Novel Synthesis of Ferric Impregnated Silica Nanoparticles and Their Evaluation as a Matrix for Enzyme Immobilization

Abstract

Silica nanoparticles were synthesized by sol−gel route using a cationic surfactant, tetrabutylammonium bromide (TBAB), as a templating agent and a nonionic surfactant block copolymer [poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol)] to regulate the silicon oxide grain size. Ferric oxide (Fe2O3) was impregnated to these silica nanoparticles by wet impregnation method. The diameter of the ferric impregnated silicon oxide particle (FSP) was within 10 nm. The nature of ferric species (Fe+3) in FSP was confirmed by X-ray diffraction (XRD) and FT-IR studies. Diastase enzyme was immobilized onto FSP, and its presence was evidenced by the appearance of the N1s peak in the XPS spectra. Scanning electron microscopic and transmission electron microscopic studies revealed the presence of enzyme on the surface of FSP. The enzyme immobilized particles (EI-FSP) were characterized for biocatalytic activity and kinetic behavior of bound diastase enzyme. The physiological environment (the temperature and pH of the reaction mixture) influenced the nature of the enzyme binding. Reusability studies indicated that this EI-FSP could be used more than 50 cycles without any significant loss of enzyme activity. This is the first report of its kind in preparation of ferric impregnated silicon oxide nanoparticles and its application as matrix material for enzyme immobilization for biocatalyst reusability.