Figure 4: TEM images of C. vulgaris control cells (a) and cells treated during 96 h with 100 mg L−1 of NiO-NPs (b). In the lower part (c), energy-dispersive X-ray spectroscopy analysis of metals found in the cytoplasm of C. vulgaris cells treated with 100 mg L−1 of NiO-NPs. cw, cell wall; thy, thylakoids; pm, plasma membrane.