Abstract This studdy investigates synthsis and antimicrobial activity of silver nanoparticles using citrus aurantifolia leaf extract to achieve, the fresh leaf of citrus aurantifolia was collected, authenticated, prepared, extracted with de-ionzed water and concentrated using standard procedures. Four different concentrations of plant extract were prepared in the ratio of (1:1, 2:1, 3:1, 4:1) by increasing the concentration of plant extract in the solution mixture. 0.17% of 1mM AgNO3 metal ion was added to the prepared plant extract. Then the bio-reduced aqueous component solution turned colloidal and different in colour, which suggested the formation of Citrus auratifolia leaf extract silver nanoparticles however, a control solution was made by 10 mL of citrus auratifolia leaf extract (solution) without silver nitrate solution. Citrus auratifolia leaf extract silver nanoparticles so obtained were scraped, coded (As, Bs, Cs, Ds) thereafter, inhibitory effects were sreened against S. typhi, S. aureus and K. pneumonia using disc diffusion method at three different concentrations of 100µg/ml, 200µg/ml 300µg/ml, 400µg/ml respectively. The nano particle coded As has demostrated inhibitory effects of 4mm and 3mm against S. typhi and S. aureus at the concetration of 200µg/ml. However, nano particle coded Bs shows inhibitory effects of 4mm and 3mm against S. typhi and S. aureus at the concetration of 200µg/ml while Cs shows inhibitory effects of 4mm and 2mm against S. typhi and S. aureus at the concentration of 200µg/mlfurthermore, nano particle coded Ds also shows inhibitory effects of 5mm and 3mm against S. typhi and S. aureus respectively at the concentration of 200µg/ml on the other hand, 3mm, 2mm, 2mm and 1mm inhibitory effects were observed against K. pneumonia at the concentration of 300µg/ml for all the sample tested. The activity of the standard drug (amoxicillin) was found to be higher compared to all the samples tested except against K. pneumonia in which no inhibition was observe for the amoxicillin at all the concentrations tested. The inhibitory effects observed for the Citrus aurantifolia leaf extract silver nanoparticles (As, Bs, Cs, and Ds) were comparable to that of the standard drug (amoxicillin) this could probably be considered as an indication for the antimicrobial property of the Citrus aurantifolia leaf extract silver nanoparticles.Reports suggest that bactericidal effect of silver nano particles by destroying the enzymes that transport the cell nutient and weakening the cell membrane or cell wall, leading to increase cell peamiability and cell death.The remarkable antimicrobial effects observed may be due to the formation of nano particles by the leaf extract of Citrus aurantifolia since, no inhibition was observed for the Citrus aurantifolia leaf extract solution (E) alone against all the microorganisms tested.
Keywords: Citrus aurantifolia, silver nanoparticles, antimicrobial.