Available online www.jocpr.com Journal of Chemical and Pharmaceutical Research, 2015, 7(3):191-195 Research Article ISSN : 0975-7384 CODEN(USA) : JCPRC5 191 Enhanced bactericidal effect of silver nanoparticles synthesized using marine brown macro algae Sunitha S. 1 , A. Nageswara Rao 1 , L. Stanley Abraham 2* , E. Dhayalan 3 , R. Thirugnanasambandam 2 and V. Ganesh Kumar 2 1 Department of Chemistry, Sathyabama University, Chennai, Tamil Nadu, India 2 Centre for Ocean Research, Sathyabama University, Chennai, Tamil Nadu, India 3 Department of Biotechnology, Sathyabama University, Chennai, Tamil Nadu, India _____________________________________________________________________________________________ ABSTRACT In the present investigation silver nanoparticles of spherical shape was synthesized biologically by rapid biological drip method using marine brown macro algae, Sargassum wightii (S. Wightii). Seaweed extract act as a reducing agent for silver nitrate. Silver nanoparticles have been characterized by UV-Visible spectrophotometer, Fourier- Transform Infrared spectroscopy (FTIR), X-ray diffractometer (XRD) and High Resolution Transmission Electron Microscope (HR-TEM). Antibacterial activity of these nanoparticles was carried out by antibiotic disc diffusion method against pathogenic microorganisms such as Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Klebsiella pneumoniae. Seaweed S. wightii mediated silver nanoparticles were found to be effective against these pathogens than silver nitrate. Keywords: Brown algae, Sargassum wightii, Silver nanoparticles, Biosynthesis, antibacterial activity. _____________________________________________________________________________________________ INTRODUCTION Recently there is an increasing trend to develop environmentally benign synthetic methods to produce nanoparticles that do not utilize toxic chemicals in the synthesis procedure. In connection to this biological approach towards the synthesis of nanoparticles has gained importance as bioactive compounds responsible for synthesis and considered as the most active area in modern material science [1-3]. Biological production of nanoparticles possessing entirely new or enhanced properties based on specific characteristics like size, distribution and morphology has become a challenging task. In recent years scientists have proposed the microorganisms as possible eco-friendly method, for the synthesis of cadmium, gold and silver nanoparticles [4-9]. Few researchers support the idea that silver species release the Ag + ions and they interact with the thiol groups in bacterial proteins [10]. It is a well known fact that silver ions and silver based compounds inhibit the growth of pathogenic microorganisms[11, 12]. Silver is known for its antiseptic property due to its better anti bacterial property [13]. This unique property of silver makes it an excellent choice for multiple usages in the medical field. Silver nanoparticles can be synthesized in many ways depicted in various literature surveys which include physical, chemical and biological methods. The physical and chemical methods are cost intensive and involves the use of hazardous substances which are not environment friendly. Hence to synthesize silver nanoparticles an alternative feasible method is biological process using microbes and plants [14]. Seaweeds or sea vegetables are important sources of pharmaceuticals, nutraceuticals, food and plant growth regulators [15]. In the present study brown macro algae Sargassum wightii was collected as potential source and capsulating agent for the synthesis of silver nanoparticles using rapid drip method. Further these nanoparticles were tested for its antibacterial activity against clinical pathogenic microorganisms such as Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Klebsiella pneumonia.