Green Synthesis of Magnesium Oxide Nanoparticles Using Mariposa christia vespertilionis Leaves Extract and Its Antimicrobial Study Toward S. aureus and E. coli

Magnesium oxide nanoparticles (MgO-NPs) have received considerable attention from researchers these days because of their wide-ranging applications in areas such as pharmaceuticals, manufacturing, and dermatology. Therefore, in the present study, we have synthesized MgO-NPs with a green approach. The MgO-NPs from aqueous leaf extract of Mariposa christia vespertilionis have been successfully synthesized and checked its resistance to antimicrobial activity. The green-synthesized MgO-NPs samples were calcined at three different calcination temperatures (400 °C, 600 °C, and 900 °C) and subjected to characterization. The antimicrobial activity of the MgO-NPs against gram-positive (S. aureus) bacteria and gram-negative (E. coli) bacteria was also established. UV–Vis spectroscopy was used to confirm the formation of the nanoparticles. Based on Fourier transform infrared spectroscopy, the Mg–O stretching is found in the range of 400 cm−1 to 500 cm−1. The scanning electron microscopy showed the spherical shape of the MgO-NPs and transmission electron microscopy revealed that the smallest crystallite size of MgO-NPs calcined at 600 °C was found to be around 17 nm which is less than the size of the MgO-NPs calcined at 400 °C (90 nm) and 900 °C (158 nm). X-ray diffractometer diffractograms show highly crystalline with hexagonal wurtzite structure. Finally, the antimicrobial activities of MgO-NPs showed an efficient effect against gram-positive bacteria, but a negative effect against gram-negative bacteria. The study revealed that the prepared MgO-NPs have shown a promising result as antibacterial agents.