Characterisation of Silver Nanoparticles Synthesized Using Psidium guajava Leaves and Their Synergistic Effect with Antibiotics (Research Article)

Author(s): Shiji Thomas* and K. Fathimathu Zuhara

Abstract: Synthesis of silver nanoparticles (AgNPs) using plant extracts have been successfully carried out utilizing several economic and eco-friendly processes. Biogenic reduction of metal precursors helps in the synthesis of NPs which are free of chemical contaminants for various medical and biological applications where purity of NPs is most important. The objective of the present study is to synthesize silver nanoparticles using the aqueous extract of Psidium guajava leaves and to analyse their synergistic antimicrobial potential when used in combination with the commercially available antibiotics. The silver nanoparticles obtained through this green synthesis method were characterized by UV-visible spectra analysis, Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) studies. The formation of AgNPs was confirmed using the surface plasmon resonance band exhibited in UV–vis spectrophotometry. For the identification of the compounds responsible for the bioreduction of Ag+ ions and the stabilization of AgNPs produced, the functional groups present in AgNPs was investigated using FTIR. The crystalline nature of nanoparticles was confirmed from analysing the XRD pattern. Thereafter, the green synthesized AgNPs were analysed for the antimicrobial efficacy against the clinical isolate, methicillin resistant Staphylococcus aureus (MRSA). Furthermore, the synergistic antimicrobial activity of the nanoparticles with four different antibiotics viz. tetracycline, streptomycin, ampicillin and ciprofloxacin were analysed against the MRSA strain. The green synthesized AgNPs proved to be an effective antibacterial agent and exhibited synergistic antibacterial effect when used in combination with the antibiotics.

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