Medhinee Mangesh Malvankar, Manish Bhat
Abstract: Metal nanoparticles are being increasingly used in many sectors of economy, and there is a growing interest in ensuring biological and environmental safety of their production. Green synthesis of nanoparticles is considered an optimum approach due to it being inexpensive and eco-friendly. In the present study, after green synthesis of silver nanoparticles (AgNPs) from Citrus limon fruit peel extract, its antibacterial activity was studied against gram-negative and gram-positive microorganisms. Antibacterial activity of lemon peel extract in methanol, ethanol and distilled water was studied too. The maximum activity was obtained against C. diptheriae at 27 mm in ethanol extract; and for synergistic studies, the maximum activity was obtained against S. aureus in crude extract at 29 mm in methanol extract of lemon and kokum. Synthesized AgNPs were characterized by UV-visible spectroscopy, TEM and FTIR. UV-visible spectroscopy showed peaks in the range of 445 nm to 455 nm. TEM analysis showed the size of nanoparticles ranging from 20 nm to 50 nm. FTIR analysis showed presence of functional groups in the aqueous sample. Mainly C=C, C=O, C-O, N-H, C-H, C-I and C-Br groups were present. The AgNPs of Citrus limon fruit peel aqueous extract showed the maximum antibacterial activity against E. coli at 21 mm zone of inhibition at 45 minutes sunlight exposure followed by 24-hour room temperature incubation. This study encourages to use AgNPs as an effective antibacterial agent.
Keywords: Green synthesis, Silver nanoparticles, Citrus limon, Antibacterial activity