Abstract: Biogenic silver annoparticles (AgNPs) and gold nanoparticles (AuNPs) were successfully synthesized by a simple single-step method using extract from Callisia fragrans (Lindl.) Woodson (CF) leaves as reducing as well as stabilizing agents. Major parameters affecting the formation of CF-AgNPs and CF-AuNPs, including metal ions concentration, reaction time, and reaction temperature were optimized using ultraviolet-visible (UV-Vis) measurements at characteristic maximum absorbance of about 420 and 560 nm, respectively. The formation of the nanoparticles was determined through the UV-Vis method. Scanning electron microscopy (SEM) images show that CF-AgNPs and CF-AuNPs are nearly spherical in shape with unequal size distribution. X-ray diffraction (XRD) method determined the structure of the crystalline phases. Fourrier transform infrared spectroscopy (FT-IR) identified functional groups present in the leaf extract of Callisia fragrans to stabilize AgNPs, AuNPs. EDX spectra confirmed the presence of gold and silver elements in the nanomaterials. For the antibacterial investigation, the CF-AgNPs particles showed antibacterial activity against Staphylococcus aureus, Bacillus cereus, Bacillus subtilis, Escherichia coli, Salmonella typhi and Pseudomonas aeruginosa with antibacterial ring diameters ranging from 7.2±0.2 mm to 11.2±0.2 mm. Meanwhile, CF-AuNPs have no antibacterial ability against the above bacterial strains. The results showed that, Callisia fragrans is a potential biological resource in synthesizing AgNPs for antibacterial application, and AuNPs for other applications.

Keywords: Silver nanoparticles, gold nanoparticles, biosynthesis, Callisia fragrans, biological activity, antibacterial activity.