Fig. 1
![Fig. 1](http://media.springernature.com/full/springer-static/image/art%3A10.1186%2Fs12917-020-02482-5/MediaObjects/12917_2020_2482_Fig1_HTML.png)
Characterization of zinc oxide nanoparticles. a a high-resolution transmission electron microscope (HRTEM) images of ZnO-NPs where its size is between 40 nm. b The field emission scanning electron microscopy (FESEM) images of ZnO-NPs where its particle size was approximately 60–95 nm. c Energy dispersive X-ray spectra (EDS) of ZnO-NPs. d average size distribution and e surface charge of prepared ZnO-NPs by using dynamic light scattering technique via Zetasizer instrument