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Issue 40, 2008
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Immobilization of yeast and bacteria cells in alginate microbeads coated with silica membranes: procedures, physico-chemical features and bioactivity

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Abstract

Salt alginate beads are used to entrap yeast or bacteria cells and exploited as protective environment for deposition of silica gel membranes. This inorganic layer is obtained through different methods: by dipping the beads in a silica sol (method A), by further consolidating them with tetraethoxysilane in an apolar solvent (method B), and by coating the beads with methyltriethoxysilane in the gas phase (method C). Physical–chemical and biological features are investigated. The pyrolysis study elucidates the features of the polymeric organic layer. Elemental analysis and 29Si solid state NMR prove the presence and the condensation degrees of the silica membranes. The bioactivity is studied by evaluating both glucose (Saccharomyces cerevisiae) and L-malic acid (Oenococcus oeni) fermentations. The fermentation performance is discussed considering possible limitations of mass transport across the silica gel layer. Method A produces an inorganic layer made by of 57.3% Si(OSi[triple bond, length as m-dash])4 and 42.7% HO–Si(OSi[triple bond, length as m-dash])3 units). In this case a linear relation is found among different contact times between silica sol and beads and both silica amount and average thickness. Method B appears to be successful in building up the layer, but it is also detrimental to cell viability. Method C is very efficient in terms of mass deposit, cell viability maintenance and leakage reduction. In this case the membrane is constituted by H3C–Si(OSi[triple bond, length as m-dash])2OH and H3C–Si(OSi[triple bond, length as m-dash])3 units in an almost 1 : 1 ratio.

Graphical abstract: Immobilization of yeast and bacteria cells in alginate microbeads coated with silica membranes: procedures, physico-chemical features and bioactivity

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Supplementary files

Article information


Submitted
30 Apr 2008
Accepted
16 Jul 2008
First published
08 Sep 2008

J. Mater. Chem., 2008,18, 4839-4848
Article type
Paper

Immobilization of yeast and bacteria cells in alginate microbeads coated with silica membranes: procedures, physico-chemical features and bioactivity

E. Callone, R. Campostrini, G. Carturan, A. Cavazza and R. Guzzon, J. Mater. Chem., 2008, 18, 4839
DOI: 10.1039/B807301E

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