recently, Wan et al reported the synthesis of porous Fe 3 O 4 /silica microspheres by formation of ␣-Fe 2 O 3 /silica composite microspheres by ureaformaldehyde polymerization and then calcination in situ transformation of the iron oxide in the composites by hydrogen reductive reaction [43]. Kim's group demonstrated the preparation of Fe 3 O 4 /silica core/shell NPs by using reverse micelles as nanoreactors [44].…”

Preparation of silica-magnetite nanoparticle mixed hemimicelle sorbents for extraction of several typical phenolic compounds from environmental water samples

“…Silica has been considered as one of the most ideal materials for protecting Fe 3 O 4 NPs due to its reliable chemical stability, biocompatibility and versatility in surface modification [7]. It is anticipated that incorporating silica coating on a magnetic core could attain the advantage of silica and without sacrificing the unique magnetization characteristics of Fe 3 O 4 .…”