Abstract: The nanoparticles are used for an efficient removal of pollutants and germs in the area of water purification. Among them, the use of silver nanoparticles have obtained massive attraction. Different types of physical and chemical methods are employed for the synthesis of silver nanoparticles. But, synthesis of silver nanoparticles using plant extract has been advantageous over other methods as they are cost effective, environmental friendly and easily scaled up for large scale synthesis. This study was mainly focused on synthesis of silver nanoparticles using Azadirachta indica (Neem) leaf extract. In this method, physiologically stable, bio-compatible silver nanoparticles were synthesized by reacting an aqueous solution of 10-3 M Silver Nitrate (AgNO3) and 2.5 g/100 mL crude neem leaf extract at nine different ratios (1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9) at room temperature without varying the other conditions. Initially, biosynthesized silver nanoparticles were observed by colour change and then characterized by using ultraviolet-visible spectroscopy. The synthesized silver nanoparticles were then separated by centrifuging the silver nanoparticle solution at 5000 rpm for 20 min and separated nanoparticles were kept in oven for 16 h to collect silver nanoparticles. Antibacterial activity of silver nanoparticles made from 1:8 ratio was evaluated against selected highly abundant bacteria in wastewater such as E. coli, Staphyloococuus aureus, Salmonella typhimorium and Pseudomonas aeruginosa by using spread plate method. Both the color change from pale yellow to yellowish brown color and the absorption peak observed in ultraviolet-visible spectrum in the range of 325-477 nm confirmed the formation of silver nanoparticles in the solution. However, strong peak was observed in 1:8 with the maximum absorbance value of 3.733. These silver nanoparticles showed effectiveness in suppressing E. coli and Staphyloococuus aureus. In conclusion, silver nanoparticles can possibly be used as effective growth inhibitors in microorganisms thereby applicable to water purifications and wastewater treatments.
K. Vivehananthan, A.H.V.V. Kumari, W.H. De Silva and C.A.N. Fernando, 2015. Synthesis and Evaluation of Antimicrobial Property of Bionanoparticles. Research Journal of Applied Sciences, 10: 161-166.