Antibacterial properties of silver nanoparticles greenly synthesized using guava fruit extract as a reducing agent and stabilizer

The silver nanoparticles (AgNPs) were prepared via a green synthesis method using guava fruit extract (Gfe) as a reducing agent and stabilizer. Factors affecting the synthesis such as temperature and Gfe volume were studied. The interactions between the synthesized AgNPs and Gfe were confirmed by the Fourier-transform infrared (FT–IR) measurement. The formation of AgNPs, for which the maximum surface plasmon absorption was observed at the wavelength of about 410 nm, was determined by the Ultraviolet–Visible (UV–Vis) spectroscopy. The transmission electron microscopy (TEM) analysis showed that the AgNPs had a spherical shape with an average diameter of 6.19 ± 2.44 nm at room temperature. In addition, the antibacterial properties of AgNPs against the Escherichia coli (E. coli) bacteria investigated using the disc diffusion and colony counting methods indicated that the synthesized AgNPs-Gfe inhibited the growth of E. coli with an excellent antibacterial activity of 99.99% at 5.6 × 106 CFU/ml of the initial E. coli concentration. This antibacterial activity of AgNPs-Gfe is much better than those of AgNPs–AA, and AgNPs–G (AA: Ascorbic Acid and G: Glucose). The AgNPs covered by organic compounds (tannin and flavonoid) have a high antioxidant activity and are good for health. These AgNPs-Gfe are, therefore, good candidates for biomedical applications.