Comparative Analysis of Nanosilver Particles Synthesized by Different Approaches and Their Antimicrobial Efficacy

Silver nanoparticles (AgNPs) were extensively used in different fields worldwide. There is a continued increase in their productions to fulfill various uses. Biological and chemical AgNP syntheses were the most popular mechanisms in this field. Agrowastes are rich in proteins, phenolics, and flavonoids that could act as bioreductant agents in AgNP biological synthesis. The present study was aimed at synthesizing AgNPs via chemical and biological methods using trisodium citrate, pomegranate fruit peel, and coffee ground waste extracts. Moreover, silver nanoparticles were monitored by UV-vis spectroscopy and characterized using zeta potential, size distribution mean, scanning electron microscope (SEM), X-ray diffractometer (XRD), and Fourier transforms infrared spectroscopy (FTIR). Four pathogenic bacterial strains (Enterobacter aerogenes, Klebsiella pneumoniae, Pseudomonas aeruginosa, and MRSA) were used to assess the antimicrobial effect of the synthesized AgNPs (2, 4, and 8 mg/ml). Results report the successful formation of silver nanoparticles chemically (AgNPs_Chem) and biologically by using pomegranate peel extract (AgNPs_PPE) and coffee ground waste extract (AgNPs_CE) due to the change of color to dark brown that is confirmed by UV-vis sharp absorption spectra at specific wavelengths. Characterization using SEM and XRD revealed their crystalline shape with a mean size of AgNPs_Chem=62.75, AgNPs_CE=273.7 nm, and AgNPs_PPE=591.9 nm. AgNPs_Chem show higher negativity of zeta potential (−46.7 mV) than AgNPs_CE (−12.6 mV), followed by AgNPs_PPE (−7.98 mV), which had the least stability. All the synthesized AgNPs show antimicrobial potential on all selected strains. However, 8 mg/ml shows the most effective concentration and has more efficiency on K. pneumoniae than others. Overall, the results highlight that the use of agrowastes could be an ecofriendly way to synthesize AgNPs biologically that have the same antimicrobial effect as the chemically synthesized AgNPs.