A reaction-diffusion frame for accessing metabolic O2 fluxes in single microalgae cells with low-cost wide-field imaging of nanosensor luminescence lifetime

In cells, many small molecules are membrane-permeant. This feature opens a road to analyze their flux of production or consumption by quantitatively interpreting the map of their extracellular concentration within a reaction-diffusion frame. Here, this approach has been implemented with a new wide-field lifetime imaging protocol applied to single microalgae cells sparsely deposited on an agarose pad loaded with a luminescent O2 nanosensor. The resulting maps were processed to access the spatial distribution of the O2 concentration in the plane of the cells. After fitting the data, the cellular O2 flux was extracted, evidencing a span of magnitudes and angular dependencies in the balance between photosynthesis and respiration. Beyond pointing to the disparity of individual behavior within a same colony, this work validates a simple approach for characterizing metabolic fluxes of membrane-permeant molecules down to the single-cell level.