Preparation of core–shell Fe3O4/SiO2 microspheres as adsorbents for purification of DNA

Abstract

Nearly monodisperse core–shell Fe3O4/SiO2 microspheres have been prepared via a glycol reduction method followed by a modified Stöber process. The thickness of the silica shells can be tuned in the range 33–53 nm by varying the amount of tetraethyl silicate (TEOS) during syntheses. The magnetic composite microspheres were characterized with XRD, XPS, FTIR, TEM, ICP–OES and VSM, and further tested as adsorbents for purification of plasmid DNA from Escherichia coli DH5α cells. The magnetic purification of plasmid DNA leads to satisfying integrity, yield and purity in comparison with those isolated by the traditional phenol–chloroform extraction.