Green Synthesis of Silver Nanoparticles using Azadirachta Indica Leaf Extract for the Application in Cotton Fibres as Antibacterial Coatings

Abstract

The present investigation reports a facile, eco-friendly, economical method for synthesizing stable silver nanoparticles (AgNPs) at room temperature using Azadirachta indica (neem) leaf extract as the reducing, capping and stabilizing agent. A visual colour change primarily confirmed the formation of AgNPs. The UV-visible spectroscopy analysis was performed for further confirmation and showed that surface plasmon resonance peaks varied from 425 to 436 nm depending upon the concentration of the silver salt. Structural analysis revealed that AgNPs exhibit face-centered cubic crystal structure with preferential orientation along (111) plane and the average crystallite size was ⁓ 20 nm. The surface morphology of the synthesized AgNPs was investigated using Field Emission Scanning Electron Microscopy and Transmission Electron Microscopy imaging, which showed that the synthesized NPs were spherical and average size varied from 27 to 32 nm. Energy Dispersive X-ray Spectroscopy analysis confirmed the presence of silver. Fourier Transform Infrared spectroscopy revealed that biomolecules present in the leaf extract acted as reducing and capping agents. The thermal stability of AgNPs was studied by TGA and DSC analyses. The zeta potential measurement showed a negative value of ⁓ -23.2 mV that proved the stability of AgNPs. Further, synthesized AgNPs were incorporated onto oxygen plasma-treated cotton fibres to test their antibacterial efficacy and they exhibited good antibacterial activity against Escherichia coli and Staphylococcus aureus bacteria. Hence, these antibacterial cotton fibres have great potential for utilization in burn/wound dressings and the fabrication of antibacterial textiles finishing.