Green synthesis of silver nanoparticles using carob leaf extract and its antibacterial activity

Background: This paper describes a rapid and eco-friendly method for green synthesis of silver nanoparticles from aqueous solution of silver nitrate using carob leaf extract (Ceratonia siliqua) in a single-pot process. Results: Formation of stable silver nanoparticles at different concentrations of AgNO3 gave mostly spherical particles with a diameter ranging from 5 to 40 nm. It was observed that the use of carob leaf extract makes a fast and convenient method for the synthesis of silver nanoparticles and can reduce silver ions into silver nanoparticles within 2 min of reaction time without using any severe conditions. Green synthesis of silver nanoparticles (AgNPs) was characterized by UV-visible (UV-vis) spectroscopy, scanning electron microscopy, atomic absorption spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction (XRD). The UV-vis spectra gave surface plasmon resonance for synthesized silver nanoparticles at 420 nm. The XRD analysis showed that the AgNPs are crystalline in nature and have face-centered cubic geometry. Conclusion: Further, the AgNPs showed an effective antibacterial activity toward Escherichia coli pathogen.