EFFECT OF SILVER NANOPARTICLES SYNTHESIZED USING AQUEOUS LEAF EXTRACT OF AMHERSTIA NOBILIS ON MARINE BIOFILMS Meenakshi K., Pracheta Salunkhe and Indu A.G.* * Department of Life Sciences, University of Mumbai, Kalina Campus, Vidyanagari, Santacruz (E), Mumbai (Maharashtra) India Abstract The present study emphasized the synthesis of silver nanoparticles (SNP) from silver nitrate through bioreduction method using Amherstia nobilis leaf extract and evaluation of anti-marine biofilm activity of the synthesized particles. The phytosynthesis of silver nanoparticles was demonstrated firstly by visual observation and then by spectral methods : UV- Visible absorption spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR) and Dynamic Light Scattering technique (DLS). The Energy dispersive X-ray spectrum of the colloidal solution confirmed the presence of an elemental silver signal. Transmission Electron Microscopy analysis revealed that the nanoparticles were mostly spherical in shape and the particle size ranges from 3.74nm to 40.43nm. The stability of the silver nanoparticles was checked by ξ-potential measurements. It is found that silver nanoparticles synthesized by aqueous leaf extract of A. nobilis were effective against biofilm formation of microbes such as marine B. subtilis and marine E. coli. Key words: SNP, A. nobilis, Green synthesis, marine biofilm, E. coli, B. subtilis Introduction Silver nanoparticles (SNPs) have attracted intensive research interest because of their important applications as antimicrobials in textile/fabric industry and plastic industry to eliminate microorganisms and as a catalyst Baker et al. (2005), Shahverdi et al., (2007). Generally, silver nanoparticles are synthesized and stabilized through chemical methods, mechanical methods, electrochemical techniques Patakfalvi et al. (2010), Rodriguez-Sanchez et al. (2000), Pileni et al. (2000), Sun et al. (2001), Henglein et al. (2001) and nowadays via green chemistry methods Mondal et al. (2011), Begum et al. (2009). Application of green chemistry to synthesize nanomaterials has vital importance in medicinal and technological aspects. It is also gaining importance due to its simplicity and eco-friendliness. Several biological systems including microorganisms Klaus et al. (1999), Nair et al. (2002), Konishi et al. (2007), fungi Vigneshwaran et al. (2007) and plants have been used in the synthesis of nanoparticles. The living plants are considerably preferred for biosynthesis of silver nanoparticles due to their rich diversity of phytochemicals that have strong antioxidant properties. Shankar et al. (2004), Chandran et al. (2006), Jae et al. (2009). Amherstia nobilis, ‘The Pride of Burma’ is one of the most popular ornamental trees belonging to the family Fabaceae (Leguminosae). It is also known as Tree of heaven, Noble Amherstia and Queen of flowering trees. The present study is the first report on the synthesis of stable silver nanoparticles in ambient conditions using Amherstia nobilis leaf extract as a reducing and stabilizing agent. This study is further designed to determine the effect of synthesized silver nanoparticles on the biofilm of marine biofouling organisms such as E. coli and B. subtilis. Biofilm formation leads to biofouling which is an undesirable accumulation of microbes on damp or moist surfaces. The primary function of a biofilm is protection, adherence or attachment to surfaces which may be of biotic or abiotic origin and resilience of bacteria. Marine biofouling refers to uncontrolled growth of marine Plant Archives Vol. 18 No. 1, 2018 pp. 251-256 ISSN 0972-5210 *Author for correspondence : E-mail : indu66@yahoo.com