Immobilization of plant cells in hybrid sol-gel materials

Cells of three different plant species were immobilized on a glass fiber fabric by sol-gel deposition. The process involved the following steps: (1) reinforcement of glass-fiber supports by coating with a gelling solution of hybrid-SiO₂ precursors, (2) entrapment of cells by stuffing the voids of the support with a suspension cell culture, (3) achievement of a definite immobilization by a primary treatment with SiO₂-sol, followed by gas phase reaction of tetraethoxysilane and diethoxymethylsilane with OH groups of cell wall and of surface silica. Immobilized cells maintained their viability as tested by the positive reaction to TTC and by the development of calli from stretched samples. The samples did not release cells in solution over a time period of four months, at least. The biosynthetic capability of one of immobilized species, Coronilla vaginalis, was studied by periodically monitoring the production of umbelliferone and marmesin which constituted the major secondary metabolites produced by in vitro cultured cells of this species. The results were evaluated in order to determine the versatility of the method and its potential for exploitation in continuous industrial-scale production of rare and fine chemicals.Abbreviations 2,4-D = 2,4-dichlorophenoxyacetic acid - K = kinetin - IAA = indol-3-acetic acid - NAA = naphthalenacetic acid - B5 = Gamborg's medium - MS = Murashige and Skoog medium - TEOS = tetraethoxysilane - DEMS = diethoxymethylsilane - DEDMS = diethoxydimethylsilane - TTC = tetrazolium salt