Monitoring of the Viability of Cells Immobilized by Sol-Gel Process

Three different types of cells, Pseudomonas fluorescens HK44, Saccharomyces cerevisiae strain SP4 and plant cells Nicotiana tabacum L. BY-2, were immobilized by entrapment in tetramethoxysilane prepolymer (TMOS) gel or in composite gel containing prepolymer TMOS and alginate in various ratios. Their growth and viability were monitored by bioluminescence and 2-D fluorescence spectra, which are fast and do not need the dissolution of a matrix. The resulting biocomposite gels were obtained by gelation of the mixtures of TMOS prep. or TMOS/alginate sols and the particular cells in proper media on glass supports to provide films ∼1 mm thick. The effect of the following parameters on the growth and viability of the cells was studied: (a) the composition of the biocomposites, (b) the preparation conditions of TMOS and (c) the conditions of the procedure of entrapment. All three types of cells were tested in TMOS gel and the composite TMOS/alginate = 1:1 (v/v). The sensitivity of the cells to the changes of conditions increased in the sequence: P. fluorescence HK44 < S. cerevisiae strain SP4 < N. tabacum L. BY-2. Cell viability decreased with the increasing content of Si in biocomposites. The entrapment into alginate–silica composites resulted in the leakage of microbial and yeast cells. However, it had positive effects on the growth and metabolic activity of plant cells.