Fig. 4: HAp synthesis mediated by the osteoyeast platform using correlative imaging analyses.

a Scheme for correlative imaging analysis. b–e The time course of HAp synthesis mediated by the osteoyeast platform. The arrows indicate (b) emergence of extracellular vesicles, (c) fusion of two extracellular vesicles to a single vesicle, (d) conversion to HAp, and (e) exudate from the ruptured yeast cell. f–h Optical imaging of extracellular vesicles and HAP-like particles. The EVs and HAP-like particles appear in the mCherry channel (f) and the calcein channel (g) and are observable by bright-field imaging (h). i–n Analysis of a ruptured yeast cell during HAp synthesis using fluorescence microscopy. j A HAADF-STEM analysis of a ruptured yeast cell. k A STEM-EDX analysis of Ca from the ruptured yeast cell. i–k The asterisks denote the same locations analyzed using different microscopy methods. l Analysis of yeast cells during HAp synthesis using fluorescence microscopy. m, n TEM analysis of (l) with increased magnification. l–n The asterisks denote the same locations analyzed using different microscopy methods. o A HAADF-STEM analysis of the zone denoted with the rectangle. p–r STEM-EDX analyses of Ca, P, and C. The experiment was performed with at least three biological replicates, all yielding similar results. Representative data are shown.