The green synthesis of Zinc Oxide nanoparticles utilizing Camellia Sinensis var. Assamica found in commercial tea dust, and their broad spectrum antibacterial activity

The antibacterial activity of biosynthesized Zinc Oxide (ZnO) nanofluid was investigated against three gram-positive bacteria (Enterococcus faecalis, Methicillin-resistant Staphylococcus aureus, Staphylococcus saprophyticus) and two gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa). Tea dust, obtained from “Lipton® black tea decaffeinated” tea bags, and distilled water was used to prepare an extract; with zinc acetate and sodium hydroxide as precursors to synthesize the ZnO nanoparticles, the extract was used as a reducing agent. ZnO nanoparticles were synthesized using a green method involving tea extract and characterized by EDX, TEM, and UV-VIS spectroscopy, revealing particles between 40–60 nm, with some particles as small as 18 nm, and the nanoparticles exhibited an agglomerated, sponge-like asymmetrical shape and maximum absorption at 380 nm. Despite its performance being slightly lower than standard antibiotics like Ciprofloxacin, Meropenem and Vancomycin, the ZnO nano-fluid still demonstrated significant antibacterial activity.