Optimizing Silica Encapsulation of Living Cells: In Situ Evaluation of Cellular Stress;

MERCEDES PERULLINI, MATIAS JOBBAGY, MARIANA BERMUDEZ MORETTI, SUSANA CORREA GARCIA, AND SARA ALDABE BILMES;

CHEMISTRY OF MATERIALS

ACS

Año: 2007

0897-4756

Sol-gel chemistry of silicates has emerged as an outstanding strategy to obtain cell-entrapping ceramics. This field of research is developing rapidly with a large number of bioceramics already developed for different applications. Until now, the biocompatibility of the different encapsulation procedures was limited to the measure of the initial viability and the degree of survival of cells submitted to entrapment. For particular applications, however, the entire biosynthetic machinery is compromised and the physiology status of cells becomes of great importance. Since viability is not an indicator of biosynthetic capacity, we present here a method to assess the influence of the principal synthesis parameters over the cellular stress status of yeasts submitted to different silica encapsulation procedures. The method is based in the encapsulation of a genetic modified Sacharomyces cerevisiae strain that encodes for the fusion protein Hsp12:Green Fluorescent Protein (GFP). Heat Shock Protein 12 (Hsp12p) is a small, hydrophilic general stress response protein whose transcription is up-regulated by a wide variety of stressing factors. Monitoring the expression of this construct under the control of the Hsp12 promoter by confocal microscopy images allows a direct measure of the stress status of cells during the different stages of synthesis, giving invaluable information about the aggressiveness of the processes. These results make possible the optimization of sol-gel synthesis parameters to minimally damage cells during the encapsulation process.