CONICET | Buscador de Institutos y Recursos Humanos

During the past decade, several approach succeeded in the encapsulation of living cells or culture within silica-based hydrogels, giving birth to a new family of biomaterials.1 The development of a two-step process, based on the pre-encapsulation in Ca(II)-alginate beads allowed using a broader range of chemical conditions (pH, ionic strenght, nature of hydrogel precursor) for which the straight one pot encapsulation results citotoxic.2 The main goal of the present work lies on the design of biomaterials based on zirconia hydrogels in which living and metabolically active cells are confined, ensuring high viability levels as well as low stress. To this aim, the physiological status of model microorganisms (Escherichia coli and Sacharomyces cerevisiae) was assessed during the whole encapsulation process. Stress level was monitored employing genetically modified strains that codified different fusion proteins, offering detailed information related with the inherent aggressiveness of each encapsulation procedure. In parallel, the level of reactive oxygen species, indicative of oxidative stress, was monitored with a fluorescent probe, 2?-7?-dichlorofluorescein diacetate. Zirconia hydrogles were prepared by the non-alcoxidic sol gel route, based on the epoxide driven alkalinization. ZrOCl2 aqueous solution was geled in the presence of glycidol, due to the nucleophilic attack of chloride anions on the epoxide, and the subsequent OH release. Highly transparent hydrogels were obtained at room temperature in the scale of minutes to hours.3 As in most of the sol gel procedures, the synthesis conditions (solvent, initial pH, precursors? concentration) strongly affect the final microstructure of the hydrogel. The effect of the aforementioned variables was assessed by small angle X ray scattering (SAXS). Preparation of stable hydrogles able to offer high inherent biocompatibility and low cellular stress was achieved

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