This investigation was done to synthesize silver nanoparticles (AgNPs) using Curcuma longa (C. longa) extract as a capping, and stabilizing, reducing agent. The impact of C. longa raw material/water ratio, extraction duration and temperature, the volume ratios of AgNO3 solution/C. longa extract, and AgNO3 concentration in the formation of AgNPs were evaluated. The obtained AgNPs were analyzed by UV-Vis spectroscopy, FTIR, X-ray diffraction pattern (XRD), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), and the size distribution estimated by zeta instrument. The presence of AgNPs exhibited surface plasmon resonance peak approximately at 442 nm. FTIR study demonstrated that hydroxyl functional groups existed in the extract that reduced Ag+ to Ag°. XRD pattern was used to identify the crystalline structure of AgNPs. The morphology and size of the synthesized AgNPs were determined by TEM. The obtained AgNPs with a face-centered cubic structure were nearly spherical in shape and 5‒30 nm in diameter, and the average size of particles was 28.0 nm. The antibacterial activity of AgNPs was investigated against Bacillus cereus (B. cereus), Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), and Salmonella typhi (Salmonella) by disc diffusion method. The inhibition zone of obtained AgNPs against bacteria varied in a range of 15‒20 mm and the minimum inhibitory concentrations were determined only 2.81 - 11.5 mg.ml-1.
