Zinc oxide nanoparticles from leaf extract of Eclipta prostrata: Biosynthesis and characterization towards potential agent against film forming bacteria in metal working fluids

Industrially important metal working fluids are reported to be vulnerable to microbial growth, leading to loss of its working efficiency. The present study is dedicated towards the green synthesis of Zinc Oxide (ZnO) nanoparticles using Eclipta prostrata leaf extract and investigated for antimicrobial activity. Characterization studies using Scanning Electron Microscopy (SEM) and Fourier Transform Infrared spectroscopy (FT-IR) displayed the presence of agglomerated rod shaped ZnO nanoparticles with characteristic peak between 700 and 500 cm⁻¹, respectively. Antimicrobial testing against gram-positive and gram-negative bacteria, as well as fungi, showed the ZnO nanoparticles' effectiveness. Against gram-positive bacteria, inhibition ranged from 0.48 to 1.51 at concentrations of 25 μl to 100 μl. Against gram-negative bacteria, inhibition ranged from 0.82 to 2.02, and against fungi, inhibition ranged from 1.20 to 2.34, all at the highest concentration tested. The results of the study indicate that the ZnO nanoparticles were effective against both fungi and bacteria, more effectively against gram negative bacteria. The results suggest that the green synthesized ZnO nanoparticles from Eclipta prostrata can be exploited to reduce the load of microbial contamination in metal working fluids.