Synthesis and characterization of silica core/multilayered cobalt ferrite-silica shell particles for lipase immobilization

Abstract

Multilayered core/shell particles were prepared by four-step deposition of cobalt ferrite layers and then deposition of external silica layer on the surface of silica core particles. The ferrite nanoparticles were obtained by co-precipitation of Co2+ and Fe3+ ions at pH=11 and pH=15, respectively. The agglomerated silica core/cobalt ferrite shell particles were obtained at extremely basic pH (pH=15), while at pH =11, monodispersed and non-aggregated core-shell particles were obtained. The poly(diallyldimethylammonium chloride)-functionalized silica core/ferrite shell particles were used as templates for deposition of mesoporous silica layers (obtained by neutralization of highly basic sodium silicate solution). The obtained porous multilayered core/shell particles were used as a host for covalent lipase immobilization inside the external silica layer. The initial activity of immobilized enzymes was about 13-fold lower than the native one, however, it showed good reusability and improved thermal stability compared to native ones.