The physicochemical and biological properties of metals change as the particles are reduced to nanoscale. This ability increases the application of nanoparticles in commercial and medical industries. Keeping in view this importance, we have reported a fast, convenient and extracellular method for the synthesis of silver nanoparticles by reducing silver nitrate with the help of Polyalthialongifolia aqueous leaf extract. The nanoparticles were analyzed by using UV- Visible Spectrophotometer and were optimized for different parameters including time, silver nitrate concentration, silver nitrate to leaf extract concentration ratio, temperature and pH. The nanoparticles optimized at 1mMsilver nitrate concentration, 15 ml leaf extract concentration, 24 hours of reaction time, 30°C temperature and acidic pH (5) were collected and assayed for antibacterial activity against four different human pathogenic bacteria i.e. E.coli, Klebsiellapneumoniae, Bacillus subtilisand Pseudomonas aeruginosa. The bactericidal property of nanoparticles was analyzed by Broth dilution method as well as Agar well diffusion method and the synthesized nanoparticles were found to be efficient against human pathogenic bacteria.
