Fig. 2.

Material characterizations. AFM imaging and height profile of a) 2D GO nanosheets and b) 2D BP nanosheets. TEM images of c) GO and d) BP nanosheets. Detailed e) SEM images and f) TEM images of BP nanosheets (marked with *) wrapped with GO nanosheets. g) Element mapping of carbon (red), oxygen (blue), and phosphorous (green) of GO@BP mixtures. h) Schematic demonstration of wrapping BP with GO nanosheets to create 2DHNL. i) SEM image of pure stem cell spheroids and functionalized spheroids that incorporated with GO, BP, and GO@BP nanosheets.