Mesoporous silica–magnetite nanocomposites: Fabrication, characterisation and applications in biosciences

Template assisted fabrication of magnetic mesoporous silica–magnetite nanocomposites and their performance in binding and elution of Salmon sperm DNA has been reported. The effect of reaction pH (10–2) during the fabrication of nanocomposites has been studied. All materials fabricated at various pH were characterised by XRD, TEM, FT-IR, nitrogen adsorption and magnetic susceptibility measurements. Fabrication at neutral pH (7) in the presence of a cationic surfactant (cetyl trimethyl ammonium bromide; CTAB) produced core–shell nanocomposites of quasi spherical and rod shaped morphologies with mesoporous (pore size ∼3.5 nm) silica shell and rhombic magnetite core. Fabrication at alkaline pH (10) produced monolithic mesoporous silica composites with embedded magnetite nanoparticles. Fabrication at acidic pH (4 and 2) produced a biphasic mixture of rhombic magnetite and amorphous silica rods. A similar fabrication at acidic pH (2) in the absence of CTAB produced a biphasic mixture of rhombic magnetite and spherical silica nanoparticles. All materials exhibited a high value of Salmon sperm DNA binding at physiological pH whereas elution value of DNA was observed to be dependent on the extent of silica coating on magnetite nanoparticles.