Synthesis of Biofunctional Zinc Oxide Nanoparticles using Cymbopogon citratus: Characterization and in vitro Biological Assessment

Nanoparticles (NPs) especially of minerals have wider applications in the field of medicine and therapeutics. The present study was carried out to synthesize zinc oxide nanoparticles (ZnONPs) using the extracts of Cymbopogon citratus (C. citratus) and investigate its synthesis characterization and in vitro biological activities. Synthesis of ZnONPs was confirmed by the absorption bands at 391 nm using an UV-vis analysis. The average particle size of ZnONPs was 8.7 nm under the DLS assay and SEM revealed the formation of spherical shaped particles with a size of 8.23 nm. The XRD diffraction indicated the crystalline nature of synthesized ZnONPs with a wurtzite hexagonal structure and a crystalline size of 5 nm. FTIR spectroscopy identified the functional groups present in the ZnONPs, including the Zn-O bonds and other biomolecules of the leaf extract. The biological evaluations demonstrated a dose-dependent anti-bacterial action against E. coli and Salmonella spp. at 1000 µg/mL. The synthesized nanoparticles were not effective against Staphylococcus aureus. The free radical scavenging assay using DPPH revealed the pro-oxidant behavior of the ZnONPs across all tested concentrations, with a significant (P < 0.05) value of -1.24 observed at 100 µg/mL and − 15.03 at 1000 µg/mL. Further, ZnONPs showed significant (P < 0.05) dose-dependent anti-inflammatory activity, achieving 99.78% protection at 1000 µg/mL, highlighting their therapeutic potential. The study demonstrated that using the extract of C. citratus as green synthesizing agent can yield nanoparticles with ideal physical characteristics and do have potential applications in both food industry as well as in therapeutics.