3.1.2. Transmission Electron Microscopy

The TEM micrographs exhibit the occurrence of spherical to hexagonal-shaped ZnNPs having well-defined crystal edges and planes (Figure 3a–f). Partial (Figure 3c,e,f) to high (a, b, and d) agglomeration can also be observed. The nanoparticle size distribution was substantially variable for the reducing/capping agents used for the generation of ZnNPs. The lowest size distribution ranges of 8 to 26 nm and 6 to 22 nm were observed for thiourea (RA) and starch (CA) ZnNPs respectively. However, the starch (CA) ZnNPs appeared to be adorned on electronically less dense substrate material possibly derived from burning/charring of the starch during the calcination process. The average mean diameter of the nanoparticles (nm ± S.E.) was as follows; NaOH (RA) (31.37 ± 2.48), thiourea (RA) (15.86 ± 0.59), starch (RA) (36.82 ± 2.41), albumin (CA) (82.94 ± 3.64), starch (CA) (11.78 ± 0.74) and cellulose (CA) (209.18 ± 15.02).

**Figure 2.** Variable UV-Vis absorbance spectra of the synthesized ZnO nanoparticles. RA: reducing agent, CA: capping/complexing agent.

**Figure 3.** Transmission electron micrographs depicting the variation in the ZnO nanoparticle dimensions for the reducing (RA) and capping/complexing (CA) agents. (**a**) Sodium hydroxide (RA), (**b**) Thiourea (RA), (**c**) Starch (RA), (**d**) Bovine serum albumin (CA), (**e**) Starch (CA), and (**f**) Cellulose (CA).
