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 Co 2+ and Fe 3+ 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.

Fe-Doped SrCoOx FET Sensors for Extreme Alkaline pH Sensing

“…Perovskite oxides hold great promise as candidate materials for field effect transistors (FETs), sensors, and memristors due to their rich electronic properties. − The adjustable oxygen vacancies in these materials act as tunable defects that can influence surface reactions and the electronic states of adsorbates. By modulating these vacancies, it is possible to transform insulating and semiconducting oxides into metallic conductors, modify magnetic properties, and enhance ion conductivity. − The precise measurement of pH, particularly in highly alkaline environments, is a critical parameter in various industrial processes, including metal smelting, leatherworking, papermaking, nuclear fuel reprocessing, and waste treatment. − Recent scientific endeavors have focused on pH sensing in highly alkaline conditions, resulting in the discovery of promising materials and devices. Li et al developed a polybisphenol-based pH electrode that exhibited a good potentiometric response across a pH range of 0 to 15 .…”