BIOSYNTHESIS OF SILVER NANOPARTICLES BYLEAFEXTRACT OF EUCALIYPTUS CINEREA AND EVALUATION OF ITS ANTIMICROBIAL ACTIVITY

In this work, biosynthesized silver nanoparticles, AgNP, wereobtainedusing aqueousleaf extract of theEucalyptus cinerea (Ec). The optimal ratio for silver nanoparticle biosynthesis, was the combination of 10 mL of the extract with 20 mL of a 5 mM AgNO3 solution. An analysis by Fourier transform IR spectroscopy of the AgNP was carried out in order to examine the possible reducing groups of the silver ion. The size of AgNP was studied usingdynamic light scattering spectroscopy. The data analysis by Dynamic Light Scattering, DLS, revealedthat the particle size distribution of AgNp in solutionwere between 10 and 60 nm and its average size 14 nm. The AFM image revealed that AgNp were spherical covered by extract matrix and size average of 90nm. The biosynthesis of silver nanoparticle was monitored continuously by UV-VIS spectrophotometric analysis. In thevisible spectrum of AgNP dissolution,was observethe appearance of absorption peak at ∼450nm, as a result of its surface Plasmon resonance. The antimicrobial activity of AgNP was evaluated against Bacillus cereus and Salmonella thiphymurium by the agar diffusion method. Antibacterial activity was obtained against B. cereus and S. thiphymurium; the activity varied according to the concentration, showing the appearance of inhibition halos at 100% concentration of AgNP in both microorganisms