Detecting oxygen consumption in the proximity of Saccharomyces cerevisiae cells using self-assembled fluorescent nanosensors

We describe a strategy for the preparation and self-assembly of fluorescent nanosensors onto Saccharomyces cerevisiae cell surfaces for dynamically measuring oxygen concentration in the proximity of living cells. Amine functionalized polystyrene nanobeads were impregnated with an oxygen-sensitive ruthenium(II) complex and the beads' surface was coated with polyethylenimine. The resulting nanosensors were assembled on individual S. cerevisiae cells in a controlled manner at physiological pH for continuously monitoring oxygen consumption. This approach exemplifies a general scheme for assembling fluorescent nanosensors on cells for the non-invasive, reversible, and real-time measurement of other physiologically relevant processes, such as the efflux of protons and carbon dioxide, or the influx of glucose.