Antimicrobial and toxicological effects of phytosynthesized silver nanoparticles in contact with E-coli and C-elegans

The eco-friendly synthesis of silver nanoparticles (AgNPs) is reported from thereduction of an aqueous silver nitrate solution (10 mM) using a natural extract ofguava leaves (Psidium Guajava). The properties of the synthesized nanoparticleswere determined by SEM and UV-vis spectroscopy, showing an average particlesize of 31±7 nm, with the presence of the wavelength peak at about 414 nm.Antimicrobial capacity was evaluated using Escherichia coli ATCC 25922through the diffusion disc method, showing inhibition zones up to 1.5 mm withconcentration of 3.1 mg/mL of nanoparticles. The toxicity of AgNPs wasevaluated using the nematode Caenorhabditis elegans as biological modelexposing at different AgNPs concentration (500, 1000, 2000 and 4000 µg/L).After 24 h of contact time no significant toxicity effects were observed onmortality, locomotion, and growth, suggesting the potential of these nanoparticlesfor biological applications.