Silver nanoparticles biosynthesis: Characterization and antibacterial activity.

AIASSA MARTÍNEZ IM; PÁEZ PL; QUINTEROS MA; DALMASSO PR; PINO G; BERDAKIN M; ALBESA I

Rosario

Congreso; 2º Reunión Internacional de Ciencias Farmacéuticas.; 2012

Introduction Nanoparticles show unique physical and chemical properties and have attracted much attention for their distinct characteristics. That?s because they represent an increasingly important material in the development of nanotechnology and nanoparticles which can be used in numerous applications. Microorganisms play an important role in the eco-friendly synthesis of metal nanoparticles [1,2]. Resistance of bacteria to antimicrobial agents has increased in recent years. Nanoparticles interaction with biomolecules and microorganisms is expanding the field of research. This study illustrates the synthesis of silver nanoparticles (Ag-Nps) using the bacterium Pseudomonas aeruginosa and their antibacterial activity against Escherichia coli. Materials and methods The Ag-Nps were synthesized following the method described by Shahverdi et al. [3] being formed from the reduction of silver ions by the supernatant of bacterial cells of P. aeruginosa ATCC 27853. The size of silver nanoparticles in aqueous solution has been estimated using UV?Vis spectroscopy and Dynamic Light Scattering technique (DLS). E. coli was grown aerobically in trypticase soy broth. The antimicrobial activity of the Ag-Nps was evaluated by using the standard tube dilution method on Mueller Hinton Broth Bacterial growth was observed at 18 h of incubation, following the indications of the Clinical and Laboratory Standards Institute. Results In the present study, the extracellular biosynthesis of Ag-Nps by the culture supernatant of P. aeruginosa was studied. Visual observation showed a colour change of silver nitrate solution from yellow to brown whereas no colour change was observed in the culture supernatant without silver nitrate or in media with silver nitrate alone. The average size of the nanoparticles obtained was found to be in the order of 150 nm. The biosynthesized nanoparticles were tested against reference and clinical strains of E. coli isolated from patients with Hemolytic Uremic Syndrome (HUS). A macrodilution method was used to determine the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC). This study shows that Ag-Nps have antibacterial activity against E. coli. Conclusions Authors reported the extracellular biosynthesis of Ag-Nps using the bacterium P. aeruginosa and their characterization. The Ag-Nps were found to be bioactive showing inhibitory effect on an important human pathogen, E. coli associated HUS. It is also clear that P. aeruginosa can be used to synthesize nanoparticles efficiently and in a non-toxic manner.