Comparative investigation on antibacterial studies of Oxalis corniculata and silver nanoparticle stabilized graphene surface

In this study, we report a facile method for the partial exfoliation of graphite into graphene and simultaneous surface stabilization of graphene and silver nanoparticles using a plant extract from Oxalis corniculata (Puliyarai Keerai). Four graphene composites were prepared through sonication: graphene–plant extract prepared at room temperature of about 27 °C (G-PRT) and 70 °C (G-PHT), and graphene–plant extract with silver nanoparticles prepared using NH₄OH (G-PAgNH₄) and NaOH (G-PAgNa). The composites were characterized using X-ray diffraction, Raman spectroscopy, field-emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and thermogravimetric analyses. The characterizations revealed the small sizes of the graphene sheets in the composites than in graphite, silver nanoparticles (AgNPs) with diameters of ~ 10 nm, and uniform distributions of the plant extract and AgNPs on the graphene surface. The graphene composites exhibited significant antibacterial potential against both Gram-negative (Salmonella typhimurium and Escherichia coli) and Gram-positive (Bacillus cereus and Staphylococcus aureus) microorganisms. G-PAgNa composites exhibited the lowest (10 µg/mL) minimum inhibitory concentration and minimum bacterial concentration values against S. aureus and S. typhimurium. Graphical Abstract: [Figure not available: see fulltext.]