Mechanism Study of Green Synthesis and Antibacterial Attribute of Polyalthia longifolia Based Gold Nanoparticles

Drug resistant microbial strains are becoming continuous dilemma for researchers; hence, some alternates are required to combat this issue. In this way, nanotechnology is fascinating researchers to put forward a step in order to synthesize metals nanoparticles via adopting an ecofriendly, facile, and quick approach using medicinal plants. By means of aqueous extract of Polyalthia longifolia (AEPl), gold nanoparticles (AuPl) were synthesized for the mechanism study of synthesis and antibacterial bahavior. The reddish colored solution was an indicative clue of synthesis showing surface plasmon band at 540nm using UV/Visble spectroscopy. Various functional groups in the extract were identified which participated in the reduction of metal ions to metallic form as indicated from the Fourier Transform Infrared (FTIR) spectra of AuPl. Moving ahead, the synthesized AuPl were characterized through Transmission Electron Microscopy (TEM) showed spherical shape with more or less 50nm size. Besides, Scanning Electron Microscopy (SEM) study revealed some aggregates formation. Further, structural characterization via X-Rays Diffractometry (XRD) displayed crystallline nature of these nanoparticles. Finally, Energy Dispersive X-rays (EDX) analysis described their metallic form. The antibacterial activity at increased concentration when measured; AuPl showed 15 and 18mm bacterial growth inhibition zones against Escherichia coli and Bacillus subtilis at 100μg/mL concentration respectively. In addition, significant least minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of AuPl against these microbes were also observed. In the light of the above knowledge, it is inferred that the biogenic AuPl exhibit strong antibacterial potential enabling them to be a good substitute of antibiotics.