English: a Time sequence of optical microscopy images of a single dextran-in-PEG micro-droplet containing entrapped Chlorella cells and undergoing shrinkage after immersion in hyperosmotic PEG solution at 0, 30, 70 and 110 s; scale bar, 50 μm. b Corresponding plots of brightness line profiles before (blue; t = 0 s) and after (red; t = 110 s) hyperosmotic compression. Scale bar, 50 μm (inset). c Plots of diameters of Chlorella-loaded droplets prepared at different spinning rates, before (navy blue) and after (deep cyan) hyperosmotic compression. Data are presented as mean values ± SD, error bars indicate standard deviations. d SEM image of a single multicellular spheroid; scale bar, 10 μm. e, f Confocal microscopy fluorescence images of Chlorella cell-based spheroids after FDA staining showing viable algal cells after hyperosmotic compression within the spheroids (e); red fluorescence is from intracellular chlorophyll (f); scale bars, 75 μm. g Sequence of fluorescence microscopy images showing slow diffusion of fluorescein into a single Chlorella cell-based spheroid recorded at t = 0, 5, 10 and 15 min after addition of the dye; scale bar, 30 μm. All relevant experiments were performed independently at least three times with similar results. Source data underlying Fig. 3b, c are provided as a Source Data file.