Green Synthesis of AgNP-Decorated MWCNTs via Origanum dubium for Enhanced Antimicrobial and Antioxidant Activity.

A sustainable method has been developed to produce multi-walled carbon nanotubes (MWCNTs) that are adorned with a unique silver nanoparticle, using a plant extract (Origanum dubium) as a mediator. Gas chromatography/mass spectrometry (GC/MS) technique was used to investigate the chemical components of the plant extract. Silver nanoparticles (AgNPs) have been deposited on the MWCNTs as well as acid-functionalized MWCNTs (f-MWCNTs) via an in situ solution method. The present study presents a sustainable and economical approach to the synthesis of AgNPs. The biosynthesis of Ag nanoparticles has been optimized by varying several parameters, including pH, temperature, reaction time, concentration of plant extract, and duration of UV exposure. The nanohybrids composed of AgNPs, MWCNTs, acid-treated MWCNTs, and AgNP-decorated MWCNT nanocomposites were successfully synthesized and evaluated for their antibacterial potential against the Gram-positive methicillin-resistant Staphylococcus aureus (MRSA) and the Gram-negative Escherichia coli (E. coli) strains. Their radical scavenging activities were also evaluated against DPPH and hydrogen peroxide. X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FTIR), and UV-vis spectroscopy were used to investigate the structure and nature of f-MWCNT and decorated nanocomposites. The scanning electron microscopy (SEM) technique was used to analyze the dispersion state of carbon nanotubes and the immobilization of AgNPs. The study reveals that the modified AgNPs possess viable antimicrobial and antioxidant activities.