Green synthesis of silver nanoparticles using marine polysaccharide: Study of in-vitro antibacterial activity

The present contribution deals with one pot method for synthesis of silver nanoparticles through green route using sulfated polysaccharide isolated from marine red algae (Porphyra vietnamensis). The obtained silver nanoparticles showed surface plasmon resonance centered at 404 nm with average particle size measured to be 13 +/- 3 nm. FTIR spectra revealed the involvement of sulfate moiety of polysaccharide for reduction of silver nitrate. The capping of anionic polysaccharide on the surface of nanoparticles was confirmed by zeta potential measurement (-35.05 mV) and is responsible for the electrostatic stability. The silver nanoparticles were highly stable at wide range of pH (2-10) and electrolyte concentration (up to 10(-2) M of NaCl). The dose dependent effect of synthesized silver nanoparticles revealed strong antibacterial activity against gram negative bacteria as compared to gram positive bacteria. (C) 2011 Elsevier B.V. All rights reserved.