The development of alginate-based amperometric nanoreactors for biochemical profiling of living yeast cells

This study describes the development of a one-pot electrochemical miniaturized system for simultaneous cultivation and monitoring of the oxidative status of living cells. This system consisted of screen-printed electrodes modified by electroplated Pd-NPs as an electrocatalyst (i) and living yeast cells (Saccharomyces cerevisiae) (ii) immobilized on the cytocompatible alginate layer (iii). Briefly, during the course of electrochemical investigations a novel electroactive compound methylhydrazine derivative as a secondary metabolite and result of microbial activity was found in yeast cells and used as a signaling molecule for their biochemical profiling. Under the optimized experimental conditions the signal corresponding to the found electroactive secondary metabolite formed in medium of living cells was measured without sample collecting, transport, storage or pre-treatment steps (i.e. extraction, pre-concentration, chemical derivatization or labeling). The electrochemical dependencies, which were derived by a miniaturized electroanalytical system, were fully validated in a conventional three-electrode system under inert atmosphere (Ar) and in the presence of oxygen (air, O₂). It is believed that the proposed one-pot nanoreactors serving simultaneously as nanofermenters and amperometric detectors for the quantification of secondary metabolites formed in medium of living cells can significantly enhance the understanding of ongoing fermentation processes in the future and our knowledge on the biochemistry of yeasts.