Synthesis and optimization of plant-based silver nanoparticles and evaluation of antimicrobial properties

Department of Horticulture Science, Science and Research Branch, Islamic Azad University, Tehran, Iran Department of Horticultural Science, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran E-mail: delshad.mojtaba313@gmail.com, delshad@ut.ac.in Department of Plant Protection, Science and Research Branch, Islamic Azad University, Tehran, Iran National Institute of Genetic Engineering and Biotechnology, Tehran, Iran Department of Chemistry, East Tehran Branch, Islamic Azad University, Tehran, Iran Manuscript received 06 March 2018, revised 28 June 2018, accepted 02 July 2018 Silver nanoparticles, which have high surface areas and high fractions of surface atoms, have a high antimicrobial effect com­pared to their bulk counterpart. The present study showed green synthesis of Ag-NPs by using aqueous extract of bitter or­ange peel and silver nitrate for the reduction of silver ions to silver nanoparticles. Silver nitrate solutions and aqueous ex­tract % v/v were respectively used at light and dark conditions, neutral pH and room temperature (96:4, 93:7, 99:1). Accord­ing to design-expert methodology, at dark and light conditions, silver nitrate solutions (413 and 377 jiM) and extract density of 4% could provide the smallest size, lowest polydispersity index (PDI) and highest count rate of the optimized samples. These nanoparticles were found to possess potential antifungal and antibacterial activity against Fusarium oxysporum f.sp. Lycopersici (F16) and Ralestonia solanacearum (bivar 2). The results showed that the increase of AgNO3 had a more signifi­cant effect on the size of nanoparticles compared with that of the extract concentration. AgNO3 and extract concentration had the same effect on PDI. The optimized silver nanoparticles had more effects on the inhibitory growth fungi (Fusarium oxysporum) at a dark condition. The antifungal effect of the optimized Ag-NPs was greater than its antibacterial effect