International Journal of NanoScience and Nanotechnology. ISSN 0974-3081 Volume 2, Number 2 (2011), pp. 103-117 © International Research Publication House http://www.irphouse.com Green Synthesis (Ocimum tenuiflorum) of Silver Nanoparticles and Toxicity Studies in Zebra Fish (Danio rerio) Model S.C.G. Kiruba Daniel 1 , R. Kumar 2 , V. Sathish 2 , M. Sivakumar 1 , S. Sunitha 2 and T. Anitha Sironmani 3* 1 Dept. Nanoscience and Nanotechnology, Anna University of Technology, Trichy, India 2 Dept. of Biotechnology, St. Michael College of Engg. & Tech., Kalayarkoil, Sivagangai, India 3* School of Biotechnology, Madurai Kamaraj University, Madurai 625021, India E-mail: a_sironmani@yahoo.co.in / asironmani@gmail.com Abstract Silver nanoparticles of different size and shape were synthesized using Ocimum tenuiflorum leaf extract. The nanoparticles were characterized by UV– visible, TEM, XRD and FTIR measurements. The toxicity of the silver nanoparticles was evaluated against zebra fish Danio rerio using direct exposure to silver nanoparticles and indirectly through food chain via feeding silver nanoparticles exposed chironomous larva) There was no toxicity developed against Ocimum tenuiflorum stabilized silver nanoparticles and it could penetrate all tissues including the brain through BBB Life time protection can be given to healthy young ones at a very low concentration (160ug) by simple bathing method. Introduction Compared with larger particles of the bulk material Nanoparticles exhibit completely new or improved properties based on specific characteristics such as size, distribution and morphology. Nanoparticles present a higher surface-to-volume ratio is relevant for catalytic reactivity and other related properties such as antimicrobial activity in silver nanoparticles. Generally, nanoparticles are prepared by a variety of chemical and physical methods such as chemical reduction [1-4], photochemical reduction [4- 6], electrochemical reduction [7, 8] heat evaporation [9,10] etc., which are not environmental friendly..