Characterization of Silver Nanoparticles Synthesized by Leaves of Lonicera japonica Thunb

Background: The leaves of L. japonica (LLJ) are widely used as medicine in China. It is rich in caffeoylquinic acids, flavonoids and iridoid glycosides and has strong reducing capacities. Therefore, it can be used as a green material to synthesize silver nanoparticles. Methods: LLJ was used as a reducing agent to produce the LLJ-mediated silver nanoparticles (LLJ-AgNPs). The structure and physicochemical properties of LLJ-AgNPs were characterized by ultraviolet spectroscopy (UV-Vis), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and x-ray powder diffraction (XRD). Antioxidant activity of LLJ-AgNPs was determined by 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging. Antibacterial activity was determined by 96 well plates (AGAR) gradient dilution, while the anticancer potential was determined by MTT assay. Results: The results showed LLJ-AgNPs had a spherical structure with the maximum UV-Vis absorption at 400 nm. In addition, LLJ-AgNPs exhibited excellent antioxidant properties, where the free radical scavenging rate of LLJ-AgNPs was increased from 39% to 92% at concentrations from 0.25 to 1.0 mg/mL. Moreover, LLJ-AgNPs displayed excellent antibacterial properties against E. coli and Salmonella at room temperature, with minimum inhibitory values of 10(-6) and 10(-5) g/L, respectively. In addition, the synthetic LLJ-AgNPs exhibited a better inhibition effect in the proliferation of cancer cells (HepG2, MDA-MB -231, and Hela cells). Conclusion: The present study provides a green approach to synthesize LLJ-AgNPs. All those findings illustrated that the produced LLJ-AgNPs can be used as an economical and efficient functional material for further applications in food and pharmaceutical fields.