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.