Partial characterization and the evaluation of antimicrobial activities of silver nanoparticles biosynthesized from Cymbopogon citratus leaf extract

Abstract

BackgroundSilver nanoparticles (AgNPs) are toxic to microorganisms and can potentially kill multidrug-resistant bacteria. Nanoparticles can be synthesized in many different ways, such as physical or chemical methods. Recently, it has been found that plant molecules can perform the same reduction reactions necessary for the production of nanoparticles but in a much more efficient way. ResultsHere, green chemistry was employed to synthesize silver nanoparticles using leaf extracts of Cymbopogon citratus. Effects of different parameters such as temperature, pH and volume of plant extract were also tested using their absorbance pattern at different wavelengths. The Surface Plasmon Resonance (SPR) changed with the changes in parameters. Changes in temperature from 20{degrees}C to 60{degrees}C have changed the highest absorbance from 0.972 to 3.893 with an SPR of 470 nm. At higher pH (11.1), the particles become highly unstable and have irregular shapes and sizes. At lower pH (3.97), the peak shifts to the right, indicating a smaller but unstable compound. We have also investigated the effect of the volume of plant extracts on the reaction time. The sample with the highest amount of plant extract showed the most absorbance with a value of 0.963 at {lambda}max, which was calculated to be 470 nm. The total formation of the AgNPs was observed visually with a color change from yellow to brownish-black. UV-visible spectroscopy was used to monitor the quantitative formation of silver nanoparticles, showing a signature peak in absorbance between 400 and 500 nm. We have estimated the size of the nanoparticles as 47nm by comparing the experimental data with the theoretical value using Mieplot. The biosynthesized silver nanoparticles showed enhanced antibacterial activity against several multidrug-resistant bacteria, determined based on the minimal inhibitory concentration and zone of inhibition. ConclusionThe findings of this study indicate that an aqueous extract of C. citratus can synthesize silver nanoparticles when silver nitrate is used as a precursor and silver nanoparticles act as antimicrobial properties enhancers. These findings can influence further studies in this field to better understand the properties and applications of nanoparticles.