Fig. 4
Morphological analysis, AFM images, and particle size distribution of Co3O4 NPs. a, b Transmission electron microscopy (TEM) and (c–e) high resolution-transmission electron microscopy (HR-TEM) images of the NPs. f, h Represent 2D images, while (g, i) represent 3D images of Co3O4 NPs; f, g are on a scale of 0.8 µm, and (h, i) are on a scale of 2 µm. j–l Particle size distribution pattern in RPMI 1640, DMEM-HG, and water medium with the PDI of 0.22, 0.24, and 0.92, respectively. m Zeta potential of Co3O4 NPs in different solutions. Biosynthesized Co3O4 NPs are spherical particles ranging in size from 19 to 69 nm and their heights are reported to range from 4.5 to 10 nm