Green Synthesis of Rod Shaped ZnO using Extract of Origanum majorana Leaf and Investigation for Antibacterial Applications

Abstract

In this research article, we have fabricated the zinc oxide (ZnO) nanoparticles (NPs) with help of aqueous extract of leaf of Origanum majorana and studied their antimicrobial activity. Origanum majorana is one of medicinally important plant of Lamiaceae/Labiatae family. Green-approach of NPs has been favoured over traditional synthesis methods, as plant-based extracts have phytochemicals, which are non-toxic and biologically safe. The phytochemicals such as flavonoids, derivatives of phenol and polyphenolic biomolecules are found to be in aqueous leaf extract of Origanum majorana which used as capping and reducing agents. They include many functional groups such as-OH, -C=O and more which improve the physicochemical properties of NPs and consequently affect their targeting towards specific molecules. Plant mediated synthesis of ZnO NPs with fresh leave extract of Origanun majorana is also simple, quick and provides a vast array of functionalised NPs of particular size and morphology. Herein, ZnO NPs have been prepared with 3 mL of 25% (w/v) of leaf extract of Origanum majorana (Maruva). These synthesized NPs have been characterized using PXRD (Powder X-ray diffraction), FT-IR (Fourier transform-infra-red spectroscopy), UV-Visible spectroscopy, SEM (Scanning electron microscopy) with EDS (Energy dispersive spectroscopy). UV-Visible spectrum shows maximum absorbance at 379.75 nm and energy band gap have been evaluated 2.84 eV using tauc plot. Obtained PXRD pattern shows hexagonal wurtzite crystalline structure which is similar as reported in the literature (JCPDS No-36-1451). The morphology of synthesized NPs has been obtained with SEM images. These NPs are rod shaped with width calculated approximately 90 nm-125 nm and length 0.5μm-1.2μm respectively. The EDS analysis shows the 51.41% of zinc (Zn) and 48.49% of oxygen (O)elemental composition of fabricated nanoparticles. Antimicrobial activity has been performed on gram negative and gram positive microbes with the help of broth dilution method. These synthesized NPs shows very great bactericidal activity against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Streptococcus pneumoniae respectively. Minimum inhibitory concentrations (MIC) have been investigated 175μg/mL for Pseudomonas aeruginosa, 125 μg/mL for Escherichia coli and 100 μg/mL for both the Staphylococcus aureus and Streptococcus pneumoniae respectively.