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J Livage

Publications and source records attributed to J Livage.

4 recordsLinked to original sources

Silica-alginate composites for microencapsulation.

Optimisation of membrane properties of alginate microcapsules is a key factor for the application of microencapsulation techniques to bioartificial organ elaboration. Coacervation and layer-by-layer processes involving additional biopolymers have been extensively studied. Recently, the use of silica as a membrane-forming agent was investigated. This approach was rendered possible by the development of biocompatible routes to silica formation. The composites exhibit enhanced mechanical and thermal stability as well as suitable diffusion properties. Moreover, encapsulated enzymes and cells retain their biological activities. Similarly, silica can be associated to many other biopolymers, opening a promising route for new biocomposites design and biotechnology applications.

Alginates↗

Effect of some amino acids and peptides on silicic acid polymerization.

The polymerization of silicic acid in aqueous solutions at different pH was followed by the colorimetric molybdosilicate method. The role of four amino acids (serine, lysine, proline and aspartic acid) and the corresponding homopeptides was studied. All four amino acids behave the same way and favor the condensation of silicic acid. Peptides exhibit a stronger catalytic effect than amino acids but they appear to behave in very different ways depending on the nature of side-groups and pH. Poly-lysine and poly-proline for instance lead to the precipitation of solid phases containing both silica and peptides. The role of these biomolecules on the polymerization of silicic acid is discussed in terms of electrostatic interactions, hydrogen bonds and solubility.

Journal Article↗

[Fixation and immunological reactivity of parasitic protozoa in sol-gel matrices].

Parasitic protozoa have been entrapped within sol-gel silica matrices. Stationary phase promastigote cells of Leishmania donovani infantum are mixed with a silicon alkoxide solution. They remain trapped within the growing oxide network formed upon hydrolysis and condensation of the alkoxide. Electron microscopy shows the preservation of the cellular organization and the integrity of the plasma membrane of entrapped parasites. Specific antigen-antibody reactions have been performed within the sol-gel matrix via enzyme-linked immunosorbent assays (ELISA) currently used for the diagnostic of visceral leishmaniasis. A clear-cut difference in optical density was measured between positive and negative sera from dogs. Entrapped protozoa antigens are still able to react with specific antibodies through the open porosity of the silica network. These results suggest that sol-gel matrices could be used for the development of immunodiagnostic assays requiring whole cell parasites as antigens.

Animals↗