(a) Cell viability determined by MTT assay at different times for HDF cells exposed to either Rhodamine-loaded polymersomes or CellTracker (n = 3, error bar = SEM; *p<0.05). (b) Fluorescence intensity from HDF cells plated at different initial densities and exposed to daily dose of Rhodamine-loaded polymersomes (0.005 mM) (n = 3, error bar = SEM). (c) Fluorescence intensity exhibited by HDF cells after a single dose of polymersomes loaded with varying amounts of Rhodamine or CellTracker (n = 3, error bar = SEM). (d) Fluorescence micrographs of HDF cells recorded for the same exposure at different days after a single dose of Rhodamine-loaded polymersomes. (e) Fluorescence micrographs of primary HDF cells after 24 h incubation with PMPC-PDPA polymersomes loaded with membrane-staining amphiphilic Rhodamine B octadecyl ester perchlorate, (f) BODIPY TR ceramide, (g) fluorescein 1,2-dihexadecylphosphatidylethanolamine (DHPE), (h) labelled NBD cholesterol, (i) DNA staining membrane-impermeable propidium iodide, (l) FITC-labelled antibody anti α-tubulin, (m) labelled nucleic acids, (n) or large quantum dots. Figure bar = 0.02 mm.