Synthesis and Characterization of Silica Core/Multilayered Cobalt Ferrite-Silica Shell Particles for Lipase Immobilization

Milan P Nikolić,Vladimir V Srdić,Slobodanka Stanojević-Nikolić,Katarina V Pavlović,Aleksa Maričić

doi:10.1590/1980-5373-mr-2021-0130

Milan P Nikolić, Vladimir V Srdić + Show 3 more

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https://doi.org/10.1590/1980-5373-mr-2021-0130

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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.

Highlights

Enzymes are versatile biocatalysts and have been used in a wide range of sectors including food[1], textile[2], ultrasensitive biosensing and development of pharmaceuticals[3], fine chemicals and environmental engineering[4]
SEM and TEM micrographs of the particles obtained by coprecipitation of Co2+ and Fe3+ ions at pH=15 onto PDDAfunctionalized silica core particles via two-step coating method followed by functionalization of previously deposited ferrite layer with poly(diallyldimethylammonium chloride) (PDDA) are shown on Figure 4 a-b, respectively
The results have shown that, since the immobilized lipase has good recyclability, materials with mesoporous silica layer assembled onto silica core/ferrite shell particles are suitable for covalent immobilization of lipase

Summary

Introduction

Enzymes are versatile biocatalysts and have been used in a wide range of sectors including food[1], textile[2], ultrasensitive biosensing and development of pharmaceuticals[3], fine chemicals and environmental engineering[4]. The application of natural enzymes is hampered by difficulties in reuse, product contamination and separation, as well as the poor catalytic efficiency and stored durability. These drawbacks can generally be overcome by immobilization of enzymes using various support materials and immobilization protocols[5]. Significant progress has been made in order to develop new biocatalytic systems based on immobilization of enzyme or whole cells onto magnetic nanocarriers. The epoxy-functionalized magnetic nanoparticles were used as the carriers for immobilization of alcohol dehydrogenase, and immobilized enzyme retained 84% initial activity after five cycles[7].

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