Synthesis and characterization of zinc oxide nanoparticles by the aerial part of <i>Artemisia roxburghiana</i> extract and assessment of their biological activities

The zinc oxide nanoparticle (ZnONPs) used in this study were synthesized using <i>Artemisia roxburghiana</i> extract (aerial part). The absorption peak at 353 nm in UV spectroscopy indicates the production of zinc oxide nanoparticles. The synthesis of ZnONPs using extracts of the aerial part of <i>A</i>. <i>roxburghiana</i> is also supported by FTIR peaks around 622 cm^-1. DLS analysis showed the synthesis of A-ZnONPs (zinc oxide nanoparticle synthesized by extracts of aerial part <i>A. roxburghiana</i>) with a particle size of 6-10 nm. XRD pattern's detection of a hexagonal crystal structure of A-ZnONPs. HRTEM image confirming the preparation of irregularly shaped A-ZnONPs. The preparation, capping, and stabilization of A-ZnONPs are facilitated by bioactive compounds in the plant's aerial parts. This gives a plant with high total phenol content (TPC) of 93.4 ± 0.53 μg GAE/mg and total flavonoid content (TFC) of 23.22 ± 0.23 μg CE/mg, both of which are responsible for antioxidant activities. A-ZnONPs exhibited more significant antioxidant activity (IC50 = 147.4 μg/mL) and antibacterial activity against <i>Salmonella abony</i>, <i>Escherichia coli</i>, <i>Bacillus subtilis</i>, and <i>Staphylococcus aureus</i>. A-ZnONPs exhibited improved inhibition as their concentration increased. A maximum inhibition zone of 23 mm is observed for <i>E. coli</i>, suggesting that it has antibacterial and antioxidant properties to combat illnesses.