Biosynthesis of silver nanoparticles using Plectranthus amboinicus leaf extract and its antimicrobial activity

•Nearly spherical Ag NPs are prepared using P. amboinicus leaf extract.•The green synthesis route is simple, nontoxic, reliable and eco-friendly benign.•XRD and SAED patterns attested the crystalline nature of the samples.•Biomolecules of the leaf extract play dual role as both reducing and capping agents.•It exhibited effective antimicrobial efficacy against E. coli and Penicillium spp.

This study reports the simple green synthesis method for the preparation of silver nanoparticles (Ag NPs) using Plectranthus amboinicus leaf extract. The pathway of nanoparticles formation is by means of reduction of AgNO3 by leaf extract, which acts as both reducing and capping agents. Synthesized Ag NPs were subjected to different characterizations for studying the structural, chemical, morphological, optical and antimicrobial properties. The bright circular fringes in SAED pattern and diffraction peaks in XRD profile reveals high crystalline nature of biosynthesized Ag NPs. Morphological studies shows the formation of nearly spherical nanoparticles. FTIR spectrum confirms the existence of various functional groups of biomolecules capping the nanoparticles. UV–visible spectrum displays single SPR band at 428 nm indicating the absence of anisotropic particles. The synthesized Ag NPs exhibited better antimicrobial property towards gram negative Escherichia coli and towards tested Penicillium spp. than other tested microorganisms using disc diffusion method. Finally it has proven that the synthesized bio-inspired Ag NPs have potent antimicrobial effect.

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